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 | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 55 | |
Paul E. McKenney | 9f77da9 | 2009-08-22 13:56:45 -0700 | [diff] [blame] | 56 | #include "rcutree.h" |
Paul E. McKenney | 29c00b4 | 2011-06-17 15:53:19 -0700 | [diff] [blame] | 57 | #include <trace/events/rcu.h> |
| 58 | |
| 59 | #include "rcu.h" |
Paul E. McKenney | 9f77da9 | 2009-08-22 13:56:45 -0700 | [diff] [blame] | 60 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 61 | /* Data structures. */ |
| 62 | |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 63 | static struct lock_class_key rcu_node_class[NUM_RCU_LVLS]; |
Peter Zijlstra | 88b91c7 | 2009-10-26 10:24:31 -0700 | [diff] [blame] | 64 | |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 65 | #define RCU_STATE_INITIALIZER(structname) { \ |
Paul E. McKenney | e99033c | 2011-06-21 00:13:44 -0700 | [diff] [blame] | 66 | .level = { &structname##_state.node[0] }, \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 67 | .levelcnt = { \ |
| 68 | NUM_RCU_LVL_0, /* root of hierarchy. */ \ |
| 69 | NUM_RCU_LVL_1, \ |
| 70 | NUM_RCU_LVL_2, \ |
Paul E. McKenney | cf244dc | 2009-12-02 12:10:14 -0800 | [diff] [blame] | 71 | NUM_RCU_LVL_3, \ |
| 72 | NUM_RCU_LVL_4, /* == MAX_RCU_LVLS */ \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 73 | }, \ |
Paul E. McKenney | af446b7 | 2011-09-10 21:54:08 -0700 | [diff] [blame] | 74 | .fqs_state = RCU_GP_IDLE, \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 75 | .gpnum = -300, \ |
| 76 | .completed = -300, \ |
Paul E. McKenney | e99033c | 2011-06-21 00:13:44 -0700 | [diff] [blame] | 77 | .onofflock = __RAW_SPIN_LOCK_UNLOCKED(&structname##_state.onofflock), \ |
| 78 | .fqslock = __RAW_SPIN_LOCK_UNLOCKED(&structname##_state.fqslock), \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 79 | .n_force_qs = 0, \ |
| 80 | .n_force_qs_ngp = 0, \ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 81 | .name = #structname, \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 82 | } |
| 83 | |
Paul E. McKenney | e99033c | 2011-06-21 00:13:44 -0700 | [diff] [blame] | 84 | struct rcu_state rcu_sched_state = RCU_STATE_INITIALIZER(rcu_sched); |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 85 | DEFINE_PER_CPU(struct rcu_data, rcu_sched_data); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 86 | |
Paul E. McKenney | e99033c | 2011-06-21 00:13:44 -0700 | [diff] [blame] | 87 | struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh); |
Ingo Molnar | 6258c4f | 2009-03-25 16:42:24 +0100 | [diff] [blame] | 88 | DEFINE_PER_CPU(struct rcu_data, rcu_bh_data); |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 89 | |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 90 | static struct rcu_state *rcu_state; |
| 91 | |
Paul E. McKenney | b0d3041 | 2011-07-10 15:57:35 -0700 | [diff] [blame] | 92 | /* |
| 93 | * The rcu_scheduler_active variable transitions from zero to one just |
| 94 | * before the first task is spawned. So when this variable is zero, RCU |
| 95 | * can assume that there is but one task, allowing RCU to (for example) |
| 96 | * optimized synchronize_sched() to a simple barrier(). When this variable |
| 97 | * is one, RCU must actually do all the hard work required to detect real |
| 98 | * grace periods. This variable is also used to suppress boot-time false |
| 99 | * positives from lockdep-RCU error checking. |
| 100 | */ |
Paul E. McKenney | bbad937 | 2010-04-02 16:17:17 -0700 | [diff] [blame] | 101 | int rcu_scheduler_active __read_mostly; |
| 102 | EXPORT_SYMBOL_GPL(rcu_scheduler_active); |
| 103 | |
Paul E. McKenney | b0d3041 | 2011-07-10 15:57:35 -0700 | [diff] [blame] | 104 | /* |
| 105 | * The rcu_scheduler_fully_active variable transitions from zero to one |
| 106 | * during the early_initcall() processing, which is after the scheduler |
| 107 | * is capable of creating new tasks. So RCU processing (for example, |
| 108 | * creating tasks for RCU priority boosting) must be delayed until after |
| 109 | * rcu_scheduler_fully_active transitions from zero to one. We also |
| 110 | * currently delay invocation of any RCU callbacks until after this point. |
| 111 | * |
| 112 | * It might later prove better for people registering RCU callbacks during |
| 113 | * early boot to take responsibility for these callbacks, but one step at |
| 114 | * a time. |
| 115 | */ |
| 116 | static int rcu_scheduler_fully_active __read_mostly; |
| 117 | |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 118 | #ifdef CONFIG_RCU_BOOST |
| 119 | |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 120 | /* |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 121 | * Control variables for per-CPU and per-rcu_node kthreads. These |
| 122 | * handle all flavors of RCU. |
| 123 | */ |
| 124 | static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task); |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 125 | DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status); |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 126 | DEFINE_PER_CPU(int, rcu_cpu_kthread_cpu); |
Paul E. McKenney | 5ece5ba | 2011-04-22 18:08:51 -0700 | [diff] [blame] | 127 | DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 128 | DEFINE_PER_CPU(char, rcu_cpu_has_work); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 129 | |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 130 | #endif /* #ifdef CONFIG_RCU_BOOST */ |
| 131 | |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 132 | static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu); |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 133 | static void invoke_rcu_core(void); |
| 134 | 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] | 135 | |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 136 | /* |
Paul E. McKenney | 4a29865 | 2011-04-03 21:33:51 -0700 | [diff] [blame] | 137 | * Track the rcutorture test sequence number and the update version |
| 138 | * number within a given test. The rcutorture_testseq is incremented |
| 139 | * on every rcutorture module load and unload, so has an odd value |
| 140 | * when a test is running. The rcutorture_vernum is set to zero |
| 141 | * when rcutorture starts and is incremented on each rcutorture update. |
| 142 | * These variables enable correlating rcutorture output with the |
| 143 | * RCU tracing information. |
| 144 | */ |
| 145 | unsigned long rcutorture_testseq; |
| 146 | unsigned long rcutorture_vernum; |
| 147 | |
| 148 | /* |
Paul E. McKenney | fc2219d4 | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 149 | * Return true if an RCU grace period is in progress. The ACCESS_ONCE()s |
| 150 | * permit this function to be invoked without holding the root rcu_node |
| 151 | * structure's ->lock, but of course results can be subject to change. |
| 152 | */ |
| 153 | static int rcu_gp_in_progress(struct rcu_state *rsp) |
| 154 | { |
| 155 | return ACCESS_ONCE(rsp->completed) != ACCESS_ONCE(rsp->gpnum); |
| 156 | } |
| 157 | |
| 158 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 159 | * Note a quiescent state. Because we do not need to know |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 160 | * how many quiescent states passed, just if there was at least |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 161 | * 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] | 162 | * The caller must have disabled preemption. |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 163 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 164 | void rcu_sched_qs(int cpu) |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 165 | { |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 166 | struct rcu_data *rdp = &per_cpu(rcu_sched_data, cpu); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 167 | |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 168 | rdp->passed_quiesce_gpnum = rdp->gpnum; |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 169 | barrier(); |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 170 | if (rdp->passed_quiesce == 0) |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 171 | trace_rcu_grace_period("rcu_sched", rdp->gpnum, "cpuqs"); |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 172 | rdp->passed_quiesce = 1; |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 173 | } |
| 174 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 175 | void rcu_bh_qs(int cpu) |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 176 | { |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 177 | struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 178 | |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 179 | rdp->passed_quiesce_gpnum = rdp->gpnum; |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 180 | barrier(); |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 181 | if (rdp->passed_quiesce == 0) |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 182 | trace_rcu_grace_period("rcu_bh", rdp->gpnum, "cpuqs"); |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 183 | rdp->passed_quiesce = 1; |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 184 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 185 | |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 186 | /* |
| 187 | * Note a context switch. This is a quiescent state for RCU-sched, |
| 188 | * and requires special handling for preemptible RCU. |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 189 | * The caller must have disabled preemption. |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 190 | */ |
| 191 | void rcu_note_context_switch(int cpu) |
| 192 | { |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 193 | trace_rcu_utilization("Start context switch"); |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 194 | rcu_sched_qs(cpu); |
| 195 | rcu_preempt_note_context_switch(cpu); |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 196 | trace_rcu_utilization("End context switch"); |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 197 | } |
Gleb Natapov | 29ce831 | 2011-05-04 16:31:03 +0300 | [diff] [blame] | 198 | EXPORT_SYMBOL_GPL(rcu_note_context_switch); |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 199 | |
Paul E. McKenney | 90a4d2c | 2009-01-04 11:41:11 -0800 | [diff] [blame] | 200 | DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { |
Paul E. McKenney | 4145fa7 | 2011-10-31 15:01:54 -0700 | [diff] [blame] | 201 | .dynticks_nesting = DYNTICK_TASK_NESTING, |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 202 | .dynticks = ATOMIC_INIT(1), |
Paul E. McKenney | 90a4d2c | 2009-01-04 11:41:11 -0800 | [diff] [blame] | 203 | }; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 204 | |
Paul E. McKenney | e0f2306 | 2011-06-21 01:29:39 -0700 | [diff] [blame] | 205 | static int blimit = 10; /* Maximum callbacks per rcu_do_batch. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 206 | static int qhimark = 10000; /* If this many pending, ignore blimit. */ |
| 207 | static int qlowmark = 100; /* Once only this many pending, use blimit. */ |
| 208 | |
Paul E. McKenney | 3d76c08 | 2009-09-28 07:46:32 -0700 | [diff] [blame] | 209 | module_param(blimit, int, 0); |
| 210 | module_param(qhimark, int, 0); |
| 211 | module_param(qlowmark, int, 0); |
| 212 | |
Paul E. McKenney | 13cfcca | 2012-01-13 15:32:18 -0800 | [diff] [blame] | 213 | int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */ |
| 214 | int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT; |
| 215 | |
Paul E. McKenney | f2e0dd7 | 2010-07-14 14:38:30 -0700 | [diff] [blame] | 216 | module_param(rcu_cpu_stall_suppress, int, 0644); |
Paul E. McKenney | 13cfcca | 2012-01-13 15:32:18 -0800 | [diff] [blame] | 217 | module_param(rcu_cpu_stall_timeout, int, 0644); |
Paul E. McKenney | 742734e | 2010-06-30 11:43:52 -0700 | [diff] [blame] | 218 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 219 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed); |
