Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Read-Copy Update mechanism for mutual exclusion |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation; either version 2 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, write to the Free Software |
| 16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 17 | * |
| 18 | * Copyright IBM Corporation, 2008 |
| 19 | * |
| 20 | * Authors: Dipankar Sarma <dipankar@in.ibm.com> |
| 21 | * Manfred Spraul <manfred@colorfullife.com> |
| 22 | * Paul E. McKenney <paulmck@linux.vnet.ibm.com> Hierarchical version |
| 23 | * |
| 24 | * Based on the original work by Paul McKenney <paulmck@us.ibm.com> |
| 25 | * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. |
| 26 | * |
| 27 | * For detailed explanation of Read-Copy Update mechanism see - |
Paul E. McKenney | a71fca5 | 2009-09-18 10:28:19 -0700 | [diff] [blame] | 28 | * Documentation/RCU |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 29 | */ |
| 30 | #include <linux/types.h> |
| 31 | #include <linux/kernel.h> |
| 32 | #include <linux/init.h> |
| 33 | #include <linux/spinlock.h> |
| 34 | #include <linux/smp.h> |
| 35 | #include <linux/rcupdate.h> |
| 36 | #include <linux/interrupt.h> |
| 37 | #include <linux/sched.h> |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 38 | #include <linux/nmi.h> |
Paul E. McKenney | 8826f3b | 2011-05-11 05:41:41 -0700 | [diff] [blame] | 39 | #include <linux/atomic.h> |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 40 | #include <linux/bitops.h> |
Paul Gortmaker | 9984de1 | 2011-05-23 14:51:41 -0400 | [diff] [blame] | 41 | #include <linux/export.h> |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 42 | #include <linux/completion.h> |
| 43 | #include <linux/moduleparam.h> |
| 44 | #include <linux/percpu.h> |
| 45 | #include <linux/notifier.h> |
| 46 | #include <linux/cpu.h> |
| 47 | #include <linux/mutex.h> |
| 48 | #include <linux/time.h> |
Paul E. McKenney | bbad937 | 2010-04-02 16:17:17 -0700 | [diff] [blame] | 49 | #include <linux/kernel_stat.h> |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 50 | #include <linux/wait.h> |
| 51 | #include <linux/kthread.h> |
Linus Torvalds | 268bb0c | 2011-05-20 12:50:29 -0700 | [diff] [blame] | 52 | #include <linux/prefetch.h> |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 53 | #include <linux/delay.h> |
| 54 | #include <linux/stop_machine.h> |
Paul E. McKenney | 661a85d | 2012-07-07 05:57:03 -0700 | [diff] [blame] | 55 | #include <linux/random.h> |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 56 | #include <linux/ftrace_event.h> |
Borislav Petkov | d1d74d1 | 2013-04-22 00:12:42 +0200 | [diff] [blame] | 57 | #include <linux/suspend.h> |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 58 | |
Paul E. McKenney | 9f77da9 | 2009-08-22 13:56:45 -0700 | [diff] [blame] | 59 | #include "rcutree.h" |
Paul E. McKenney | 29c00b4 | 2011-06-17 15:53:19 -0700 | [diff] [blame] | 60 | #include <trace/events/rcu.h> |
| 61 | |
| 62 | #include "rcu.h" |
Paul E. McKenney | 9f77da9 | 2009-08-22 13:56:45 -0700 | [diff] [blame] | 63 | |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 64 | /* |
| 65 | * Strings used in tracepoints need to be exported via the |
| 66 | * tracing system such that tools like perf and trace-cmd can |
| 67 | * translate the string address pointers to actual text. |
| 68 | */ |
| 69 | #define TPS(x) tracepoint_string(x) |
| 70 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 71 | /* Data structures. */ |
| 72 | |
Paul E. McKenney | f885b7f | 2012-04-23 15:52:53 -0700 | [diff] [blame] | 73 | static struct lock_class_key rcu_node_class[RCU_NUM_LVLS]; |
Paul E. McKenney | 394f276 | 2012-06-26 17:00:35 -0700 | [diff] [blame] | 74 | static struct lock_class_key rcu_fqs_class[RCU_NUM_LVLS]; |
Peter Zijlstra | 88b91c7 | 2009-10-26 10:24:31 -0700 | [diff] [blame] | 75 | |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 76 | /* |
| 77 | * In order to export the rcu_state name to the tracing tools, it |
| 78 | * needs to be added in the __tracepoint_string section. |
| 79 | * This requires defining a separate variable tp_<sname>_varname |
| 80 | * that points to the string being used, and this will allow |
| 81 | * the tracing userspace tools to be able to decipher the string |
| 82 | * address to the matching string. |
| 83 | */ |
Steven Rostedt (Red Hat) | a41bfeb | 2013-07-12 17:00:28 -0400 | [diff] [blame] | 84 | #define RCU_STATE_INITIALIZER(sname, sabbr, cr) \ |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 85 | static char sname##_varname[] = #sname; \ |
| 86 | static const char *tp_##sname##_varname __used __tracepoint_string = sname##_varname; \ |
Steven Rostedt (Red Hat) | a41bfeb | 2013-07-12 17:00:28 -0400 | [diff] [blame] | 87 | struct rcu_state sname##_state = { \ |
Paul E. McKenney | 6c90cc7 | 2012-05-28 19:41:41 -0700 | [diff] [blame] | 88 | .level = { &sname##_state.node[0] }, \ |
Paul E. McKenney | 037b64e | 2012-05-28 23:26:01 -0700 | [diff] [blame] | 89 | .call = cr, \ |
Paul E. McKenney | af446b7 | 2011-09-10 21:54:08 -0700 | [diff] [blame] | 90 | .fqs_state = RCU_GP_IDLE, \ |
Paul E. McKenney | 42c3533 | 2012-09-28 10:49:58 -0700 | [diff] [blame] | 91 | .gpnum = 0UL - 300UL, \ |
| 92 | .completed = 0UL - 300UL, \ |
Paul E. McKenney | 7b2e601 | 2012-10-08 10:54:03 -0700 | [diff] [blame] | 93 | .orphan_lock = __RAW_SPIN_LOCK_UNLOCKED(&sname##_state.orphan_lock), \ |
Paul E. McKenney | 6c90cc7 | 2012-05-28 19:41:41 -0700 | [diff] [blame] | 94 | .orphan_nxttail = &sname##_state.orphan_nxtlist, \ |
| 95 | .orphan_donetail = &sname##_state.orphan_donelist, \ |
Paul E. McKenney | 7be7f0b | 2012-05-29 05:18:53 -0700 | [diff] [blame] | 96 | .barrier_mutex = __MUTEX_INITIALIZER(sname##_state.barrier_mutex), \ |
Paul E. McKenney | a4fbe35 | 2012-10-07 08:36:12 -0700 | [diff] [blame] | 97 | .onoff_mutex = __MUTEX_INITIALIZER(sname##_state.onoff_mutex), \ |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 98 | .name = sname##_varname, \ |
Paul E. McKenney | a488985 | 2012-12-03 08:16:28 -0800 | [diff] [blame] | 99 | .abbr = sabbr, \ |
Steven Rostedt (Red Hat) | a41bfeb | 2013-07-12 17:00:28 -0400 | [diff] [blame] | 100 | }; \ |
| 101 | DEFINE_PER_CPU(struct rcu_data, sname##_data) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 102 | |
Steven Rostedt (Red Hat) | a41bfeb | 2013-07-12 17:00:28 -0400 | [diff] [blame] | 103 | RCU_STATE_INITIALIZER(rcu_sched, 's', call_rcu_sched); |
| 104 | RCU_STATE_INITIALIZER(rcu_bh, 'b', call_rcu_bh); |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 105 | |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 106 | static struct rcu_state *rcu_state; |
Paul E. McKenney | 6ce75a2 | 2012-06-12 11:01:13 -0700 | [diff] [blame] | 107 | LIST_HEAD(rcu_struct_flavors); |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 108 | |
Paul E. McKenney | f885b7f | 2012-04-23 15:52:53 -0700 | [diff] [blame] | 109 | /* Increase (but not decrease) the CONFIG_RCU_FANOUT_LEAF at boot time. */ |
| 110 | static int rcu_fanout_leaf = CONFIG_RCU_FANOUT_LEAF; |
Paul E. McKenney | 7e5c2df | 2012-07-01 15:42:33 -0700 | [diff] [blame] | 111 | module_param(rcu_fanout_leaf, int, 0444); |
Paul E. McKenney | f885b7f | 2012-04-23 15:52:53 -0700 | [diff] [blame] | 112 | int rcu_num_lvls __read_mostly = RCU_NUM_LVLS; |
| 113 | static int num_rcu_lvl[] = { /* Number of rcu_nodes at specified level. */ |
| 114 | NUM_RCU_LVL_0, |
| 115 | NUM_RCU_LVL_1, |
| 116 | NUM_RCU_LVL_2, |
| 117 | NUM_RCU_LVL_3, |
| 118 | NUM_RCU_LVL_4, |
| 119 | }; |
| 120 | int rcu_num_nodes __read_mostly = NUM_RCU_NODES; /* Total # rcu_nodes in use. */ |
| 121 | |
Paul E. McKenney | b0d3041 | 2011-07-10 15:57:35 -0700 | [diff] [blame] | 122 | /* |
| 123 | * The rcu_scheduler_active variable transitions from zero to one just |
| 124 | * before the first task is spawned. So when this variable is zero, RCU |
| 125 | * can assume that there is but one task, allowing RCU to (for example) |
Cody P Schafer | b44f665 | 2013-01-04 12:59:40 -0500 | [diff] [blame] | 126 | * optimize synchronize_sched() to a simple barrier(). When this variable |
Paul E. McKenney | b0d3041 | 2011-07-10 15:57:35 -0700 | [diff] [blame] | 127 | * is one, RCU must actually do all the hard work required to detect real |
| 128 | * grace periods. This variable is also used to suppress boot-time false |
| 129 | * positives from lockdep-RCU error checking. |
| 130 | */ |
Paul E. McKenney | bbad937 | 2010-04-02 16:17:17 -0700 | [diff] [blame] | 131 | int rcu_scheduler_active __read_mostly; |
| 132 | EXPORT_SYMBOL_GPL(rcu_scheduler_active); |
| 133 | |
Paul E. McKenney | b0d3041 | 2011-07-10 15:57:35 -0700 | [diff] [blame] | 134 | /* |
| 135 | * The rcu_scheduler_fully_active variable transitions from zero to one |
| 136 | * during the early_initcall() processing, which is after the scheduler |
| 137 | * is capable of creating new tasks. So RCU processing (for example, |
| 138 | * creating tasks for RCU priority boosting) must be delayed until after |
| 139 | * rcu_scheduler_fully_active transitions from zero to one. We also |
| 140 | * currently delay invocation of any RCU callbacks until after this point. |
| 141 | * |
| 142 | * It might later prove better for people registering RCU callbacks during |
| 143 | * early boot to take responsibility for these callbacks, but one step at |
| 144 | * a time. |
| 145 | */ |
| 146 | static int rcu_scheduler_fully_active __read_mostly; |
| 147 | |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 148 | #ifdef CONFIG_RCU_BOOST |
| 149 | |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 150 | /* |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 151 | * Control variables for per-CPU and per-rcu_node kthreads. These |
| 152 | * handle all flavors of RCU. |
| 153 | */ |
| 154 | static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task); |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 155 | DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status); |
Paul E. McKenney | 5ece5ba | 2011-04-22 18:08:51 -0700 | [diff] [blame] | 156 | DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 157 | DEFINE_PER_CPU(char, rcu_cpu_has_work); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 158 | |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 159 | #endif /* #ifdef CONFIG_RCU_BOOST */ |
| 160 | |
Thomas Gleixner | 5d01bbd | 2012-07-16 10:42:35 +0000 | [diff] [blame] | 161 | static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu); |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 162 | static void invoke_rcu_core(void); |
| 163 | static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 164 | |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 165 | /* |
Paul E. McKenney | 4a29865 | 2011-04-03 21:33:51 -0700 | [diff] [blame] | 166 | * Track the rcutorture test sequence number and the update version |
| 167 | * number within a given test. The rcutorture_testseq is incremented |
| 168 | * on every rcutorture module load and unload, so has an odd value |
| 169 | * when a test is running. The rcutorture_vernum is set to zero |
| 170 | * when rcutorture starts and is incremented on each rcutorture update. |
| 171 | * These variables enable correlating rcutorture output with the |
| 172 | * RCU tracing information. |
| 173 | */ |
| 174 | unsigned long rcutorture_testseq; |
| 175 | unsigned long rcutorture_vernum; |
| 176 | |
| 177 | /* |
Paul E. McKenney | fc2219d4 | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 178 | * Return true if an RCU grace period is in progress. The ACCESS_ONCE()s |
| 179 | * permit this function to be invoked without holding the root rcu_node |
| 180 | * structure's ->lock, but of course results can be subject to change. |
| 181 | */ |
| 182 | static int rcu_gp_in_progress(struct rcu_state *rsp) |
| 183 | { |
| 184 | return ACCESS_ONCE(rsp->completed) != ACCESS_ONCE(rsp->gpnum); |
| 185 | } |
| 186 | |
| 187 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 188 | * Note a quiescent state. Because we do not need to know |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 189 | * how many quiescent states passed, just if there was at least |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 190 | * one since the start of the grace period, this just sets a flag. |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 191 | * The caller must have disabled preemption. |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 192 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 193 | void rcu_sched_qs(int cpu) |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 194 | { |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 195 | struct rcu_data *rdp = &per_cpu(rcu_sched_data, cpu); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 196 | |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 197 | if (rdp->passed_quiesce == 0) |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 198 | trace_rcu_grace_period(TPS("rcu_sched"), rdp->gpnum, TPS("cpuqs")); |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 199 | rdp->passed_quiesce = 1; |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 200 | } |
| 201 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 202 | void rcu_bh_qs(int cpu) |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 203 | { |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 204 | struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 205 | |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 206 | if (rdp->passed_quiesce == 0) |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 207 | trace_rcu_grace_period(TPS("rcu_bh"), rdp->gpnum, TPS("cpuqs")); |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 208 | rdp->passed_quiesce = 1; |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 209 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 210 | |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 211 | /* |
| 212 | * Note a context switch. This is a quiescent state for RCU-sched, |
| 213 | * and requires special handling for preemptible RCU. |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 214 | * The caller must have disabled preemption. |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 215 | */ |
| 216 | void rcu_note_context_switch(int cpu) |
| 217 | { |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 218 | trace_rcu_utilization(TPS("Start context switch")); |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 219 | rcu_sched_qs(cpu); |
Paul E. McKenney | cba6d0d | 2012-07-02 07:08:42 -0700 | [diff] [blame] | 220 | rcu_preempt_note_context_switch(cpu); |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 221 | trace_rcu_utilization(TPS("End context switch")); |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 222 | } |
Gleb Natapov | 29ce831 | 2011-05-04 16:31:03 +0300 | [diff] [blame] | 223 | EXPORT_SYMBOL_GPL(rcu_note_context_switch); |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 224 | |
Paul E. McKenney | 90a4d2c | 2009-01-04 11:41:11 -0800 | [diff] [blame] | 225 | DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { |
Paul E. McKenney | 29e37d8 | 2011-11-17 16:55:56 -0800 | [diff] [blame] | 226 | .dynticks_nesting = DYNTICK_TASK_EXIT_IDLE, |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 227 | .dynticks = ATOMIC_INIT(1), |
Paul E. McKenney | 2333210 | 2013-06-21 12:34:33 -0700 | [diff] [blame] | 228 | #ifdef CONFIG_NO_HZ_FULL_SYSIDLE |
| 229 | .dynticks_idle_nesting = DYNTICK_TASK_NEST_VALUE, |
| 230 | .dynticks_idle = ATOMIC_INIT(1), |
| 231 | #endif /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */ |
Paul E. McKenney | 90a4d2c | 2009-01-04 11:41:11 -0800 | [diff] [blame] | 232 | }; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 233 | |
Eric Dumazet | 878d743 | 2012-10-18 04:55:36 -0700 | [diff] [blame] | 234 | static long blimit = 10; /* Maximum callbacks per rcu_do_batch. */ |
| 235 | static long qhimark = 10000; /* If this many pending, ignore blimit. */ |
| 236 | static long qlowmark = 100; /* Once only this many pending, use blimit. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 237 | |
Eric Dumazet | 878d743 | 2012-10-18 04:55:36 -0700 | [diff] [blame] | 238 | module_param(blimit, long, 0444); |
| 239 | module_param(qhimark, long, 0444); |
| 240 | module_param(qlowmark, long, 0444); |
Paul E. McKenney | 3d76c08 | 2009-09-28 07:46:32 -0700 | [diff] [blame] | 241 | |
Paul E. McKenney | 026ad28 | 2013-04-03 22:14:11 -0700 | [diff] [blame] | 242 | static ulong jiffies_till_first_fqs = ULONG_MAX; |
| 243 | static ulong jiffies_till_next_fqs = ULONG_MAX; |
Paul E. McKenney | d40011f | 2012-06-26 20:45:57 -0700 | [diff] [blame] | 244 | |
| 245 | module_param(jiffies_till_first_fqs, ulong, 0644); |
| 246 | module_param(jiffies_till_next_fqs, ulong, 0644); |
| 247 | |
Paul E. McKenney | 910ee45 | 2012-12-31 02:24:21 -0800 | [diff] [blame] | 248 | static void rcu_start_gp_advanced(struct rcu_state *rsp, struct rcu_node *rnp, |
| 249 | struct rcu_data *rdp); |
Paul E. McKenney | 217af2a | 2013-06-21 15:39:06 -0700 | [diff] [blame] | 250 | static void force_qs_rnp(struct rcu_state *rsp, |
| 251 | int (*f)(struct rcu_data *rsp, bool *isidle, |
| 252 | unsigned long *maxj), |
| 253 | bool *isidle, unsigned long *maxj); |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 254 | static void force_quiescent_state(struct rcu_state *rsp); |
Paul E. McKenney | a157229 | 2009-08-22 13:56:51 -0700 | [diff] [blame] | 255 | static int rcu_pending(int cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 256 | |
| 257 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 258 | * Return the number of RCU-sched batches processed thus far for debug & stats. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 259 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 260 | long rcu_batches_completed_sched(void) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 261 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 262 | return rcu_sched_state.completed; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 263 | } |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 264 | EXPORT_SYMBOL_GPL(rcu_batches_completed_sched); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 265 | |
| 266 | /* |
| 267 | * Return the number of RCU BH batches processed thus far for debug & stats. |
| 268 | */ |
| 269 | long rcu_batches_completed_bh(void) |
| 270 | { |
| 271 | return rcu_bh_state.completed; |
| 272 | } |
| 273 | EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); |
| 274 | |
| 275 | /* |
Paul E. McKenney | bf66f18 | 2010-01-04 15:09:10 -0800 | [diff] [blame] | 276 | * Force a quiescent state for RCU BH. |
| 277 | */ |
| 278 | void rcu_bh_force_quiescent_state(void) |
| 279 | { |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 280 | force_quiescent_state(&rcu_bh_state); |
Paul E. McKenney | bf66f18 | 2010-01-04 15:09:10 -0800 | [diff] [blame] | 281 | } |
| 282 | EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state); |
| 283 | |
| 284 | /* |
Paul E. McKenney | 4a29865 | 2011-04-03 21:33:51 -0700 | [diff] [blame] | 285 | * Record the number of times rcutorture tests have been initiated and |
| 286 | * terminated. This information allows the debugfs tracing stats to be |
| 287 | * correlated to the rcutorture messages, even when the rcutorture module |
| 288 | * is being repeatedly loaded and unloaded. In other words, we cannot |
| 289 | * store this state in rcutorture itself. |
| 290 | */ |
| 291 | void rcutorture_record_test_transition(void) |
| 292 | { |
| 293 | rcutorture_testseq++; |
| 294 | rcutorture_vernum = 0; |
| 295 | } |
| 296 | EXPORT_SYMBOL_GPL(rcutorture_record_test_transition); |
| 297 | |
| 298 | /* |
| 299 | * Record the number of writer passes through the current rcutorture test. |
| 300 | * This is also used to correlate debugfs tracing stats with the rcutorture |
| 301 | * messages. |
| 302 | */ |
| 303 | void rcutorture_record_progress(unsigned long vernum) |
| 304 | { |
| 305 | rcutorture_vernum++; |
| 306 | } |
| 307 | EXPORT_SYMBOL_GPL(rcutorture_record_progress); |
| 308 | |
| 309 | /* |
Paul E. McKenney | bf66f18 | 2010-01-04 15:09:10 -0800 | [diff] [blame] | 310 | * Force a quiescent state for RCU-sched. |
| 311 | */ |
| 312 | void rcu_sched_force_quiescent_state(void) |
| 313 | { |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 314 | force_quiescent_state(&rcu_sched_state); |
Paul E. McKenney | bf66f18 | 2010-01-04 15:09:10 -0800 | [diff] [blame] | 315 | } |
| 316 | EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state); |
| 317 | |
| 318 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 319 | * Does the CPU have callbacks ready to be invoked? |
| 320 | */ |
| 321 | static int |
| 322 | cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp) |
| 323 | { |
Paul E. McKenney | 3fbfbf7 | 2012-08-19 21:35:53 -0700 | [diff] [blame] | 324 | return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL] && |
| 325 | rdp->nxttail[RCU_DONE_TAIL] != NULL; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 326 | } |
| 327 | |
| 328 | /* |
Paul E. McKenney | dc35c89 | 2012-12-03 13:52:00 -0800 | [diff] [blame] | 329 | * Does the current CPU require a not-yet-started grace period? |
| 330 | * The caller must have disabled interrupts to prevent races with |
| 331 | * normal callback registry. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 332 | */ |
| 333 | static int |
| 334 | cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp) |
| 335 | { |
Paul E. McKenney | dc35c89 | 2012-12-03 13:52:00 -0800 | [diff] [blame] | 336 | int i; |
Paul E. McKenney | 3fbfbf7 | 2012-08-19 21:35:53 -0700 | [diff] [blame] | 337 | |
Paul E. McKenney | dc35c89 | 2012-12-03 13:52:00 -0800 | [diff] [blame] | 338 | if (rcu_gp_in_progress(rsp)) |
| 339 | return 0; /* No, a grace period is already in progress. */ |
Paul E. McKenney | dae6e64 | 2013-02-10 20:48:58 -0800 | [diff] [blame] | 340 | if (rcu_nocb_needs_gp(rsp)) |
Paul E. McKenney | 34ed6246 | 2013-01-07 13:37:42 -0800 | [diff] [blame] | 341 | return 1; /* Yes, a no-CBs CPU needs one. */ |
Paul E. McKenney | dc35c89 | 2012-12-03 13:52:00 -0800 | [diff] [blame] | 342 | if (!rdp->nxttail[RCU_NEXT_TAIL]) |
| 343 | return 0; /* No, this is a no-CBs (or offline) CPU. */ |
| 344 | if (*rdp->nxttail[RCU_NEXT_READY_TAIL]) |
| 345 | return 1; /* Yes, this CPU has newly registered callbacks. */ |
| 346 | for (i = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++) |
| 347 | if (rdp->nxttail[i - 1] != rdp->nxttail[i] && |
| 348 | ULONG_CMP_LT(ACCESS_ONCE(rsp->completed), |
| 349 | rdp->nxtcompleted[i])) |
| 350 | return 1; /* Yes, CBs for future grace period. */ |
| 351 | return 0; /* No grace period needed. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 352 | } |
| 353 | |
| 354 | /* |
| 355 | * Return the root node of the specified rcu_state structure. |
| 356 | */ |
| 357 | static struct rcu_node *rcu_get_root(struct rcu_state *rsp) |
| 358 | { |
| 359 | return &rsp->node[0]; |
| 360 | } |
| 361 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 362 | /* |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 363 | * rcu_eqs_enter_common - current CPU is moving towards extended quiescent state |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 364 | * |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 365 | * If the new value of the ->dynticks_nesting counter now is zero, |
| 366 | * we really have entered idle, and must do the appropriate accounting. |
| 367 | * The caller must have disabled interrupts. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 368 | */ |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 369 | static void rcu_eqs_enter_common(struct rcu_dynticks *rdtp, long long oldval, |
| 370 | bool user) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 371 | { |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 372 | trace_rcu_dyntick(TPS("Start"), oldval, rdtp->dynticks_nesting); |
Paul E. McKenney | cb349ca | 2012-09-04 17:35:31 -0700 | [diff] [blame] | 373 | if (!user && !is_idle_task(current)) { |
Paul E. McKenney | 0989cb4 | 2011-11-01 08:57:21 -0700 | [diff] [blame] | 374 | struct task_struct *idle = idle_task(smp_processor_id()); |
| 375 | |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 376 | trace_rcu_dyntick(TPS("Error on entry: not idle task"), oldval, 0); |
Paul E. McKenney | bf1304e | 2012-05-09 15:55:39 -0700 | [diff] [blame] | 377 | ftrace_dump(DUMP_ORIG); |
Paul E. McKenney | 0989cb4 | 2011-11-01 08:57:21 -0700 | [diff] [blame] | 378 | WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s", |
| 379 | current->pid, current->comm, |
| 380 | idle->pid, idle->comm); /* must be idle task! */ |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 381 | } |
Paul E. McKenney | aea1b35 | 2011-11-02 06:54:54 -0700 | [diff] [blame] | 382 | rcu_prepare_for_idle(smp_processor_id()); |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 383 | /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ |
| 384 | smp_mb__before_atomic_inc(); /* See above. */ |
| 385 | atomic_inc(&rdtp->dynticks); |
| 386 | smp_mb__after_atomic_inc(); /* Force ordering with next sojourn. */ |
| 387 | WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); |
Paul E. McKenney | c44e2cd | 2012-01-12 13:08:18 -0800 | [diff] [blame] | 388 | |
| 389 | /* |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 390 | * It is illegal to enter an extended quiescent state while |
Paul E. McKenney | c44e2cd | 2012-01-12 13:08:18 -0800 | [diff] [blame] | 391 | * in an RCU read-side critical section. |
| 392 | */ |
| 393 | rcu_lockdep_assert(!lock_is_held(&rcu_lock_map), |