Paul E. McKenney | a157229 | 2009-08-22 13:56:51 -0700 | [diff] [blame] | 220 | static int rcu_pending(int cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 221 | |
| 222 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 223 | * 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] | 224 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 225 | long rcu_batches_completed_sched(void) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 226 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 227 | return rcu_sched_state.completed; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 228 | } |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 229 | EXPORT_SYMBOL_GPL(rcu_batches_completed_sched); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 230 | |
| 231 | /* |
| 232 | * Return the number of RCU BH batches processed thus far for debug & stats. |
| 233 | */ |
| 234 | long rcu_batches_completed_bh(void) |
| 235 | { |
| 236 | return rcu_bh_state.completed; |
| 237 | } |
| 238 | EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); |
| 239 | |
| 240 | /* |
Paul E. McKenney | bf66f18 | 2010-01-04 15:09:10 -0800 | [diff] [blame] | 241 | * Force a quiescent state for RCU BH. |
| 242 | */ |
| 243 | void rcu_bh_force_quiescent_state(void) |
| 244 | { |
| 245 | force_quiescent_state(&rcu_bh_state, 0); |
| 246 | } |
| 247 | EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state); |
| 248 | |
| 249 | /* |
Paul E. McKenney | 4a29865 | 2011-04-03 21:33:51 -0700 | [diff] [blame] | 250 | * Record the number of times rcutorture tests have been initiated and |
| 251 | * terminated. This information allows the debugfs tracing stats to be |
| 252 | * correlated to the rcutorture messages, even when the rcutorture module |
| 253 | * is being repeatedly loaded and unloaded. In other words, we cannot |
| 254 | * store this state in rcutorture itself. |
| 255 | */ |
| 256 | void rcutorture_record_test_transition(void) |
| 257 | { |
| 258 | rcutorture_testseq++; |
| 259 | rcutorture_vernum = 0; |
| 260 | } |
| 261 | EXPORT_SYMBOL_GPL(rcutorture_record_test_transition); |
| 262 | |
| 263 | /* |
| 264 | * Record the number of writer passes through the current rcutorture test. |
| 265 | * This is also used to correlate debugfs tracing stats with the rcutorture |
| 266 | * messages. |
| 267 | */ |
| 268 | void rcutorture_record_progress(unsigned long vernum) |
| 269 | { |
| 270 | rcutorture_vernum++; |
| 271 | } |
| 272 | EXPORT_SYMBOL_GPL(rcutorture_record_progress); |
| 273 | |
| 274 | /* |
Paul E. McKenney | bf66f18 | 2010-01-04 15:09:10 -0800 | [diff] [blame] | 275 | * Force a quiescent state for RCU-sched. |
| 276 | */ |
| 277 | void rcu_sched_force_quiescent_state(void) |
| 278 | { |
| 279 | force_quiescent_state(&rcu_sched_state, 0); |
| 280 | } |
| 281 | EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state); |
| 282 | |
| 283 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 284 | * Does the CPU have callbacks ready to be invoked? |
| 285 | */ |
| 286 | static int |
| 287 | cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp) |
| 288 | { |
| 289 | return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]; |
| 290 | } |
| 291 | |
| 292 | /* |
| 293 | * Does the current CPU require a yet-as-unscheduled grace period? |
| 294 | */ |
| 295 | static int |
| 296 | cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp) |
| 297 | { |
Paul E. McKenney | fc2219d4 | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 298 | return *rdp->nxttail[RCU_DONE_TAIL] && !rcu_gp_in_progress(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 299 | } |
| 300 | |
| 301 | /* |
| 302 | * Return the root node of the specified rcu_state structure. |
| 303 | */ |
| 304 | static struct rcu_node *rcu_get_root(struct rcu_state *rsp) |
| 305 | { |
| 306 | return &rsp->node[0]; |
| 307 | } |
| 308 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 309 | /* |
| 310 | * If the specified CPU is offline, tell the caller that it is in |
| 311 | * a quiescent state. Otherwise, whack it with a reschedule IPI. |
| 312 | * Grace periods can end up waiting on an offline CPU when that |
| 313 | * CPU is in the process of coming online -- it will be added to the |
| 314 | * rcu_node bitmasks before it actually makes it online. The same thing |
| 315 | * can happen while a CPU is in the process of coming online. Because this |
| 316 | * race is quite rare, we check for it after detecting that the grace |
| 317 | * period has been delayed rather than checking each and every CPU |
| 318 | * each and every time we start a new grace period. |
| 319 | */ |
| 320 | static int rcu_implicit_offline_qs(struct rcu_data *rdp) |
| 321 | { |
| 322 | /* |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 323 | * If the CPU is offline for more than a jiffy, it is in a quiescent |
| 324 | * state. We can trust its state not to change because interrupts |
| 325 | * are disabled. The reason for the jiffy's worth of slack is to |
| 326 | * handle CPUs initializing on the way up and finding their way |
| 327 | * to the idle loop on the way down. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 328 | */ |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 329 | if (cpu_is_offline(rdp->cpu) && |
| 330 | ULONG_CMP_LT(rdp->rsp->gp_start + 2, jiffies)) { |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 331 | trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, "ofl"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 332 | rdp->offline_fqs++; |
| 333 | return 1; |
| 334 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 335 | return 0; |
| 336 | } |
| 337 | |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 338 | /* |
| 339 | * rcu_idle_enter_common - inform RCU that current CPU is moving towards idle |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 340 | * |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 341 | * If the new value of the ->dynticks_nesting counter now is zero, |
| 342 | * we really have entered idle, and must do the appropriate accounting. |
| 343 | * The caller must have disabled interrupts. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 344 | */ |
Paul E. McKenney | 4145fa7 | 2011-10-31 15:01:54 -0700 | [diff] [blame] | 345 | static void rcu_idle_enter_common(struct rcu_dynticks *rdtp, long long oldval) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 346 | { |
Frederic Weisbecker | facc4e1 | 2011-11-28 16:26:56 -0800 | [diff] [blame] | 347 | trace_rcu_dyntick("Start", oldval, 0); |
Paul E. McKenney | 99745b6 | 2011-11-10 15:48:45 -0800 | [diff] [blame] | 348 | if (!is_idle_task(current)) { |
Paul E. McKenney | 0989cb4 | 2011-11-01 08:57:21 -0700 | [diff] [blame] | 349 | struct task_struct *idle = idle_task(smp_processor_id()); |
| 350 | |
Frederic Weisbecker | facc4e1 | 2011-11-28 16:26:56 -0800 | [diff] [blame] | 351 | trace_rcu_dyntick("Error on entry: not idle task", oldval, 0); |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 352 | ftrace_dump(DUMP_ALL); |
Paul E. McKenney | 0989cb4 | 2011-11-01 08:57:21 -0700 | [diff] [blame] | 353 | WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s", |
| 354 | current->pid, current->comm, |
| 355 | idle->pid, idle->comm); /* must be idle task! */ |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 356 | } |
Paul E. McKenney | aea1b35 | 2011-11-02 06:54:54 -0700 | [diff] [blame] | 357 | rcu_prepare_for_idle(smp_processor_id()); |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 358 | /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ |
| 359 | smp_mb__before_atomic_inc(); /* See above. */ |
| 360 | atomic_inc(&rdtp->dynticks); |
| 361 | smp_mb__after_atomic_inc(); /* Force ordering with next sojourn. */ |
| 362 | WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); |
Paul E. McKenney | c44e2cd | 2012-01-12 13:08:18 -0800 | [diff] [blame] | 363 | |
| 364 | /* |
| 365 | * The idle task is not permitted to enter the idle loop while |
| 366 | * in an RCU read-side critical section. |
| 367 | */ |
| 368 | rcu_lockdep_assert(!lock_is_held(&rcu_lock_map), |
| 369 | "Illegal idle entry in RCU read-side critical section."); |
| 370 | rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map), |
| 371 | "Illegal idle entry in RCU-bh read-side critical section."); |
| 372 | rcu_lockdep_assert(!lock_is_held(&rcu_sched_lock_map), |
| 373 | "Illegal idle entry in RCU-sched read-side critical section."); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 374 | } |
| 375 | |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 376 | /** |
| 377 | * rcu_idle_enter - inform RCU that current CPU is entering idle |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 378 | * |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 379 | * Enter idle mode, in other words, -leave- the mode in which RCU |
| 380 | * read-side critical sections can occur. (Though RCU read-side |
| 381 | * critical sections can occur in irq handlers in idle, a possibility |
| 382 | * handled by irq_enter() and irq_exit().) |
| 383 | * |
| 384 | * We crowbar the ->dynticks_nesting field to zero to allow for |
| 385 | * the possibility of usermode upcalls having messed up our count |
| 386 | * of interrupt nesting level during the prior busy period. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 387 | */ |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 388 | void rcu_idle_enter(void) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 389 | { |
| 390 | unsigned long flags; |
Paul E. McKenney | 4145fa7 | 2011-10-31 15:01:54 -0700 | [diff] [blame] | 391 | long long oldval; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 392 | struct rcu_dynticks *rdtp; |
| 393 | |
| 394 | local_irq_save(flags); |
| 395 | rdtp = &__get_cpu_var(rcu_dynticks); |
Paul E. McKenney | 4145fa7 | 2011-10-31 15:01:54 -0700 | [diff] [blame] | 396 | oldval = rdtp->dynticks_nesting; |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 397 | rdtp->dynticks_nesting = 0; |
Paul E. McKenney | 4145fa7 | 2011-10-31 15:01:54 -0700 | [diff] [blame] | 398 | rcu_idle_enter_common(rdtp, oldval); |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 399 | local_irq_restore(flags); |
| 400 | } |
| 401 | |
| 402 | /** |
| 403 | * rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle |
| 404 | * |
| 405 | * Exit from an interrupt handler, which might possibly result in entering |
| 406 | * idle mode, in other words, leaving the mode in which read-side critical |
| 407 | * sections can occur. |
| 408 | * |
| 409 | * This code assumes that the idle loop never does anything that might |
| 410 | * result in unbalanced calls to irq_enter() and irq_exit(). If your |
| 411 | * architecture violates this assumption, RCU will give you what you |
| 412 | * deserve, good and hard. But very infrequently and irreproducibly. |
| 413 | * |
| 414 | * Use things like work queues to work around this limitation. |
| 415 | * |
| 416 | * You have been warned. |
| 417 | */ |
| 418 | void rcu_irq_exit(void) |
| 419 | { |
| 420 | unsigned long flags; |
Paul E. McKenney | 4145fa7 | 2011-10-31 15:01:54 -0700 | [diff] [blame] | 421 | long long oldval; |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 422 | struct rcu_dynticks *rdtp; |
| 423 | |
| 424 | local_irq_save(flags); |
| 425 | rdtp = &__get_cpu_var(rcu_dynticks); |
Paul E. McKenney | 4145fa7 | 2011-10-31 15:01:54 -0700 | [diff] [blame] | 426 | oldval = rdtp->dynticks_nesting; |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 427 | rdtp->dynticks_nesting--; |
| 428 | WARN_ON_ONCE(rdtp->dynticks_nesting < 0); |
Frederic Weisbecker | b6fc602 | 2011-11-28 16:18:56 -0800 | [diff] [blame] | 429 | if (rdtp->dynticks_nesting) |
| 430 | trace_rcu_dyntick("--=", oldval, rdtp->dynticks_nesting); |
| 431 | else |
| 432 | rcu_idle_enter_common(rdtp, oldval); |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 433 | local_irq_restore(flags); |
| 434 | } |
| 435 | |
| 436 | /* |
| 437 | * rcu_idle_exit_common - inform RCU that current CPU is moving away from idle |
| 438 | * |