| 394 | "Illegal idle entry in RCU read-side critical section."); |
| 395 | rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map), |
| 396 | "Illegal idle entry in RCU-bh read-side critical section."); |
| 397 | rcu_lockdep_assert(!lock_is_held(&rcu_sched_lock_map), |
| 398 | "Illegal idle entry in RCU-sched read-side critical section."); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 399 | } |
| 400 | |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 401 | /* |
| 402 | * Enter an RCU extended quiescent state, which can be either the |
| 403 | * idle loop or adaptive-tickless usermode execution. |
| 404 | */ |
| 405 | static void rcu_eqs_enter(bool user) |
| 406 | { |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 407 | long long oldval; |
| 408 | struct rcu_dynticks *rdtp; |
| 409 | |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 410 | rdtp = &__get_cpu_var(rcu_dynticks); |
| 411 | oldval = rdtp->dynticks_nesting; |
| 412 | WARN_ON_ONCE((oldval & DYNTICK_TASK_NEST_MASK) == 0); |
| 413 | if ((oldval & DYNTICK_TASK_NEST_MASK) == DYNTICK_TASK_NEST_VALUE) |
| 414 | rdtp->dynticks_nesting = 0; |
| 415 | else |
| 416 | rdtp->dynticks_nesting -= DYNTICK_TASK_NEST_VALUE; |
| 417 | rcu_eqs_enter_common(rdtp, oldval, user); |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 418 | } |
| 419 | |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 420 | /** |
| 421 | * rcu_idle_enter - inform RCU that current CPU is entering idle |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 422 | * |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 423 | * Enter idle mode, in other words, -leave- the mode in which RCU |
| 424 | * read-side critical sections can occur. (Though RCU read-side |
| 425 | * critical sections can occur in irq handlers in idle, a possibility |
| 426 | * handled by irq_enter() and irq_exit().) |
| 427 | * |
| 428 | * We crowbar the ->dynticks_nesting field to zero to allow for |
| 429 | * the possibility of usermode upcalls having messed up our count |
| 430 | * of interrupt nesting level during the prior busy period. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 431 | */ |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 432 | void rcu_idle_enter(void) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 433 | { |
Frederic Weisbecker | c5d900b | 2012-07-11 20:26:31 +0200 | [diff] [blame] | 434 | unsigned long flags; |
| 435 | |
| 436 | local_irq_save(flags); |
Paul E. McKenney | cb349ca | 2012-09-04 17:35:31 -0700 | [diff] [blame] | 437 | rcu_eqs_enter(false); |
Paul E. McKenney | eb348b8 | 2013-06-21 13:00:57 -0700 | [diff] [blame] | 438 | rcu_sysidle_enter(&__get_cpu_var(rcu_dynticks), 0); |
Frederic Weisbecker | c5d900b | 2012-07-11 20:26:31 +0200 | [diff] [blame] | 439 | local_irq_restore(flags); |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 440 | } |
Paul E. McKenney | 8a2ecf4 | 2012-02-02 15:42:04 -0800 | [diff] [blame] | 441 | EXPORT_SYMBOL_GPL(rcu_idle_enter); |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 442 | |
Frederic Weisbecker | 2b1d502 | 2012-07-11 20:26:30 +0200 | [diff] [blame] | 443 | #ifdef CONFIG_RCU_USER_QS |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 444 | /** |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 445 | * rcu_user_enter - inform RCU that we are resuming userspace. |
| 446 | * |
| 447 | * Enter RCU idle mode right before resuming userspace. No use of RCU |
| 448 | * is permitted between this call and rcu_user_exit(). This way the |
| 449 | * CPU doesn't need to maintain the tick for RCU maintenance purposes |
| 450 | * when the CPU runs in userspace. |
| 451 | */ |
| 452 | void rcu_user_enter(void) |
| 453 | { |
Frederic Weisbecker | 91d1aa43 | 2012-11-27 19:33:25 +0100 | [diff] [blame] | 454 | rcu_eqs_enter(1); |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 455 | } |
Frederic Weisbecker | 2b1d502 | 2012-07-11 20:26:30 +0200 | [diff] [blame] | 456 | #endif /* CONFIG_RCU_USER_QS */ |
Frederic Weisbecker | 19dd1591 | 2012-06-04 16:42:35 -0700 | [diff] [blame] | 457 | |
| 458 | /** |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 459 | * rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle |
| 460 | * |
| 461 | * Exit from an interrupt handler, which might possibly result in entering |
| 462 | * idle mode, in other words, leaving the mode in which read-side critical |
| 463 | * sections can occur. |
| 464 | * |
| 465 | * This code assumes that the idle loop never does anything that might |
| 466 | * result in unbalanced calls to irq_enter() and irq_exit(). If your |
| 467 | * architecture violates this assumption, RCU will give you what you |
| 468 | * deserve, good and hard. But very infrequently and irreproducibly. |
| 469 | * |
| 470 | * Use things like work queues to work around this limitation. |
| 471 | * |
| 472 | * You have been warned. |
| 473 | */ |
| 474 | void rcu_irq_exit(void) |
| 475 | { |
| 476 | unsigned long flags; |
Paul E. McKenney | 4145fa7 | 2011-10-31 15:01:54 -0700 | [diff] [blame] | 477 | long long oldval; |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 478 | struct rcu_dynticks *rdtp; |
| 479 | |
| 480 | local_irq_save(flags); |
| 481 | rdtp = &__get_cpu_var(rcu_dynticks); |
Paul E. McKenney | 4145fa7 | 2011-10-31 15:01:54 -0700 | [diff] [blame] | 482 | oldval = rdtp->dynticks_nesting; |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 483 | rdtp->dynticks_nesting--; |
| 484 | WARN_ON_ONCE(rdtp->dynticks_nesting < 0); |
Frederic Weisbecker | b6fc602 | 2011-11-28 16:18:56 -0800 | [diff] [blame] | 485 | if (rdtp->dynticks_nesting) |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 486 | trace_rcu_dyntick(TPS("--="), oldval, rdtp->dynticks_nesting); |
Frederic Weisbecker | b6fc602 | 2011-11-28 16:18:56 -0800 | [diff] [blame] | 487 | else |
Paul E. McKenney | cb349ca | 2012-09-04 17:35:31 -0700 | [diff] [blame] | 488 | rcu_eqs_enter_common(rdtp, oldval, true); |
Paul E. McKenney | eb348b8 | 2013-06-21 13:00:57 -0700 | [diff] [blame] | 489 | rcu_sysidle_enter(rdtp, 1); |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 490 | local_irq_restore(flags); |
| 491 | } |
| 492 | |
| 493 | /* |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 494 | * rcu_eqs_exit_common - current CPU moving away from extended quiescent state |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 495 | * |
| 496 | * If the new value of the ->dynticks_nesting counter was previously zero, |
| 497 | * we really have exited idle, and must do the appropriate accounting. |
| 498 | * The caller must have disabled interrupts. |
| 499 | */ |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 500 | static void rcu_eqs_exit_common(struct rcu_dynticks *rdtp, long long oldval, |
| 501 | int user) |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 502 | { |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 503 | smp_mb__before_atomic_inc(); /* Force ordering w/previous sojourn. */ |
| 504 | atomic_inc(&rdtp->dynticks); |
| 505 | /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ |
| 506 | smp_mb__after_atomic_inc(); /* See above. */ |
| 507 | WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); |
Paul E. McKenney | 7cb9249 | 2011-11-28 12:28:34 -0800 | [diff] [blame] | 508 | rcu_cleanup_after_idle(smp_processor_id()); |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 509 | trace_rcu_dyntick(TPS("End"), oldval, rdtp->dynticks_nesting); |
Paul E. McKenney | cb349ca | 2012-09-04 17:35:31 -0700 | [diff] [blame] | 510 | if (!user && !is_idle_task(current)) { |
Paul E. McKenney | 0989cb4 | 2011-11-01 08:57:21 -0700 | [diff] [blame] | 511 | struct task_struct *idle = idle_task(smp_processor_id()); |
| 512 | |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 513 | trace_rcu_dyntick(TPS("Error on exit: not idle task"), |
Paul E. McKenney | 4145fa7 | 2011-10-31 15:01:54 -0700 | [diff] [blame] | 514 | oldval, rdtp->dynticks_nesting); |
Paul E. McKenney | bf1304e | 2012-05-09 15:55:39 -0700 | [diff] [blame] | 515 | ftrace_dump(DUMP_ORIG); |
Paul E. McKenney | 0989cb4 | 2011-11-01 08:57:21 -0700 | [diff] [blame] | 516 | WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s", |
| 517 | current->pid, current->comm, |
| 518 | idle->pid, idle->comm); /* must be idle task! */ |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 519 | } |
| 520 | } |
| 521 | |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 522 | /* |
| 523 | * Exit an RCU extended quiescent state, which can be either the |
| 524 | * idle loop or adaptive-tickless usermode execution. |
| 525 | */ |
| 526 | static void rcu_eqs_exit(bool user) |
| 527 | { |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 528 | struct rcu_dynticks *rdtp; |
| 529 | long long oldval; |
| 530 | |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 531 | rdtp = &__get_cpu_var(rcu_dynticks); |
| 532 | oldval = rdtp->dynticks_nesting; |
| 533 | WARN_ON_ONCE(oldval < 0); |
| 534 | if (oldval & DYNTICK_TASK_NEST_MASK) |
| 535 | rdtp->dynticks_nesting += DYNTICK_TASK_NEST_VALUE; |
| 536 | else |
| 537 | rdtp->dynticks_nesting = DYNTICK_TASK_EXIT_IDLE; |
| 538 | rcu_eqs_exit_common(rdtp, oldval, user); |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 539 | } |
| 540 | |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 541 | /** |
| 542 | * rcu_idle_exit - inform RCU that current CPU is leaving idle |
| 543 | * |
| 544 | * Exit idle mode, in other words, -enter- the mode in which RCU |
| 545 | * read-side critical sections can occur. |
| 546 | * |
Paul E. McKenney | 29e37d8 | 2011-11-17 16:55:56 -0800 | [diff] [blame] | 547 | * We crowbar the ->dynticks_nesting field to DYNTICK_TASK_NEST to |
Paul E. McKenney | 4145fa7 | 2011-10-31 15:01:54 -0700 | [diff] [blame] | 548 | * allow for the possibility of usermode upcalls messing up our count |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 549 | * of interrupt nesting level during the busy period that is just |
| 550 | * now starting. |
| 551 | */ |
| 552 | void rcu_idle_exit(void) |
| 553 | { |
Frederic Weisbecker | c5d900b | 2012-07-11 20:26:31 +0200 | [diff] [blame] | 554 | unsigned long flags; |
| 555 | |
| 556 | local_irq_save(flags); |
Paul E. McKenney | cb349ca | 2012-09-04 17:35:31 -0700 | [diff] [blame] | 557 | rcu_eqs_exit(false); |
Paul E. McKenney | eb348b8 | 2013-06-21 13:00:57 -0700 | [diff] [blame] | 558 | rcu_sysidle_exit(&__get_cpu_var(rcu_dynticks), 0); |
Frederic Weisbecker | c5d900b | 2012-07-11 20:26:31 +0200 | [diff] [blame] | 559 | local_irq_restore(flags); |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 560 | } |
Paul E. McKenney | 8a2ecf4 | 2012-02-02 15:42:04 -0800 | [diff] [blame] | 561 | EXPORT_SYMBOL_GPL(rcu_idle_exit); |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 562 | |
Frederic Weisbecker | 2b1d502 | 2012-07-11 20:26:30 +0200 | [diff] [blame] | 563 | #ifdef CONFIG_RCU_USER_QS |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 564 | /** |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 565 | * rcu_user_exit - inform RCU that we are exiting userspace. |
| 566 | * |
| 567 | * Exit RCU idle mode while entering the kernel because it can |
| 568 | * run a RCU read side critical section anytime. |
| 569 | */ |
| 570 | void rcu_user_exit(void) |
| 571 | { |
Frederic Weisbecker | 91d1aa43 | 2012-11-27 19:33:25 +0100 | [diff] [blame] | 572 | rcu_eqs_exit(1); |
Frederic Weisbecker | adf5091 | 2012-06-28 11:20:21 -0700 | [diff] [blame] | 573 | } |
Frederic Weisbecker | 2b1d502 | 2012-07-11 20:26:30 +0200 | [diff] [blame] | 574 | #endif /* CONFIG_RCU_USER_QS */ |
Frederic Weisbecker | 19dd1591 | 2012-06-04 16:42:35 -0700 | [diff] [blame] | 575 | |
| 576 | /** |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 577 | * rcu_irq_enter - inform RCU that current CPU is entering irq away from idle |
| 578 | * |
| 579 | * Enter an interrupt handler, which might possibly result in exiting |
| 580 | * idle mode, in other words, entering the mode in which read-side critical |
| 581 | * sections can occur. |
| 582 | * |
| 583 | * Note that the Linux kernel is fully capable of entering an interrupt |
| 584 | * handler that it never exits, for example when doing upcalls to |
| 585 | * user mode! This code assumes that the idle loop never does upcalls to |
| 586 | * user mode. If your architecture does do upcalls from the idle loop (or |
| 587 | * does anything else that results in unbalanced calls to the irq_enter() |
| 588 | * and irq_exit() functions), RCU will give you what you deserve, good |
| 589 | * and hard. But very infrequently and irreproducibly. |
| 590 | * |
| 591 | * Use things like work queues to work around this limitation. |
| 592 | * |
| 593 | * You have been warned. |
| 594 | */ |
| 595 | void rcu_irq_enter(void) |
| 596 | { |
| 597 | unsigned long flags; |
| 598 | struct rcu_dynticks *rdtp; |
| 599 | long long oldval; |
| 600 | |
| 601 | local_irq_save(flags); |
| 602 | rdtp = &__get_cpu_var(rcu_dynticks); |
| 603 | oldval = rdtp->dynticks_nesting; |
| 604 | rdtp->dynticks_nesting++; |
| 605 | WARN_ON_ONCE(rdtp->dynticks_nesting == 0); |
Frederic Weisbecker | b6fc602 | 2011-11-28 16:18:56 -0800 | [diff] [blame] | 606 | if (oldval) |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 607 | trace_rcu_dyntick(TPS("++="), oldval, rdtp->dynticks_nesting); |
Frederic Weisbecker | b6fc602 | 2011-11-28 16:18:56 -0800 | [diff] [blame] | 608 | else |
Paul E. McKenney | cb349ca | 2012-09-04 17:35:31 -0700 | [diff] [blame] | 609 | rcu_eqs_exit_common(rdtp, oldval, true); |
Paul E. McKenney | eb348b8 | 2013-06-21 13:00:57 -0700 | [diff] [blame] | 610 | rcu_sysidle_exit(rdtp, 1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 611 | local_irq_restore(flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 612 | } |
| 613 | |
| 614 | /** |
| 615 | * rcu_nmi_enter - inform RCU of entry to NMI context |
| 616 | * |
| 617 | * If the CPU was idle with dynamic ticks active, and there is no |
| 618 | * irq handler running, this updates rdtp->dynticks_nmi to let the |
| 619 | * RCU grace-period handling know that the CPU is active. |
| 620 | */ |
| 621 | void rcu_nmi_enter(void) |
| 622 | { |
| 623 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 624 | |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 625 | if (rdtp->dynticks_nmi_nesting == 0 && |
| 626 | (atomic_read(&rdtp->dynticks) & 0x1)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 627 | return; |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 628 | rdtp->dynticks_nmi_nesting++; |
| 629 | smp_mb__before_atomic_inc(); /* Force delay from prior write. */ |
| 630 | atomic_inc(&rdtp->dynticks); |
| 631 | /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ |
| 632 | smp_mb__after_atomic_inc(); /* See above. */ |
| 633 | WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 634 | } |
| 635 | |
| 636 | /** |
| 637 | * rcu_nmi_exit - inform RCU of exit from NMI context |
| 638 | * |
| 639 | * If the CPU was idle with dynamic ticks active, and there is no |
| 640 | * irq handler running, this updates rdtp->dynticks_nmi to let the |
| 641 | * RCU grace-period handling know that the CPU is no longer active. |
| 642 | */ |
| 643 | void rcu_nmi_exit(void) |
| 644 | { |
| 645 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 646 | |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 647 | if (rdtp->dynticks_nmi_nesting == 0 || |
| 648 | --rdtp->dynticks_nmi_nesting != 0) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 649 | return; |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 650 | /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ |
| 651 | smp_mb__before_atomic_inc(); /* See above. */ |
| 652 | atomic_inc(&rdtp->dynticks); |
| 653 | smp_mb__after_atomic_inc(); /* Force delay to next write. */ |
| 654 | WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 655 | } |
| 656 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 657 | /** |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 658 | * rcu_is_cpu_idle - see if RCU thinks that the current CPU is idle |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 659 | * |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 660 | * If the current CPU is in its idle loop and is neither in an interrupt |
Paul E. McKenney | 3424069 | 2011-10-03 11:38:52 -0700 | [diff] [blame] | 661 | * or NMI handler, return true. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 662 | */ |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 663 | int rcu_is_cpu_idle(void) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 664 | { |
Paul E. McKenney | 3424069 | 2011-10-03 11:38:52 -0700 | [diff] [blame] | 665 | int ret; |
| 666 | |
| 667 | preempt_disable(); |
| 668 | ret = (atomic_read(&__get_cpu_var(rcu_dynticks).dynticks) & 0x1) == 0; |
| 669 | preempt_enable(); |
| 670 | return ret; |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 671 | } |
Frederic Weisbecker | e6b80a3 | 2011-10-07 16:25:18 -0700 | [diff] [blame] | 672 | EXPORT_SYMBOL(rcu_is_cpu_idle); |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 673 | |
Paul E. McKenney | 62fde6e | 2012-05-22 22:10:24 -0700 | [diff] [blame] | 674 | #if defined(CONFIG_PROVE_RCU) && defined(CONFIG_HOTPLUG_CPU) |
Paul E. McKenney | c0d6d01 | 2012-01-23 12:41:26 -0800 | [diff] [blame] | 675 | |
| 676 | /* |
| 677 | * Is the current CPU online? Disable preemption to avoid false positives |
| 678 | * that could otherwise happen due to the current CPU number being sampled, |
| 679 | * this task being preempted, its old CPU being taken offline, resuming |
| 680 | * on some other CPU, then determining that its old CPU is now offline. |
| 681 | * It is OK to use RCU on an offline processor during initial boot, hence |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 682 | * the check for rcu_scheduler_fully_active. Note also that it is OK |
| 683 | * for a CPU coming online to use RCU for one jiffy prior to marking itself |
| 684 | * online in the cpu_online_mask. Similarly, it is OK for a CPU going |
| 685 | * offline to continue to use RCU for one jiffy after marking itself |
| 686 | * offline in the cpu_online_mask. This leniency is necessary given the |
| 687 | * non-atomic nature of the online and offline processing, for example, |
| 688 | * the fact that a CPU enters the scheduler after completing the CPU_DYING |
| 689 | * notifiers. |
| 690 | * |
| 691 | * This is also why RCU internally marks CPUs online during the |
| 692 | * CPU_UP_PREPARE phase and offline during the CPU_DEAD phase. |
Paul E. McKenney | c0d6d01 | 2012-01-23 12:41:26 -0800 | [diff] [blame] | 693 | * |
| 694 | * Disable checking if in an NMI handler because we cannot safely report |
| 695 | * errors from NMI handlers anyway. |
| 696 | */ |
| 697 | bool rcu_lockdep_current_cpu_online(void) |
| 698 | { |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 699 | struct rcu_data *rdp; |
| 700 | struct rcu_node *rnp; |
Paul E. McKenney | c0d6d01 | 2012-01-23 12:41:26 -0800 | [diff] [blame] | 701 | bool ret; |
| 702 | |
| 703 | if (in_nmi()) |
| 704 | return 1; |
| 705 | preempt_disable(); |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 706 | rdp = &__get_cpu_var(rcu_sched_data); |
| 707 | rnp = rdp->mynode; |
| 708 | ret = (rdp->grpmask & rnp->qsmaskinit) || |
Paul E. McKenney | c0d6d01 | 2012-01-23 12:41:26 -0800 | [diff] [blame] | 709 | !rcu_scheduler_fully_active; |
| 710 | preempt_enable(); |
| 711 | return ret; |
| 712 | } |
| 713 | EXPORT_SYMBOL_GPL(rcu_lockdep_current_cpu_online); |
| 714 | |
Paul E. McKenney | 62fde6e | 2012-05-22 22:10:24 -0700 | [diff] [blame] | 715 | #endif /* #if defined(CONFIG_PROVE_RCU) && defined(CONFIG_HOTPLUG_CPU) */ |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 716 | |
| 717 | /** |
| 718 | * rcu_is_cpu_rrupt_from_idle - see if idle or immediately interrupted from idle |
| 719 | * |
| 720 | * If the current CPU is idle or running at a first-level (not nested) |
| 721 | * interrupt from idle, return true. The caller must have at least |
| 722 | * disabled preemption. |
| 723 | */ |
Josh Triplett | 62e3cb1 | 2012-11-20 09:55:26 -0800 | [diff] [blame] | 724 | static int rcu_is_cpu_rrupt_from_idle(void) |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 725 | { |
| 726 | return __get_cpu_var(rcu_dynticks).dynticks_nesting <= 1; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 727 | } |
| 728 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 729 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 730 | * Snapshot the specified CPU's dynticks counter so that we can later |
| 731 | * credit them with an implicit quiescent state. Return 1 if this CPU |
Paul E. McKenney | 1eba8f8 | 2009-09-23 09:50:42 -0700 | [diff] [blame] | 732 | * is in dynticks idle mode, which is an extended quiescent state. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 733 | */ |
Paul E. McKenney | 217af2a | 2013-06-21 15:39:06 -0700 | [diff] [blame] | 734 | static int dyntick_save_progress_counter(struct rcu_data *rdp, |
| 735 | bool *isidle, unsigned long *maxj) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 736 | { |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 737 | rdp->dynticks_snap = atomic_add_return(0, &rdp->dynticks->dynticks); |
Paul E. McKenney | 0edd1b1 | 2013-06-21 16:37:22 -0700 | [diff] [blame] | 738 | rcu_sysidle_check_cpu(rdp, isidle, maxj); |
Paul E. McKenney | f0e7c19 | 2011-11-23 15:02:05 -0800 | [diff] [blame] | 739 | return (rdp->dynticks_snap & 0x1) == 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 740 | } |
| 741 | |
| 742 | /* |
| 743 | * Return true if the specified CPU has passed through a quiescent |
| 744 | * state by virtue of being in or having passed through an dynticks |
| 745 | * idle state since the last call to dyntick_save_progress_counter() |
Paul E. McKenney | a82dcc7 | 2012-08-01 14:29:20 -0700 | [diff] [blame] | 746 | * for this same CPU, or by virtue of having been offline. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 747 | */ |
Paul E. McKenney | 217af2a | 2013-06-21 15:39:06 -0700 | [diff] [blame] | 748 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp, |
| 749 | bool *isidle, unsigned long *maxj) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 750 | { |
Paul E. McKenney | 7eb4f45 | 2011-07-30 07:32:48 -0700 | [diff] [blame] | 751 | unsigned int curr; |
| 752 | unsigned int snap; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 753 | |
Paul E. McKenney | 7eb4f45 | 2011-07-30 07:32:48 -0700 | [diff] [blame] | 754 | curr = (unsigned int)atomic_add_return(0, &rdp->dynticks->dynticks); |
| 755 | snap = (unsigned int)rdp->dynticks_snap; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 756 | |
| 757 | /* |
| 758 | * If the CPU passed through or entered a dynticks idle phase with |
| 759 | * no active irq/NMI handlers, then we can safely pretend that the CPU |
| 760 | * already acknowledged the request to pass through a quiescent |
| 761 | * state. Either way, that CPU cannot possibly be in an RCU |
| 762 | * read-side critical section that started before the beginning |
| 763 | * of the current RCU grace period. |
| 764 | */ |
Paul E. McKenney | 7eb4f45 | 2011-07-30 07:32:48 -0700 | [diff] [blame] | 765 | if ((curr & 0x1) == 0 || UINT_CMP_GE(curr, snap + 2)) { |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 766 | trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("dti")); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 767 | rdp->dynticks_fqs++; |
| 768 | return 1; |
| 769 | } |
| 770 | |
Paul E. McKenney | a82dcc7 | 2012-08-01 14:29:20 -0700 | [diff] [blame] | 771 | /* |
| 772 | * Check for the CPU being offline, but only if the grace period |
| 773 | * is old enough. We don't need to worry about the CPU changing |
| 774 | * state: If we see it offline even once, it has been through a |
| 775 | * quiescent state. |
| 776 | * |
| 777 | * The reason for insisting that the grace period be at least |
| 778 | * one jiffy old is that CPUs that are not quite online and that |
| 779 | * have just gone offline can still execute RCU read-side critical |
| 780 | * sections. |
| 781 | */ |
| 782 | if (ULONG_CMP_GE(rdp->rsp->gp_start + 2, jiffies)) |
| 783 | return 0; /* Grace period is not old enough. */ |
| 784 | barrier(); |
| 785 | if (cpu_is_offline(rdp->cpu)) { |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 786 | trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("ofl")); |
Paul E. McKenney | a82dcc7 | 2012-08-01 14:29:20 -0700 | [diff] [blame] | 787 | rdp->offline_fqs++; |
| 788 | return 1; |
| 789 | } |
Paul E. McKenney | 65d798f | 2013-04-12 16:19:10 -0700 | [diff] [blame] | 790 | |
| 791 | /* |
| 792 | * There is a possibility that a CPU in adaptive-ticks state |
| 793 | * might run in the kernel with the scheduling-clock tick disabled |
| 794 | * for an extended time period. Invoke rcu_kick_nohz_cpu() to |
| 795 | * force the CPU to restart the scheduling-clock tick in this |
| 796 | * CPU is in this state. |
| 797 | */ |
| 798 | rcu_kick_nohz_cpu(rdp->cpu); |
| 799 | |
Paul E. McKenney | a82dcc7 | 2012-08-01 14:29:20 -0700 | [diff] [blame] | 800 | return 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 801 | } |
| 802 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 803 | static void record_gp_stall_check_time(struct rcu_state *rsp) |
| 804 | { |
| 805 | rsp->gp_start = jiffies; |
Paul E. McKenney | 6bfc09e | 2012-10-19 12:49:17 -0700 | [diff] [blame] | 806 | rsp->jiffies_stall = jiffies + rcu_jiffies_till_stall_check(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 807 | } |
| 808 | |
Paul E. McKenney | b637a32 | 2012-09-19 16:58:38 -0700 | [diff] [blame] | 809 | /* |
| 810 | * Dump stacks of all tasks running on stalled CPUs. This is a fallback |
| 811 | * for architectures that do not implement trigger_all_cpu_backtrace(). |
| 812 | * The NMI-triggered stack traces are more accurate because they are |
| 813 | * printed by the target CPU. |
| 814 | */ |
| 815 | static void rcu_dump_cpu_stacks(struct rcu_state *rsp) |
| 816 | { |
| 817 | int cpu; |
| 818 | unsigned long flags; |
| 819 | struct rcu_node *rnp; |
| 820 | |
| 821 | rcu_for_each_leaf_node(rsp, rnp) { |
| 822 | raw_spin_lock_irqsave(&rnp->lock, flags); |
| 823 | if (rnp->qsmask != 0) { |
| 824 | for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++) |
| 825 | if (rnp->qsmask & (1UL << cpu)) |
| 826 | dump_cpu_task(rnp->grplo + cpu); |
| 827 | } |
| 828 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
| 829 | } |
| 830 | } |
| 831 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 832 | static void print_other_cpu_stall(struct rcu_state *rsp) |
| 833 | { |
| 834 | int cpu; |
| 835 | long delta; |
| 836 | unsigned long flags; |
Paul E. McKenney | 285fe29 | 2012-05-09 08:45:12 -0700 | [diff] [blame] | 837 | int ndetected = 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 838 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 53bb857 | 2012-09-21 16:35:25 -0700 | [diff] [blame] | 839 | long totqlen = 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 840 | |
| 841 | /* Only let one CPU complain about others per time interval. */ |
| 842 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 843 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 844 | delta = jiffies - rsp->jiffies_stall; |
Paul E. McKenney | fc2219d4 | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 845 | if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 846 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 847 | return; |
| 848 | } |
Paul E. McKenney | 6bfc09e | 2012-10-19 12:49:17 -0700 | [diff] [blame] | 849 | rsp->jiffies_stall = jiffies + 3 * rcu_jiffies_till_stall_check() + 3; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 850 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 851 | |
Paul E. McKenney | 8cdd32a | 2010-08-09 14:23:03 -0700 | [diff] [blame] | 852 | /* |
| 853 | * OK, time to rat on our buddy... |
| 854 | * See Documentation/RCU/stallwarn.txt for info on how to debug |
| 855 | * RCU CPU stall warnings. |
| 856 | */ |
Paul E. McKenney | d7f3e20 | 2013-03-18 16:19:52 -0700 | [diff] [blame] | 857 | pr_err("INFO: %s detected stalls on CPUs/tasks:", |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 858 | rsp->name); |
Paul E. McKenney | a858af2 | 2012-01-16 13:29:10 -0800 | [diff] [blame] | 859 | print_cpu_stall_info_begin(); |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 860 | rcu_for_each_leaf_node(rsp, rnp) { |
Paul E. McKenney | 3acd9eb | 2010-02-22 17:05:03 -0800 | [diff] [blame] | 861 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 9bc8b55 | 2011-08-13 13:31:47 -0700 | [diff] [blame] | 862 | ndetected += rcu_print_task_stall(rnp); |
Paul E. McKenney | c8020a6 | 2012-08-10 16:55:59 -0700 | [diff] [blame] | 863 | if (rnp->qsmask != 0) { |
| 864 | for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++) |
| 865 | if (rnp->qsmask & (1UL << cpu)) { |
| 866 | print_cpu_stall_info(rsp, |
| 867 | rnp->grplo + cpu); |
| 868 | ndetected++; |
| 869 | } |
| 870 | } |
Paul E. McKenney | 3acd9eb | 2010-02-22 17:05:03 -0800 | [diff] [blame] | 871 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 872 | } |
Paul E. McKenney | a858af2 | 2012-01-16 13:29:10 -0800 | [diff] [blame] | 873 | |
| 874 | /* |
| 875 | * Now rat on any tasks that got kicked up to the root rcu_node |
| 876 | * due to CPU offlining. |
| 877 | */ |
| 878 | rnp = rcu_get_root(rsp); |
| 879 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 285fe29 | 2012-05-09 08:45:12 -0700 | [diff] [blame] | 880 | ndetected += rcu_print_task_stall(rnp); |
Paul E. McKenney | a858af2 | 2012-01-16 13:29:10 -0800 | [diff] [blame] | 881 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
| 882 | |
| 883 | print_cpu_stall_info_end(); |
Paul E. McKenney | 53bb857 | 2012-09-21 16:35:25 -0700 | [diff] [blame] | 884 | for_each_possible_cpu(cpu) |
| 885 | totqlen += per_cpu_ptr(rsp->rda, cpu)->qlen; |
| 886 | pr_cont("(detected by %d, t=%ld jiffies, g=%lu, c=%lu, q=%lu)\n", |
Paul E. McKenney | eee0588 | 2012-09-21 14:15:05 -0700 | [diff] [blame] | 887 | smp_processor_id(), (long)(jiffies - rsp->gp_start), |
Paul E. McKenney | 53bb857 | 2012-09-21 16:35:25 -0700 | [diff] [blame] | 888 | rsp->gpnum, rsp->completed, totqlen); |
Paul E. McKenney | 9bc8b55 | 2011-08-13 13:31:47 -0700 | [diff] [blame] | 889 | if (ndetected == 0) |
Paul E. McKenney | d7f3e20 | 2013-03-18 16:19:52 -0700 | [diff] [blame] | 890 | pr_err("INFO: Stall ended before state dump start\n"); |
Paul E. McKenney | 9bc8b55 | 2011-08-13 13:31:47 -0700 | [diff] [blame] | 891 | else if (!trigger_all_cpu_backtrace()) |
Paul E. McKenney | b637a32 | 2012-09-19 16:58:38 -0700 | [diff] [blame] | 892 | rcu_dump_cpu_stacks(rsp); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 893 | |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 894 | /* Complain about tasks blocking the grace period. */ |
Paul E. McKenney | 1ed509a | 2010-02-22 17:05:05 -0800 | [diff] [blame] | 895 | |
| 896 | rcu_print_detail_task_stall(rsp); |
| 897 | |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 898 | force_quiescent_state(rsp); /* Kick them all. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 899 | } |
| 900 | |
| 901 | static void print_cpu_stall(struct rcu_state *rsp) |
| 902 | { |
Paul E. McKenney | 53bb857 | 2012-09-21 16:35:25 -0700 | [diff] [blame] | 903 | int cpu; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 904 | unsigned long flags; |
| 905 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 53bb857 | 2012-09-21 16:35:25 -0700 | [diff] [blame] | 906 | long totqlen = 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 907 | |
Paul E. McKenney | 8cdd32a | 2010-08-09 14:23:03 -0700 | [diff] [blame] | 908 | /* |
| 909 | * OK, time to rat on ourselves... |
| 910 | * See Documentation/RCU/stallwarn.txt for info on how to debug |
| 911 | * RCU CPU stall warnings. |
| 912 | */ |
Paul E. McKenney | d7f3e20 | 2013-03-18 16:19:52 -0700 | [diff] [blame] | 913 | pr_err("INFO: %s self-detected stall on CPU", rsp->name); |
Paul E. McKenney | a858af2 | 2012-01-16 13:29:10 -0800 | [diff] [blame] | 914 | print_cpu_stall_info_begin(); |
| 915 | print_cpu_stall_info(rsp, smp_processor_id()); |
| 916 | print_cpu_stall_info_end(); |
Paul E. McKenney | 53bb857 | 2012-09-21 16:35:25 -0700 | [diff] [blame] | 917 | for_each_possible_cpu(cpu) |
| 918 | totqlen += per_cpu_ptr(rsp->rda, cpu)->qlen; |
| 919 | pr_cont(" (t=%lu jiffies g=%lu c=%lu q=%lu)\n", |
| 920 | jiffies - rsp->gp_start, rsp->gpnum, rsp->completed, totqlen); |
Paul E. McKenney | 4627e24 | 2011-08-03 03:34:24 -0700 | [diff] [blame] | 921 | if (!trigger_all_cpu_backtrace()) |
| 922 | dump_stack(); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 923 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 924 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 925 | if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall)) |
Paul E. McKenney | 13cfcca | 2012-01-13 15:32:18 -0800 | [diff] [blame] | 926 | rsp->jiffies_stall = jiffies + |
Paul E. McKenney | 6bfc09e | 2012-10-19 12:49:17 -0700 | [diff] [blame] | 927 | 3 * rcu_jiffies_till_stall_check() + 3; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 928 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 929 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 930 | set_need_resched(); /* kick ourselves to get things going. */ |
| 931 | } |
| 932 | |
| 933 | static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) |
| 934 | { |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 935 | unsigned long j; |
| 936 | unsigned long js; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 937 | struct rcu_node *rnp; |
| 938 | |
Paul E. McKenney | 742734e | 2010-06-30 11:43:52 -0700 | [diff] [blame] | 939 | if (rcu_cpu_stall_suppress) |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 940 | return; |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 941 | j = ACCESS_ONCE(jiffies); |
| 942 | js = ACCESS_ONCE(rsp->jiffies_stall); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 943 | rnp = rdp->mynode; |
Paul E. McKenney | c96ea7c | 2012-08-13 11:17:06 -0700 | [diff] [blame] | 944 | if (rcu_gp_in_progress(rsp) && |
| 945 | (ACCESS_ONCE(rnp->qsmask) & rdp->grpmask) && ULONG_CMP_GE(j, js)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 946 | |
| 947 | /* We haven't checked in, so go dump stack. */ |
| 948 | print_cpu_stall(rsp); |
| 949 | |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 950 | } else if (rcu_gp_in_progress(rsp) && |
| 951 | ULONG_CMP_GE(j, js + RCU_STALL_RAT_DELAY)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 952 | |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 953 | /* They had a few time units to dump stack, so complain. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 954 | print_other_cpu_stall(rsp); |
| 955 | } |
| 956 | } |
| 957 | |
Paul E. McKenney | 53d84e0 | 2010-08-10 14:28:53 -0700 | [diff] [blame] | 958 | /** |
| 959 | * rcu_cpu_stall_reset - prevent further stall warnings in current grace period |
| 960 | * |
| 961 | * Set the stall-warning timeout way off into the future, thus preventing |
| 962 | * any RCU CPU stall-warning messages from appearing in the current set of |
| 963 | * RCU grace periods. |
| 964 | * |
| 965 | * The caller must disable hard irqs. |
| 966 | */ |
| 967 | void rcu_cpu_stall_reset(void) |
| 968 | { |
Paul E. McKenney | 6ce75a2 | 2012-06-12 11:01:13 -0700 | [diff] [blame] | 969 | struct rcu_state *rsp; |
| 970 | |
| 971 | for_each_rcu_flavor(rsp) |
| 972 | rsp->jiffies_stall = jiffies + ULONG_MAX / 2; |
Paul E. McKenney | 53d84e0 | 2010-08-10 14:28:53 -0700 | [diff] [blame] | 973 | } |
| 974 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 975 | /* |
Paul E. McKenney | 3f5d3ea | 2012-05-09 15:39:56 -0700 | [diff] [blame] | 976 | * Initialize the specified rcu_data structure's callback list to empty. |
| 977 | */ |
| 978 | static void init_callback_list(struct rcu_data *rdp) |
| 979 | { |
| 980 | int i; |
| 981 | |
Paul E. McKenney | 34ed6246 | 2013-01-07 13:37:42 -0800 | [diff] [blame] | 982 | if (init_nocb_callback_list(rdp)) |
| 983 | return; |
Paul E. McKenney | 3f5d3ea | 2012-05-09 15:39:56 -0700 | [diff] [blame] | 984 | rdp->nxtlist = NULL; |
| 985 | for (i = 0; i < RCU_NEXT_SIZE; i++) |
| 986 | rdp->nxttail[i] = &rdp->nxtlist; |
| 987 | } |
| 988 | |
| 989 | /* |
Paul E. McKenney | dc35c89 | 2012-12-03 13:52:00 -0800 | [diff] [blame] | 990 | * Determine the value that ->completed will have at the end of the |
| 991 | * next subsequent grace period. This is used to tag callbacks so that |
| 992 | * a CPU can invoke callbacks in a timely fashion even if that CPU has |
| 993 | * been dyntick-idle for an extended period with callbacks under the |
| 994 | * influence of RCU_FAST_NO_HZ. |
| 995 | * |
| 996 | * The caller must hold rnp->lock with interrupts disabled. |
| 997 | */ |
| 998 | static unsigned long rcu_cbs_completed(struct rcu_state *rsp, |
| 999 | struct rcu_node *rnp) |
| 1000 | { |
| 1001 | /* |
| 1002 | * If RCU is idle, we just wait for the next grace period. |
| 1003 | * But we can only be sure that RCU is idle if we are looking |
| 1004 | * at the root rcu_node structure -- otherwise, a new grace |
| 1005 | * period might have started, but just not yet gotten around |
| 1006 | * to initializing the current non-root rcu_node structure. |
| 1007 | */ |
| 1008 | if (rcu_get_root(rsp) == rnp && rnp->gpnum == rnp->completed) |
| 1009 | return rnp->completed + 1; |
| 1010 | |
| 1011 | /* |
| 1012 | * Otherwise, wait for a possible partial grace period and |
| 1013 | * then the subsequent full grace period. |
| 1014 | */ |
| 1015 | return rnp->completed + 2; |
| 1016 | } |
| 1017 | |
| 1018 | /* |
Paul E. McKenney | 0446be4 | 2012-12-30 15:21:01 -0800 | [diff] [blame] | 1019 | * Trace-event helper function for rcu_start_future_gp() and |
| 1020 | * rcu_nocb_wait_gp(). |
| 1021 | */ |
| 1022 | static void trace_rcu_future_gp(struct rcu_node *rnp, struct rcu_data *rdp, |
Steven Rostedt (Red Hat) | e66c33d | 2013-07-12 16:50:28 -0400 | [diff] [blame] | 1023 | unsigned long c, const char *s) |
Paul E. McKenney | 0446be4 | 2012-12-30 15:21:01 -0800 | [diff] [blame] | 1024 | { |
| 1025 | trace_rcu_future_grace_period(rdp->rsp->name, rnp->gpnum, |
| 1026 | rnp->completed, c, rnp->level, |
| 1027 | rnp->grplo, rnp->grphi, s); |
| 1028 | } |
| 1029 | |
| 1030 | /* |
| 1031 | * Start some future grace period, as needed to handle newly arrived |
| 1032 | * callbacks. The required future grace periods are recorded in each |
| 1033 | * rcu_node structure's ->need_future_gp field. |
| 1034 | * |
| 1035 | * The caller must hold the specified rcu_node structure's ->lock. |
| 1036 | */ |
| 1037 | static unsigned long __maybe_unused |
| 1038 | rcu_start_future_gp(struct rcu_node *rnp, struct rcu_data *rdp) |
| 1039 | { |
| 1040 | unsigned long c; |
| 1041 | int i; |
| 1042 | struct rcu_node *rnp_root = rcu_get_root(rdp->rsp); |
| 1043 | |
| 1044 | /* |
| 1045 | * Pick up grace-period number for new callbacks. If this |
| 1046 | * grace period is already marked as needed, return to the caller. |
| 1047 | */ |
| 1048 | c = rcu_cbs_completed(rdp->rsp, rnp); |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 1049 | trace_rcu_future_gp(rnp, rdp, c, TPS("Startleaf")); |
Paul E. McKenney | 0446be4 | 2012-12-30 15:21:01 -0800 | [diff] [blame] | 1050 | if (rnp->need_future_gp[c & 0x1]) { |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 1051 | trace_rcu_future_gp(rnp, rdp, c, TPS("Prestartleaf")); |
Paul E. McKenney | 0446be4 | 2012-12-30 15:21:01 -0800 | [diff] [blame] | 1052 | return c; |
| 1053 | } |
| 1054 | |
| 1055 | /* |
| 1056 | * If either this rcu_node structure or the root rcu_node structure |
| 1057 | * believe that a grace period is in progress, then we must wait |
| 1058 | * for the one following, which is in "c". Because our request |
| 1059 | * will be noticed at the end of the current grace period, we don't |
| 1060 | * need to explicitly start one. |
| 1061 | */ |
| 1062 | if (rnp->gpnum != rnp->completed || |
| 1063 | ACCESS_ONCE(rnp->gpnum) != ACCESS_ONCE(rnp->completed)) { |
| 1064 | rnp->need_future_gp[c & 0x1]++; |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 1065 | trace_rcu_future_gp(rnp, rdp, c, TPS("Startedleaf")); |
Paul E. McKenney | 0446be4 | 2012-12-30 15:21:01 -0800 | [diff] [blame] | 1066 | return c; |
| 1067 | } |
| 1068 | |
| 1069 | /* |
| 1070 | * There might be no grace period in progress. If we don't already |
| 1071 | * hold it, acquire the root rcu_node structure's lock in order to |
| 1072 | * start one (if needed). |
| 1073 | */ |
| 1074 | if (rnp != rnp_root) |
| 1075 | raw_spin_lock(&rnp_root->lock); |
| 1076 | |
| 1077 | /* |
| 1078 | * Get a new grace-period number. If there really is no grace |
| 1079 | * period in progress, it will be smaller than the one we obtained |
| 1080 | * earlier. Adjust callbacks as needed. Note that even no-CBs |
| 1081 | * CPUs have a ->nxtcompleted[] array, so no no-CBs checks needed. |
| 1082 | */ |
| 1083 | c = rcu_cbs_completed(rdp->rsp, rnp_root); |
| 1084 | for (i = RCU_DONE_TAIL; i < RCU_NEXT_TAIL; i++) |
| 1085 | if (ULONG_CMP_LT(c, rdp->nxtcompleted[i])) |
| 1086 | rdp->nxtcompleted[i] = c; |
| 1087 | |
| 1088 | /* |
| 1089 | * If the needed for the required grace period is already |
| 1090 | * recorded, trace and leave. |
| 1091 | */ |
| 1092 | if (rnp_root->need_future_gp[c & 0x1]) { |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 1093 | trace_rcu_future_gp(rnp, rdp, c, TPS("Prestartedroot")); |
Paul E. McKenney | 0446be4 | 2012-12-30 15:21:01 -0800 | [diff] [blame] | 1094 | goto unlock_out; |
| 1095 | } |
| 1096 | |
| 1097 | /* Record the need for the future grace period. */ |
| 1098 | rnp_root->need_future_gp[c & 0x1]++; |
| 1099 | |
| 1100 | /* If a grace period is not already in progress, start one. */ |
| 1101 | if (rnp_root->gpnum != rnp_root->completed) { |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 1102 | trace_rcu_future_gp(rnp, rdp, c, TPS("Startedleafroot")); |
Paul E. McKenney | 0446be4 | 2012-12-30 15:21:01 -0800 | [diff] [blame] | 1103 | } else { |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 1104 | trace_rcu_future_gp(rnp, rdp, c, TPS("Startedroot")); |
Paul E. McKenney | 910ee45 | 2012-12-31 02:24:21 -0800 | [diff] [blame] | 1105 | rcu_start_gp_advanced(rdp->rsp, rnp_root, rdp); |
Paul E. McKenney | 0446be4 | 2012-12-30 15:21:01 -0800 | [diff] [blame] | 1106 | } |
| 1107 | unlock_out: |
| 1108 | if (rnp != rnp_root) |
| 1109 | raw_spin_unlock(&rnp_root->lock); |
| 1110 | return c; |
| 1111 | } |
| 1112 | |
| 1113 | /* |
| 1114 | * Clean up any old requests for the just-ended grace period. Also return |
| 1115 | * whether any additional grace periods have been requested. Also invoke |
| 1116 | * rcu_nocb_gp_cleanup() in order to wake up any no-callbacks kthreads |
| 1117 | * waiting for this grace period to complete. |
| 1118 | */ |
| 1119 | static int rcu_future_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp) |
| 1120 | { |
| 1121 | int c = rnp->completed; |
| 1122 | int needmore; |
| 1123 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); |
| 1124 | |
| 1125 | rcu_nocb_gp_cleanup(rsp, rnp); |
| 1126 | rnp->need_future_gp[c & 0x1] = 0; |
| 1127 | needmore = rnp->need_future_gp[(c + 1) & 0x1]; |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 1128 | trace_rcu_future_gp(rnp, rdp, c, |
| 1129 | needmore ? TPS("CleanupMore") : TPS("Cleanup")); |
Paul E. McKenney | 0446be4 | 2012-12-30 15:21:01 -0800 | [diff] [blame] | 1130 | return needmore; |
| 1131 | } |
| 1132 | |
| 1133 | /* |
Paul E. McKenney | dc35c89 | 2012-12-03 13:52:00 -0800 | [diff] [blame] | 1134 | * If there is room, assign a ->completed number to any callbacks on |
| 1135 | * this CPU that have not already been assigned. Also accelerate any |
| 1136 | * callbacks that were previously assigned a ->completed number that has |
| 1137 | * since proven to be too conservative, which can happen if callbacks get |
| 1138 | * assigned a ->completed number while RCU is idle, but with reference to |
| 1139 | * a non-root rcu_node structure. This function is idempotent, so it does |
| 1140 | * not hurt to call it repeatedly. |
| 1141 | * |
| 1142 | * The caller must hold rnp->lock with interrupts disabled. |
| 1143 | */ |
| 1144 | static void rcu_accelerate_cbs(struct rcu_state *rsp, struct rcu_node *rnp, |
| 1145 | struct rcu_data *rdp) |
| 1146 | { |
| 1147 | unsigned long c; |
| 1148 | int i; |
| 1149 | |
| 1150 | /* If the CPU has no callbacks, nothing to do. */ |
| 1151 | if (!rdp->nxttail[RCU_NEXT_TAIL] || !*rdp->nxttail[RCU_DONE_TAIL]) |
| 1152 | return; |
| 1153 | |
| 1154 | /* |
| 1155 | * Starting from the sublist containing the callbacks most |
| 1156 | * recently assigned a ->completed number and working down, find the |
| 1157 | * first sublist that is not assignable to an upcoming grace period. |
| 1158 | * Such a sublist has something in it (first two tests) and has |
| 1159 | * a ->completed number assigned that will complete sooner than |
| 1160 | * the ->completed number for newly arrived callbacks (last test). |
| 1161 | * |
| 1162 | * The key point is that any later sublist can be assigned the |
| 1163 | * same ->completed number as the newly arrived callbacks, which |
| 1164 | * means that the callbacks in any of these later sublist can be |
| 1165 | * grouped into a single sublist, whether or not they have already |
| 1166 | * been assigned a ->completed number. |
| 1167 | */ |
| 1168 | c = rcu_cbs_completed(rsp, rnp); |
| 1169 | for (i = RCU_NEXT_TAIL - 1; i > RCU_DONE_TAIL; i--) |
| 1170 | if (rdp->nxttail[i] != rdp->nxttail[i - 1] && |
| 1171 | !ULONG_CMP_GE(rdp->nxtcompleted[i], c)) |
| 1172 | break; |
| 1173 | |
| 1174 | /* |
| 1175 | * If there are no sublist for unassigned callbacks, leave. |
| 1176 | * At the same time, advance "i" one sublist, so that "i" will |
| 1177 | * index into the sublist where all the remaining callbacks should |
| 1178 | * be grouped into. |
| 1179 | */ |
| 1180 | if (++i >= RCU_NEXT_TAIL) |
| 1181 | return; |
| 1182 | |
| 1183 | /* |
| 1184 | * Assign all subsequent callbacks' ->completed number to the next |
| 1185 | * full grace period and group them all in the sublist initially |
| 1186 | * indexed by "i". |
| 1187 | */ |
| 1188 | for (; i <= RCU_NEXT_TAIL; i++) { |
| 1189 | rdp->nxttail[i] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 1190 | rdp->nxtcompleted[i] = c; |
| 1191 | } |
Paul E. McKenney | 910ee45 | 2012-12-31 02:24:21 -0800 | [diff] [blame] | 1192 | /* Record any needed additional grace periods. */ |
| 1193 | rcu_start_future_gp(rnp, rdp); |
Paul E. McKenney | 6d4b418 | 2012-11-27 16:55:44 -0800 | [diff] [blame] | 1194 | |
| 1195 | /* Trace depending on how much we were able to accelerate. */ |
| 1196 | if (!*rdp->nxttail[RCU_WAIT_TAIL]) |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 1197 | trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("AccWaitCB")); |
Paul E. McKenney | 6d4b418 | 2012-11-27 16:55:44 -0800 | [diff] [blame] | 1198 | else |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 1199 | trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("AccReadyCB")); |
Paul E. McKenney | dc35c89 | 2012-12-03 13:52:00 -0800 | [diff] [blame] | 1200 | } |
| 1201 | |
| 1202 | /* |
| 1203 | * Move any callbacks whose grace period has completed to the |
| 1204 | * RCU_DONE_TAIL sublist, then compact the remaining sublists and |
| 1205 | * assign ->completed numbers to any callbacks in the RCU_NEXT_TAIL |
| 1206 | * sublist. This function is idempotent, so it does not hurt to |
| 1207 | * invoke it repeatedly. As long as it is not invoked -too- often... |
| 1208 | * |
| 1209 | * The caller must hold rnp->lock with interrupts disabled. |
| 1210 | */ |
| 1211 | static void rcu_advance_cbs(struct rcu_state *rsp, struct rcu_node *rnp, |
| 1212 | struct rcu_data *rdp) |
| 1213 | { |
| 1214 | int i, j; |
| 1215 | |
| 1216 | /* If the CPU has no callbacks, nothing to do. */ |
| 1217 | if (!rdp->nxttail[RCU_NEXT_TAIL] || !*rdp->nxttail[RCU_DONE_TAIL]) |
| 1218 | return; |
| 1219 | |
| 1220 | /* |
| 1221 | * Find all callbacks whose ->completed numbers indicate that they |
| 1222 | * are ready to invoke, and put them into the RCU_DONE_TAIL sublist. |
| 1223 | */ |
| 1224 | for (i = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++) { |
| 1225 | if (ULONG_CMP_LT(rnp->completed, rdp->nxtcompleted[i])) |
| 1226 | break; |
| 1227 | rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[i]; |
| 1228 | } |
| 1229 | /* Clean up any sublist tail pointers that were misordered above. */ |
| 1230 | for (j = RCU_WAIT_TAIL; j < i; j++) |
| 1231 | rdp->nxttail[j] = rdp->nxttail[RCU_DONE_TAIL]; |
| 1232 | |
| 1233 | /* Copy down callbacks to fill in empty sublists. */ |
| 1234 | for (j = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++, j++) { |
| 1235 | if (rdp->nxttail[j] == rdp->nxttail[RCU_NEXT_TAIL]) |
| 1236 | break; |
| 1237 | rdp->nxttail[j] = rdp->nxttail[i]; |
| 1238 | rdp->nxtcompleted[j] = rdp->nxtcompleted[i]; |
| 1239 | } |
| 1240 | |
| 1241 | /* Classify any remaining callbacks. */ |
| 1242 | rcu_accelerate_cbs(rsp, rnp, rdp); |
| 1243 | } |
| 1244 | |
| 1245 | /* |
Paul E. McKenney | ba9fbe9 | 2013-03-19 11:53:31 -0700 | [diff] [blame] | 1246 | * Update CPU-local rcu_data state to record the beginnings and ends of |
| 1247 | * grace periods. The caller must hold the ->lock of the leaf rcu_node |
| 1248 | * structure corresponding to the current CPU, and must have irqs disabled. |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 1249 | */ |
Paul E. McKenney | ba9fbe9 | 2013-03-19 11:53:31 -0700 | [diff] [blame] | 1250 | static void __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 1251 | { |
Paul E. McKenney | ba9fbe9 | 2013-03-19 11:53:31 -0700 | [diff] [blame] | 1252 | /* Handle the ends of any preceding grace periods first. */ |
Paul E. McKenney | dc35c89 | 2012-12-03 13:52:00 -0800 | [diff] [blame] | 1253 | if (rdp->completed == rnp->completed) { |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 1254 | |
Paul E. McKenney | ba9fbe9 | 2013-03-19 11:53:31 -0700 | [diff] [blame] | 1255 | /* No grace period end, so just accelerate recent callbacks. */ |
Paul E. McKenney | dc35c89 | 2012-12-03 13:52:00 -0800 | [diff] [blame] | 1256 | rcu_accelerate_cbs(rsp, rnp, rdp); |
| 1257 | |
| 1258 | } else { |
| 1259 | |
| 1260 | /* Advance callbacks. */ |
| 1261 | rcu_advance_cbs(rsp, rnp, rdp); |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 1262 | |
| 1263 | /* Remember that we saw this grace-period completion. */ |
| 1264 | rdp->completed = rnp->completed; |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 1265 | trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuend")); |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 1266 | } |
Paul E. McKenney | 398ebe6 | 2013-03-19 10:53:14 -0700 | [diff] [blame] | 1267 | |
Paul E. McKenney | 6eaef63 | 2013-03-19 10:08:37 -0700 | [diff] [blame] | 1268 | if (rdp->gpnum != rnp->gpnum) { |
| 1269 | /* |
| 1270 | * If the current grace period is waiting for this CPU, |
| 1271 | * set up to detect a quiescent state, otherwise don't |