| 439 | * If the new value of the ->dynticks_nesting counter was previously zero, |
| 440 | * we really have exited idle, and must do the appropriate accounting. |
| 441 | * The caller must have disabled interrupts. |
| 442 | */ |
| 443 | static void rcu_idle_exit_common(struct rcu_dynticks *rdtp, long long oldval) |
| 444 | { |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 445 | smp_mb__before_atomic_inc(); /* Force ordering w/previous sojourn. */ |
| 446 | atomic_inc(&rdtp->dynticks); |
| 447 | /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ |
| 448 | smp_mb__after_atomic_inc(); /* See above. */ |
| 449 | WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); |
Paul E. McKenney | 7cb9249 | 2011-11-28 12:28:34 -0800 | [diff] [blame] | 450 | rcu_cleanup_after_idle(smp_processor_id()); |
Paul E. McKenney | 4145fa7 | 2011-10-31 15:01:54 -0700 | [diff] [blame] | 451 | trace_rcu_dyntick("End", oldval, rdtp->dynticks_nesting); |
Paul E. McKenney | 99745b6 | 2011-11-10 15:48:45 -0800 | [diff] [blame] | 452 | if (!is_idle_task(current)) { |
Paul E. McKenney | 0989cb4 | 2011-11-01 08:57:21 -0700 | [diff] [blame] | 453 | struct task_struct *idle = idle_task(smp_processor_id()); |
| 454 | |
Paul E. McKenney | 4145fa7 | 2011-10-31 15:01:54 -0700 | [diff] [blame] | 455 | trace_rcu_dyntick("Error on exit: not idle task", |
| 456 | oldval, rdtp->dynticks_nesting); |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 457 | ftrace_dump(DUMP_ALL); |
Paul E. McKenney | 0989cb4 | 2011-11-01 08:57:21 -0700 | [diff] [blame] | 458 | WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s", |
| 459 | current->pid, current->comm, |
| 460 | idle->pid, idle->comm); /* must be idle task! */ |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 461 | } |
| 462 | } |
| 463 | |
| 464 | /** |
| 465 | * rcu_idle_exit - inform RCU that current CPU is leaving idle |
| 466 | * |
| 467 | * Exit idle mode, in other words, -enter- the mode in which RCU |
| 468 | * read-side critical sections can occur. |
| 469 | * |
Paul E. McKenney | 4145fa7 | 2011-10-31 15:01:54 -0700 | [diff] [blame] | 470 | * We crowbar the ->dynticks_nesting field to DYNTICK_TASK_NESTING to |
| 471 | * allow for the possibility of usermode upcalls messing up our count |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 472 | * of interrupt nesting level during the busy period that is just |
| 473 | * now starting. |
| 474 | */ |
| 475 | void rcu_idle_exit(void) |
| 476 | { |
| 477 | unsigned long flags; |
| 478 | struct rcu_dynticks *rdtp; |
| 479 | long long oldval; |
| 480 | |
| 481 | local_irq_save(flags); |
| 482 | rdtp = &__get_cpu_var(rcu_dynticks); |
| 483 | oldval = rdtp->dynticks_nesting; |
| 484 | WARN_ON_ONCE(oldval != 0); |
Paul E. McKenney | 4145fa7 | 2011-10-31 15:01:54 -0700 | [diff] [blame] | 485 | rdtp->dynticks_nesting = DYNTICK_TASK_NESTING; |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 486 | rcu_idle_exit_common(rdtp, oldval); |
| 487 | local_irq_restore(flags); |
| 488 | } |
| 489 | |
| 490 | /** |
| 491 | * rcu_irq_enter - inform RCU that current CPU is entering irq away from idle |
| 492 | * |
| 493 | * Enter an interrupt handler, which might possibly result in exiting |
| 494 | * idle mode, in other words, entering the mode in which read-side critical |
| 495 | * sections can occur. |
| 496 | * |
| 497 | * Note that the Linux kernel is fully capable of entering an interrupt |
| 498 | * handler that it never exits, for example when doing upcalls to |
| 499 | * user mode! This code assumes that the idle loop never does upcalls to |
| 500 | * user mode. If your architecture does do upcalls from the idle loop (or |
| 501 | * does anything else that results in unbalanced calls to the irq_enter() |
| 502 | * and irq_exit() functions), RCU will give you what you deserve, good |
| 503 | * and hard. But very infrequently and irreproducibly. |
| 504 | * |
| 505 | * Use things like work queues to work around this limitation. |
| 506 | * |
| 507 | * You have been warned. |
| 508 | */ |
| 509 | void rcu_irq_enter(void) |
| 510 | { |
| 511 | unsigned long flags; |
| 512 | struct rcu_dynticks *rdtp; |
| 513 | long long oldval; |
| 514 | |
| 515 | local_irq_save(flags); |
| 516 | rdtp = &__get_cpu_var(rcu_dynticks); |
| 517 | oldval = rdtp->dynticks_nesting; |
| 518 | rdtp->dynticks_nesting++; |
| 519 | WARN_ON_ONCE(rdtp->dynticks_nesting == 0); |
Frederic Weisbecker | b6fc602 | 2011-11-28 16:18:56 -0800 | [diff] [blame] | 520 | if (oldval) |
| 521 | trace_rcu_dyntick("++=", oldval, rdtp->dynticks_nesting); |
| 522 | else |
| 523 | rcu_idle_exit_common(rdtp, oldval); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 524 | local_irq_restore(flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 525 | } |
| 526 | |
| 527 | /** |
| 528 | * rcu_nmi_enter - inform RCU of entry to NMI context |
| 529 | * |
| 530 | * If the CPU was idle with dynamic ticks active, and there is no |
| 531 | * irq handler running, this updates rdtp->dynticks_nmi to let the |
| 532 | * RCU grace-period handling know that the CPU is active. |
| 533 | */ |
| 534 | void rcu_nmi_enter(void) |
| 535 | { |
| 536 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 537 | |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 538 | if (rdtp->dynticks_nmi_nesting == 0 && |
| 539 | (atomic_read(&rdtp->dynticks) & 0x1)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 540 | return; |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 541 | rdtp->dynticks_nmi_nesting++; |
| 542 | smp_mb__before_atomic_inc(); /* Force delay from prior write. */ |
| 543 | atomic_inc(&rdtp->dynticks); |
| 544 | /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ |
| 545 | smp_mb__after_atomic_inc(); /* See above. */ |
| 546 | WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 547 | } |
| 548 | |
| 549 | /** |
| 550 | * rcu_nmi_exit - inform RCU of exit from NMI context |
| 551 | * |
| 552 | * If the CPU was idle with dynamic ticks active, and there is no |
| 553 | * irq handler running, this updates rdtp->dynticks_nmi to let the |
| 554 | * RCU grace-period handling know that the CPU is no longer active. |
| 555 | */ |
| 556 | void rcu_nmi_exit(void) |
| 557 | { |
| 558 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 559 | |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 560 | if (rdtp->dynticks_nmi_nesting == 0 || |
| 561 | --rdtp->dynticks_nmi_nesting != 0) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 562 | return; |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 563 | /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ |
| 564 | smp_mb__before_atomic_inc(); /* See above. */ |
| 565 | atomic_inc(&rdtp->dynticks); |
| 566 | smp_mb__after_atomic_inc(); /* Force delay to next write. */ |
| 567 | WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 568 | } |
| 569 | |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 570 | #ifdef CONFIG_PROVE_RCU |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 571 | |
| 572 | /** |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 573 | * 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] | 574 | * |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 575 | * 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] | 576 | * or NMI handler, return true. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 577 | */ |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 578 | int rcu_is_cpu_idle(void) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 579 | { |
Paul E. McKenney | 3424069 | 2011-10-03 11:38:52 -0700 | [diff] [blame] | 580 | int ret; |
| 581 | |
| 582 | preempt_disable(); |
| 583 | ret = (atomic_read(&__get_cpu_var(rcu_dynticks).dynticks) & 0x1) == 0; |
| 584 | preempt_enable(); |
| 585 | return ret; |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 586 | } |
Frederic Weisbecker | e6b80a3 | 2011-10-07 16:25:18 -0700 | [diff] [blame] | 587 | EXPORT_SYMBOL(rcu_is_cpu_idle); |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 588 | |
Paul E. McKenney | c0d6d01 | 2012-01-23 12:41:26 -0800 | [diff] [blame] | 589 | #ifdef CONFIG_HOTPLUG_CPU |
| 590 | |
| 591 | /* |
| 592 | * Is the current CPU online? Disable preemption to avoid false positives |
| 593 | * that could otherwise happen due to the current CPU number being sampled, |
| 594 | * this task being preempted, its old CPU being taken offline, resuming |
| 595 | * on some other CPU, then determining that its old CPU is now offline. |
| 596 | * 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] | 597 | * the check for rcu_scheduler_fully_active. Note also that it is OK |
| 598 | * for a CPU coming online to use RCU for one jiffy prior to marking itself |
| 599 | * online in the cpu_online_mask. Similarly, it is OK for a CPU going |
| 600 | * offline to continue to use RCU for one jiffy after marking itself |
| 601 | * offline in the cpu_online_mask. This leniency is necessary given the |
| 602 | * non-atomic nature of the online and offline processing, for example, |
| 603 | * the fact that a CPU enters the scheduler after completing the CPU_DYING |
| 604 | * notifiers. |
| 605 | * |
| 606 | * This is also why RCU internally marks CPUs online during the |
| 607 | * CPU_UP_PREPARE phase and offline during the CPU_DEAD phase. |
Paul E. McKenney | c0d6d01 | 2012-01-23 12:41:26 -0800 | [diff] [blame] | 608 | * |
| 609 | * Disable checking if in an NMI handler because we cannot safely report |
| 610 | * errors from NMI handlers anyway. |
| 611 | */ |
| 612 | bool rcu_lockdep_current_cpu_online(void) |
| 613 | { |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 614 | struct rcu_data *rdp; |
| 615 | struct rcu_node *rnp; |
Paul E. McKenney | c0d6d01 | 2012-01-23 12:41:26 -0800 | [diff] [blame] | 616 | bool ret; |
| 617 | |
| 618 | if (in_nmi()) |
| 619 | return 1; |
| 620 | preempt_disable(); |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 621 | rdp = &__get_cpu_var(rcu_sched_data); |
| 622 | rnp = rdp->mynode; |
| 623 | ret = (rdp->grpmask & rnp->qsmaskinit) || |
Paul E. McKenney | c0d6d01 | 2012-01-23 12:41:26 -0800 | [diff] [blame] | 624 | !rcu_scheduler_fully_active; |
| 625 | preempt_enable(); |
| 626 | return ret; |
| 627 | } |
| 628 | EXPORT_SYMBOL_GPL(rcu_lockdep_current_cpu_online); |
| 629 | |
| 630 | #endif /* #ifdef CONFIG_HOTPLUG_CPU */ |
| 631 | |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 632 | #endif /* #ifdef CONFIG_PROVE_RCU */ |
| 633 | |
| 634 | /** |
| 635 | * rcu_is_cpu_rrupt_from_idle - see if idle or immediately interrupted from idle |
| 636 | * |
| 637 | * If the current CPU is idle or running at a first-level (not nested) |
| 638 | * interrupt from idle, return true. The caller must have at least |
| 639 | * disabled preemption. |
| 640 | */ |
| 641 | int rcu_is_cpu_rrupt_from_idle(void) |
| 642 | { |
| 643 | return __get_cpu_var(rcu_dynticks).dynticks_nesting <= 1; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 644 | } |
| 645 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 646 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 647 | * Snapshot the specified CPU's dynticks counter so that we can later |
| 648 | * 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] | 649 | * is in dynticks idle mode, which is an extended quiescent state. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 650 | */ |
| 651 | static int dyntick_save_progress_counter(struct rcu_data *rdp) |
| 652 | { |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 653 | rdp->dynticks_snap = atomic_add_return(0, &rdp->dynticks->dynticks); |
Paul E. McKenney | f0e7c19 | 2011-11-23 15:02:05 -0800 | [diff] [blame] | 654 | return (rdp->dynticks_snap & 0x1) == 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 655 | } |
| 656 | |
| 657 | /* |
| 658 | * Return true if the specified CPU has passed through a quiescent |
| 659 | * state by virtue of being in or having passed through an dynticks |
| 660 | * idle state since the last call to dyntick_save_progress_counter() |
| 661 | * for this same CPU. |