| 1272 | * go looking for one. |
| 1273 | */ |
| 1274 | rdp->gpnum = rnp->gpnum; |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 1275 | trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpustart")); |
Paul E. McKenney | 6eaef63 | 2013-03-19 10:08:37 -0700 | [diff] [blame] | 1276 | rdp->passed_quiesce = 0; |
| 1277 | rdp->qs_pending = !!(rnp->qsmask & rdp->grpmask); |
| 1278 | zero_cpu_stall_ticks(rdp); |
| 1279 | } |
| 1280 | } |
| 1281 | |
Paul E. McKenney | d34ea32 | 2013-03-19 11:10:43 -0700 | [diff] [blame] | 1282 | static void note_gp_changes(struct rcu_state *rsp, struct rcu_data *rdp) |
Paul E. McKenney | 6eaef63 | 2013-03-19 10:08:37 -0700 | [diff] [blame] | 1283 | { |
| 1284 | unsigned long flags; |
| 1285 | struct rcu_node *rnp; |
| 1286 | |
| 1287 | local_irq_save(flags); |
| 1288 | rnp = rdp->mynode; |
Paul E. McKenney | d34ea32 | 2013-03-19 11:10:43 -0700 | [diff] [blame] | 1289 | if ((rdp->gpnum == ACCESS_ONCE(rnp->gpnum) && |
| 1290 | rdp->completed == ACCESS_ONCE(rnp->completed)) || /* w/out lock. */ |
Paul E. McKenney | 6eaef63 | 2013-03-19 10:08:37 -0700 | [diff] [blame] | 1291 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
| 1292 | local_irq_restore(flags); |
| 1293 | return; |
| 1294 | } |
Paul E. McKenney | d34ea32 | 2013-03-19 11:10:43 -0700 | [diff] [blame] | 1295 | __note_gp_changes(rsp, rnp, rdp); |
Paul E. McKenney | 6eaef63 | 2013-03-19 10:08:37 -0700 | [diff] [blame] | 1296 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
| 1297 | } |
| 1298 | |
| 1299 | /* |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1300 | * Initialize a new grace period. |
| 1301 | */ |
| 1302 | static int rcu_gp_init(struct rcu_state *rsp) |
| 1303 | { |
| 1304 | struct rcu_data *rdp; |
| 1305 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 1306 | |
Paul E. McKenney | eb75767 | 2013-06-21 17:10:40 -0700 | [diff] [blame] | 1307 | rcu_bind_gp_kthread(); |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1308 | raw_spin_lock_irq(&rnp->lock); |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 1309 | rsp->gp_flags = 0; /* Clear all flags: New grace period. */ |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1310 | |
| 1311 | if (rcu_gp_in_progress(rsp)) { |
| 1312 | /* Grace period already in progress, don't start another. */ |
| 1313 | raw_spin_unlock_irq(&rnp->lock); |
| 1314 | return 0; |
| 1315 | } |
| 1316 | |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1317 | /* Advance to a new grace period and initialize state. */ |
| 1318 | rsp->gpnum++; |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 1319 | trace_rcu_grace_period(rsp->name, rsp->gpnum, TPS("start")); |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1320 | record_gp_stall_check_time(rsp); |
| 1321 | raw_spin_unlock_irq(&rnp->lock); |
| 1322 | |
| 1323 | /* Exclude any concurrent CPU-hotplug operations. */ |
Paul E. McKenney | a4fbe35 | 2012-10-07 08:36:12 -0700 | [diff] [blame] | 1324 | mutex_lock(&rsp->onoff_mutex); |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1325 | |
| 1326 | /* |
| 1327 | * Set the quiescent-state-needed bits in all the rcu_node |
| 1328 | * structures for all currently online CPUs in breadth-first order, |
| 1329 | * starting from the root rcu_node structure, relying on the layout |
| 1330 | * of the tree within the rsp->node[] array. Note that other CPUs |
| 1331 | * will access only the leaves of the hierarchy, thus seeing that no |
| 1332 | * grace period is in progress, at least until the corresponding |
| 1333 | * leaf node has been initialized. In addition, we have excluded |
| 1334 | * CPU-hotplug operations. |
| 1335 | * |
| 1336 | * The grace period cannot complete until the initialization |
| 1337 | * process finishes, because this kthread handles both. |
| 1338 | */ |
| 1339 | rcu_for_each_node_breadth_first(rsp, rnp) { |
| 1340 | raw_spin_lock_irq(&rnp->lock); |
| 1341 | rdp = this_cpu_ptr(rsp->rda); |
| 1342 | rcu_preempt_check_blocked_tasks(rnp); |
| 1343 | rnp->qsmask = rnp->qsmaskinit; |
Paul E. McKenney | 0446be4 | 2012-12-30 15:21:01 -0800 | [diff] [blame] | 1344 | ACCESS_ONCE(rnp->gpnum) = rsp->gpnum; |
Paul E. McKenney | 25d30cf | 2012-07-11 05:23:18 -0700 | [diff] [blame] | 1345 | WARN_ON_ONCE(rnp->completed != rsp->completed); |
Paul E. McKenney | 0446be4 | 2012-12-30 15:21:01 -0800 | [diff] [blame] | 1346 | ACCESS_ONCE(rnp->completed) = rsp->completed; |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1347 | if (rnp == rdp->mynode) |
Paul E. McKenney | ce3d9c0 | 2013-03-19 12:27:50 -0700 | [diff] [blame] | 1348 | __note_gp_changes(rsp, rnp, rdp); |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1349 | rcu_preempt_boost_start_gp(rnp); |
| 1350 | trace_rcu_grace_period_init(rsp->name, rnp->gpnum, |
| 1351 | rnp->level, rnp->grplo, |
| 1352 | rnp->grphi, rnp->qsmask); |
| 1353 | raw_spin_unlock_irq(&rnp->lock); |
Paul E. McKenney | 661a85d | 2012-07-07 05:57:03 -0700 | [diff] [blame] | 1354 | #ifdef CONFIG_PROVE_RCU_DELAY |
Paul E. McKenney | 971394f | 2013-06-02 07:13:57 -0700 | [diff] [blame] | 1355 | if ((prandom_u32() % (rcu_num_nodes + 1)) == 0 && |
Paul E. McKenney | 81e5949 | 2013-03-10 15:44:52 -0700 | [diff] [blame] | 1356 | system_state == SYSTEM_RUNNING) |
Paul E. McKenney | 971394f | 2013-06-02 07:13:57 -0700 | [diff] [blame] | 1357 | udelay(200); |
Paul E. McKenney | 661a85d | 2012-07-07 05:57:03 -0700 | [diff] [blame] | 1358 | #endif /* #ifdef CONFIG_PROVE_RCU_DELAY */ |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1359 | cond_resched(); |
| 1360 | } |
| 1361 | |
Paul E. McKenney | a4fbe35 | 2012-10-07 08:36:12 -0700 | [diff] [blame] | 1362 | mutex_unlock(&rsp->onoff_mutex); |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1363 | return 1; |
| 1364 | } |
| 1365 | |
| 1366 | /* |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 1367 | * Do one round of quiescent-state forcing. |
| 1368 | */ |
| 1369 | int rcu_gp_fqs(struct rcu_state *rsp, int fqs_state_in) |
| 1370 | { |
| 1371 | int fqs_state = fqs_state_in; |
Paul E. McKenney | 217af2a | 2013-06-21 15:39:06 -0700 | [diff] [blame] | 1372 | bool isidle = false; |
| 1373 | unsigned long maxj; |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 1374 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 1375 | |
| 1376 | rsp->n_force_qs++; |
| 1377 | if (fqs_state == RCU_SAVE_DYNTICK) { |
| 1378 | /* Collect dyntick-idle snapshots. */ |
Paul E. McKenney | 0edd1b1 | 2013-06-21 16:37:22 -0700 | [diff] [blame] | 1379 | if (is_sysidle_rcu_state(rsp)) { |
| 1380 | isidle = 1; |
| 1381 | maxj = jiffies - ULONG_MAX / 4; |
| 1382 | } |
Paul E. McKenney | 217af2a | 2013-06-21 15:39:06 -0700 | [diff] [blame] | 1383 | force_qs_rnp(rsp, dyntick_save_progress_counter, |
| 1384 | &isidle, &maxj); |
Paul E. McKenney | 0edd1b1 | 2013-06-21 16:37:22 -0700 | [diff] [blame] | 1385 | rcu_sysidle_report_gp(rsp, isidle, maxj); |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 1386 | fqs_state = RCU_FORCE_QS; |
| 1387 | } else { |
| 1388 | /* Handle dyntick-idle and offline CPUs. */ |
Paul E. McKenney | 0edd1b1 | 2013-06-21 16:37:22 -0700 | [diff] [blame] | 1389 | isidle = 0; |
Paul E. McKenney | 217af2a | 2013-06-21 15:39:06 -0700 | [diff] [blame] | 1390 | force_qs_rnp(rsp, rcu_implicit_dynticks_qs, &isidle, &maxj); |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 1391 | } |
| 1392 | /* Clear flag to prevent immediate re-entry. */ |
| 1393 | if (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) { |
| 1394 | raw_spin_lock_irq(&rnp->lock); |
| 1395 | rsp->gp_flags &= ~RCU_GP_FLAG_FQS; |
| 1396 | raw_spin_unlock_irq(&rnp->lock); |
| 1397 | } |
| 1398 | return fqs_state; |
| 1399 | } |
| 1400 | |
| 1401 | /* |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1402 | * Clean up after the old grace period. |
| 1403 | */ |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 1404 | static void rcu_gp_cleanup(struct rcu_state *rsp) |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1405 | { |
| 1406 | unsigned long gp_duration; |
Paul E. McKenney | dae6e64 | 2013-02-10 20:48:58 -0800 | [diff] [blame] | 1407 | int nocb = 0; |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1408 | struct rcu_data *rdp; |
| 1409 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 1410 | |
| 1411 | raw_spin_lock_irq(&rnp->lock); |
| 1412 | gp_duration = jiffies - rsp->gp_start; |
| 1413 | if (gp_duration > rsp->gp_max) |
| 1414 | rsp->gp_max = gp_duration; |
| 1415 | |
| 1416 | /* |
| 1417 | * We know the grace period is complete, but to everyone else |
| 1418 | * it appears to still be ongoing. But it is also the case |
| 1419 | * that to everyone else it looks like there is nothing that |
| 1420 | * they can do to advance the grace period. It is therefore |
| 1421 | * safe for us to drop the lock in order to mark the grace |
| 1422 | * period as completed in all of the rcu_node structures. |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1423 | */ |
Paul E. McKenney | 5d4b865 | 2012-07-07 07:56:57 -0700 | [diff] [blame] | 1424 | raw_spin_unlock_irq(&rnp->lock); |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1425 | |
Paul E. McKenney | 5d4b865 | 2012-07-07 07:56:57 -0700 | [diff] [blame] | 1426 | /* |
| 1427 | * Propagate new ->completed value to rcu_node structures so |
| 1428 | * that other CPUs don't have to wait until the start of the next |
| 1429 | * grace period to process their callbacks. This also avoids |
| 1430 | * some nasty RCU grace-period initialization races by forcing |
| 1431 | * the end of the current grace period to be completely recorded in |
| 1432 | * all of the rcu_node structures before the beginning of the next |
| 1433 | * grace period is recorded in any of the rcu_node structures. |
| 1434 | */ |
| 1435 | rcu_for_each_node_breadth_first(rsp, rnp) { |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1436 | raw_spin_lock_irq(&rnp->lock); |
Paul E. McKenney | 0446be4 | 2012-12-30 15:21:01 -0800 | [diff] [blame] | 1437 | ACCESS_ONCE(rnp->completed) = rsp->gpnum; |
Paul E. McKenney | b11cc57 | 2012-12-17 14:21:14 -0800 | [diff] [blame] | 1438 | rdp = this_cpu_ptr(rsp->rda); |
| 1439 | if (rnp == rdp->mynode) |
Paul E. McKenney | 470716f | 2013-03-19 11:32:11 -0700 | [diff] [blame] | 1440 | __note_gp_changes(rsp, rnp, rdp); |
Paul E. McKenney | 0446be4 | 2012-12-30 15:21:01 -0800 | [diff] [blame] | 1441 | nocb += rcu_future_gp_cleanup(rsp, rnp); |
Paul E. McKenney | 5d4b865 | 2012-07-07 07:56:57 -0700 | [diff] [blame] | 1442 | raw_spin_unlock_irq(&rnp->lock); |
| 1443 | cond_resched(); |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1444 | } |
Paul E. McKenney | 5d4b865 | 2012-07-07 07:56:57 -0700 | [diff] [blame] | 1445 | rnp = rcu_get_root(rsp); |
| 1446 | raw_spin_lock_irq(&rnp->lock); |
Paul E. McKenney | dae6e64 | 2013-02-10 20:48:58 -0800 | [diff] [blame] | 1447 | rcu_nocb_gp_set(rnp, nocb); |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1448 | |
| 1449 | rsp->completed = rsp->gpnum; /* Declare grace period done. */ |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 1450 | trace_rcu_grace_period(rsp->name, rsp->completed, TPS("end")); |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1451 | rsp->fqs_state = RCU_GP_IDLE; |
Paul E. McKenney | 5d4b865 | 2012-07-07 07:56:57 -0700 | [diff] [blame] | 1452 | rdp = this_cpu_ptr(rsp->rda); |
Paul E. McKenney | b11cc57 | 2012-12-17 14:21:14 -0800 | [diff] [blame] | 1453 | rcu_advance_cbs(rsp, rnp, rdp); /* Reduce false positives below. */ |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1454 | if (cpu_needs_another_gp(rsp, rdp)) |
| 1455 | rsp->gp_flags = 1; |
| 1456 | raw_spin_unlock_irq(&rnp->lock); |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1457 | } |
| 1458 | |
| 1459 | /* |
Paul E. McKenney | b3dbec7 | 2012-06-18 18:36:08 -0700 | [diff] [blame] | 1460 | * Body of kthread that handles grace periods. |
| 1461 | */ |
Paul E. McKenney | 755609a | 2012-06-19 17:18:20 -0700 | [diff] [blame] | 1462 | static int __noreturn rcu_gp_kthread(void *arg) |
Paul E. McKenney | b3dbec7 | 2012-06-18 18:36:08 -0700 | [diff] [blame] | 1463 | { |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 1464 | int fqs_state; |
Paul E. McKenney | d40011f | 2012-06-26 20:45:57 -0700 | [diff] [blame] | 1465 | unsigned long j; |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 1466 | int ret; |
Paul E. McKenney | b3dbec7 | 2012-06-18 18:36:08 -0700 | [diff] [blame] | 1467 | struct rcu_state *rsp = arg; |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1468 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | b3dbec7 | 2012-06-18 18:36:08 -0700 | [diff] [blame] | 1469 | |
| 1470 | for (;;) { |
| 1471 | |
| 1472 | /* Handle grace-period start. */ |
Paul E. McKenney | b3dbec7 | 2012-06-18 18:36:08 -0700 | [diff] [blame] | 1473 | for (;;) { |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 1474 | wait_event_interruptible(rsp->gp_wq, |
| 1475 | rsp->gp_flags & |
| 1476 | RCU_GP_FLAG_INIT); |
| 1477 | if ((rsp->gp_flags & RCU_GP_FLAG_INIT) && |
| 1478 | rcu_gp_init(rsp)) |
Paul E. McKenney | b3dbec7 | 2012-06-18 18:36:08 -0700 | [diff] [blame] | 1479 | break; |
Paul E. McKenney | 7fdefc1 | 2012-06-22 11:08:41 -0700 | [diff] [blame] | 1480 | cond_resched(); |
Paul E. McKenney | b3dbec7 | 2012-06-18 18:36:08 -0700 | [diff] [blame] | 1481 | flush_signals(current); |
| 1482 | } |
Paul E. McKenney | cabc49c | 2012-06-20 17:07:14 -0700 | [diff] [blame] | 1483 | |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 1484 | /* Handle quiescent-state forcing. */ |
| 1485 | fqs_state = RCU_SAVE_DYNTICK; |
Paul E. McKenney | d40011f | 2012-06-26 20:45:57 -0700 | [diff] [blame] | 1486 | j = jiffies_till_first_fqs; |
| 1487 | if (j > HZ) { |
| 1488 | j = HZ; |
| 1489 | jiffies_till_first_fqs = HZ; |
| 1490 | } |
Paul E. McKenney | cabc49c | 2012-06-20 17:07:14 -0700 | [diff] [blame] | 1491 | for (;;) { |
Paul E. McKenney | d40011f | 2012-06-26 20:45:57 -0700 | [diff] [blame] | 1492 | rsp->jiffies_force_qs = jiffies + j; |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 1493 | ret = wait_event_interruptible_timeout(rsp->gp_wq, |
| 1494 | (rsp->gp_flags & RCU_GP_FLAG_FQS) || |
| 1495 | (!ACCESS_ONCE(rnp->qsmask) && |
| 1496 | !rcu_preempt_blocked_readers_cgp(rnp)), |
Paul E. McKenney | d40011f | 2012-06-26 20:45:57 -0700 | [diff] [blame] | 1497 | j); |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 1498 | /* If grace period done, leave loop. */ |
Paul E. McKenney | cabc49c | 2012-06-20 17:07:14 -0700 | [diff] [blame] | 1499 | if (!ACCESS_ONCE(rnp->qsmask) && |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 1500 | !rcu_preempt_blocked_readers_cgp(rnp)) |
Paul E. McKenney | cabc49c | 2012-06-20 17:07:14 -0700 | [diff] [blame] | 1501 | break; |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 1502 | /* If time for quiescent-state forcing, do it. */ |
| 1503 | if (ret == 0 || (rsp->gp_flags & RCU_GP_FLAG_FQS)) { |
| 1504 | fqs_state = rcu_gp_fqs(rsp, fqs_state); |
| 1505 | cond_resched(); |
| 1506 | } else { |
| 1507 | /* Deal with stray signal. */ |
| 1508 | cond_resched(); |
| 1509 | flush_signals(current); |
| 1510 | } |
Paul E. McKenney | d40011f | 2012-06-26 20:45:57 -0700 | [diff] [blame] | 1511 | j = jiffies_till_next_fqs; |
| 1512 | if (j > HZ) { |
| 1513 | j = HZ; |
| 1514 | jiffies_till_next_fqs = HZ; |
| 1515 | } else if (j < 1) { |
| 1516 | j = 1; |
| 1517 | jiffies_till_next_fqs = 1; |
| 1518 | } |
Paul E. McKenney | cabc49c | 2012-06-20 17:07:14 -0700 | [diff] [blame] | 1519 | } |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 1520 | |
| 1521 | /* Handle grace-period end. */ |
| 1522 | rcu_gp_cleanup(rsp); |
Paul E. McKenney | b3dbec7 | 2012-06-18 18:36:08 -0700 | [diff] [blame] | 1523 | } |
Paul E. McKenney | b3dbec7 | 2012-06-18 18:36:08 -0700 | [diff] [blame] | 1524 | } |
| 1525 | |
Steven Rostedt | 016a8d5 | 2013-05-28 17:32:53 -0400 | [diff] [blame] | 1526 | static void rsp_wakeup(struct irq_work *work) |
| 1527 | { |
| 1528 | struct rcu_state *rsp = container_of(work, struct rcu_state, wakeup_work); |
| 1529 | |
| 1530 | /* Wake up rcu_gp_kthread() to start the grace period. */ |
| 1531 | wake_up(&rsp->gp_wq); |
| 1532 | } |
| 1533 | |
Paul E. McKenney | b3dbec7 | 2012-06-18 18:36:08 -0700 | [diff] [blame] | 1534 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1535 | * Start a new RCU grace period if warranted, re-initializing the hierarchy |
| 1536 | * in preparation for detecting the next grace period. The caller must hold |
Paul E. McKenney | b846208 | 2012-12-29 22:04:18 -0800 | [diff] [blame] | 1537 | * the root node's ->lock and hard irqs must be disabled. |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1538 | * |
| 1539 | * Note that it is legal for a dying CPU (which is marked as offline) to |
| 1540 | * invoke this function. This can happen when the dying CPU reports its |
| 1541 | * quiescent state. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1542 | */ |
| 1543 | static void |
Paul E. McKenney | 910ee45 | 2012-12-31 02:24:21 -0800 | [diff] [blame] | 1544 | rcu_start_gp_advanced(struct rcu_state *rsp, struct rcu_node *rnp, |
| 1545 | struct rcu_data *rdp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1546 | { |
Paul E. McKenney | b846208 | 2012-12-29 22:04:18 -0800 | [diff] [blame] | 1547 | if (!rsp->gp_kthread || !cpu_needs_another_gp(rsp, rdp)) { |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 1548 | /* |
Paul E. McKenney | b3dbec7 | 2012-06-18 18:36:08 -0700 | [diff] [blame] | 1549 | * Either we have not yet spawned the grace-period |
Paul E. McKenney | 62da192 | 2012-09-20 16:02:49 -0700 | [diff] [blame] | 1550 | * task, this CPU does not need another grace period, |
| 1551 | * or a grace period is already in progress. |
Paul E. McKenney | b3dbec7 | 2012-06-18 18:36:08 -0700 | [diff] [blame] | 1552 | * Either way, don't start a new grace period. |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 1553 | */ |
Paul E. McKenney | afe24b1 | 2011-08-24 16:52:09 -0700 | [diff] [blame] | 1554 | return; |
| 1555 | } |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 1556 | rsp->gp_flags = RCU_GP_FLAG_INIT; |
Paul E. McKenney | 62da192 | 2012-09-20 16:02:49 -0700 | [diff] [blame] | 1557 | |
Steven Rostedt | 016a8d5 | 2013-05-28 17:32:53 -0400 | [diff] [blame] | 1558 | /* |
| 1559 | * We can't do wakeups while holding the rnp->lock, as that |
Paul E. McKenney | 1eafd31 | 2013-06-20 13:50:40 -0700 | [diff] [blame] | 1560 | * could cause possible deadlocks with the rq->lock. Defer |
| 1561 | * the wakeup to interrupt context. And don't bother waking |
| 1562 | * up the running kthread. |
Steven Rostedt | 016a8d5 | 2013-05-28 17:32:53 -0400 | [diff] [blame] | 1563 | */ |
Paul E. McKenney | 1eafd31 | 2013-06-20 13:50:40 -0700 | [diff] [blame] | 1564 | if (current != rsp->gp_kthread) |
| 1565 | irq_work_queue(&rsp->wakeup_work); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1566 | } |
| 1567 | |
| 1568 | /* |
Paul E. McKenney | 910ee45 | 2012-12-31 02:24:21 -0800 | [diff] [blame] | 1569 | * Similar to rcu_start_gp_advanced(), but also advance the calling CPU's |
| 1570 | * callbacks. Note that rcu_start_gp_advanced() cannot do this because it |
| 1571 | * is invoked indirectly from rcu_advance_cbs(), which would result in |
| 1572 | * endless recursion -- or would do so if it wasn't for the self-deadlock |
| 1573 | * that is encountered beforehand. |
| 1574 | */ |
| 1575 | static void |
| 1576 | rcu_start_gp(struct rcu_state *rsp) |
| 1577 | { |
| 1578 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); |
| 1579 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 1580 | |
| 1581 | /* |
| 1582 | * If there is no grace period in progress right now, any |
| 1583 | * callbacks we have up to this point will be satisfied by the |
| 1584 | * next grace period. Also, advancing the callbacks reduces the |
| 1585 | * probability of false positives from cpu_needs_another_gp() |
| 1586 | * resulting in pointless grace periods. So, advance callbacks |
| 1587 | * then start the grace period! |
| 1588 | */ |
| 1589 | rcu_advance_cbs(rsp, rnp, rdp); |
| 1590 | rcu_start_gp_advanced(rsp, rnp, rdp); |
| 1591 | } |
| 1592 | |
| 1593 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1594 | * Report a full set of quiescent states to the specified rcu_state |
| 1595 | * data structure. This involves cleaning up after the prior grace |
| 1596 | * period and letting rcu_start_gp() start up the next grace period |
Paul E. McKenney | b846208 | 2012-12-29 22:04:18 -0800 | [diff] [blame] | 1597 | * if one is needed. Note that the caller must hold rnp->lock, which |
| 1598 | * is released before return. |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1599 | */ |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1600 | static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags) |
Paul E. McKenney | fc2219d4 | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 1601 | __releases(rcu_get_root(rsp)->lock) |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1602 | { |
Paul E. McKenney | fc2219d4 | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 1603 | WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); |
Paul E. McKenney | cabc49c | 2012-06-20 17:07:14 -0700 | [diff] [blame] | 1604 | raw_spin_unlock_irqrestore(&rcu_get_root(rsp)->lock, flags); |
| 1605 | wake_up(&rsp->gp_wq); /* Memory barrier implied by wake_up() path. */ |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1606 | } |
| 1607 | |
| 1608 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1609 | * Similar to rcu_report_qs_rdp(), for which it is a helper function. |
| 1610 | * Allows quiescent states for a group of CPUs to be reported at one go |
| 1611 | * to the specified rcu_node structure, though all the CPUs in the group |
| 1612 | * must be represented by the same rcu_node structure (which need not be |
| 1613 | * a leaf rcu_node structure, though it often will be). That structure's |
| 1614 | * lock must be held upon entry, and it is released before return. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1615 | */ |
| 1616 | static void |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1617 | rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp, |
| 1618 | struct rcu_node *rnp, unsigned long flags) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1619 | __releases(rnp->lock) |
| 1620 | { |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 1621 | struct rcu_node *rnp_c; |
| 1622 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1623 | /* Walk up the rcu_node hierarchy. */ |
| 1624 | for (;;) { |
| 1625 | if (!(rnp->qsmask & mask)) { |
| 1626 | |
| 1627 | /* Our bit has already been cleared, so done. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1628 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1629 | return; |
| 1630 | } |
| 1631 | rnp->qsmask &= ~mask; |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 1632 | trace_rcu_quiescent_state_report(rsp->name, rnp->gpnum, |
| 1633 | mask, rnp->qsmask, rnp->level, |
| 1634 | rnp->grplo, rnp->grphi, |
| 1635 | !!rnp->gp_tasks); |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1636 | if (rnp->qsmask != 0 || rcu_preempt_blocked_readers_cgp(rnp)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1637 | |
| 1638 | /* Other bits still set at this level, so done. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1639 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1640 | return; |
| 1641 | } |
| 1642 | mask = rnp->grpmask; |
| 1643 | if (rnp->parent == NULL) { |
| 1644 | |
| 1645 | /* No more levels. Exit loop holding root lock. */ |
| 1646 | |
| 1647 | break; |
| 1648 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1649 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 1650 | rnp_c = rnp; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1651 | rnp = rnp->parent; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1652 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 1653 | WARN_ON_ONCE(rnp_c->qsmask); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1654 | } |
| 1655 | |
| 1656 | /* |
| 1657 | * Get here if we are the last CPU to pass through a quiescent |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1658 | * state for this grace period. Invoke rcu_report_qs_rsp() |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1659 | * to clean up and start the next grace period if one is needed. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1660 | */ |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1661 | rcu_report_qs_rsp(rsp, flags); /* releases rnp->lock. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1662 | } |
| 1663 | |
| 1664 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1665 | * Record a quiescent state for the specified CPU to that CPU's rcu_data |
| 1666 | * structure. This must be either called from the specified CPU, or |
| 1667 | * called when the specified CPU is known to be offline (and when it is |
| 1668 | * also known that no other CPU is concurrently trying to help the offline |
| 1669 | * CPU). The lastcomp argument is used to make sure we are still in the |
| 1670 | * grace period of interest. We don't want to end the current grace period |
| 1671 | * based on quiescent states detected in an earlier grace period! |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1672 | */ |
| 1673 | static void |
Paul E. McKenney | d7d6a11 | 2012-08-21 15:00:05 -0700 | [diff] [blame] | 1674 | rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1675 | { |
| 1676 | unsigned long flags; |
| 1677 | unsigned long mask; |
| 1678 | struct rcu_node *rnp; |
| 1679 | |
| 1680 | rnp = rdp->mynode; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1681 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | d7d6a11 | 2012-08-21 15:00:05 -0700 | [diff] [blame] | 1682 | if (rdp->passed_quiesce == 0 || rdp->gpnum != rnp->gpnum || |
| 1683 | rnp->completed == rnp->gpnum) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1684 | |
| 1685 | /* |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1686 | * The grace period in which this quiescent state was |
| 1687 | * recorded has ended, so don't report it upwards. |
| 1688 | * We will instead need a new quiescent state that lies |
| 1689 | * within the current grace period. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1690 | */ |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1691 | rdp->passed_quiesce = 0; /* need qs for new gp. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1692 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1693 | return; |
| 1694 | } |
| 1695 | mask = rdp->grpmask; |
| 1696 | if ((rnp->qsmask & mask) == 0) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1697 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1698 | } else { |
| 1699 | rdp->qs_pending = 0; |
| 1700 | |
| 1701 | /* |
| 1702 | * This GP can't end until cpu checks in, so all of our |
| 1703 | * callbacks can be processed during the next GP. |
| 1704 | */ |
Paul E. McKenney | dc35c89 | 2012-12-03 13:52:00 -0800 | [diff] [blame] | 1705 | rcu_accelerate_cbs(rsp, rnp, rdp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1706 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1707 | rcu_report_qs_rnp(mask, rsp, rnp, flags); /* rlses rnp->lock */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1708 | } |
| 1709 | } |
| 1710 | |
| 1711 | /* |
| 1712 | * Check to see if there is a new grace period of which this CPU |
| 1713 | * is not yet aware, and if so, set up local rcu_data state for it. |
| 1714 | * Otherwise, see if this CPU has just passed through its first |
| 1715 | * quiescent state for this grace period, and record that fact if so. |
| 1716 | */ |
| 1717 | static void |
| 1718 | rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp) |
| 1719 | { |
Paul E. McKenney | 05eb552 | 2013-03-19 12:38:24 -0700 | [diff] [blame] | 1720 | /* Check for grace-period ends and beginnings. */ |
| 1721 | note_gp_changes(rsp, rdp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1722 | |
| 1723 | /* |
| 1724 | * Does this CPU still need to do its part for current grace period? |
| 1725 | * If no, return and let the other CPUs do their part as well. |
| 1726 | */ |
| 1727 | if (!rdp->qs_pending) |
| 1728 | return; |
| 1729 | |
| 1730 | /* |
| 1731 | * Was there a quiescent state since the beginning of the grace |
| 1732 | * period? If no, then exit and wait for the next call. |
| 1733 | */ |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1734 | if (!rdp->passed_quiesce) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1735 | return; |
| 1736 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1737 | /* |
| 1738 | * Tell RCU we are done (but rcu_report_qs_rdp() will be the |
| 1739 | * judge of that). |
| 1740 | */ |
Paul E. McKenney | d7d6a11 | 2012-08-21 15:00:05 -0700 | [diff] [blame] | 1741 | rcu_report_qs_rdp(rdp->cpu, rsp, rdp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1742 | } |
| 1743 | |
| 1744 | #ifdef CONFIG_HOTPLUG_CPU |
| 1745 | |
| 1746 | /* |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1747 | * Send the specified CPU's RCU callbacks to the orphanage. The |
| 1748 | * specified CPU must be offline, and the caller must hold the |
Paul E. McKenney | 7b2e601 | 2012-10-08 10:54:03 -0700 | [diff] [blame] | 1749 | * ->orphan_lock. |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1750 | */ |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1751 | static void |
| 1752 | rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp, |
| 1753 | struct rcu_node *rnp, struct rcu_data *rdp) |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1754 | { |
Paul E. McKenney | 3fbfbf7 | 2012-08-19 21:35:53 -0700 | [diff] [blame] | 1755 | /* No-CBs CPUs do not have orphanable callbacks. */ |
Frederic Weisbecker | d1e43fa | 2013-03-26 23:47:24 +0100 | [diff] [blame] | 1756 | if (rcu_is_nocb_cpu(rdp->cpu)) |
Paul E. McKenney | 3fbfbf7 | 2012-08-19 21:35:53 -0700 | [diff] [blame] | 1757 | return; |
| 1758 | |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1759 | /* |
| 1760 | * Orphan the callbacks. First adjust the counts. This is safe |
Paul E. McKenney | abfd6e5 | 2012-09-20 16:59:47 -0700 | [diff] [blame] | 1761 | * because _rcu_barrier() excludes CPU-hotplug operations, so it |
| 1762 | * cannot be running now. Thus no memory barrier is required. |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1763 | */ |
Paul E. McKenney | a50c3af | 2012-01-10 17:52:31 -0800 | [diff] [blame] | 1764 | if (rdp->nxtlist != NULL) { |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1765 | rsp->qlen_lazy += rdp->qlen_lazy; |
| 1766 | rsp->qlen += rdp->qlen; |
| 1767 | rdp->n_cbs_orphaned += rdp->qlen; |
Paul E. McKenney | a50c3af | 2012-01-10 17:52:31 -0800 | [diff] [blame] | 1768 | rdp->qlen_lazy = 0; |
Paul E. McKenney | 1d1fb39 | 2012-05-09 15:44:42 -0700 | [diff] [blame] | 1769 | ACCESS_ONCE(rdp->qlen) = 0; |
Paul E. McKenney | a50c3af | 2012-01-10 17:52:31 -0800 | [diff] [blame] | 1770 | } |
| 1771 | |
| 1772 | /* |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1773 | * Next, move those callbacks still needing a grace period to |
| 1774 | * the orphanage, where some other CPU will pick them up. |
| 1775 | * Some of the callbacks might have gone partway through a grace |
| 1776 | * period, but that is too bad. They get to start over because we |
| 1777 | * cannot assume that grace periods are synchronized across CPUs. |
| 1778 | * We don't bother updating the ->nxttail[] array yet, instead |
| 1779 | * we just reset the whole thing later on. |
Paul E. McKenney | a50c3af | 2012-01-10 17:52:31 -0800 | [diff] [blame] | 1780 | */ |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1781 | if (*rdp->nxttail[RCU_DONE_TAIL] != NULL) { |
| 1782 | *rsp->orphan_nxttail = *rdp->nxttail[RCU_DONE_TAIL]; |
| 1783 | rsp->orphan_nxttail = rdp->nxttail[RCU_NEXT_TAIL]; |
| 1784 | *rdp->nxttail[RCU_DONE_TAIL] = NULL; |
Paul E. McKenney | a50c3af | 2012-01-10 17:52:31 -0800 | [diff] [blame] | 1785 | } |
| 1786 | |
| 1787 | /* |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1788 | * Then move the ready-to-invoke callbacks to the orphanage, |
| 1789 | * where some other CPU will pick them up. These will not be |
| 1790 | * required to pass though another grace period: They are done. |
Paul E. McKenney | a50c3af | 2012-01-10 17:52:31 -0800 | [diff] [blame] | 1791 | */ |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1792 | if (rdp->nxtlist != NULL) { |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1793 | *rsp->orphan_donetail = rdp->nxtlist; |
| 1794 | rsp->orphan_donetail = rdp->nxttail[RCU_DONE_TAIL]; |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1795 | } |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1796 | |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1797 | /* Finally, initialize the rcu_data structure's list to empty. */ |
Paul E. McKenney | 3f5d3ea | 2012-05-09 15:39:56 -0700 | [diff] [blame] | 1798 | init_callback_list(rdp); |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1799 | } |
| 1800 | |
| 1801 | /* |
| 1802 | * Adopt the RCU callbacks from the specified rcu_state structure's |
Paul E. McKenney | 7b2e601 | 2012-10-08 10:54:03 -0700 | [diff] [blame] | 1803 | * orphanage. The caller must hold the ->orphan_lock. |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1804 | */ |
| 1805 | static void rcu_adopt_orphan_cbs(struct rcu_state *rsp) |
| 1806 | { |
| 1807 | int i; |
| 1808 | struct rcu_data *rdp = __this_cpu_ptr(rsp->rda); |
| 1809 | |
Paul E. McKenney | 3fbfbf7 | 2012-08-19 21:35:53 -0700 | [diff] [blame] | 1810 | /* No-CBs CPUs are handled specially. */ |
| 1811 | if (rcu_nocb_adopt_orphan_cbs(rsp, rdp)) |
| 1812 | return; |
| 1813 | |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1814 | /* Do the accounting first. */ |
| 1815 | rdp->qlen_lazy += rsp->qlen_lazy; |
| 1816 | rdp->qlen += rsp->qlen; |
| 1817 | rdp->n_cbs_adopted += rsp->qlen; |
Paul E. McKenney | 8f5af6f | 2012-05-04 08:31:53 -0700 | [diff] [blame] | 1818 | if (rsp->qlen_lazy != rsp->qlen) |
| 1819 | rcu_idle_count_callbacks_posted(); |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1820 | rsp->qlen_lazy = 0; |
| 1821 | rsp->qlen = 0; |
| 1822 | |
| 1823 | /* |
| 1824 | * We do not need a memory barrier here because the only way we |
| 1825 | * can get here if there is an rcu_barrier() in flight is if |
| 1826 | * we are the task doing the rcu_barrier(). |
| 1827 | */ |
| 1828 | |
| 1829 | /* First adopt the ready-to-invoke callbacks. */ |
| 1830 | if (rsp->orphan_donelist != NULL) { |
| 1831 | *rsp->orphan_donetail = *rdp->nxttail[RCU_DONE_TAIL]; |
| 1832 | *rdp->nxttail[RCU_DONE_TAIL] = rsp->orphan_donelist; |
| 1833 | for (i = RCU_NEXT_SIZE - 1; i >= RCU_DONE_TAIL; i--) |
| 1834 | if (rdp->nxttail[i] == rdp->nxttail[RCU_DONE_TAIL]) |
| 1835 | rdp->nxttail[i] = rsp->orphan_donetail; |
| 1836 | rsp->orphan_donelist = NULL; |
| 1837 | rsp->orphan_donetail = &rsp->orphan_donelist; |
| 1838 | } |
| 1839 | |
| 1840 | /* And then adopt the callbacks that still need a grace period. */ |
| 1841 | if (rsp->orphan_nxtlist != NULL) { |
| 1842 | *rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_nxtlist; |
| 1843 | rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_nxttail; |
| 1844 | rsp->orphan_nxtlist = NULL; |
| 1845 | rsp->orphan_nxttail = &rsp->orphan_nxtlist; |
| 1846 | } |
| 1847 | } |
| 1848 | |
| 1849 | /* |
| 1850 | * Trace the fact that this CPU is going offline. |
| 1851 | */ |
| 1852 | static void rcu_cleanup_dying_cpu(struct rcu_state *rsp) |
| 1853 | { |
| 1854 | RCU_TRACE(unsigned long mask); |
| 1855 | RCU_TRACE(struct rcu_data *rdp = this_cpu_ptr(rsp->rda)); |
| 1856 | RCU_TRACE(struct rcu_node *rnp = rdp->mynode); |
| 1857 | |
| 1858 | RCU_TRACE(mask = rdp->grpmask); |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1859 | trace_rcu_grace_period(rsp->name, |
| 1860 | rnp->gpnum + 1 - !!(rnp->qsmask & mask), |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 1861 | TPS("cpuofl")); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1862 | } |
| 1863 | |
| 1864 | /* |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1865 | * The CPU has been completely removed, and some other CPU is reporting |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1866 | * this fact from process context. Do the remainder of the cleanup, |
| 1867 | * including orphaning the outgoing CPU's RCU callbacks, and also |
Paul E. McKenney | 1331e7a | 2012-08-02 17:43:50 -0700 | [diff] [blame] | 1868 | * adopting them. There can only be one CPU hotplug operation at a time, |
| 1869 | * so no other CPU can be attempting to update rcu_cpu_kthread_task. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1870 | */ |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1871 | static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1872 | { |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 1873 | unsigned long flags; |
| 1874 | unsigned long mask; |
| 1875 | int need_report = 0; |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1876 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1877 | struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rdp & rnp. */ |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1878 | |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 1879 | /* Adjust any no-longer-needed kthreads. */ |
Thomas Gleixner | 5d01bbd | 2012-07-16 10:42:35 +0000 | [diff] [blame] | 1880 | rcu_boost_kthread_setaffinity(rnp, -1); |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 1881 | |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1882 | /* Remove the dead CPU from the bitmasks in the rcu_node hierarchy. */ |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 1883 | |
| 1884 | /* Exclude any attempts to start a new grace period. */ |
Paul E. McKenney | a4fbe35 | 2012-10-07 08:36:12 -0700 | [diff] [blame] | 1885 | mutex_lock(&rsp->onoff_mutex); |
Paul E. McKenney | 7b2e601 | 2012-10-08 10:54:03 -0700 | [diff] [blame] | 1886 | raw_spin_lock_irqsave(&rsp->orphan_lock, flags); |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 1887 | |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 1888 | /* Orphan the dead CPU's callbacks, and adopt them if appropriate. */ |
| 1889 | rcu_send_cbs_to_orphanage(cpu, rsp, rnp, rdp); |
| 1890 | rcu_adopt_orphan_cbs(rsp); |
| 1891 | |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 1892 | /* Remove the outgoing CPU from the masks in the rcu_node hierarchy. */ |
| 1893 | mask = rdp->grpmask; /* rnp->grplo is constant. */ |
| 1894 | do { |
| 1895 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
| 1896 | rnp->qsmaskinit &= ~mask; |
| 1897 | if (rnp->qsmaskinit != 0) { |
| 1898 | if (rnp != rdp->mynode) |
| 1899 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
| 1900 | break; |
| 1901 | } |
| 1902 | if (rnp == rdp->mynode) |
| 1903 | need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp); |
| 1904 | else |
| 1905 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
| 1906 | mask = rnp->grpmask; |
| 1907 | rnp = rnp->parent; |
| 1908 | } while (rnp != NULL); |
| 1909 | |
| 1910 | /* |
| 1911 | * We still hold the leaf rcu_node structure lock here, and |
| 1912 | * irqs are still disabled. The reason for this subterfuge is |
Paul E. McKenney | 7b2e601 | 2012-10-08 10:54:03 -0700 | [diff] [blame] | 1913 | * because invoking rcu_report_unblock_qs_rnp() with ->orphan_lock |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 1914 | * held leads to deadlock. |
| 1915 | */ |
Paul E. McKenney | 7b2e601 | 2012-10-08 10:54:03 -0700 | [diff] [blame] | 1916 | raw_spin_unlock(&rsp->orphan_lock); /* irqs remain disabled. */ |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 1917 | rnp = rdp->mynode; |
| 1918 | if (need_report & RCU_OFL_TASKS_NORM_GP) |
| 1919 | rcu_report_unblock_qs_rnp(rnp, flags); |
| 1920 | else |
| 1921 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
| 1922 | if (need_report & RCU_OFL_TASKS_EXP_GP) |
| 1923 | rcu_report_exp_rnp(rsp, rnp, true); |
Paul E. McKenney | cf01537 | 2012-06-21 11:26:42 -0700 | [diff] [blame] | 1924 | WARN_ONCE(rdp->qlen != 0 || rdp->nxtlist != NULL, |
| 1925 | "rcu_cleanup_dead_cpu: Callbacks on offline CPU %d: qlen=%lu, nxtlist=%p\n", |
| 1926 | cpu, rdp->qlen, rdp->nxtlist); |
Paul E. McKenney | 0d8ee37 | 2012-08-03 13:16:15 -0700 | [diff] [blame] | 1927 | init_callback_list(rdp); |
| 1928 | /* Disallow further callbacks on this CPU. */ |
| 1929 | rdp->nxttail[RCU_NEXT_TAIL] = NULL; |
Paul E. McKenney | a4fbe35 | 2012-10-07 08:36:12 -0700 | [diff] [blame] | 1930 | mutex_unlock(&rsp->onoff_mutex); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1931 | } |
| 1932 | |
| 1933 | #else /* #ifdef CONFIG_HOTPLUG_CPU */ |
| 1934 | |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1935 | static void rcu_cleanup_dying_cpu(struct rcu_state *rsp) |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1936 | { |
| 1937 | } |
| 1938 | |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1939 | static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1940 | { |
| 1941 | } |
| 1942 | |
| 1943 | #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */ |
| 1944 | |
| 1945 | /* |
| 1946 | * Invoke any RCU callbacks that have made it to the end of their grace |
| 1947 | * period. Thottle as specified by rdp->blimit. |
| 1948 | */ |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1949 | static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1950 | { |
| 1951 | unsigned long flags; |
| 1952 | struct rcu_head *next, *list, **tail; |
Eric Dumazet | 878d743 | 2012-10-18 04:55:36 -0700 | [diff] [blame] | 1953 | long bl, count, count_lazy; |
| 1954 | int i; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1955 | |
Paul E. McKenney | dc35c89 | 2012-12-03 13:52:00 -0800 | [diff] [blame] | 1956 | /* If no callbacks are ready, just return. */ |
Paul E. McKenney | 29c00b4 | 2011-06-17 15:53:19 -0700 | [diff] [blame] | 1957 | if (!cpu_has_callbacks_ready_to_invoke(rdp)) { |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1958 | trace_rcu_batch_start(rsp->name, rdp->qlen_lazy, rdp->qlen, 0); |
Paul E. McKenney | 4968c30 | 2011-12-07 16:32:40 -0800 | [diff] [blame] | 1959 | trace_rcu_batch_end(rsp->name, 0, !!ACCESS_ONCE(rdp->nxtlist), |
| 1960 | need_resched(), is_idle_task(current), |
| 1961 | rcu_is_callbacks_kthread()); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1962 | return; |
Paul E. McKenney | 29c00b4 | 2011-06-17 15:53:19 -0700 | [diff] [blame] | 1963 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1964 | |
| 1965 | /* |
| 1966 | * Extract the list of ready callbacks, disabling to prevent |
| 1967 | * races with call_rcu() from interrupt handlers. |
| 1968 | */ |
| 1969 | local_irq_save(flags); |
Paul E. McKenney | 8146c4e2 | 2012-01-10 14:23:29 -0800 | [diff] [blame] | 1970 | WARN_ON_ONCE(cpu_is_offline(smp_processor_id())); |
Paul E. McKenney | 29c00b4 | 2011-06-17 15:53:19 -0700 | [diff] [blame] | 1971 | bl = rdp->blimit; |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1972 | trace_rcu_batch_start(rsp->name, rdp->qlen_lazy, rdp->qlen, bl); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1973 | list = rdp->nxtlist; |
| 1974 | rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL]; |
| 1975 | *rdp->nxttail[RCU_DONE_TAIL] = NULL; |
| 1976 | tail = rdp->nxttail[RCU_DONE_TAIL]; |
Paul E. McKenney | b41772a | 2012-06-21 20:50:42 -0700 | [diff] [blame] | 1977 | for (i = RCU_NEXT_SIZE - 1; i >= 0; i--) |
| 1978 | if (rdp->nxttail[i] == rdp->nxttail[RCU_DONE_TAIL]) |
| 1979 | rdp->nxttail[i] = &rdp->nxtlist; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1980 | local_irq_restore(flags); |
| 1981 | |
| 1982 | /* Invoke callbacks. */ |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1983 | count = count_lazy = 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1984 | while (list) { |
| 1985 | next = list->next; |
| 1986 | prefetch(next); |
Mathieu Desnoyers | 551d55a | 2010-04-17 08:48:42 -0400 | [diff] [blame] | 1987 | debug_rcu_head_unqueue(list); |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1988 | if (__rcu_reclaim(rsp->name, list)) |
| 1989 | count_lazy++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1990 | list = next; |
Paul E. McKenney | dff1672 | 2011-11-29 15:57:13 -0800 | [diff] [blame] | 1991 | /* Stop only if limit reached and CPU has something to do. */ |
| 1992 | if (++count >= bl && |
| 1993 | (need_resched() || |
| 1994 | (!is_idle_task(current) && !rcu_is_callbacks_kthread()))) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1995 | break; |
| 1996 | } |
| 1997 | |
| 1998 | local_irq_save(flags); |
Paul E. McKenney | 4968c30 | 2011-12-07 16:32:40 -0800 | [diff] [blame] | 1999 | trace_rcu_batch_end(rsp->name, count, !!list, need_resched(), |
| 2000 | is_idle_task(current), |
| 2001 | rcu_is_callbacks_kthread()); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2002 | |
| 2003 | /* Update count, and requeue any remaining callbacks. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2004 | if (list != NULL) { |
| 2005 | *tail = rdp->nxtlist; |
| 2006 | rdp->nxtlist = list; |
Paul E. McKenney | b41772a | 2012-06-21 20:50:42 -0700 | [diff] [blame] | 2007 | for (i = 0; i < RCU_NEXT_SIZE; i++) |
| 2008 | if (&rdp->nxtlist == rdp->nxttail[i]) |
| 2009 | rdp->nxttail[i] = tail; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2010 | else |
| 2011 | break; |
| 2012 | } |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2013 | smp_mb(); /* List handling before counting for rcu_barrier(). */ |
| 2014 | rdp->qlen_lazy -= count_lazy; |
Paul E. McKenney | 1d1fb39 | 2012-05-09 15:44:42 -0700 | [diff] [blame] | 2015 | ACCESS_ONCE(rdp->qlen) -= count; |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2016 | rdp->n_cbs_invoked += count; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2017 | |
| 2018 | /* Reinstate batch limit if we have worked down the excess. */ |
| 2019 | if (rdp->blimit == LONG_MAX && rdp->qlen <= qlowmark) |
| 2020 | rdp->blimit = blimit; |
| 2021 | |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 2022 | /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */ |
| 2023 | if (rdp->qlen == 0 && rdp->qlen_last_fqs_check != 0) { |
| 2024 | rdp->qlen_last_fqs_check = 0; |
| 2025 | rdp->n_force_qs_snap = rsp->n_force_qs; |
| 2026 | } else if (rdp->qlen < rdp->qlen_last_fqs_check - qhimark) |
| 2027 | rdp->qlen_last_fqs_check = rdp->qlen; |
Paul E. McKenney | cfca927 | 2012-06-25 12:54:17 -0700 | [diff] [blame] | 2028 | WARN_ON_ONCE((rdp->nxtlist == NULL) != (rdp->qlen == 0)); |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 2029 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2030 | local_irq_restore(flags); |
| 2031 | |
Paul E. McKenney | e0f2306 | 2011-06-21 01:29:39 -0700 | [diff] [blame] | 2032 | /* Re-invoke RCU core processing if there are callbacks remaining. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2033 | if (cpu_has_callbacks_ready_to_invoke(rdp)) |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 2034 | invoke_rcu_core(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2035 | } |
| 2036 | |
| 2037 | /* |
| 2038 | * Check to see if this CPU is in a non-context-switch quiescent state |
| 2039 | * (user mode or idle loop for rcu, non-softirq execution for rcu_bh). |
Paul E. McKenney | e0f2306 | 2011-06-21 01:29:39 -0700 | [diff] [blame] | 2040 | * Also schedule RCU core processing. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2041 | * |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 2042 | * This function must be called from hardirq context. It is normally |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2043 | * invoked from the scheduling-clock interrupt. If rcu_pending returns |
| 2044 | * false, there is no point in invoking rcu_check_callbacks(). |
| 2045 | */ |
| 2046 | void rcu_check_callbacks(int cpu, int user) |
| 2047 | { |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 2048 | trace_rcu_utilization(TPS("Start scheduler-tick")); |
Paul E. McKenney | a858af2 | 2012-01-16 13:29:10 -0800 | [diff] [blame] | 2049 | increment_cpu_stall_ticks(); |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 2050 | if (user || rcu_is_cpu_rrupt_from_idle()) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2051 | |
| 2052 | /* |
| 2053 | * Get here if this CPU took its interrupt from user |
| 2054 | * mode or from the idle loop, and if this is not a |
| 2055 | * nested interrupt. In this case, the CPU is in |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 2056 | * a quiescent state, so note it. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2057 | * |
| 2058 | * No memory barrier is required here because both |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 2059 | * rcu_sched_qs() and rcu_bh_qs() reference only CPU-local |
| 2060 | * variables that other CPUs neither access nor modify, |
| 2061 | * at least not while the corresponding CPU is online. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2062 | */ |
| 2063 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 2064 | rcu_sched_qs(cpu); |
| 2065 | rcu_bh_qs(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2066 | |
| 2067 | } else if (!in_softirq()) { |
| 2068 | |
| 2069 | /* |
| 2070 | * Get here if this CPU did not take its interrupt from |
| 2071 | * softirq, in other words, if it is not interrupting |
| 2072 | * a rcu_bh read-side critical section. This is an _bh |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 2073 | * critical section, so note it. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2074 | */ |
| 2075 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 2076 | rcu_bh_qs(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2077 | } |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2078 | rcu_preempt_check_callbacks(cpu); |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 2079 | if (rcu_pending(cpu)) |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 2080 | invoke_rcu_core(); |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 2081 | trace_rcu_utilization(TPS("End scheduler-tick")); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2082 | } |
| 2083 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2084 | /* |
| 2085 | * Scan the leaf rcu_node structures, processing dyntick state for any that |
| 2086 | * have not yet encountered a quiescent state, using the function specified. |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 2087 | * Also initiate boosting for any threads blocked on the root rcu_node. |
| 2088 | * |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 2089 | * The caller must have suppressed start of new grace periods. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2090 | */ |
Paul E. McKenney | 217af2a | 2013-06-21 15:39:06 -0700 | [diff] [blame] | 2091 | static void force_qs_rnp(struct rcu_state *rsp, |
| 2092 | int (*f)(struct rcu_data *rsp, bool *isidle, |
| 2093 | unsigned long *maxj), |
| 2094 | bool *isidle, unsigned long *maxj) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2095 | { |
| 2096 | unsigned long bit; |
| 2097 | int cpu; |
| 2098 | unsigned long flags; |