| 662 | */ |
| 663 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) |
| 664 | { |
Paul E. McKenney | 7eb4f45 | 2011-07-30 07:32:48 -0700 | [diff] [blame] | 665 | unsigned int curr; |
| 666 | unsigned int snap; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 667 | |
Paul E. McKenney | 7eb4f45 | 2011-07-30 07:32:48 -0700 | [diff] [blame] | 668 | curr = (unsigned int)atomic_add_return(0, &rdp->dynticks->dynticks); |
| 669 | snap = (unsigned int)rdp->dynticks_snap; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 670 | |
| 671 | /* |
| 672 | * If the CPU passed through or entered a dynticks idle phase with |
| 673 | * no active irq/NMI handlers, then we can safely pretend that the CPU |
| 674 | * already acknowledged the request to pass through a quiescent |
| 675 | * state. Either way, that CPU cannot possibly be in an RCU |
| 676 | * read-side critical section that started before the beginning |
| 677 | * of the current RCU grace period. |
| 678 | */ |
Paul E. McKenney | 7eb4f45 | 2011-07-30 07:32:48 -0700 | [diff] [blame] | 679 | if ((curr & 0x1) == 0 || UINT_CMP_GE(curr, snap + 2)) { |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 680 | trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, "dti"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 681 | rdp->dynticks_fqs++; |
| 682 | return 1; |
| 683 | } |
| 684 | |
| 685 | /* Go check for the CPU being offline. */ |
| 686 | return rcu_implicit_offline_qs(rdp); |
| 687 | } |
| 688 | |
Paul E. McKenney | 13cfcca | 2012-01-13 15:32:18 -0800 | [diff] [blame] | 689 | static int jiffies_till_stall_check(void) |
| 690 | { |
| 691 | int till_stall_check = ACCESS_ONCE(rcu_cpu_stall_timeout); |
| 692 | |
| 693 | /* |
| 694 | * Limit check must be consistent with the Kconfig limits |
| 695 | * for CONFIG_RCU_CPU_STALL_TIMEOUT. |
| 696 | */ |
| 697 | if (till_stall_check < 3) { |
| 698 | ACCESS_ONCE(rcu_cpu_stall_timeout) = 3; |
| 699 | till_stall_check = 3; |
| 700 | } else if (till_stall_check > 300) { |
| 701 | ACCESS_ONCE(rcu_cpu_stall_timeout) = 300; |
| 702 | till_stall_check = 300; |
| 703 | } |
| 704 | return till_stall_check * HZ + RCU_STALL_DELAY_DELTA; |
| 705 | } |
| 706 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 707 | static void record_gp_stall_check_time(struct rcu_state *rsp) |
| 708 | { |
| 709 | rsp->gp_start = jiffies; |
Paul E. McKenney | 13cfcca | 2012-01-13 15:32:18 -0800 | [diff] [blame] | 710 | rsp->jiffies_stall = jiffies + jiffies_till_stall_check(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 711 | } |
| 712 | |
| 713 | static void print_other_cpu_stall(struct rcu_state *rsp) |
| 714 | { |
| 715 | int cpu; |
| 716 | long delta; |
| 717 | unsigned long flags; |
Paul E. McKenney | 9bc8b55 | 2011-08-13 13:31:47 -0700 | [diff] [blame] | 718 | int ndetected; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 719 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 720 | |
| 721 | /* Only let one CPU complain about others per time interval. */ |
| 722 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 723 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 724 | delta = jiffies - rsp->jiffies_stall; |
Paul E. McKenney | fc2219d4 | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 725 | if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 726 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 727 | return; |
| 728 | } |
Paul E. McKenney | 13cfcca | 2012-01-13 15:32:18 -0800 | [diff] [blame] | 729 | rsp->jiffies_stall = jiffies + 3 * jiffies_till_stall_check() + 3; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 730 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 731 | |
Paul E. McKenney | 8cdd32a | 2010-08-09 14:23:03 -0700 | [diff] [blame] | 732 | /* |
| 733 | * OK, time to rat on our buddy... |
| 734 | * See Documentation/RCU/stallwarn.txt for info on how to debug |
| 735 | * RCU CPU stall warnings. |
| 736 | */ |
Paul E. McKenney | a858af2 | 2012-01-16 13:29:10 -0800 | [diff] [blame] | 737 | printk(KERN_ERR "INFO: %s detected stalls on CPUs/tasks:", |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 738 | rsp->name); |
Paul E. McKenney | a858af2 | 2012-01-16 13:29:10 -0800 | [diff] [blame] | 739 | print_cpu_stall_info_begin(); |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 740 | rcu_for_each_leaf_node(rsp, rnp) { |
Paul E. McKenney | 3acd9eb | 2010-02-22 17:05:03 -0800 | [diff] [blame] | 741 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 9bc8b55 | 2011-08-13 13:31:47 -0700 | [diff] [blame] | 742 | ndetected += rcu_print_task_stall(rnp); |
Paul E. McKenney | 3acd9eb | 2010-02-22 17:05:03 -0800 | [diff] [blame] | 743 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 744 | if (rnp->qsmask == 0) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 745 | continue; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 746 | for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++) |
Paul E. McKenney | 9bc8b55 | 2011-08-13 13:31:47 -0700 | [diff] [blame] | 747 | if (rnp->qsmask & (1UL << cpu)) { |
Paul E. McKenney | a858af2 | 2012-01-16 13:29:10 -0800 | [diff] [blame] | 748 | print_cpu_stall_info(rsp, rnp->grplo + cpu); |
Paul E. McKenney | 9bc8b55 | 2011-08-13 13:31:47 -0700 | [diff] [blame] | 749 | ndetected++; |
| 750 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 751 | } |
Paul E. McKenney | a858af2 | 2012-01-16 13:29:10 -0800 | [diff] [blame] | 752 | |
| 753 | /* |
| 754 | * Now rat on any tasks that got kicked up to the root rcu_node |
| 755 | * due to CPU offlining. |
| 756 | */ |
| 757 | rnp = rcu_get_root(rsp); |
| 758 | raw_spin_lock_irqsave(&rnp->lock, flags); |
| 759 | ndetected = rcu_print_task_stall(rnp); |
| 760 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
| 761 | |
| 762 | print_cpu_stall_info_end(); |
| 763 | printk(KERN_CONT "(detected by %d, t=%ld jiffies)\n", |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 764 | smp_processor_id(), (long)(jiffies - rsp->gp_start)); |
Paul E. McKenney | 9bc8b55 | 2011-08-13 13:31:47 -0700 | [diff] [blame] | 765 | if (ndetected == 0) |
| 766 | printk(KERN_ERR "INFO: Stall ended before state dump start\n"); |
| 767 | else if (!trigger_all_cpu_backtrace()) |
Paul E. McKenney | 4627e24 | 2011-08-03 03:34:24 -0700 | [diff] [blame] | 768 | dump_stack(); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 769 | |
Paul E. McKenney | 1ed509a | 2010-02-22 17:05:05 -0800 | [diff] [blame] | 770 | /* If so configured, complain about tasks blocking the grace period. */ |
| 771 | |
| 772 | rcu_print_detail_task_stall(rsp); |
| 773 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 774 | force_quiescent_state(rsp, 0); /* Kick them all. */ |
| 775 | } |
| 776 | |
| 777 | static void print_cpu_stall(struct rcu_state *rsp) |
| 778 | { |
| 779 | unsigned long flags; |
| 780 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 781 | |
Paul E. McKenney | 8cdd32a | 2010-08-09 14:23:03 -0700 | [diff] [blame] | 782 | /* |
| 783 | * OK, time to rat on ourselves... |
| 784 | * See Documentation/RCU/stallwarn.txt for info on how to debug |
| 785 | * RCU CPU stall warnings. |
| 786 | */ |
Paul E. McKenney | a858af2 | 2012-01-16 13:29:10 -0800 | [diff] [blame] | 787 | printk(KERN_ERR "INFO: %s self-detected stall on CPU", rsp->name); |
| 788 | print_cpu_stall_info_begin(); |
| 789 | print_cpu_stall_info(rsp, smp_processor_id()); |
| 790 | print_cpu_stall_info_end(); |
| 791 | printk(KERN_CONT " (t=%lu jiffies)\n", jiffies - rsp->gp_start); |
Paul E. McKenney | 4627e24 | 2011-08-03 03:34:24 -0700 | [diff] [blame] | 792 | if (!trigger_all_cpu_backtrace()) |
| 793 | dump_stack(); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 794 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 795 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 796 | if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall)) |
Paul E. McKenney | 13cfcca | 2012-01-13 15:32:18 -0800 | [diff] [blame] | 797 | rsp->jiffies_stall = jiffies + |
| 798 | 3 * jiffies_till_stall_check() + 3; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 799 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 800 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 801 | set_need_resched(); /* kick ourselves to get things going. */ |
| 802 | } |
| 803 | |
| 804 | static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) |
| 805 | { |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 806 | unsigned long j; |
| 807 | unsigned long js; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 808 | struct rcu_node *rnp; |
| 809 | |
Paul E. McKenney | 742734e | 2010-06-30 11:43:52 -0700 | [diff] [blame] | 810 | if (rcu_cpu_stall_suppress) |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 811 | return; |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 812 | j = ACCESS_ONCE(jiffies); |
| 813 | js = ACCESS_ONCE(rsp->jiffies_stall); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 814 | rnp = rdp->mynode; |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 815 | if ((ACCESS_ONCE(rnp->qsmask) & rdp->grpmask) && ULONG_CMP_GE(j, js)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 816 | |
| 817 | /* We haven't checked in, so go dump stack. */ |
| 818 | print_cpu_stall(rsp); |
| 819 | |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 820 | } else if (rcu_gp_in_progress(rsp) && |
| 821 | ULONG_CMP_GE(j, js + RCU_STALL_RAT_DELAY)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 822 | |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 823 | /* They had a few time units to dump stack, so complain. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 824 | print_other_cpu_stall(rsp); |
| 825 | } |
| 826 | } |
| 827 | |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 828 | static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr) |
| 829 | { |
Paul E. McKenney | 742734e | 2010-06-30 11:43:52 -0700 | [diff] [blame] | 830 | rcu_cpu_stall_suppress = 1; |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 831 | return NOTIFY_DONE; |
| 832 | } |
| 833 | |
Paul E. McKenney | 53d84e0 | 2010-08-10 14:28:53 -0700 | [diff] [blame] | 834 | /** |
| 835 | * rcu_cpu_stall_reset - prevent further stall warnings in current grace period |
| 836 | * |
| 837 | * Set the stall-warning timeout way off into the future, thus preventing |
| 838 | * any RCU CPU stall-warning messages from appearing in the current set of |
| 839 | * RCU grace periods. |
| 840 | * |
| 841 | * The caller must disable hard irqs. |
| 842 | */ |
| 843 | void rcu_cpu_stall_reset(void) |
| 844 | { |
| 845 | rcu_sched_state.jiffies_stall = jiffies + ULONG_MAX / 2; |
| 846 | rcu_bh_state.jiffies_stall = jiffies + ULONG_MAX / 2; |
| 847 | rcu_preempt_stall_reset(); |
| 848 | } |
| 849 | |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 850 | static struct notifier_block rcu_panic_block = { |
| 851 | .notifier_call = rcu_panic, |
| 852 | }; |
| 853 | |
| 854 | static void __init check_cpu_stall_init(void) |
| 855 | { |
| 856 | atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block); |
| 857 | } |
| 858 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 859 | /* |
| 860 | * Update CPU-local rcu_data state to record the newly noticed grace period. |
| 861 | * This is used both when we started the grace period and when we notice |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 862 | * that someone else started the grace period. The caller must hold the |
| 863 | * ->lock of the leaf rcu_node structure corresponding to the current CPU, |
| 864 | * and must have irqs disabled. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 865 | */ |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 866 | static void __note_new_gpnum(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
| 867 | { |
| 868 | if (rdp->gpnum != rnp->gpnum) { |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 869 | /* |
| 870 | * If the current grace period is waiting for this CPU, |
| 871 | * set up to detect a quiescent state, otherwise don't |