| 2099 | unsigned long mask; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 2100 | struct rcu_node *rnp; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2101 | |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 2102 | rcu_for_each_leaf_node(rsp, rnp) { |
Paul E. McKenney | b4be093f | 2012-06-25 08:41:11 -0700 | [diff] [blame] | 2103 | cond_resched(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2104 | mask = 0; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2105 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 2106 | if (!rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2107 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 0f10dc82 | 2010-01-04 15:09:06 -0800 | [diff] [blame] | 2108 | return; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2109 | } |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 2110 | if (rnp->qsmask == 0) { |
Paul E. McKenney | 1217ed1 | 2011-05-04 21:43:49 -0700 | [diff] [blame] | 2111 | rcu_initiate_boost(rnp, flags); /* releases rnp->lock */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2112 | continue; |
| 2113 | } |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 2114 | cpu = rnp->grplo; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2115 | bit = 1; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 2116 | for (; cpu <= rnp->grphi; cpu++, bit <<= 1) { |
Paul E. McKenney | 0edd1b1 | 2013-06-21 16:37:22 -0700 | [diff] [blame] | 2117 | if ((rnp->qsmask & bit) != 0) { |
| 2118 | if ((rnp->qsmaskinit & bit) != 0) |
| 2119 | *isidle = 0; |
| 2120 | if (f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj)) |
| 2121 | mask |= bit; |
| 2122 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2123 | } |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 2124 | if (mask != 0) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2125 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 2126 | /* rcu_report_qs_rnp() releases rnp->lock. */ |
| 2127 | rcu_report_qs_rnp(mask, rsp, rnp, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2128 | continue; |
| 2129 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2130 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2131 | } |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 2132 | rnp = rcu_get_root(rsp); |
Paul E. McKenney | 1217ed1 | 2011-05-04 21:43:49 -0700 | [diff] [blame] | 2133 | if (rnp->qsmask == 0) { |
| 2134 | raw_spin_lock_irqsave(&rnp->lock, flags); |
| 2135 | rcu_initiate_boost(rnp, flags); /* releases rnp->lock. */ |
| 2136 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2137 | } |
| 2138 | |
| 2139 | /* |
| 2140 | * Force quiescent states on reluctant CPUs, and also detect which |
| 2141 | * CPUs are in dyntick-idle mode. |
| 2142 | */ |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 2143 | static void force_quiescent_state(struct rcu_state *rsp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2144 | { |
| 2145 | unsigned long flags; |
Paul E. McKenney | 394f276 | 2012-06-26 17:00:35 -0700 | [diff] [blame] | 2146 | bool ret; |
| 2147 | struct rcu_node *rnp; |
| 2148 | struct rcu_node *rnp_old = NULL; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2149 | |
Paul E. McKenney | 394f276 | 2012-06-26 17:00:35 -0700 | [diff] [blame] | 2150 | /* Funnel through hierarchy to reduce memory contention. */ |
| 2151 | rnp = per_cpu_ptr(rsp->rda, raw_smp_processor_id())->mynode; |
| 2152 | for (; rnp != NULL; rnp = rnp->parent) { |
| 2153 | ret = (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) || |
| 2154 | !raw_spin_trylock(&rnp->fqslock); |
| 2155 | if (rnp_old != NULL) |
| 2156 | raw_spin_unlock(&rnp_old->fqslock); |
| 2157 | if (ret) { |
| 2158 | rsp->n_force_qs_lh++; |
| 2159 | return; |
| 2160 | } |
| 2161 | rnp_old = rnp; |
| 2162 | } |
| 2163 | /* rnp_old == rcu_get_root(rsp), rnp == NULL. */ |
| 2164 | |
| 2165 | /* Reached the root of the rcu_node tree, acquire lock. */ |
| 2166 | raw_spin_lock_irqsave(&rnp_old->lock, flags); |
| 2167 | raw_spin_unlock(&rnp_old->fqslock); |
| 2168 | if (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) { |
| 2169 | rsp->n_force_qs_lh++; |
| 2170 | raw_spin_unlock_irqrestore(&rnp_old->lock, flags); |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 2171 | return; /* Someone beat us to it. */ |
Paul E. McKenney | 46a1e34 | 2010-01-04 15:09:09 -0800 | [diff] [blame] | 2172 | } |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 2173 | rsp->gp_flags |= RCU_GP_FLAG_FQS; |
Paul E. McKenney | 394f276 | 2012-06-26 17:00:35 -0700 | [diff] [blame] | 2174 | raw_spin_unlock_irqrestore(&rnp_old->lock, flags); |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 2175 | wake_up(&rsp->gp_wq); /* Memory barrier implied by wake_up() path. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2176 | } |
| 2177 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2178 | /* |
Paul E. McKenney | e0f2306 | 2011-06-21 01:29:39 -0700 | [diff] [blame] | 2179 | * This does the RCU core processing work for the specified rcu_state |
| 2180 | * and rcu_data structures. This may be called only from the CPU to |
| 2181 | * whom the rdp belongs. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2182 | */ |
| 2183 | static void |
Paul E. McKenney | 1bca8cf | 2012-06-12 09:40:38 -0700 | [diff] [blame] | 2184 | __rcu_process_callbacks(struct rcu_state *rsp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2185 | { |
| 2186 | unsigned long flags; |
Paul E. McKenney | 1bca8cf | 2012-06-12 09:40:38 -0700 | [diff] [blame] | 2187 | struct rcu_data *rdp = __this_cpu_ptr(rsp->rda); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2188 | |
Paul E. McKenney | 2e59755 | 2009-08-15 09:53:48 -0700 | [diff] [blame] | 2189 | WARN_ON_ONCE(rdp->beenonline == 0); |
| 2190 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2191 | /* Update RCU state based on any recent quiescent states. */ |
| 2192 | rcu_check_quiescent_state(rsp, rdp); |
| 2193 | |
| 2194 | /* Does this CPU require a not-yet-started grace period? */ |
Paul E. McKenney | dc35c89 | 2012-12-03 13:52:00 -0800 | [diff] [blame] | 2195 | local_irq_save(flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2196 | if (cpu_needs_another_gp(rsp, rdp)) { |
Paul E. McKenney | dc35c89 | 2012-12-03 13:52:00 -0800 | [diff] [blame] | 2197 | raw_spin_lock(&rcu_get_root(rsp)->lock); /* irqs disabled. */ |
Paul E. McKenney | b846208 | 2012-12-29 22:04:18 -0800 | [diff] [blame] | 2198 | rcu_start_gp(rsp); |
| 2199 | raw_spin_unlock_irqrestore(&rcu_get_root(rsp)->lock, flags); |
Paul E. McKenney | dc35c89 | 2012-12-03 13:52:00 -0800 | [diff] [blame] | 2200 | } else { |
| 2201 | local_irq_restore(flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2202 | } |
| 2203 | |
| 2204 | /* If there are callbacks ready, invoke them. */ |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 2205 | if (cpu_has_callbacks_ready_to_invoke(rdp)) |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 2206 | invoke_rcu_callbacks(rsp, rdp); |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 2207 | } |
| 2208 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2209 | /* |
Paul E. McKenney | e0f2306 | 2011-06-21 01:29:39 -0700 | [diff] [blame] | 2210 | * Do RCU core processing for the current CPU. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2211 | */ |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 2212 | static void rcu_process_callbacks(struct softirq_action *unused) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2213 | { |
Paul E. McKenney | 6ce75a2 | 2012-06-12 11:01:13 -0700 | [diff] [blame] | 2214 | struct rcu_state *rsp; |
| 2215 | |
Paul E. McKenney | bfa00b4 | 2012-06-21 09:54:10 -0700 | [diff] [blame] | 2216 | if (cpu_is_offline(smp_processor_id())) |
| 2217 | return; |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 2218 | trace_rcu_utilization(TPS("Start RCU core")); |
Paul E. McKenney | 6ce75a2 | 2012-06-12 11:01:13 -0700 | [diff] [blame] | 2219 | for_each_rcu_flavor(rsp) |
| 2220 | __rcu_process_callbacks(rsp); |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 2221 | trace_rcu_utilization(TPS("End RCU core")); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2222 | } |
| 2223 | |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 2224 | /* |
Paul E. McKenney | e0f2306 | 2011-06-21 01:29:39 -0700 | [diff] [blame] | 2225 | * Schedule RCU callback invocation. If the specified type of RCU |
| 2226 | * does not support RCU priority boosting, just do a direct call, |
| 2227 | * otherwise wake up the per-CPU kernel kthread. Note that because we |
| 2228 | * are running on the current CPU with interrupts disabled, the |
| 2229 | * rcu_cpu_kthread_task cannot disappear out from under us. |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 2230 | */ |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 2231 | static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 2232 | { |
Paul E. McKenney | b0d3041 | 2011-07-10 15:57:35 -0700 | [diff] [blame] | 2233 | if (unlikely(!ACCESS_ONCE(rcu_scheduler_fully_active))) |
| 2234 | return; |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 2235 | if (likely(!rsp->boost)) { |
| 2236 | rcu_do_batch(rsp, rdp); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 2237 | return; |
| 2238 | } |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 2239 | invoke_rcu_callbacks_kthread(); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 2240 | } |
| 2241 | |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 2242 | static void invoke_rcu_core(void) |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 2243 | { |
Paul E. McKenney | b0f7403 | 2013-02-04 12:14:24 -0800 | [diff] [blame] | 2244 | if (cpu_online(smp_processor_id())) |
| 2245 | raise_softirq(RCU_SOFTIRQ); |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 2246 | } |
| 2247 | |
Paul E. McKenney | 29154c5 | 2012-05-30 03:21:48 -0700 | [diff] [blame] | 2248 | /* |
| 2249 | * Handle any core-RCU processing required by a call_rcu() invocation. |
| 2250 | */ |
| 2251 | static void __call_rcu_core(struct rcu_state *rsp, struct rcu_data *rdp, |
| 2252 | struct rcu_head *head, unsigned long flags) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2253 | { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2254 | /* |
Paul E. McKenney | 29154c5 | 2012-05-30 03:21:48 -0700 | [diff] [blame] | 2255 | * If called from an extended quiescent state, invoke the RCU |
| 2256 | * core in order to force a re-evaluation of RCU's idleness. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2257 | */ |
Paul E. McKenney | 29154c5 | 2012-05-30 03:21:48 -0700 | [diff] [blame] | 2258 | if (rcu_is_cpu_idle() && cpu_online(smp_processor_id())) |
| 2259 | invoke_rcu_core(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2260 | |
Paul E. McKenney | 29154c5 | 2012-05-30 03:21:48 -0700 | [diff] [blame] | 2261 | /* If interrupts were disabled or CPU offline, don't invoke RCU core. */ |
| 2262 | if (irqs_disabled_flags(flags) || cpu_is_offline(smp_processor_id())) |
Paul E. McKenney | 2655d57 | 2011-04-07 22:47:23 -0700 | [diff] [blame] | 2263 | return; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2264 | |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 2265 | /* |
| 2266 | * Force the grace period if too many callbacks or too long waiting. |
| 2267 | * Enforce hysteresis, and don't invoke force_quiescent_state() |
| 2268 | * if some other CPU has recently done so. Also, don't bother |
| 2269 | * invoking force_quiescent_state() if the newly enqueued callback |
| 2270 | * is the only one waiting for a grace period to complete. |
| 2271 | */ |
Paul E. McKenney | 2655d57 | 2011-04-07 22:47:23 -0700 | [diff] [blame] | 2272 | if (unlikely(rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) { |
Paul E. McKenney | b52573d | 2010-12-14 17:36:02 -0800 | [diff] [blame] | 2273 | |
| 2274 | /* Are we ignoring a completed grace period? */ |
Paul E. McKenney | 470716f | 2013-03-19 11:32:11 -0700 | [diff] [blame] | 2275 | note_gp_changes(rsp, rdp); |
Paul E. McKenney | b52573d | 2010-12-14 17:36:02 -0800 | [diff] [blame] | 2276 | |
| 2277 | /* Start a new grace period if one not already started. */ |
| 2278 | if (!rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | b52573d | 2010-12-14 17:36:02 -0800 | [diff] [blame] | 2279 | struct rcu_node *rnp_root = rcu_get_root(rsp); |
| 2280 | |
Paul E. McKenney | b846208 | 2012-12-29 22:04:18 -0800 | [diff] [blame] | 2281 | raw_spin_lock(&rnp_root->lock); |
| 2282 | rcu_start_gp(rsp); |
| 2283 | raw_spin_unlock(&rnp_root->lock); |
Paul E. McKenney | b52573d | 2010-12-14 17:36:02 -0800 | [diff] [blame] | 2284 | } else { |
| 2285 | /* Give the grace period a kick. */ |
| 2286 | rdp->blimit = LONG_MAX; |
| 2287 | if (rsp->n_force_qs == rdp->n_force_qs_snap && |
| 2288 | *rdp->nxttail[RCU_DONE_TAIL] != head) |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 2289 | force_quiescent_state(rsp); |
Paul E. McKenney | b52573d | 2010-12-14 17:36:02 -0800 | [diff] [blame] | 2290 | rdp->n_force_qs_snap = rsp->n_force_qs; |
| 2291 | rdp->qlen_last_fqs_check = rdp->qlen; |
| 2292 | } |
Paul E. McKenney | 4cdfc175 | 2012-06-22 17:06:26 -0700 | [diff] [blame] | 2293 | } |
Paul E. McKenney | 29154c5 | 2012-05-30 03:21:48 -0700 | [diff] [blame] | 2294 | } |
| 2295 | |
Paul E. McKenney | 3fbfbf7 | 2012-08-19 21:35:53 -0700 | [diff] [blame] | 2296 | /* |
Paul E. McKenney | ae15018 | 2013-04-23 13:20:57 -0700 | [diff] [blame] | 2297 | * RCU callback function to leak a callback. |
| 2298 | */ |
| 2299 | static void rcu_leak_callback(struct rcu_head *rhp) |
| 2300 | { |
| 2301 | } |
| 2302 | |
| 2303 | /* |
Paul E. McKenney | 3fbfbf7 | 2012-08-19 21:35:53 -0700 | [diff] [blame] | 2304 | * Helper function for call_rcu() and friends. The cpu argument will |
| 2305 | * normally be -1, indicating "currently running CPU". It may specify |
| 2306 | * a CPU only if that CPU is a no-CBs CPU. Currently, only _rcu_barrier() |
| 2307 | * is expected to specify a CPU. |
| 2308 | */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2309 | static void |
| 2310 | __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), |
Paul E. McKenney | 3fbfbf7 | 2012-08-19 21:35:53 -0700 | [diff] [blame] | 2311 | struct rcu_state *rsp, int cpu, bool lazy) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2312 | { |
| 2313 | unsigned long flags; |
| 2314 | struct rcu_data *rdp; |
| 2315 | |
| 2316 | WARN_ON_ONCE((unsigned long)head & 0x3); /* Misaligned rcu_head! */ |
Paul E. McKenney | ae15018 | 2013-04-23 13:20:57 -0700 | [diff] [blame] | 2317 | if (debug_rcu_head_queue(head)) { |
| 2318 | /* Probable double call_rcu(), so leak the callback. */ |
| 2319 | ACCESS_ONCE(head->func) = rcu_leak_callback; |
| 2320 | WARN_ONCE(1, "__call_rcu(): Leaked duplicate callback\n"); |
| 2321 | return; |
| 2322 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2323 | head->func = func; |
| 2324 | head->next = NULL; |
| 2325 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2326 | /* |
| 2327 | * Opportunistically note grace-period endings and beginnings. |
| 2328 | * Note that we might see a beginning right after we see an |
| 2329 | * end, but never vice versa, since this CPU has to pass through |
| 2330 | * a quiescent state betweentimes. |
| 2331 | */ |
| 2332 | local_irq_save(flags); |
| 2333 | rdp = this_cpu_ptr(rsp->rda); |
| 2334 | |
| 2335 | /* Add the callback to our list. */ |
Paul E. McKenney | 3fbfbf7 | 2012-08-19 21:35:53 -0700 | [diff] [blame] | 2336 | if (unlikely(rdp->nxttail[RCU_NEXT_TAIL] == NULL) || cpu != -1) { |
| 2337 | int offline; |
| 2338 | |
| 2339 | if (cpu != -1) |
| 2340 | rdp = per_cpu_ptr(rsp->rda, cpu); |
| 2341 | offline = !__call_rcu_nocb(rdp, head, lazy); |
| 2342 | WARN_ON_ONCE(offline); |
Paul E. McKenney | 0d8ee37 | 2012-08-03 13:16:15 -0700 | [diff] [blame] | 2343 | /* _call_rcu() is illegal on offline CPU; leak the callback. */ |
Paul E. McKenney | 0d8ee37 | 2012-08-03 13:16:15 -0700 | [diff] [blame] | 2344 | local_irq_restore(flags); |
| 2345 | return; |
| 2346 | } |
Paul E. McKenney | 1d1fb39 | 2012-05-09 15:44:42 -0700 | [diff] [blame] | 2347 | ACCESS_ONCE(rdp->qlen)++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2348 | if (lazy) |
| 2349 | rdp->qlen_lazy++; |
| 2350 | else |
| 2351 | rcu_idle_count_callbacks_posted(); |
| 2352 | smp_mb(); /* Count before adding callback for rcu_barrier(). */ |
| 2353 | *rdp->nxttail[RCU_NEXT_TAIL] = head; |
| 2354 | rdp->nxttail[RCU_NEXT_TAIL] = &head->next; |
| 2355 | |
| 2356 | if (__is_kfree_rcu_offset((unsigned long)func)) |
| 2357 | trace_rcu_kfree_callback(rsp->name, head, (unsigned long)func, |
| 2358 | rdp->qlen_lazy, rdp->qlen); |
| 2359 | else |
| 2360 | trace_rcu_callback(rsp->name, head, rdp->qlen_lazy, rdp->qlen); |
| 2361 | |
Paul E. McKenney | 29154c5 | 2012-05-30 03:21:48 -0700 | [diff] [blame] | 2362 | /* Go handle any RCU core processing required. */ |
| 2363 | __call_rcu_core(rsp, rdp, head, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2364 | local_irq_restore(flags); |
| 2365 | } |
| 2366 | |
| 2367 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 2368 | * Queue an RCU-sched callback for invocation after a grace period. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2369 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 2370 | void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2371 | { |
Paul E. McKenney | 3fbfbf7 | 2012-08-19 21:35:53 -0700 | [diff] [blame] | 2372 | __call_rcu(head, func, &rcu_sched_state, -1, 0); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2373 | } |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 2374 | EXPORT_SYMBOL_GPL(call_rcu_sched); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2375 | |
| 2376 | /* |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 2377 | * Queue an RCU callback for invocation after a quicker grace period. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2378 | */ |
| 2379 | void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) |
| 2380 | { |
Paul E. McKenney | 3fbfbf7 | 2012-08-19 21:35:53 -0700 | [diff] [blame] | 2381 | __call_rcu(head, func, &rcu_bh_state, -1, 0); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2382 | } |
| 2383 | EXPORT_SYMBOL_GPL(call_rcu_bh); |
| 2384 | |
Paul E. McKenney | 6d81339 | 2012-02-23 13:30:16 -0800 | [diff] [blame] | 2385 | /* |
| 2386 | * Because a context switch is a grace period for RCU-sched and RCU-bh, |
| 2387 | * any blocking grace-period wait automatically implies a grace period |
| 2388 | * if there is only one CPU online at any point time during execution |
| 2389 | * of either synchronize_sched() or synchronize_rcu_bh(). It is OK to |
| 2390 | * occasionally incorrectly indicate that there are multiple CPUs online |
| 2391 | * when there was in fact only one the whole time, as this just adds |
| 2392 | * some overhead: RCU still operates correctly. |
Paul E. McKenney | 6d81339 | 2012-02-23 13:30:16 -0800 | [diff] [blame] | 2393 | */ |
| 2394 | static inline int rcu_blocking_is_gp(void) |
| 2395 | { |
Paul E. McKenney | 95f0c1d | 2012-06-19 11:58:27 -0700 | [diff] [blame] | 2396 | int ret; |
| 2397 | |
Paul E. McKenney | 6d81339 | 2012-02-23 13:30:16 -0800 | [diff] [blame] | 2398 | might_sleep(); /* Check for RCU read-side critical section. */ |
Paul E. McKenney | 95f0c1d | 2012-06-19 11:58:27 -0700 | [diff] [blame] | 2399 | preempt_disable(); |
| 2400 | ret = num_online_cpus() <= 1; |
| 2401 | preempt_enable(); |
| 2402 | return ret; |
Paul E. McKenney | 6d81339 | 2012-02-23 13:30:16 -0800 | [diff] [blame] | 2403 | } |
| 2404 | |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 2405 | /** |
| 2406 | * synchronize_sched - wait until an rcu-sched grace period has elapsed. |
| 2407 | * |
| 2408 | * Control will return to the caller some time after a full rcu-sched |
| 2409 | * grace period has elapsed, in other words after all currently executing |
| 2410 | * rcu-sched read-side critical sections have completed. These read-side |
| 2411 | * critical sections are delimited by rcu_read_lock_sched() and |
| 2412 | * rcu_read_unlock_sched(), and may be nested. Note that preempt_disable(), |
| 2413 | * local_irq_disable(), and so on may be used in place of |
| 2414 | * rcu_read_lock_sched(). |
| 2415 | * |
| 2416 | * This means that all preempt_disable code sequences, including NMI and |
Paul E. McKenney | f0a0e6f | 2012-10-23 13:47:01 -0700 | [diff] [blame] | 2417 | * non-threaded hardware-interrupt handlers, in progress on entry will |
| 2418 | * have completed before this primitive returns. However, this does not |
| 2419 | * guarantee that softirq handlers will have completed, since in some |
| 2420 | * kernels, these handlers can run in process context, and can block. |
| 2421 | * |
| 2422 | * Note that this guarantee implies further memory-ordering guarantees. |
| 2423 | * On systems with more than one CPU, when synchronize_sched() returns, |
| 2424 | * each CPU is guaranteed to have executed a full memory barrier since the |
| 2425 | * end of its last RCU-sched read-side critical section whose beginning |
| 2426 | * preceded the call to synchronize_sched(). In addition, each CPU having |
| 2427 | * an RCU read-side critical section that extends beyond the return from |
| 2428 | * synchronize_sched() is guaranteed to have executed a full memory barrier |
| 2429 | * after the beginning of synchronize_sched() and before the beginning of |
| 2430 | * that RCU read-side critical section. Note that these guarantees include |
| 2431 | * CPUs that are offline, idle, or executing in user mode, as well as CPUs |
| 2432 | * that are executing in the kernel. |
| 2433 | * |
| 2434 | * Furthermore, if CPU A invoked synchronize_sched(), which returned |
| 2435 | * to its caller on CPU B, then both CPU A and CPU B are guaranteed |
| 2436 | * to have executed a full memory barrier during the execution of |
| 2437 | * synchronize_sched() -- even if CPU A and CPU B are the same CPU (but |
| 2438 | * again only if the system has more than one CPU). |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 2439 | * |
| 2440 | * This primitive provides the guarantees made by the (now removed) |
| 2441 | * synchronize_kernel() API. In contrast, synchronize_rcu() only |
| 2442 | * guarantees that rcu_read_lock() sections will have completed. |
| 2443 | * In "classic RCU", these two guarantees happen to be one and |
| 2444 | * the same, but can differ in realtime RCU implementations. |
| 2445 | */ |
| 2446 | void synchronize_sched(void) |
| 2447 | { |
Paul E. McKenney | fe15d70 | 2012-01-04 13:30:33 -0800 | [diff] [blame] | 2448 | rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) && |
| 2449 | !lock_is_held(&rcu_lock_map) && |
| 2450 | !lock_is_held(&rcu_sched_lock_map), |
| 2451 | "Illegal synchronize_sched() in RCU-sched read-side critical section"); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 2452 | if (rcu_blocking_is_gp()) |
| 2453 | return; |
Antti P Miettinen | 3705b88 | 2012-10-05 09:59:15 +0300 | [diff] [blame] | 2454 | if (rcu_expedited) |
| 2455 | synchronize_sched_expedited(); |
| 2456 | else |
| 2457 | wait_rcu_gp(call_rcu_sched); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 2458 | } |
| 2459 | EXPORT_SYMBOL_GPL(synchronize_sched); |
| 2460 | |
| 2461 | /** |
| 2462 | * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed. |
| 2463 | * |
| 2464 | * Control will return to the caller some time after a full rcu_bh grace |
| 2465 | * period has elapsed, in other words after all currently executing rcu_bh |
| 2466 | * read-side critical sections have completed. RCU read-side critical |
| 2467 | * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(), |
| 2468 | * and may be nested. |
Paul E. McKenney | f0a0e6f | 2012-10-23 13:47:01 -0700 | [diff] [blame] | 2469 | * |
| 2470 | * See the description of synchronize_sched() for more detailed information |
| 2471 | * on memory ordering guarantees. |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 2472 | */ |
| 2473 | void synchronize_rcu_bh(void) |
| 2474 | { |
Paul E. McKenney | fe15d70 | 2012-01-04 13:30:33 -0800 | [diff] [blame] | 2475 | rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) && |
| 2476 | !lock_is_held(&rcu_lock_map) && |
| 2477 | !lock_is_held(&rcu_sched_lock_map), |
| 2478 | "Illegal synchronize_rcu_bh() in RCU-bh read-side critical section"); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 2479 | if (rcu_blocking_is_gp()) |
| 2480 | return; |
Antti P Miettinen | 3705b88 | 2012-10-05 09:59:15 +0300 | [diff] [blame] | 2481 | if (rcu_expedited) |
| 2482 | synchronize_rcu_bh_expedited(); |
| 2483 | else |
| 2484 | wait_rcu_gp(call_rcu_bh); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 2485 | } |
| 2486 | EXPORT_SYMBOL_GPL(synchronize_rcu_bh); |
| 2487 | |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2488 | static int synchronize_sched_expedited_cpu_stop(void *data) |
| 2489 | { |
| 2490 | /* |
| 2491 | * There must be a full memory barrier on each affected CPU |
| 2492 | * between the time that try_stop_cpus() is called and the |
| 2493 | * time that it returns. |
| 2494 | * |
| 2495 | * In the current initial implementation of cpu_stop, the |
| 2496 | * above condition is already met when the control reaches |
| 2497 | * this point and the following smp_mb() is not strictly |
| 2498 | * necessary. Do smp_mb() anyway for documentation and |
| 2499 | * robustness against future implementation changes. |
| 2500 | */ |
| 2501 | smp_mb(); /* See above comment block. */ |
| 2502 | return 0; |
| 2503 | } |
| 2504 | |
Paul E. McKenney | 236fefa | 2012-01-31 14:00:41 -0800 | [diff] [blame] | 2505 | /** |