| 872 | * go looking for one. |
| 873 | */ |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 874 | rdp->gpnum = rnp->gpnum; |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 875 | trace_rcu_grace_period(rsp->name, rdp->gpnum, "cpustart"); |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 876 | if (rnp->qsmask & rdp->grpmask) { |
| 877 | rdp->qs_pending = 1; |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 878 | rdp->passed_quiesce = 0; |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 879 | } else |
| 880 | rdp->qs_pending = 0; |
Paul E. McKenney | a858af2 | 2012-01-16 13:29:10 -0800 | [diff] [blame] | 881 | zero_cpu_stall_ticks(rdp); |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 882 | } |
| 883 | } |
| 884 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 885 | static void note_new_gpnum(struct rcu_state *rsp, struct rcu_data *rdp) |
| 886 | { |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 887 | unsigned long flags; |
| 888 | struct rcu_node *rnp; |
| 889 | |
| 890 | local_irq_save(flags); |
| 891 | rnp = rdp->mynode; |
| 892 | if (rdp->gpnum == ACCESS_ONCE(rnp->gpnum) || /* outside lock. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 893 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 894 | local_irq_restore(flags); |
| 895 | return; |
| 896 | } |
| 897 | __note_new_gpnum(rsp, rnp, rdp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 898 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 899 | } |
| 900 | |
| 901 | /* |
| 902 | * Did someone else start a new RCU grace period start since we last |
| 903 | * checked? Update local state appropriately if so. Must be called |
| 904 | * on the CPU corresponding to rdp. |
| 905 | */ |
| 906 | static int |
| 907 | check_for_new_grace_period(struct rcu_state *rsp, struct rcu_data *rdp) |
| 908 | { |
| 909 | unsigned long flags; |
| 910 | int ret = 0; |
| 911 | |
| 912 | local_irq_save(flags); |
| 913 | if (rdp->gpnum != rsp->gpnum) { |
| 914 | note_new_gpnum(rsp, rdp); |
| 915 | ret = 1; |
| 916 | } |
| 917 | local_irq_restore(flags); |
| 918 | return ret; |
| 919 | } |
| 920 | |
| 921 | /* |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 922 | * Advance this CPU's callbacks, but only if the current grace period |
| 923 | * has ended. This may be called only from the CPU to whom the rdp |
| 924 | * belongs. In addition, the corresponding leaf rcu_node structure's |
| 925 | * ->lock must be held by the caller, with irqs disabled. |
| 926 | */ |
| 927 | static void |
| 928 | __rcu_process_gp_end(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
| 929 | { |
| 930 | /* Did another grace period end? */ |
| 931 | if (rdp->completed != rnp->completed) { |
| 932 | |
| 933 | /* Advance callbacks. No harm if list empty. */ |
| 934 | rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL]; |
| 935 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL]; |
| 936 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 937 | |
| 938 | /* Remember that we saw this grace-period completion. */ |
| 939 | rdp->completed = rnp->completed; |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 940 | trace_rcu_grace_period(rsp->name, rdp->gpnum, "cpuend"); |
Frederic Weisbecker | 20377f3 | 2010-12-10 22:11:10 +0100 | [diff] [blame] | 941 | |
| 942 | /* |
Frederic Weisbecker | 5ff8e6f | 2010-12-10 22:11:11 +0100 | [diff] [blame] | 943 | * If we were in an extended quiescent state, we may have |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 944 | * missed some grace periods that others CPUs handled on |
Frederic Weisbecker | 5ff8e6f | 2010-12-10 22:11:11 +0100 | [diff] [blame] | 945 | * our behalf. Catch up with this state to avoid noting |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 946 | * spurious new grace periods. If another grace period |
| 947 | * has started, then rnp->gpnum will have advanced, so |
| 948 | * we will detect this later on. |
Frederic Weisbecker | 5ff8e6f | 2010-12-10 22:11:11 +0100 | [diff] [blame] | 949 | */ |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 950 | if (ULONG_CMP_LT(rdp->gpnum, rdp->completed)) |
Frederic Weisbecker | 5ff8e6f | 2010-12-10 22:11:11 +0100 | [diff] [blame] | 951 | rdp->gpnum = rdp->completed; |
| 952 | |
| 953 | /* |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 954 | * If RCU does not need a quiescent state from this CPU, |
| 955 | * then make sure that this CPU doesn't go looking for one. |
Frederic Weisbecker | 20377f3 | 2010-12-10 22:11:10 +0100 | [diff] [blame] | 956 | */ |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 957 | if ((rnp->qsmask & rdp->grpmask) == 0) |
Frederic Weisbecker | 20377f3 | 2010-12-10 22:11:10 +0100 | [diff] [blame] | 958 | rdp->qs_pending = 0; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 959 | } |
| 960 | } |
| 961 | |
| 962 | /* |
| 963 | * Advance this CPU's callbacks, but only if the current grace period |
| 964 | * has ended. This may be called only from the CPU to whom the rdp |
| 965 | * belongs. |
| 966 | */ |
| 967 | static void |
| 968 | rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp) |
| 969 | { |
| 970 | unsigned long flags; |
| 971 | struct rcu_node *rnp; |
| 972 | |
| 973 | local_irq_save(flags); |
| 974 | rnp = rdp->mynode; |
| 975 | if (rdp->completed == ACCESS_ONCE(rnp->completed) || /* outside lock. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 976 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 977 | local_irq_restore(flags); |
| 978 | return; |
| 979 | } |
| 980 | __rcu_process_gp_end(rsp, rnp, rdp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 981 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 982 | } |
| 983 | |
| 984 | /* |
| 985 | * Do per-CPU grace-period initialization for running CPU. The caller |
| 986 | * must hold the lock of the leaf rcu_node structure corresponding to |
| 987 | * this CPU. |
| 988 | */ |
| 989 | static void |
| 990 | rcu_start_gp_per_cpu(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
| 991 | { |
| 992 | /* Prior grace period ended, so advance callbacks for current CPU. */ |
| 993 | __rcu_process_gp_end(rsp, rnp, rdp); |
| 994 | |
| 995 | /* |
| 996 | * Because this CPU just now started the new grace period, we know |
| 997 | * that all of its callbacks will be covered by this upcoming grace |
| 998 | * period, even the ones that were registered arbitrarily recently. |
| 999 | * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL. |
| 1000 | * |
| 1001 | * Other CPUs cannot be sure exactly when the grace period started. |
| 1002 | * Therefore, their recently registered callbacks must pass through |
| 1003 | * an additional RCU_NEXT_READY stage, so that they will be handled |
| 1004 | * by the next RCU grace period. |
| 1005 | */ |
| 1006 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 1007 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 1008 | |
| 1009 | /* Set state so that this CPU will detect the next quiescent state. */ |
| 1010 | __note_new_gpnum(rsp, rnp, rdp); |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 1011 | } |
| 1012 | |
| 1013 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1014 | * Start a new RCU grace period if warranted, re-initializing the hierarchy |
| 1015 | * in preparation for detecting the next grace period. The caller must hold |
| 1016 | * the root node's ->lock, which is released before return. Hard irqs must |
| 1017 | * be disabled. |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1018 | * |
| 1019 | * Note that it is legal for a dying CPU (which is marked as offline) to |
| 1020 | * invoke this function. This can happen when the dying CPU reports its |
| 1021 | * quiescent state. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1022 | */ |
| 1023 | static void |
| 1024 | rcu_start_gp(struct rcu_state *rsp, unsigned long flags) |
| 1025 | __releases(rcu_get_root(rsp)->lock) |
| 1026 | { |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1027 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1028 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1029 | |
Paul E. McKenney | 037067a | 2011-08-07 20:26:31 -0700 | [diff] [blame] | 1030 | if (!rcu_scheduler_fully_active || |
Paul E. McKenney | afe24b1 | 2011-08-24 16:52:09 -0700 | [diff] [blame] | 1031 | !cpu_needs_another_gp(rsp, rdp)) { |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 1032 | /* |
Paul E. McKenney | afe24b1 | 2011-08-24 16:52:09 -0700 | [diff] [blame] | 1033 | * Either the scheduler hasn't yet spawned the first |
| 1034 | * non-idle task or this CPU does not need another |
| 1035 | * grace period. Either way, don't start a new grace |
| 1036 | * period. |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 1037 | */ |
Paul E. McKenney | afe24b1 | 2011-08-24 16:52:09 -0700 | [diff] [blame] | 1038 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
| 1039 | return; |
| 1040 | } |
| 1041 | |
| 1042 | if (rsp->fqs_active) { |
| 1043 | /* |
| 1044 | * This CPU needs a grace period, but force_quiescent_state() |
| 1045 | * is running. Tell it to start one on this CPU's behalf. |
| 1046 | */ |
| 1047 | rsp->fqs_need_gp = 1; |
| 1048 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1049 | return; |
| 1050 | } |
| 1051 | |
| 1052 | /* Advance to a new grace period and initialize state. */ |
| 1053 | rsp->gpnum++; |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 1054 | trace_rcu_grace_period(rsp->name, rsp->gpnum, "start"); |
Paul E. McKenney | af446b7 | 2011-09-10 21:54:08 -0700 | [diff] [blame] | 1055 | WARN_ON_ONCE(rsp->fqs_state == RCU_GP_INIT); |
| 1056 | rsp->fqs_state = RCU_GP_INIT; /* Hold off force_quiescent_state. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1057 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1058 | record_gp_stall_check_time(rsp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1059 | raw_spin_unlock(&rnp->lock); /* leave irqs disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1060 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1061 | /* Exclude any concurrent CPU-hotplug operations. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1062 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1063 | |
| 1064 | /* |
Paul E. McKenney | b835db1 | 2009-09-08 15:54:37 -0700 | [diff] [blame] | 1065 | * Set the quiescent-state-needed bits in all the rcu_node |
| 1066 | * structures for all currently online CPUs in breadth-first |
| 1067 | * order, starting from the root rcu_node structure. This |
| 1068 | * operation relies on the layout of the hierarchy within the |
| 1069 | * rsp->node[] array. Note that other CPUs will access only |
| 1070 | * the leaves of the hierarchy, which still indicate that no |
| 1071 | * grace period is in progress, at least until the corresponding |
| 1072 | * leaf node has been initialized. In addition, we have excluded |
| 1073 | * CPU-hotplug operations. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1074 | * |
| 1075 | * Note that the grace period cannot complete until we finish |
| 1076 | * the initialization process, as there will be at least one |
| 1077 | * qsmask bit set in the root node until that time, namely the |
Paul E. McKenney | b835db1 | 2009-09-08 15:54:37 -0700 | [diff] [blame] | 1078 | * one corresponding to this CPU, due to the fact that we have |
| 1079 | * irqs disabled. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1080 | */ |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1081 | rcu_for_each_node_breadth_first(rsp, rnp) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1082 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | b0e165c0 | 2009-09-13 09:15:09 -0700 | [diff] [blame] | 1083 | rcu_preempt_check_blocked_tasks(rnp); |
Paul E. McKenney | 49e2912 | 2009-09-18 09:50:19 -0700 | [diff] [blame] | 1084 | rnp->qsmask = rnp->qsmaskinit; |
Paul E. McKenney | de078d8 | 2009-09-08 15:54:36 -0700 | [diff] [blame] | 1085 | rnp->gpnum = rsp->gpnum; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 1086 | rnp->completed = rsp->completed; |