| 2506 | * synchronize_sched_expedited - Brute-force RCU-sched grace period |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2507 | * |
Paul E. McKenney | 236fefa | 2012-01-31 14:00:41 -0800 | [diff] [blame] | 2508 | * Wait for an RCU-sched grace period to elapse, but use a "big hammer" |
| 2509 | * approach to force the grace period to end quickly. This consumes |
| 2510 | * significant time on all CPUs and is unfriendly to real-time workloads, |
| 2511 | * so is thus not recommended for any sort of common-case code. In fact, |
| 2512 | * if you are using synchronize_sched_expedited() in a loop, please |
| 2513 | * restructure your code to batch your updates, and then use a single |
| 2514 | * synchronize_sched() instead. |
| 2515 | * |
| 2516 | * Note that it is illegal to call this function while holding any lock |
| 2517 | * that is acquired by a CPU-hotplug notifier. And yes, it is also illegal |
| 2518 | * to call this function from a CPU-hotplug notifier. Failing to observe |
| 2519 | * these restriction will result in deadlock. |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2520 | * |
| 2521 | * This implementation can be thought of as an application of ticket |
| 2522 | * locking to RCU, with sync_sched_expedited_started and |
| 2523 | * sync_sched_expedited_done taking on the roles of the halves |
| 2524 | * of the ticket-lock word. Each task atomically increments |
| 2525 | * sync_sched_expedited_started upon entry, snapshotting the old value, |
| 2526 | * then attempts to stop all the CPUs. If this succeeds, then each |
| 2527 | * CPU will have executed a context switch, resulting in an RCU-sched |
| 2528 | * grace period. We are then done, so we use atomic_cmpxchg() to |
| 2529 | * update sync_sched_expedited_done to match our snapshot -- but |
| 2530 | * only if someone else has not already advanced past our snapshot. |
| 2531 | * |
| 2532 | * On the other hand, if try_stop_cpus() fails, we check the value |
| 2533 | * of sync_sched_expedited_done. If it has advanced past our |
| 2534 | * initial snapshot, then someone else must have forced a grace period |
| 2535 | * some time after we took our snapshot. In this case, our work is |
| 2536 | * done for us, and we can simply return. Otherwise, we try again, |
| 2537 | * but keep our initial snapshot for purposes of checking for someone |
| 2538 | * doing our work for us. |
| 2539 | * |
| 2540 | * If we fail too many times in a row, we fall back to synchronize_sched(). |
| 2541 | */ |
| 2542 | void synchronize_sched_expedited(void) |
| 2543 | { |
Paul E. McKenney | 1924bcb | 2012-10-11 12:30:37 -0700 | [diff] [blame] | 2544 | long firstsnap, s, snap; |
| 2545 | int trycount = 0; |
Paul E. McKenney | 40694d6 | 2012-10-11 15:24:03 -0700 | [diff] [blame] | 2546 | struct rcu_state *rsp = &rcu_sched_state; |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2547 | |
Paul E. McKenney | 1924bcb | 2012-10-11 12:30:37 -0700 | [diff] [blame] | 2548 | /* |
| 2549 | * If we are in danger of counter wrap, just do synchronize_sched(). |
| 2550 | * By allowing sync_sched_expedited_started to advance no more than |
| 2551 | * ULONG_MAX/8 ahead of sync_sched_expedited_done, we are ensuring |
| 2552 | * that more than 3.5 billion CPUs would be required to force a |
| 2553 | * counter wrap on a 32-bit system. Quite a few more CPUs would of |
| 2554 | * course be required on a 64-bit system. |
| 2555 | */ |
Paul E. McKenney | 40694d6 | 2012-10-11 15:24:03 -0700 | [diff] [blame] | 2556 | if (ULONG_CMP_GE((ulong)atomic_long_read(&rsp->expedited_start), |
| 2557 | (ulong)atomic_long_read(&rsp->expedited_done) + |
Paul E. McKenney | 1924bcb | 2012-10-11 12:30:37 -0700 | [diff] [blame] | 2558 | ULONG_MAX / 8)) { |
| 2559 | synchronize_sched(); |
Paul E. McKenney | a30489c | 2012-10-11 16:18:09 -0700 | [diff] [blame] | 2560 | atomic_long_inc(&rsp->expedited_wrap); |
Paul E. McKenney | 1924bcb | 2012-10-11 12:30:37 -0700 | [diff] [blame] | 2561 | return; |
| 2562 | } |
| 2563 | |
| 2564 | /* |
| 2565 | * Take a ticket. Note that atomic_inc_return() implies a |
| 2566 | * full memory barrier. |
| 2567 | */ |
Paul E. McKenney | 40694d6 | 2012-10-11 15:24:03 -0700 | [diff] [blame] | 2568 | snap = atomic_long_inc_return(&rsp->expedited_start); |
Paul E. McKenney | 1924bcb | 2012-10-11 12:30:37 -0700 | [diff] [blame] | 2569 | firstsnap = snap; |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2570 | get_online_cpus(); |
Hugh Dickins | 1cc8596 | 2012-02-17 13:20:31 -0800 | [diff] [blame] | 2571 | WARN_ON_ONCE(cpu_is_offline(raw_smp_processor_id())); |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2572 | |
| 2573 | /* |
| 2574 | * Each pass through the following loop attempts to force a |
| 2575 | * context switch on each CPU. |
| 2576 | */ |
| 2577 | while (try_stop_cpus(cpu_online_mask, |
| 2578 | synchronize_sched_expedited_cpu_stop, |
| 2579 | NULL) == -EAGAIN) { |
| 2580 | put_online_cpus(); |
Paul E. McKenney | a30489c | 2012-10-11 16:18:09 -0700 | [diff] [blame] | 2581 | atomic_long_inc(&rsp->expedited_tryfail); |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2582 | |
Paul E. McKenney | 1924bcb | 2012-10-11 12:30:37 -0700 | [diff] [blame] | 2583 | /* Check to see if someone else did our work for us. */ |
Paul E. McKenney | 40694d6 | 2012-10-11 15:24:03 -0700 | [diff] [blame] | 2584 | s = atomic_long_read(&rsp->expedited_done); |
Paul E. McKenney | 1924bcb | 2012-10-11 12:30:37 -0700 | [diff] [blame] | 2585 | if (ULONG_CMP_GE((ulong)s, (ulong)firstsnap)) { |
Paul E. McKenney | a30489c | 2012-10-11 16:18:09 -0700 | [diff] [blame] | 2586 | /* ensure test happens before caller kfree */ |
| 2587 | smp_mb__before_atomic_inc(); /* ^^^ */ |
| 2588 | atomic_long_inc(&rsp->expedited_workdone1); |
Paul E. McKenney | 1924bcb | 2012-10-11 12:30:37 -0700 | [diff] [blame] | 2589 | return; |
| 2590 | } |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2591 | |
| 2592 | /* No joy, try again later. Or just synchronize_sched(). */ |
Paul E. McKenney | c701d5d | 2012-06-28 08:08:25 -0700 | [diff] [blame] | 2593 | if (trycount++ < 10) { |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2594 | udelay(trycount * num_online_cpus()); |
Paul E. McKenney | c701d5d | 2012-06-28 08:08:25 -0700 | [diff] [blame] | 2595 | } else { |
Antti P Miettinen | 3705b88 | 2012-10-05 09:59:15 +0300 | [diff] [blame] | 2596 | wait_rcu_gp(call_rcu_sched); |
Paul E. McKenney | a30489c | 2012-10-11 16:18:09 -0700 | [diff] [blame] | 2597 | atomic_long_inc(&rsp->expedited_normal); |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2598 | return; |
| 2599 | } |
| 2600 | |
Paul E. McKenney | 1924bcb | 2012-10-11 12:30:37 -0700 | [diff] [blame] | 2601 | /* Recheck to see if someone else did our work for us. */ |
Paul E. McKenney | 40694d6 | 2012-10-11 15:24:03 -0700 | [diff] [blame] | 2602 | s = atomic_long_read(&rsp->expedited_done); |
Paul E. McKenney | 1924bcb | 2012-10-11 12:30:37 -0700 | [diff] [blame] | 2603 | if (ULONG_CMP_GE((ulong)s, (ulong)firstsnap)) { |
Paul E. McKenney | a30489c | 2012-10-11 16:18:09 -0700 | [diff] [blame] | 2604 | /* ensure test happens before caller kfree */ |
| 2605 | smp_mb__before_atomic_inc(); /* ^^^ */ |
| 2606 | atomic_long_inc(&rsp->expedited_workdone2); |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2607 | return; |
| 2608 | } |
| 2609 | |
| 2610 | /* |
| 2611 | * Refetching sync_sched_expedited_started allows later |
Paul E. McKenney | 1924bcb | 2012-10-11 12:30:37 -0700 | [diff] [blame] | 2612 | * callers to piggyback on our grace period. We retry |
| 2613 | * after they started, so our grace period works for them, |
| 2614 | * and they started after our first try, so their grace |
| 2615 | * period works for us. |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2616 | */ |
| 2617 | get_online_cpus(); |
Paul E. McKenney | 40694d6 | 2012-10-11 15:24:03 -0700 | [diff] [blame] | 2618 | snap = atomic_long_read(&rsp->expedited_start); |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2619 | smp_mb(); /* ensure read is before try_stop_cpus(). */ |
| 2620 | } |
Paul E. McKenney | a30489c | 2012-10-11 16:18:09 -0700 | [diff] [blame] | 2621 | atomic_long_inc(&rsp->expedited_stoppedcpus); |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2622 | |
| 2623 | /* |
| 2624 | * Everyone up to our most recent fetch is covered by our grace |
| 2625 | * period. Update the counter, but only if our work is still |
| 2626 | * relevant -- which it won't be if someone who started later |
Paul E. McKenney | 1924bcb | 2012-10-11 12:30:37 -0700 | [diff] [blame] | 2627 | * than we did already did their update. |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2628 | */ |
| 2629 | do { |
Paul E. McKenney | a30489c | 2012-10-11 16:18:09 -0700 | [diff] [blame] | 2630 | atomic_long_inc(&rsp->expedited_done_tries); |
Paul E. McKenney | 40694d6 | 2012-10-11 15:24:03 -0700 | [diff] [blame] | 2631 | s = atomic_long_read(&rsp->expedited_done); |
Paul E. McKenney | 1924bcb | 2012-10-11 12:30:37 -0700 | [diff] [blame] | 2632 | if (ULONG_CMP_GE((ulong)s, (ulong)snap)) { |
Paul E. McKenney | a30489c | 2012-10-11 16:18:09 -0700 | [diff] [blame] | 2633 | /* ensure test happens before caller kfree */ |
| 2634 | smp_mb__before_atomic_inc(); /* ^^^ */ |
| 2635 | atomic_long_inc(&rsp->expedited_done_lost); |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2636 | break; |
| 2637 | } |
Paul E. McKenney | 40694d6 | 2012-10-11 15:24:03 -0700 | [diff] [blame] | 2638 | } while (atomic_long_cmpxchg(&rsp->expedited_done, s, snap) != s); |
Paul E. McKenney | a30489c | 2012-10-11 16:18:09 -0700 | [diff] [blame] | 2639 | atomic_long_inc(&rsp->expedited_done_exit); |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 2640 | |
| 2641 | put_online_cpus(); |
| 2642 | } |
| 2643 | EXPORT_SYMBOL_GPL(synchronize_sched_expedited); |
| 2644 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2645 | /* |
| 2646 | * Check to see if there is any immediate RCU-related work to be done |
| 2647 | * by the current CPU, for the specified type of RCU, returning 1 if so. |
| 2648 | * The checks are in order of increasing expense: checks that can be |
| 2649 | * carried out against CPU-local state are performed first. However, |
| 2650 | * we must check for CPU stalls first, else we might not get a chance. |
| 2651 | */ |
| 2652 | static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) |
| 2653 | { |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 2654 | struct rcu_node *rnp = rdp->mynode; |
| 2655 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2656 | rdp->n_rcu_pending++; |
| 2657 | |
| 2658 | /* Check for CPU stalls, if enabled. */ |
| 2659 | check_cpu_stall(rsp, rdp); |
| 2660 | |
| 2661 | /* Is the RCU core waiting for a quiescent state from this CPU? */ |
Paul E. McKenney | 5c51dd7 | 2011-08-04 06:59:03 -0700 | [diff] [blame] | 2662 | if (rcu_scheduler_fully_active && |
| 2663 | rdp->qs_pending && !rdp->passed_quiesce) { |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 2664 | rdp->n_rp_qs_pending++; |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 2665 | } else if (rdp->qs_pending && rdp->passed_quiesce) { |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 2666 | rdp->n_rp_report_qs++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2667 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2668 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2669 | |
| 2670 | /* Does this CPU have callbacks ready to invoke? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2671 | if (cpu_has_callbacks_ready_to_invoke(rdp)) { |
| 2672 | rdp->n_rp_cb_ready++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2673 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2674 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2675 | |
| 2676 | /* Has RCU gone idle with this CPU needing another grace period? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2677 | if (cpu_needs_another_gp(rsp, rdp)) { |
| 2678 | rdp->n_rp_cpu_needs_gp++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2679 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2680 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2681 | |
| 2682 | /* Has another RCU grace period completed? */ |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 2683 | if (ACCESS_ONCE(rnp->completed) != rdp->completed) { /* outside lock */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2684 | rdp->n_rp_gp_completed++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2685 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2686 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2687 | |
| 2688 | /* Has a new RCU grace period started? */ |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 2689 | if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum) { /* outside lock */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2690 | rdp->n_rp_gp_started++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2691 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2692 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2693 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2694 | /* nothing to do */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2695 | rdp->n_rp_need_nothing++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2696 | return 0; |
| 2697 | } |
| 2698 | |
| 2699 | /* |
| 2700 | * Check to see if there is any immediate RCU-related work to be done |
| 2701 | * by the current CPU, returning 1 if so. This function is part of the |
| 2702 | * RCU implementation; it is -not- an exported member of the RCU API. |
| 2703 | */ |
Paul E. McKenney | a157229 | 2009-08-22 13:56:51 -0700 | [diff] [blame] | 2704 | static int rcu_pending(int cpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2705 | { |
Paul E. McKenney | 6ce75a2 | 2012-06-12 11:01:13 -0700 | [diff] [blame] | 2706 | struct rcu_state *rsp; |
| 2707 | |
| 2708 | for_each_rcu_flavor(rsp) |
| 2709 | if (__rcu_pending(rsp, per_cpu_ptr(rsp->rda, cpu))) |
| 2710 | return 1; |
| 2711 | return 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2712 | } |
| 2713 | |
| 2714 | /* |
Paul E. McKenney | c0f4dfd | 2012-12-28 11:30:36 -0800 | [diff] [blame] | 2715 | * Return true if the specified CPU has any callback. If all_lazy is |
| 2716 | * non-NULL, store an indication of whether all callbacks are lazy. |
| 2717 | * (If there are no callbacks, all of them are deemed to be lazy.) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2718 | */ |
Paul E. McKenney | c0f4dfd | 2012-12-28 11:30:36 -0800 | [diff] [blame] | 2719 | static int rcu_cpu_has_callbacks(int cpu, bool *all_lazy) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2720 | { |
Paul E. McKenney | c0f4dfd | 2012-12-28 11:30:36 -0800 | [diff] [blame] | 2721 | bool al = true; |
| 2722 | bool hc = false; |
| 2723 | struct rcu_data *rdp; |
Paul E. McKenney | 6ce75a2 | 2012-06-12 11:01:13 -0700 | [diff] [blame] | 2724 | struct rcu_state *rsp; |
| 2725 | |
Paul E. McKenney | c0f4dfd | 2012-12-28 11:30:36 -0800 | [diff] [blame] | 2726 | for_each_rcu_flavor(rsp) { |
| 2727 | rdp = per_cpu_ptr(rsp->rda, cpu); |
| 2728 | if (rdp->qlen != rdp->qlen_lazy) |
| 2729 | al = false; |
| 2730 | if (rdp->nxtlist) |
| 2731 | hc = true; |
| 2732 | } |
| 2733 | if (all_lazy) |
| 2734 | *all_lazy = al; |
| 2735 | return hc; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2736 | } |
| 2737 | |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2738 | /* |
Paul E. McKenney | a83eff0 | 2012-05-23 18:47:05 -0700 | [diff] [blame] | 2739 | * Helper function for _rcu_barrier() tracing. If tracing is disabled, |
| 2740 | * the compiler is expected to optimize this away. |
| 2741 | */ |
Steven Rostedt (Red Hat) | e66c33d | 2013-07-12 16:50:28 -0400 | [diff] [blame] | 2742 | static void _rcu_barrier_trace(struct rcu_state *rsp, const char *s, |
Paul E. McKenney | a83eff0 | 2012-05-23 18:47:05 -0700 | [diff] [blame] | 2743 | int cpu, unsigned long done) |
| 2744 | { |
| 2745 | trace_rcu_barrier(rsp->name, s, cpu, |
| 2746 | atomic_read(&rsp->barrier_cpu_count), done); |
| 2747 | } |
| 2748 | |
| 2749 | /* |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2750 | * RCU callback function for _rcu_barrier(). If we are last, wake |
| 2751 | * up the task executing _rcu_barrier(). |
| 2752 | */ |
Paul E. McKenney | 24ebbca | 2012-05-29 00:34:56 -0700 | [diff] [blame] | 2753 | static void rcu_barrier_callback(struct rcu_head *rhp) |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2754 | { |
Paul E. McKenney | 24ebbca | 2012-05-29 00:34:56 -0700 | [diff] [blame] | 2755 | struct rcu_data *rdp = container_of(rhp, struct rcu_data, barrier_head); |
| 2756 | struct rcu_state *rsp = rdp->rsp; |
| 2757 | |
Paul E. McKenney | a83eff0 | 2012-05-23 18:47:05 -0700 | [diff] [blame] | 2758 | if (atomic_dec_and_test(&rsp->barrier_cpu_count)) { |
| 2759 | _rcu_barrier_trace(rsp, "LastCB", -1, rsp->n_barrier_done); |
Paul E. McKenney | 7db74df | 2012-05-29 03:03:37 -0700 | [diff] [blame] | 2760 | complete(&rsp->barrier_completion); |
Paul E. McKenney | a83eff0 | 2012-05-23 18:47:05 -0700 | [diff] [blame] | 2761 | } else { |
| 2762 | _rcu_barrier_trace(rsp, "CB", -1, rsp->n_barrier_done); |
| 2763 | } |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2764 | } |
| 2765 | |
| 2766 | /* |
| 2767 | * Called with preemption disabled, and from cross-cpu IRQ context. |
| 2768 | */ |
| 2769 | static void rcu_barrier_func(void *type) |
| 2770 | { |
Paul E. McKenney | 037b64e | 2012-05-28 23:26:01 -0700 | [diff] [blame] | 2771 | struct rcu_state *rsp = type; |
Paul E. McKenney | 06668ef | 2012-05-28 23:57:46 -0700 | [diff] [blame] | 2772 | struct rcu_data *rdp = __this_cpu_ptr(rsp->rda); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2773 | |
Paul E. McKenney | a83eff0 | 2012-05-23 18:47:05 -0700 | [diff] [blame] | 2774 | _rcu_barrier_trace(rsp, "IRQ", -1, rsp->n_barrier_done); |
Paul E. McKenney | 24ebbca | 2012-05-29 00:34:56 -0700 | [diff] [blame] | 2775 | atomic_inc(&rsp->barrier_cpu_count); |
Paul E. McKenney | 06668ef | 2012-05-28 23:57:46 -0700 | [diff] [blame] | 2776 | rsp->call(&rdp->barrier_head, rcu_barrier_callback); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2777 | } |
| 2778 | |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2779 | /* |
| 2780 | * Orchestrate the specified type of RCU barrier, waiting for all |
| 2781 | * RCU callbacks of the specified type to complete. |
| 2782 | */ |
Paul E. McKenney | 037b64e | 2012-05-28 23:26:01 -0700 | [diff] [blame] | 2783 | static void _rcu_barrier(struct rcu_state *rsp) |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2784 | { |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2785 | int cpu; |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2786 | struct rcu_data *rdp; |
Paul E. McKenney | cf3a9c4 | 2012-05-29 14:56:46 -0700 | [diff] [blame] | 2787 | unsigned long snap = ACCESS_ONCE(rsp->n_barrier_done); |
| 2788 | unsigned long snap_done; |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2789 | |
Paul E. McKenney | a83eff0 | 2012-05-23 18:47:05 -0700 | [diff] [blame] | 2790 | _rcu_barrier_trace(rsp, "Begin", -1, snap); |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2791 | |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 2792 | /* Take mutex to serialize concurrent rcu_barrier() requests. */ |
Paul E. McKenney | 7be7f0b | 2012-05-29 05:18:53 -0700 | [diff] [blame] | 2793 | mutex_lock(&rsp->barrier_mutex); |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2794 | |
Paul E. McKenney | cf3a9c4 | 2012-05-29 14:56:46 -0700 | [diff] [blame] | 2795 | /* |
| 2796 | * Ensure that all prior references, including to ->n_barrier_done, |
| 2797 | * are ordered before the _rcu_barrier() machinery. |
| 2798 | */ |
| 2799 | smp_mb(); /* See above block comment. */ |
| 2800 | |
| 2801 | /* |
| 2802 | * Recheck ->n_barrier_done to see if others did our work for us. |
| 2803 | * This means checking ->n_barrier_done for an even-to-odd-to-even |
| 2804 | * transition. The "if" expression below therefore rounds the old |
| 2805 | * value up to the next even number and adds two before comparing. |
| 2806 | */ |
Paul E. McKenney | 458fb38 | 2013-07-26 20:47:42 -0700 | [diff] [blame] | 2807 | snap_done = rsp->n_barrier_done; |
Paul E. McKenney | a83eff0 | 2012-05-23 18:47:05 -0700 | [diff] [blame] | 2808 | _rcu_barrier_trace(rsp, "Check", -1, snap_done); |
Paul E. McKenney | 458fb38 | 2013-07-26 20:47:42 -0700 | [diff] [blame] | 2809 | |
| 2810 | /* |
| 2811 | * If the value in snap is odd, we needed to wait for the current |
| 2812 | * rcu_barrier() to complete, then wait for the next one, in other |
| 2813 | * words, we need the value of snap_done to be three larger than |
| 2814 | * the value of snap. On the other hand, if the value in snap is |
| 2815 | * even, we only had to wait for the next rcu_barrier() to complete, |
| 2816 | * in other words, we need the value of snap_done to be only two |
| 2817 | * greater than the value of snap. The "(snap + 3) & ~0x1" computes |
| 2818 | * this for us (thank you, Linus!). |
| 2819 | */ |
| 2820 | if (ULONG_CMP_GE(snap_done, (snap + 3) & ~0x1)) { |
Paul E. McKenney | a83eff0 | 2012-05-23 18:47:05 -0700 | [diff] [blame] | 2821 | _rcu_barrier_trace(rsp, "EarlyExit", -1, snap_done); |
Paul E. McKenney | cf3a9c4 | 2012-05-29 14:56:46 -0700 | [diff] [blame] | 2822 | smp_mb(); /* caller's subsequent code after above check. */ |
| 2823 | mutex_unlock(&rsp->barrier_mutex); |
| 2824 | return; |
| 2825 | } |
| 2826 | |
| 2827 | /* |
| 2828 | * Increment ->n_barrier_done to avoid duplicate work. Use |
| 2829 | * ACCESS_ONCE() to prevent the compiler from speculating |
| 2830 | * the increment to precede the early-exit check. |
| 2831 | */ |
| 2832 | ACCESS_ONCE(rsp->n_barrier_done)++; |
| 2833 | WARN_ON_ONCE((rsp->n_barrier_done & 0x1) != 1); |
Paul E. McKenney | a83eff0 | 2012-05-23 18:47:05 -0700 | [diff] [blame] | 2834 | _rcu_barrier_trace(rsp, "Inc1", -1, rsp->n_barrier_done); |
Paul E. McKenney | cf3a9c4 | 2012-05-29 14:56:46 -0700 | [diff] [blame] | 2835 | smp_mb(); /* Order ->n_barrier_done increment with below mechanism. */ |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2836 | |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2837 | /* |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2838 | * Initialize the count to one rather than to zero in order to |
| 2839 | * avoid a too-soon return to zero in case of a short grace period |
Paul E. McKenney | 1331e7a | 2012-08-02 17:43:50 -0700 | [diff] [blame] | 2840 | * (or preemption of this task). Exclude CPU-hotplug operations |
| 2841 | * to ensure that no offline CPU has callbacks queued. |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2842 | */ |
Paul E. McKenney | 7db74df | 2012-05-29 03:03:37 -0700 | [diff] [blame] | 2843 | init_completion(&rsp->barrier_completion); |
Paul E. McKenney | 24ebbca | 2012-05-29 00:34:56 -0700 | [diff] [blame] | 2844 | atomic_set(&rsp->barrier_cpu_count, 1); |
Paul E. McKenney | 1331e7a | 2012-08-02 17:43:50 -0700 | [diff] [blame] | 2845 | get_online_cpus(); |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2846 | |
| 2847 | /* |
Paul E. McKenney | 1331e7a | 2012-08-02 17:43:50 -0700 | [diff] [blame] | 2848 | * Force each CPU with callbacks to register a new callback. |
| 2849 | * When that callback is invoked, we will know that all of the |
| 2850 | * corresponding CPU's preceding callbacks have been invoked. |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2851 | */ |
Paul E. McKenney | 3fbfbf7 | 2012-08-19 21:35:53 -0700 | [diff] [blame] | 2852 | for_each_possible_cpu(cpu) { |
Frederic Weisbecker | d1e43fa | 2013-03-26 23:47:24 +0100 | [diff] [blame] | 2853 | if (!cpu_online(cpu) && !rcu_is_nocb_cpu(cpu)) |
Paul E. McKenney | 3fbfbf7 | 2012-08-19 21:35:53 -0700 | [diff] [blame] | 2854 | continue; |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2855 | rdp = per_cpu_ptr(rsp->rda, cpu); |
Frederic Weisbecker | d1e43fa | 2013-03-26 23:47:24 +0100 | [diff] [blame] | 2856 | if (rcu_is_nocb_cpu(cpu)) { |
Paul E. McKenney | 3fbfbf7 | 2012-08-19 21:35:53 -0700 | [diff] [blame] | 2857 | _rcu_barrier_trace(rsp, "OnlineNoCB", cpu, |
| 2858 | rsp->n_barrier_done); |
| 2859 | atomic_inc(&rsp->barrier_cpu_count); |
| 2860 | __call_rcu(&rdp->barrier_head, rcu_barrier_callback, |
| 2861 | rsp, cpu, 0); |
| 2862 | } else if (ACCESS_ONCE(rdp->qlen)) { |
Paul E. McKenney | a83eff0 | 2012-05-23 18:47:05 -0700 | [diff] [blame] | 2863 | _rcu_barrier_trace(rsp, "OnlineQ", cpu, |
| 2864 | rsp->n_barrier_done); |
Paul E. McKenney | 037b64e | 2012-05-28 23:26:01 -0700 | [diff] [blame] | 2865 | smp_call_function_single(cpu, rcu_barrier_func, rsp, 1); |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2866 | } else { |
Paul E. McKenney | a83eff0 | 2012-05-23 18:47:05 -0700 | [diff] [blame] | 2867 | _rcu_barrier_trace(rsp, "OnlineNQ", cpu, |
| 2868 | rsp->n_barrier_done); |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2869 | } |
| 2870 | } |
Paul E. McKenney | 1331e7a | 2012-08-02 17:43:50 -0700 | [diff] [blame] | 2871 | put_online_cpus(); |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2872 | |
| 2873 | /* |
| 2874 | * Now that we have an rcu_barrier_callback() callback on each |
| 2875 | * CPU, and thus each counted, remove the initial count. |
| 2876 | */ |
Paul E. McKenney | 24ebbca | 2012-05-29 00:34:56 -0700 | [diff] [blame] | 2877 | if (atomic_dec_and_test(&rsp->barrier_cpu_count)) |
Paul E. McKenney | 7db74df | 2012-05-29 03:03:37 -0700 | [diff] [blame] | 2878 | complete(&rsp->barrier_completion); |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2879 | |