| 1087 | if (rnp == rdp->mynode) |
| 1088 | rcu_start_gp_per_cpu(rsp, rnp, rdp); |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1089 | rcu_preempt_boost_start_gp(rnp); |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 1090 | trace_rcu_grace_period_init(rsp->name, rnp->gpnum, |
| 1091 | rnp->level, rnp->grplo, |
| 1092 | rnp->grphi, rnp->qsmask); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1093 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1094 | } |
| 1095 | |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 1096 | rnp = rcu_get_root(rsp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1097 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | af446b7 | 2011-09-10 21:54:08 -0700 | [diff] [blame] | 1098 | rsp->fqs_state = RCU_SIGNAL_INIT; /* force_quiescent_state now OK. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1099 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
| 1100 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1101 | } |
| 1102 | |
| 1103 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1104 | * Report a full set of quiescent states to the specified rcu_state |
| 1105 | * data structure. This involves cleaning up after the prior grace |
| 1106 | * period and letting rcu_start_gp() start up the next grace period |
| 1107 | * if one is needed. Note that the caller must hold rnp->lock, as |
| 1108 | * required by rcu_start_gp(), which will release it. |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1109 | */ |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1110 | 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] | 1111 | __releases(rcu_get_root(rsp)->lock) |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1112 | { |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 1113 | unsigned long gp_duration; |
Paul E. McKenney | afe24b1 | 2011-08-24 16:52:09 -0700 | [diff] [blame] | 1114 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 1115 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 1116 | |
Paul E. McKenney | fc2219d4 | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 1117 | WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); |
Paul E. McKenney | 0bbcc52 | 2011-05-16 02:24:04 -0700 | [diff] [blame] | 1118 | |
| 1119 | /* |
| 1120 | * Ensure that all grace-period and pre-grace-period activity |
| 1121 | * is seen before the assignment to rsp->completed. |
| 1122 | */ |
| 1123 | smp_mb(); /* See above block comment. */ |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 1124 | gp_duration = jiffies - rsp->gp_start; |
| 1125 | if (gp_duration > rsp->gp_max) |
| 1126 | rsp->gp_max = gp_duration; |
Paul E. McKenney | afe24b1 | 2011-08-24 16:52:09 -0700 | [diff] [blame] | 1127 | |
| 1128 | /* |
| 1129 | * We know the grace period is complete, but to everyone else |
| 1130 | * it appears to still be ongoing. But it is also the case |
| 1131 | * that to everyone else it looks like there is nothing that |
| 1132 | * they can do to advance the grace period. It is therefore |
| 1133 | * safe for us to drop the lock in order to mark the grace |
| 1134 | * period as completed in all of the rcu_node structures. |
| 1135 | * |
| 1136 | * But if this CPU needs another grace period, it will take |
| 1137 | * care of this while initializing the next grace period. |
| 1138 | * We use RCU_WAIT_TAIL instead of the usual RCU_DONE_TAIL |
| 1139 | * because the callbacks have not yet been advanced: Those |
| 1140 | * callbacks are waiting on the grace period that just now |
| 1141 | * completed. |
| 1142 | */ |
| 1143 | if (*rdp->nxttail[RCU_WAIT_TAIL] == NULL) { |
| 1144 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
| 1145 | |
| 1146 | /* |
| 1147 | * Propagate new ->completed value to rcu_node structures |
| 1148 | * so that other CPUs don't have to wait until the start |
| 1149 | * of the next grace period to process their callbacks. |
| 1150 | */ |
| 1151 | rcu_for_each_node_breadth_first(rsp, rnp) { |
| 1152 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
| 1153 | rnp->completed = rsp->gpnum; |
| 1154 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
| 1155 | } |
| 1156 | rnp = rcu_get_root(rsp); |
| 1157 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
| 1158 | } |
| 1159 | |
| 1160 | rsp->completed = rsp->gpnum; /* Declare the grace period complete. */ |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 1161 | trace_rcu_grace_period(rsp->name, rsp->completed, "end"); |
Paul E. McKenney | af446b7 | 2011-09-10 21:54:08 -0700 | [diff] [blame] | 1162 | rsp->fqs_state = RCU_GP_IDLE; |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1163 | rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */ |
| 1164 | } |
| 1165 | |
| 1166 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1167 | * Similar to rcu_report_qs_rdp(), for which it is a helper function. |
| 1168 | * Allows quiescent states for a group of CPUs to be reported at one go |
| 1169 | * to the specified rcu_node structure, though all the CPUs in the group |
| 1170 | * must be represented by the same rcu_node structure (which need not be |
| 1171 | * a leaf rcu_node structure, though it often will be). That structure's |
| 1172 | * 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] | 1173 | */ |
| 1174 | static void |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1175 | rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp, |
| 1176 | struct rcu_node *rnp, unsigned long flags) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1177 | __releases(rnp->lock) |
| 1178 | { |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 1179 | struct rcu_node *rnp_c; |
| 1180 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1181 | /* Walk up the rcu_node hierarchy. */ |
| 1182 | for (;;) { |
| 1183 | if (!(rnp->qsmask & mask)) { |
| 1184 | |
| 1185 | /* Our bit has already been cleared, so done. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1186 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1187 | return; |
| 1188 | } |
| 1189 | rnp->qsmask &= ~mask; |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 1190 | trace_rcu_quiescent_state_report(rsp->name, rnp->gpnum, |
| 1191 | mask, rnp->qsmask, rnp->level, |
| 1192 | rnp->grplo, rnp->grphi, |
| 1193 | !!rnp->gp_tasks); |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1194 | if (rnp->qsmask != 0 || rcu_preempt_blocked_readers_cgp(rnp)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1195 | |
| 1196 | /* Other bits still set at this level, so done. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1197 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1198 | return; |
| 1199 | } |
| 1200 | mask = rnp->grpmask; |
| 1201 | if (rnp->parent == NULL) { |
| 1202 | |
| 1203 | /* No more levels. Exit loop holding root lock. */ |
| 1204 | |
| 1205 | break; |
| 1206 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1207 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 1208 | rnp_c = rnp; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1209 | rnp = rnp->parent; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1210 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 1211 | WARN_ON_ONCE(rnp_c->qsmask); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1212 | } |
| 1213 | |
| 1214 | /* |
| 1215 | * 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] | 1216 | * state for this grace period. Invoke rcu_report_qs_rsp() |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1217 | * 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] | 1218 | */ |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1219 | rcu_report_qs_rsp(rsp, flags); /* releases rnp->lock. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1220 | } |
| 1221 | |
| 1222 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1223 | * Record a quiescent state for the specified CPU to that CPU's rcu_data |
| 1224 | * structure. This must be either called from the specified CPU, or |
| 1225 | * called when the specified CPU is known to be offline (and when it is |
| 1226 | * also known that no other CPU is concurrently trying to help the offline |
| 1227 | * CPU). The lastcomp argument is used to make sure we are still in the |
| 1228 | * grace period of interest. We don't want to end the current grace period |
| 1229 | * based on quiescent states detected in an earlier grace period! |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1230 | */ |
| 1231 | static void |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1232 | rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastgp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1233 | { |
| 1234 | unsigned long flags; |
| 1235 | unsigned long mask; |
| 1236 | struct rcu_node *rnp; |
| 1237 | |
| 1238 | rnp = rdp->mynode; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1239 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1240 | if (lastgp != rnp->gpnum || rnp->completed == rnp->gpnum) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1241 | |
| 1242 | /* |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1243 | * The grace period in which this quiescent state was |
| 1244 | * recorded has ended, so don't report it upwards. |
| 1245 | * We will instead need a new quiescent state that lies |
| 1246 | * within the current grace period. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1247 | */ |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1248 | rdp->passed_quiesce = 0; /* need qs for new gp. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1249 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1250 | return; |
| 1251 | } |
| 1252 | mask = rdp->grpmask; |
| 1253 | if ((rnp->qsmask & mask) == 0) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1254 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1255 | } else { |
| 1256 | rdp->qs_pending = 0; |
| 1257 | |
| 1258 | /* |
| 1259 | * This GP can't end until cpu checks in, so all of our |
| 1260 | * callbacks can be processed during the next GP. |
| 1261 | */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1262 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 1263 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1264 | rcu_report_qs_rnp(mask, rsp, rnp, flags); /* rlses rnp->lock */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1265 | } |
| 1266 | } |
| 1267 | |
| 1268 | /* |
| 1269 | * Check to see if there is a new grace period of which this CPU |
| 1270 | * is not yet aware, and if so, set up local rcu_data state for it. |
| 1271 | * Otherwise, see if this CPU has just passed through its first |
| 1272 | * quiescent state for this grace period, and record that fact if so. |
| 1273 | */ |
| 1274 | static void |
| 1275 | rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp) |
| 1276 | { |
| 1277 | /* If there is now a new grace period, record and return. */ |
| 1278 | if (check_for_new_grace_period(rsp, rdp)) |
| 1279 | return; |
| 1280 | |
| 1281 | /* |
| 1282 | * Does this CPU still need to do its part for current grace period? |
| 1283 | * If no, return and let the other CPUs do their part as well. |
| 1284 | */ |
| 1285 | if (!rdp->qs_pending) |
| 1286 | return; |
| 1287 | |
| 1288 | /* |
| 1289 | * Was there a quiescent state since the beginning of the grace |
| 1290 | * period? If no, then exit and wait for the next call. |
| 1291 | */ |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1292 | if (!rdp->passed_quiesce) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1293 | return; |
| 1294 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1295 | /* |
| 1296 | * Tell RCU we are done (but rcu_report_qs_rdp() will be the |
| 1297 | * judge of that). |
| 1298 | */ |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1299 | rcu_report_qs_rdp(rdp->cpu, rsp, rdp, rdp->passed_quiesce_gpnum); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1300 | } |
| 1301 | |
| 1302 | #ifdef CONFIG_HOTPLUG_CPU |
| 1303 | |
| 1304 | /* |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1305 | * Move a dying CPU's RCU callbacks to online CPU's callback list. |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1306 | * Also record a quiescent state for this CPU for the current grace period. |
| 1307 | * Synchronization and interrupt disabling are not required because |
| 1308 | * this function executes in stop_machine() context. Therefore, cleanup |
| 1309 | * operations that might block must be done later from the CPU_DEAD |
| 1310 | * notifier. |
| 1311 | * |
| 1312 | * Note that the outgoing CPU's bit has already been cleared in the |
| 1313 | * cpu_online_mask. This allows us to randomly pick a callback |
| 1314 | * destination from the bits set in that mask. |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1315 | */ |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1316 | static void rcu_cleanup_dying_cpu(struct rcu_state *rsp) |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1317 | { |
| 1318 | int i; |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1319 | unsigned long mask; |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1320 | int receive_cpu = cpumask_any(cpu_online_mask); |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1321 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1322 | struct rcu_data *receive_rdp = per_cpu_ptr(rsp->rda, receive_cpu); |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 1323 | RCU_TRACE(struct rcu_node *rnp = rdp->mynode); /* For dying CPU. */ |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1324 | |
Paul E. McKenney | a50c3af | 2012-01-10 17:52:31 -0800 | [diff] [blame] | 1325 | /* First, adjust the counts. */ |
| 1326 | if (rdp->nxtlist != NULL) { |
| 1327 | receive_rdp->qlen_lazy += rdp->qlen_lazy; |
| 1328 | receive_rdp->qlen += rdp->qlen; |
| 1329 | rdp->qlen_lazy = 0; |
| 1330 | rdp->qlen = 0; |
| 1331 | } |
| 1332 | |
| 1333 | /* |
| 1334 | * Next, move ready-to-invoke callbacks to be invoked on some |
| 1335 | * other CPU. These will not be required to pass through another |
| 1336 | * grace period: They are done, regardless of CPU. |
| 1337 | */ |
| 1338 | if (rdp->nxtlist != NULL && |
| 1339 | rdp->nxttail[RCU_DONE_TAIL] != &rdp->nxtlist) { |
| 1340 | struct rcu_head *oldhead; |
| 1341 | struct rcu_head **oldtail; |
| 1342 | struct rcu_head **newtail; |
| 1343 | |
| 1344 | oldhead = rdp->nxtlist; |
| 1345 | oldtail = receive_rdp->nxttail[RCU_DONE_TAIL]; |
| 1346 | rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL]; |
| 1347 | *rdp->nxttail[RCU_DONE_TAIL] = *oldtail; |
| 1348 | *receive_rdp->nxttail[RCU_DONE_TAIL] = oldhead; |
| 1349 | newtail = rdp->nxttail[RCU_DONE_TAIL]; |
| 1350 | for (i = RCU_DONE_TAIL; i < RCU_NEXT_SIZE; i++) { |
| 1351 | if (receive_rdp->nxttail[i] == oldtail) |
| 1352 | receive_rdp->nxttail[i] = newtail; |
| 1353 | if (rdp->nxttail[i] == newtail) |
| 1354 | rdp->nxttail[i] = &rdp->nxtlist; |
| 1355 | } |
| 1356 | } |
| 1357 | |
| 1358 | /* |
| 1359 | * Finally, put the rest of the callbacks at the end of the list. |
| 1360 | * The ones that made it partway through get to start over: We |
| 1361 | * cannot assume that grace periods are synchronized across CPUs. |
| 1362 | * (We could splice RCU_WAIT_TAIL into RCU_NEXT_READY_TAIL, but |
| 1363 | * this does not seem compelling. Not yet, anyway.) |
| 1364 | */ |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1365 | if (rdp->nxtlist != NULL) { |
| 1366 | *receive_rdp->nxttail[RCU_NEXT_TAIL] = rdp->nxtlist; |
| 1367 | receive_rdp->nxttail[RCU_NEXT_TAIL] = |
| 1368 | rdp->nxttail[RCU_NEXT_TAIL]; |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1369 | receive_rdp->n_cbs_adopted += rdp->qlen; |
| 1370 | rdp->n_cbs_orphaned += rdp->qlen; |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1371 | |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1372 | rdp->nxtlist = NULL; |
| 1373 | for (i = 0; i < RCU_NEXT_SIZE; i++) |
| 1374 | rdp->nxttail[i] = &rdp->nxtlist; |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1375 | } |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1376 | |
Paul E. McKenney | a50c3af | 2012-01-10 17:52:31 -0800 | [diff] [blame] | 1377 | /* |
| 1378 | * Record a quiescent state for the dying CPU. This is safe |
| 1379 | * only because we have already cleared out the callbacks. |
| 1380 | * (Otherwise, the RCU core might try to schedule the invocation |
| 1381 | * of callbacks on this now-offline CPU, which would be bad.) |
| 1382 | */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1383 | mask = rdp->grpmask; /* rnp->grplo is constant. */ |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1384 | trace_rcu_grace_period(rsp->name, |
| 1385 | rnp->gpnum + 1 - !!(rnp->qsmask & mask), |
| 1386 | "cpuofl"); |
| 1387 | rcu_report_qs_rdp(smp_processor_id(), rsp, rdp, rsp->gpnum); |
| 1388 | /* Note that rcu_report_qs_rdp() might call trace_rcu_grace_period(). */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1389 | } |
| 1390 | |
| 1391 | /* |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1392 | * The CPU has been completely removed, and some other CPU is reporting |
| 1393 | * this fact from process context. Do the remainder of the cleanup. |
| 1394 | * There can only be one CPU hotplug operation at a time, so no other |
| 1395 | * CPU can be attempting to update rcu_cpu_kthread_task. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1396 | */ |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1397 | 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] | 1398 | { |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 1399 | unsigned long flags; |
| 1400 | unsigned long mask; |
| 1401 | int need_report = 0; |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1402 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 1403 | struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rnp. */ |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1404 | |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 1405 | /* Adjust any no-longer-needed kthreads. */ |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1406 | rcu_stop_cpu_kthread(cpu); |
| 1407 | rcu_node_kthread_setaffinity(rnp, -1); |
Paul E. McKenney | 2036d94 | 2012-01-30 17:02:47 -0800 | [diff] [blame] | 1408 | |
| 1409 | /* Remove the dying CPU from the bitmasks in the rcu_node hierarchy. */ |
| 1410 | |
| 1411 | /* Exclude any attempts to start a new grace period. */ |
| 1412 | raw_spin_lock_irqsave(&rsp->onofflock, flags); |
| 1413 | |
| 1414 | /* Remove the outgoing CPU from the masks in the rcu_node hierarchy. */ |
| 1415 | mask = rdp->grpmask; /* rnp->grplo is constant. */ |
| 1416 | do { |
| 1417 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
| 1418 | rnp->qsmaskinit &= ~mask; |
| 1419 | if (rnp->qsmaskinit != 0) { |
| 1420 | if (rnp != rdp->mynode) |
| 1421 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
| 1422 | break; |
| 1423 | } |
| 1424 | if (rnp == rdp->mynode) |
| 1425 | need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp); |
| 1426 | else |
| 1427 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
| 1428 | mask = rnp->grpmask; |
| 1429 | rnp = rnp->parent; |
| 1430 | } while (rnp != NULL); |
| 1431 | |
| 1432 | /* |
| 1433 | * We still hold the leaf rcu_node structure lock here, and |
| 1434 | * irqs are still disabled. The reason for this subterfuge is |
| 1435 | * because invoking rcu_report_unblock_qs_rnp() with ->onofflock |
| 1436 | * held leads to deadlock. |
| 1437 | */ |
| 1438 | raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ |
| 1439 | rnp = rdp->mynode; |
| 1440 | if (need_report & RCU_OFL_TASKS_NORM_GP) |
| 1441 | rcu_report_unblock_qs_rnp(rnp, flags); |
| 1442 | else |
| 1443 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
| 1444 | if (need_report & RCU_OFL_TASKS_EXP_GP) |
| 1445 | rcu_report_exp_rnp(rsp, rnp, true); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1446 | } |
| 1447 | |
| 1448 | #else /* #ifdef CONFIG_HOTPLUG_CPU */ |
| 1449 | |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1450 | static void rcu_cleanup_dying_cpu(struct rcu_state *rsp) |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1451 | { |
| 1452 | } |
| 1453 | |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1454 | 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] | 1455 | { |
| 1456 | } |
| 1457 | |
| 1458 | #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */ |
| 1459 | |
| 1460 | /* |
| 1461 | * Invoke any RCU callbacks that have made it to the end of their grace |
| 1462 | * period. Thottle as specified by rdp->blimit. |
| 1463 | */ |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1464 | 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] | 1465 | { |
| 1466 | unsigned long flags; |
| 1467 | struct rcu_head *next, *list, **tail; |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1468 | int bl, count, count_lazy; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1469 | |
| 1470 | /* If no callbacks are ready, just return.*/ |
Paul E. McKenney | 29c00b4 | 2011-06-17 15:53:19 -0700 | [diff] [blame] | 1471 | if (!cpu_has_callbacks_ready_to_invoke(rdp)) { |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1472 | 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] | 1473 | trace_rcu_batch_end(rsp->name, 0, !!ACCESS_ONCE(rdp->nxtlist), |
| 1474 | need_resched(), is_idle_task(current), |
| 1475 | rcu_is_callbacks_kthread()); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1476 | return; |
Paul E. McKenney | 29c00b4 | 2011-06-17 15:53:19 -0700 | [diff] [blame] | 1477 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1478 | |
| 1479 | /* |
| 1480 | * Extract the list of ready callbacks, disabling to prevent |
| 1481 | * races with call_rcu() from interrupt handlers. |
| 1482 | */ |
| 1483 | local_irq_save(flags); |
Paul E. McKenney | 8146c4e2 | 2012-01-10 14:23:29 -0800 | [diff] [blame] | 1484 | WARN_ON_ONCE(cpu_is_offline(smp_processor_id())); |
Paul E. McKenney | 29c00b4 | 2011-06-17 15:53:19 -0700 | [diff] [blame] | 1485 | bl = rdp->blimit; |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1486 | 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] | 1487 | list = rdp->nxtlist; |
| 1488 | rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL]; |
| 1489 | *rdp->nxttail[RCU_DONE_TAIL] = NULL; |
| 1490 | tail = rdp->nxttail[RCU_DONE_TAIL]; |
| 1491 | for (count = RCU_NEXT_SIZE - 1; count >= 0; count--) |
| 1492 | if (rdp->nxttail[count] == rdp->nxttail[RCU_DONE_TAIL]) |
| 1493 | rdp->nxttail[count] = &rdp->nxtlist; |
| 1494 | local_irq_restore(flags); |
| 1495 | |
| 1496 | /* Invoke callbacks. */ |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1497 | count = count_lazy = 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1498 | while (list) { |
| 1499 | next = list->next; |
| 1500 | prefetch(next); |
Mathieu Desnoyers | 551d55a | 2010-04-17 08:48:42 -0400 | [diff] [blame] | 1501 | debug_rcu_head_unqueue(list); |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1502 | if (__rcu_reclaim(rsp->name, list)) |
| 1503 | count_lazy++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1504 | list = next; |
Paul E. McKenney | dff1672 | 2011-11-29 15:57:13 -0800 | [diff] [blame] | 1505 | /* Stop only if limit reached and CPU has something to do. */ |
| 1506 | if (++count >= bl && |
| 1507 | (need_resched() || |
| 1508 | (!is_idle_task(current) && !rcu_is_callbacks_kthread()))) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1509 | break; |
| 1510 | } |
| 1511 | |
| 1512 | local_irq_save(flags); |
Paul E. McKenney | 4968c30 | 2011-12-07 16:32:40 -0800 | [diff] [blame] | 1513 | trace_rcu_batch_end(rsp->name, count, !!list, need_resched(), |
| 1514 | is_idle_task(current), |
| 1515 | rcu_is_callbacks_kthread()); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1516 | |
| 1517 | /* Update count, and requeue any remaining callbacks. */ |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1518 | rdp->qlen_lazy -= count_lazy; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1519 | rdp->qlen -= count; |