Paul E. McKenney | cf3a9c4 | 2012-05-29 14:56:46 -0700 | [diff] [blame] | 2880 | /* Increment ->n_barrier_done to prevent duplicate work. */ |
| 2881 | smp_mb(); /* Keep increment after above mechanism. */ |
| 2882 | ACCESS_ONCE(rsp->n_barrier_done)++; |
| 2883 | WARN_ON_ONCE((rsp->n_barrier_done & 0x1) != 0); |
Paul E. McKenney | a83eff0 | 2012-05-23 18:47:05 -0700 | [diff] [blame] | 2884 | _rcu_barrier_trace(rsp, "Inc2", -1, rsp->n_barrier_done); |
Paul E. McKenney | cf3a9c4 | 2012-05-29 14:56:46 -0700 | [diff] [blame] | 2885 | smp_mb(); /* Keep increment before caller's subsequent code. */ |
| 2886 | |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2887 | /* Wait for all rcu_barrier_callback() callbacks to be invoked. */ |
Paul E. McKenney | 7db74df | 2012-05-29 03:03:37 -0700 | [diff] [blame] | 2888 | wait_for_completion(&rsp->barrier_completion); |
Paul E. McKenney | b1420f1 | 2012-03-01 13:18:08 -0800 | [diff] [blame] | 2889 | |
| 2890 | /* Other rcu_barrier() invocations can now safely proceed. */ |
Paul E. McKenney | 7be7f0b | 2012-05-29 05:18:53 -0700 | [diff] [blame] | 2891 | mutex_unlock(&rsp->barrier_mutex); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2892 | } |
| 2893 | |
| 2894 | /** |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2895 | * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete. |
| 2896 | */ |
| 2897 | void rcu_barrier_bh(void) |
| 2898 | { |
Paul E. McKenney | 037b64e | 2012-05-28 23:26:01 -0700 | [diff] [blame] | 2899 | _rcu_barrier(&rcu_bh_state); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2900 | } |
| 2901 | EXPORT_SYMBOL_GPL(rcu_barrier_bh); |
| 2902 | |
| 2903 | /** |
| 2904 | * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks. |
| 2905 | */ |
| 2906 | void rcu_barrier_sched(void) |
| 2907 | { |
Paul E. McKenney | 037b64e | 2012-05-28 23:26:01 -0700 | [diff] [blame] | 2908 | _rcu_barrier(&rcu_sched_state); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2909 | } |
| 2910 | EXPORT_SYMBOL_GPL(rcu_barrier_sched); |
| 2911 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2912 | /* |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2913 | * Do boot-time initialization of a CPU's per-CPU RCU data. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2914 | */ |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2915 | static void __init |
| 2916 | rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2917 | { |
| 2918 | unsigned long flags; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2919 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2920 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 2921 | |
| 2922 | /* Set up local state, ensuring consistent view of global state. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2923 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2924 | rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo); |
Paul E. McKenney | 3f5d3ea | 2012-05-09 15:39:56 -0700 | [diff] [blame] | 2925 | init_callback_list(rdp); |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 2926 | rdp->qlen_lazy = 0; |
Paul E. McKenney | 1d1fb39 | 2012-05-09 15:44:42 -0700 | [diff] [blame] | 2927 | ACCESS_ONCE(rdp->qlen) = 0; |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2928 | rdp->dynticks = &per_cpu(rcu_dynticks, cpu); |
Paul E. McKenney | 29e37d8 | 2011-11-17 16:55:56 -0800 | [diff] [blame] | 2929 | WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_EXIT_IDLE); |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 2930 | WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2931 | rdp->cpu = cpu; |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 2932 | rdp->rsp = rsp; |
Paul E. McKenney | 3fbfbf7 | 2012-08-19 21:35:53 -0700 | [diff] [blame] | 2933 | rcu_boot_init_nocb_percpu_data(rdp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2934 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2935 | } |
| 2936 | |
| 2937 | /* |
| 2938 | * Initialize a CPU's per-CPU RCU data. Note that only one online or |
| 2939 | * offline event can be happening at a given time. Note also that we |
| 2940 | * can accept some slop in the rsp->completed access due to the fact |
| 2941 | * that this CPU cannot possibly have any RCU callbacks in flight yet. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2942 | */ |
Paul Gortmaker | 49fb4c6 | 2013-06-19 14:52:21 -0400 | [diff] [blame] | 2943 | static void |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 2944 | rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2945 | { |
| 2946 | unsigned long flags; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2947 | unsigned long mask; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2948 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2949 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 2950 | |
Paul E. McKenney | a4fbe35 | 2012-10-07 08:36:12 -0700 | [diff] [blame] | 2951 | /* Exclude new grace periods. */ |
| 2952 | mutex_lock(&rsp->onoff_mutex); |
| 2953 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2954 | /* Set up local state, ensuring consistent view of global state. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2955 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2956 | rdp->beenonline = 1; /* We have now been online. */ |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 2957 | rdp->preemptible = preemptible; |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 2958 | rdp->qlen_last_fqs_check = 0; |
| 2959 | rdp->n_force_qs_snap = rsp->n_force_qs; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2960 | rdp->blimit = blimit; |
Paul E. McKenney | 0d8ee37 | 2012-08-03 13:16:15 -0700 | [diff] [blame] | 2961 | init_callback_list(rdp); /* Re-enable callbacks on this CPU. */ |
Paul E. McKenney | 29e37d8 | 2011-11-17 16:55:56 -0800 | [diff] [blame] | 2962 | rdp->dynticks->dynticks_nesting = DYNTICK_TASK_EXIT_IDLE; |
Paul E. McKenney | 2333210 | 2013-06-21 12:34:33 -0700 | [diff] [blame] | 2963 | rcu_sysidle_init_percpu_data(rdp->dynticks); |
Paul E. McKenney | c92b131 | 2011-11-23 13:38:58 -0800 | [diff] [blame] | 2964 | atomic_set(&rdp->dynticks->dynticks, |
| 2965 | (atomic_read(&rdp->dynticks->dynticks) & ~0x1) + 1); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2966 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2967 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2968 | /* Add CPU to rcu_node bitmasks. */ |
| 2969 | rnp = rdp->mynode; |
| 2970 | mask = rdp->grpmask; |
| 2971 | do { |
| 2972 | /* Exclude any attempts to start a new GP on small systems. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2973 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2974 | rnp->qsmaskinit |= mask; |
| 2975 | mask = rnp->grpmask; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 2976 | if (rnp == rdp->mynode) { |
Paul E. McKenney | 06ae115a | 2011-08-14 15:56:54 -0700 | [diff] [blame] | 2977 | /* |
| 2978 | * If there is a grace period in progress, we will |
| 2979 | * set up to wait for it next time we run the |
| 2980 | * RCU core code. |
| 2981 | */ |
| 2982 | rdp->gpnum = rnp->completed; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 2983 | rdp->completed = rnp->completed; |
Paul E. McKenney | 06ae115a | 2011-08-14 15:56:54 -0700 | [diff] [blame] | 2984 | rdp->passed_quiesce = 0; |
| 2985 | rdp->qs_pending = 0; |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 2986 | trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuonl")); |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 2987 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2988 | raw_spin_unlock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2989 | rnp = rnp->parent; |
| 2990 | } while (rnp != NULL && !(rnp->qsmaskinit & mask)); |
Paul E. McKenney | a4fbe35 | 2012-10-07 08:36:12 -0700 | [diff] [blame] | 2991 | local_irq_restore(flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2992 | |
Paul E. McKenney | a4fbe35 | 2012-10-07 08:36:12 -0700 | [diff] [blame] | 2993 | mutex_unlock(&rsp->onoff_mutex); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2994 | } |
| 2995 | |
Paul Gortmaker | 49fb4c6 | 2013-06-19 14:52:21 -0400 | [diff] [blame] | 2996 | static void rcu_prepare_cpu(int cpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2997 | { |
Paul E. McKenney | 6ce75a2 | 2012-06-12 11:01:13 -0700 | [diff] [blame] | 2998 | struct rcu_state *rsp; |
| 2999 | |
| 3000 | for_each_rcu_flavor(rsp) |
| 3001 | rcu_init_percpu_data(cpu, rsp, |
| 3002 | strcmp(rsp->name, "rcu_preempt") == 0); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3003 | } |
| 3004 | |
| 3005 | /* |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 3006 | * Handle CPU online/offline notification events. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3007 | */ |
Paul Gortmaker | 49fb4c6 | 2013-06-19 14:52:21 -0400 | [diff] [blame] | 3008 | static int rcu_cpu_notify(struct notifier_block *self, |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 3009 | unsigned long action, void *hcpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3010 | { |
| 3011 | long cpu = (long)hcpu; |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 3012 | struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 3013 | struct rcu_node *rnp = rdp->mynode; |
Paul E. McKenney | 6ce75a2 | 2012-06-12 11:01:13 -0700 | [diff] [blame] | 3014 | struct rcu_state *rsp; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3015 | |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 3016 | trace_rcu_utilization(TPS("Start CPU hotplug")); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3017 | switch (action) { |
| 3018 | case CPU_UP_PREPARE: |
| 3019 | case CPU_UP_PREPARE_FROZEN: |
Peter Zijlstra | d72bce0 | 2011-05-30 13:34:51 +0200 | [diff] [blame] | 3020 | rcu_prepare_cpu(cpu); |
| 3021 | rcu_prepare_kthreads(cpu); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 3022 | break; |
| 3023 | case CPU_ONLINE: |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 3024 | case CPU_DOWN_FAILED: |
Thomas Gleixner | 5d01bbd | 2012-07-16 10:42:35 +0000 | [diff] [blame] | 3025 | rcu_boost_kthread_setaffinity(rnp, -1); |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 3026 | break; |
| 3027 | case CPU_DOWN_PREPARE: |
Paul E. McKenney | 34ed6246 | 2013-01-07 13:37:42 -0800 | [diff] [blame] | 3028 | rcu_boost_kthread_setaffinity(rnp, cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3029 | break; |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 3030 | case CPU_DYING: |
| 3031 | case CPU_DYING_FROZEN: |
Paul E. McKenney | 6ce75a2 | 2012-06-12 11:01:13 -0700 | [diff] [blame] | 3032 | for_each_rcu_flavor(rsp) |
| 3033 | rcu_cleanup_dying_cpu(rsp); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 3034 | break; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3035 | case CPU_DEAD: |
| 3036 | case CPU_DEAD_FROZEN: |
| 3037 | case CPU_UP_CANCELED: |
| 3038 | case CPU_UP_CANCELED_FROZEN: |
Paul E. McKenney | 6ce75a2 | 2012-06-12 11:01:13 -0700 | [diff] [blame] | 3039 | for_each_rcu_flavor(rsp) |
| 3040 | rcu_cleanup_dead_cpu(cpu, rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3041 | break; |
| 3042 | default: |
| 3043 | break; |
| 3044 | } |
Steven Rostedt (Red Hat) | f7f7bac | 2013-07-12 17:18:47 -0400 | [diff] [blame] | 3045 | trace_rcu_utilization(TPS("End CPU hotplug")); |
Paul E. McKenney | 34ed6246 | 2013-01-07 13:37:42 -0800 | [diff] [blame] | 3046 | return NOTIFY_OK; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3047 | } |
| 3048 | |
Borislav Petkov | d1d74d1 | 2013-04-22 00:12:42 +0200 | [diff] [blame] | 3049 | static int rcu_pm_notify(struct notifier_block *self, |
| 3050 | unsigned long action, void *hcpu) |
| 3051 | { |
| 3052 | switch (action) { |
| 3053 | case PM_HIBERNATION_PREPARE: |
| 3054 | case PM_SUSPEND_PREPARE: |
| 3055 | if (nr_cpu_ids <= 256) /* Expediting bad for large systems. */ |
| 3056 | rcu_expedited = 1; |
| 3057 | break; |
| 3058 | case PM_POST_HIBERNATION: |
| 3059 | case PM_POST_SUSPEND: |
| 3060 | rcu_expedited = 0; |
| 3061 | break; |
| 3062 | default: |
| 3063 | break; |
| 3064 | } |
| 3065 | return NOTIFY_OK; |
| 3066 | } |
| 3067 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3068 | /* |
Paul E. McKenney | b3dbec7 | 2012-06-18 18:36:08 -0700 | [diff] [blame] | 3069 | * Spawn the kthread that handles this RCU flavor's grace periods. |
| 3070 | */ |
| 3071 | static int __init rcu_spawn_gp_kthread(void) |
| 3072 | { |
| 3073 | unsigned long flags; |
| 3074 | struct rcu_node *rnp; |
| 3075 | struct rcu_state *rsp; |
| 3076 | struct task_struct *t; |
| 3077 | |
| 3078 | for_each_rcu_flavor(rsp) { |
Kees Cook | f170168 | 2013-07-03 15:04:58 -0700 | [diff] [blame] | 3079 | t = kthread_run(rcu_gp_kthread, rsp, "%s", rsp->name); |
Paul E. McKenney | b3dbec7 | 2012-06-18 18:36:08 -0700 | [diff] [blame] | 3080 | BUG_ON(IS_ERR(t)); |
| 3081 | rnp = rcu_get_root(rsp); |
| 3082 | raw_spin_lock_irqsave(&rnp->lock, flags); |
| 3083 | rsp->gp_kthread = t; |
| 3084 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 3fbfbf7 | 2012-08-19 21:35:53 -0700 | [diff] [blame] | 3085 | rcu_spawn_nocb_kthreads(rsp); |
Paul E. McKenney | b3dbec7 | 2012-06-18 18:36:08 -0700 | [diff] [blame] | 3086 | } |
| 3087 | return 0; |
| 3088 | } |
| 3089 | early_initcall(rcu_spawn_gp_kthread); |
| 3090 | |
| 3091 | /* |
Paul E. McKenney | bbad937 | 2010-04-02 16:17:17 -0700 | [diff] [blame] | 3092 | * This function is invoked towards the end of the scheduler's initialization |
| 3093 | * process. Before this is called, the idle task might contain |
| 3094 | * RCU read-side critical sections (during which time, this idle |
| 3095 | * task is booting the system). After this function is called, the |
| 3096 | * idle tasks are prohibited from containing RCU read-side critical |
| 3097 | * sections. This function also enables RCU lockdep checking. |
| 3098 | */ |
| 3099 | void rcu_scheduler_starting(void) |
| 3100 | { |
| 3101 | WARN_ON(num_online_cpus() != 1); |
| 3102 | WARN_ON(nr_context_switches() > 0); |
| 3103 | rcu_scheduler_active = 1; |
| 3104 | } |
| 3105 | |
| 3106 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3107 | * Compute the per-level fanout, either using the exact fanout specified |
| 3108 | * or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT. |
| 3109 | */ |
| 3110 | #ifdef CONFIG_RCU_FANOUT_EXACT |
| 3111 | static void __init rcu_init_levelspread(struct rcu_state *rsp) |
| 3112 | { |
| 3113 | int i; |
| 3114 | |
Paul E. McKenney | f885b7f | 2012-04-23 15:52:53 -0700 | [diff] [blame] | 3115 | for (i = rcu_num_lvls - 1; i > 0; i--) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3116 | rsp->levelspread[i] = CONFIG_RCU_FANOUT; |
Paul E. McKenney | f885b7f | 2012-04-23 15:52:53 -0700 | [diff] [blame] | 3117 | rsp->levelspread[0] = rcu_fanout_leaf; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3118 | } |
| 3119 | #else /* #ifdef CONFIG_RCU_FANOUT_EXACT */ |
| 3120 | static void __init rcu_init_levelspread(struct rcu_state *rsp) |
| 3121 | { |
| 3122 | int ccur; |
| 3123 | int cprv; |
| 3124 | int i; |
| 3125 | |
Paul E. McKenney | 4dbd6bb3 | 2012-09-05 21:43:57 -0700 | [diff] [blame] | 3126 | cprv = nr_cpu_ids; |
Paul E. McKenney | f885b7f | 2012-04-23 15:52:53 -0700 | [diff] [blame] | 3127 | for (i = rcu_num_lvls - 1; i >= 0; i--) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3128 | ccur = rsp->levelcnt[i]; |
| 3129 | rsp->levelspread[i] = (cprv + ccur - 1) / ccur; |
| 3130 | cprv = ccur; |
| 3131 | } |
| 3132 | } |
| 3133 | #endif /* #else #ifdef CONFIG_RCU_FANOUT_EXACT */ |
| 3134 | |
| 3135 | /* |
| 3136 | * Helper function for rcu_init() that initializes one rcu_state structure. |
| 3137 | */ |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 3138 | static void __init rcu_init_one(struct rcu_state *rsp, |
| 3139 | struct rcu_data __percpu *rda) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3140 | { |
Paul E. McKenney | 394f276 | 2012-06-26 17:00:35 -0700 | [diff] [blame] | 3141 | static char *buf[] = { "rcu_node_0", |
| 3142 | "rcu_node_1", |
| 3143 | "rcu_node_2", |
| 3144 | "rcu_node_3" }; /* Match MAX_RCU_LVLS */ |
| 3145 | static char *fqs[] = { "rcu_node_fqs_0", |
| 3146 | "rcu_node_fqs_1", |
| 3147 | "rcu_node_fqs_2", |
| 3148 | "rcu_node_fqs_3" }; /* Match MAX_RCU_LVLS */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3149 | int cpustride = 1; |
| 3150 | int i; |
| 3151 | int j; |
| 3152 | struct rcu_node *rnp; |
| 3153 | |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 3154 | BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */ |
| 3155 | |
Paul E. McKenney | 4930521 | 2012-11-29 13:49:00 -0800 | [diff] [blame] | 3156 | /* Silence gcc 4.8 warning about array index out of range. */ |
| 3157 | if (rcu_num_lvls > RCU_NUM_LVLS) |
| 3158 | panic("rcu_init_one: rcu_num_lvls overflow"); |
| 3159 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3160 | /* Initialize the level-tracking arrays. */ |
| 3161 | |
Paul E. McKenney | f885b7f | 2012-04-23 15:52:53 -0700 | [diff] [blame] | 3162 | for (i = 0; i < rcu_num_lvls; i++) |
| 3163 | rsp->levelcnt[i] = num_rcu_lvl[i]; |
| 3164 | for (i = 1; i < rcu_num_lvls; i++) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3165 | rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1]; |
| 3166 | rcu_init_levelspread(rsp); |
| 3167 | |
| 3168 | /* Initialize the elements themselves, starting from the leaves. */ |
| 3169 | |
Paul E. McKenney | f885b7f | 2012-04-23 15:52:53 -0700 | [diff] [blame] | 3170 | for (i = rcu_num_lvls - 1; i >= 0; i--) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3171 | cpustride *= rsp->levelspread[i]; |
| 3172 | rnp = rsp->level[i]; |
| 3173 | for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 3174 | raw_spin_lock_init(&rnp->lock); |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 3175 | lockdep_set_class_and_name(&rnp->lock, |
| 3176 | &rcu_node_class[i], buf[i]); |
Paul E. McKenney | 394f276 | 2012-06-26 17:00:35 -0700 | [diff] [blame] | 3177 | raw_spin_lock_init(&rnp->fqslock); |
| 3178 | lockdep_set_class_and_name(&rnp->fqslock, |
| 3179 | &rcu_fqs_class[i], fqs[i]); |
Paul E. McKenney | 25d30cf | 2012-07-11 05:23:18 -0700 | [diff] [blame] | 3180 | rnp->gpnum = rsp->gpnum; |
| 3181 | rnp->completed = rsp->completed; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3182 | rnp->qsmask = 0; |
| 3183 | rnp->qsmaskinit = 0; |
| 3184 | rnp->grplo = j * cpustride; |
| 3185 | rnp->grphi = (j + 1) * cpustride - 1; |
| 3186 | if (rnp->grphi >= NR_CPUS) |
| 3187 | rnp->grphi = NR_CPUS - 1; |
| 3188 | if (i == 0) { |
| 3189 | rnp->grpnum = 0; |
| 3190 | rnp->grpmask = 0; |
| 3191 | rnp->parent = NULL; |
| 3192 | } else { |
| 3193 | rnp->grpnum = j % rsp->levelspread[i - 1]; |
| 3194 | rnp->grpmask = 1UL << rnp->grpnum; |
| 3195 | rnp->parent = rsp->level[i - 1] + |
| 3196 | j / rsp->levelspread[i - 1]; |
| 3197 | } |
| 3198 | rnp->level = i; |
Paul E. McKenney | 12f5f52 | 2010-11-29 21:56:39 -0800 | [diff] [blame] | 3199 | INIT_LIST_HEAD(&rnp->blkd_tasks); |
Paul E. McKenney | dae6e64 | 2013-02-10 20:48:58 -0800 | [diff] [blame] | 3200 | rcu_init_one_nocb(rnp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3201 | } |
| 3202 | } |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 3203 | |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 3204 | rsp->rda = rda; |
Paul E. McKenney | b3dbec7 | 2012-06-18 18:36:08 -0700 | [diff] [blame] | 3205 | init_waitqueue_head(&rsp->gp_wq); |
Steven Rostedt | 016a8d5 | 2013-05-28 17:32:53 -0400 | [diff] [blame] | 3206 | init_irq_work(&rsp->wakeup_work, rsp_wakeup); |
Paul E. McKenney | f885b7f | 2012-04-23 15:52:53 -0700 | [diff] [blame] | 3207 | rnp = rsp->level[rcu_num_lvls - 1]; |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 3208 | for_each_possible_cpu(i) { |
Paul E. McKenney | 4a90a06 | 2010-04-14 16:48:11 -0700 | [diff] [blame] | 3209 | while (i > rnp->grphi) |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 3210 | rnp++; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 3211 | per_cpu_ptr(rsp->rda, i)->mynode = rnp; |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 3212 | rcu_boot_init_percpu_data(i, rsp); |
| 3213 | } |
Paul E. McKenney | 6ce75a2 | 2012-06-12 11:01:13 -0700 | [diff] [blame] | 3214 | list_add(&rsp->flavors, &rcu_struct_flavors); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3215 | } |
| 3216 | |
Paul E. McKenney | f885b7f | 2012-04-23 15:52:53 -0700 | [diff] [blame] | 3217 | /* |
| 3218 | * Compute the rcu_node tree geometry from kernel parameters. This cannot |
| 3219 | * replace the definitions in rcutree.h because those are needed to size |
| 3220 | * the ->node array in the rcu_state structure. |
| 3221 | */ |
| 3222 | static void __init rcu_init_geometry(void) |
| 3223 | { |
Paul E. McKenney | 026ad28 | 2013-04-03 22:14:11 -0700 | [diff] [blame] | 3224 | ulong d; |
Paul E. McKenney | f885b7f | 2012-04-23 15:52:53 -0700 | [diff] [blame] | 3225 | int i; |
| 3226 | int j; |
Paul E. McKenney | cca6f39 | 2012-05-08 21:00:28 -0700 | [diff] [blame] | 3227 | int n = nr_cpu_ids; |
Paul E. McKenney | f885b7f | 2012-04-23 15:52:53 -0700 | [diff] [blame] | 3228 | int rcu_capacity[MAX_RCU_LVLS + 1]; |
| 3229 | |
Paul E. McKenney | 026ad28 | 2013-04-03 22:14:11 -0700 | [diff] [blame] | 3230 | /* |
| 3231 | * Initialize any unspecified boot parameters. |
| 3232 | * The default values of jiffies_till_first_fqs and |
| 3233 | * jiffies_till_next_fqs are set to the RCU_JIFFIES_TILL_FORCE_QS |
| 3234 | * value, which is a function of HZ, then adding one for each |
| 3235 | * RCU_JIFFIES_FQS_DIV CPUs that might be on the system. |
| 3236 | */ |
| 3237 | d = RCU_JIFFIES_TILL_FORCE_QS + nr_cpu_ids / RCU_JIFFIES_FQS_DIV; |
| 3238 | if (jiffies_till_first_fqs == ULONG_MAX) |
| 3239 | jiffies_till_first_fqs = d; |
| 3240 | if (jiffies_till_next_fqs == ULONG_MAX) |
| 3241 | jiffies_till_next_fqs = d; |
| 3242 | |
Paul E. McKenney | f885b7f | 2012-04-23 15:52:53 -0700 | [diff] [blame] | 3243 | /* If the compile-time values are accurate, just leave. */ |
Paul E. McKenney | b17c703 | 2012-09-06 15:38:02 -0700 | [diff] [blame] | 3244 | if (rcu_fanout_leaf == CONFIG_RCU_FANOUT_LEAF && |
| 3245 | nr_cpu_ids == NR_CPUS) |
Paul E. McKenney | f885b7f | 2012-04-23 15:52:53 -0700 | [diff] [blame] | 3246 | return; |
| 3247 | |
| 3248 | /* |
| 3249 | * Compute number of nodes that can be handled an rcu_node tree |
| 3250 | * with the given number of levels. Setting rcu_capacity[0] makes |
| 3251 | * some of the arithmetic easier. |
| 3252 | */ |
| 3253 | rcu_capacity[0] = 1; |
| 3254 | rcu_capacity[1] = rcu_fanout_leaf; |
| 3255 | for (i = 2; i <= MAX_RCU_LVLS; i++) |
| 3256 | rcu_capacity[i] = rcu_capacity[i - 1] * CONFIG_RCU_FANOUT; |
| 3257 | |
| 3258 | /* |
| 3259 | * The boot-time rcu_fanout_leaf parameter is only permitted |
| 3260 | * to increase the leaf-level fanout, not decrease it. Of course, |
| 3261 | * the leaf-level fanout cannot exceed the number of bits in |
| 3262 | * the rcu_node masks. Finally, the tree must be able to accommodate |
| 3263 | * the configured number of CPUs. Complain and fall back to the |
| 3264 | * compile-time values if these limits are exceeded. |
| 3265 | */ |
| 3266 | if (rcu_fanout_leaf < CONFIG_RCU_FANOUT_LEAF || |
| 3267 | rcu_fanout_leaf > sizeof(unsigned long) * 8 || |
| 3268 | n > rcu_capacity[MAX_RCU_LVLS]) { |
| 3269 | WARN_ON(1); |
| 3270 | return; |
| 3271 | } |
| 3272 | |
| 3273 | /* Calculate the number of rcu_nodes at each level of the tree. */ |
| 3274 | for (i = 1; i <= MAX_RCU_LVLS; i++) |
| 3275 | if (n <= rcu_capacity[i]) { |
| 3276 | for (j = 0; j <= i; j++) |
| 3277 | num_rcu_lvl[j] = |
| 3278 | DIV_ROUND_UP(n, rcu_capacity[i - j]); |
| 3279 | rcu_num_lvls = i; |
| 3280 | for (j = i + 1; j <= MAX_RCU_LVLS; j++) |
| 3281 | num_rcu_lvl[j] = 0; |
| 3282 | break; |
| 3283 | } |
| 3284 | |
| 3285 | /* Calculate the total number of rcu_node structures. */ |
| 3286 | rcu_num_nodes = 0; |
| 3287 | for (i = 0; i <= MAX_RCU_LVLS; i++) |
| 3288 | rcu_num_nodes += num_rcu_lvl[i]; |
| 3289 | rcu_num_nodes -= n; |
| 3290 | } |
| 3291 | |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 3292 | void __init rcu_init(void) |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 3293 | { |
Paul E. McKenney | 017c426 | 2010-01-14 16:10:58 -0800 | [diff] [blame] | 3294 | int cpu; |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 3295 | |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 3296 | rcu_bootup_announce(); |
Paul E. McKenney | f885b7f | 2012-04-23 15:52:53 -0700 | [diff] [blame] | 3297 | rcu_init_geometry(); |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 3298 | rcu_init_one(&rcu_sched_state, &rcu_sched_data); |
| 3299 | rcu_init_one(&rcu_bh_state, &rcu_bh_data); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 3300 | __rcu_init_preempt(); |
Jiang Fang | b5b3936 | 2013-02-02 14:13:42 -0800 | [diff] [blame] | 3301 | open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 3302 | |
| 3303 | /* |
| 3304 | * We don't need protection against CPU-hotplug here because |
| 3305 | * this is called early in boot, before either interrupts |
| 3306 | * or the scheduler are operational. |
| 3307 | */ |
| 3308 | cpu_notifier(rcu_cpu_notify, 0); |
Borislav Petkov | d1d74d1 | 2013-04-22 00:12:42 +0200 | [diff] [blame] | 3309 | pm_notifier(rcu_pm_notify, 0); |
Paul E. McKenney | 017c426 | 2010-01-14 16:10:58 -0800 | [diff] [blame] | 3310 | for_each_online_cpu(cpu) |
| 3311 | rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 3312 | } |
| 3313 | |
Paul E. McKenney | 1eba8f8 | 2009-09-23 09:50:42 -0700 | [diff] [blame] | 3314 | #include "rcutree_plugin.h" |