Paul E. McKenney | 269dcc1 | 2010-09-07 14:23:09 -0700 | [diff] [blame] | 1520 | rdp->n_cbs_invoked += count; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1521 | if (list != NULL) { |
| 1522 | *tail = rdp->nxtlist; |
| 1523 | rdp->nxtlist = list; |
| 1524 | for (count = 0; count < RCU_NEXT_SIZE; count++) |
| 1525 | if (&rdp->nxtlist == rdp->nxttail[count]) |
| 1526 | rdp->nxttail[count] = tail; |
| 1527 | else |
| 1528 | break; |
| 1529 | } |
| 1530 | |
| 1531 | /* Reinstate batch limit if we have worked down the excess. */ |
| 1532 | if (rdp->blimit == LONG_MAX && rdp->qlen <= qlowmark) |
| 1533 | rdp->blimit = blimit; |
| 1534 | |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1535 | /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */ |
| 1536 | if (rdp->qlen == 0 && rdp->qlen_last_fqs_check != 0) { |
| 1537 | rdp->qlen_last_fqs_check = 0; |
| 1538 | rdp->n_force_qs_snap = rsp->n_force_qs; |
| 1539 | } else if (rdp->qlen < rdp->qlen_last_fqs_check - qhimark) |
| 1540 | rdp->qlen_last_fqs_check = rdp->qlen; |
| 1541 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1542 | local_irq_restore(flags); |
| 1543 | |
Paul E. McKenney | e0f2306 | 2011-06-21 01:29:39 -0700 | [diff] [blame] | 1544 | /* Re-invoke RCU core processing if there are callbacks remaining. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1545 | if (cpu_has_callbacks_ready_to_invoke(rdp)) |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1546 | invoke_rcu_core(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1547 | } |
| 1548 | |
| 1549 | /* |
| 1550 | * Check to see if this CPU is in a non-context-switch quiescent state |
| 1551 | * (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] | 1552 | * Also schedule RCU core processing. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1553 | * |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 1554 | * This function must be called from hardirq context. It is normally |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1555 | * invoked from the scheduling-clock interrupt. If rcu_pending returns |
| 1556 | * false, there is no point in invoking rcu_check_callbacks(). |
| 1557 | */ |
| 1558 | void rcu_check_callbacks(int cpu, int user) |
| 1559 | { |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1560 | trace_rcu_utilization("Start scheduler-tick"); |
Paul E. McKenney | a858af2 | 2012-01-16 13:29:10 -0800 | [diff] [blame] | 1561 | increment_cpu_stall_ticks(); |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 1562 | if (user || rcu_is_cpu_rrupt_from_idle()) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1563 | |
| 1564 | /* |
| 1565 | * Get here if this CPU took its interrupt from user |
| 1566 | * mode or from the idle loop, and if this is not a |
| 1567 | * nested interrupt. In this case, the CPU is in |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1568 | * a quiescent state, so note it. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1569 | * |
| 1570 | * No memory barrier is required here because both |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1571 | * rcu_sched_qs() and rcu_bh_qs() reference only CPU-local |
| 1572 | * variables that other CPUs neither access nor modify, |
| 1573 | * at least not while the corresponding CPU is online. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1574 | */ |
| 1575 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1576 | rcu_sched_qs(cpu); |
| 1577 | rcu_bh_qs(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1578 | |
| 1579 | } else if (!in_softirq()) { |
| 1580 | |
| 1581 | /* |
| 1582 | * Get here if this CPU did not take its interrupt from |
| 1583 | * softirq, in other words, if it is not interrupting |
| 1584 | * a rcu_bh read-side critical section. This is an _bh |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1585 | * critical section, so note it. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1586 | */ |
| 1587 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1588 | rcu_bh_qs(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1589 | } |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1590 | rcu_preempt_check_callbacks(cpu); |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 1591 | if (rcu_pending(cpu)) |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1592 | invoke_rcu_core(); |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1593 | trace_rcu_utilization("End scheduler-tick"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1594 | } |
| 1595 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1596 | /* |
| 1597 | * Scan the leaf rcu_node structures, processing dyntick state for any that |
| 1598 | * have not yet encountered a quiescent state, using the function specified. |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1599 | * Also initiate boosting for any threads blocked on the root rcu_node. |
| 1600 | * |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1601 | * The caller must have suppressed start of new grace periods. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1602 | */ |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1603 | static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1604 | { |
| 1605 | unsigned long bit; |
| 1606 | int cpu; |
| 1607 | unsigned long flags; |
| 1608 | unsigned long mask; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1609 | struct rcu_node *rnp; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1610 | |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1611 | rcu_for_each_leaf_node(rsp, rnp) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1612 | mask = 0; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1613 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1614 | if (!rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1615 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 0f10dc82 | 2010-01-04 15:09:06 -0800 | [diff] [blame] | 1616 | return; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1617 | } |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1618 | if (rnp->qsmask == 0) { |
Paul E. McKenney | 1217ed1 | 2011-05-04 21:43:49 -0700 | [diff] [blame] | 1619 | rcu_initiate_boost(rnp, flags); /* releases rnp->lock */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1620 | continue; |
| 1621 | } |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1622 | cpu = rnp->grplo; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1623 | bit = 1; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1624 | for (; cpu <= rnp->grphi; cpu++, bit <<= 1) { |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1625 | if ((rnp->qsmask & bit) != 0 && |
| 1626 | f(per_cpu_ptr(rsp->rda, cpu))) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1627 | mask |= bit; |
| 1628 | } |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1629 | if (mask != 0) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1630 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1631 | /* rcu_report_qs_rnp() releases rnp->lock. */ |
| 1632 | rcu_report_qs_rnp(mask, rsp, rnp, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1633 | continue; |
| 1634 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1635 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1636 | } |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1637 | rnp = rcu_get_root(rsp); |
Paul E. McKenney | 1217ed1 | 2011-05-04 21:43:49 -0700 | [diff] [blame] | 1638 | if (rnp->qsmask == 0) { |
| 1639 | raw_spin_lock_irqsave(&rnp->lock, flags); |
| 1640 | rcu_initiate_boost(rnp, flags); /* releases rnp->lock. */ |
| 1641 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1642 | } |
| 1643 | |
| 1644 | /* |
| 1645 | * Force quiescent states on reluctant CPUs, and also detect which |
| 1646 | * CPUs are in dyntick-idle mode. |
| 1647 | */ |
| 1648 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) |
| 1649 | { |
| 1650 | unsigned long flags; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1651 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1652 | |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1653 | trace_rcu_utilization("Start fqs"); |
| 1654 | if (!rcu_gp_in_progress(rsp)) { |
| 1655 | trace_rcu_utilization("End fqs"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1656 | return; /* No grace period in progress, nothing to force. */ |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1657 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1658 | if (!raw_spin_trylock_irqsave(&rsp->fqslock, flags)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1659 | rsp->n_force_qs_lh++; /* Inexact, can lose counts. Tough! */ |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1660 | trace_rcu_utilization("End fqs"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1661 | return; /* Someone else is already on the job. */ |
| 1662 | } |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1663 | if (relaxed && ULONG_CMP_GE(rsp->jiffies_force_qs, jiffies)) |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1664 | goto unlock_fqs_ret; /* no emergency and done recently. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1665 | rsp->n_force_qs++; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1666 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1667 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
Paul E. McKenney | 560d4bc | 2009-11-13 19:51:38 -0800 | [diff] [blame] | 1668 | if(!rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1669 | rsp->n_force_qs_ngp++; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1670 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1671 | goto unlock_fqs_ret; /* no GP in progress, time updated. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1672 | } |
Paul E. McKenney | 07079d5 | 2010-01-04 15:09:02 -0800 | [diff] [blame] | 1673 | rsp->fqs_active = 1; |
Paul E. McKenney | af446b7 | 2011-09-10 21:54:08 -0700 | [diff] [blame] | 1674 | switch (rsp->fqs_state) { |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 1675 | case RCU_GP_IDLE: |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1676 | case RCU_GP_INIT: |
| 1677 | |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 1678 | break; /* grace period idle or initializing, ignore. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1679 | |
| 1680 | case RCU_SAVE_DYNTICK: |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1681 | if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK) |
| 1682 | break; /* So gcc recognizes the dead code. */ |
| 1683 | |
Lai Jiangshan | f261414 | 2010-03-28 11:15:20 +0800 | [diff] [blame] | 1684 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
| 1685 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1686 | /* Record dyntick-idle state. */ |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1687 | force_qs_rnp(rsp, dyntick_save_progress_counter); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1688 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1689 | if (rcu_gp_in_progress(rsp)) |
Paul E. McKenney | af446b7 | 2011-09-10 21:54:08 -0700 | [diff] [blame] | 1690 | rsp->fqs_state = RCU_FORCE_QS; |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1691 | break; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1692 | |
| 1693 | case RCU_FORCE_QS: |
| 1694 | |
| 1695 | /* Check dyntick-idle state, send IPI to laggarts. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1696 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1697 | force_qs_rnp(rsp, rcu_implicit_dynticks_qs); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1698 | |
| 1699 | /* Leave state in case more forcing is required. */ |
| 1700 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1701 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1702 | break; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1703 | } |
Paul E. McKenney | 07079d5 | 2010-01-04 15:09:02 -0800 | [diff] [blame] | 1704 | rsp->fqs_active = 0; |
Paul E. McKenney | 46a1e34 | 2010-01-04 15:09:09 -0800 | [diff] [blame] | 1705 | if (rsp->fqs_need_gp) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1706 | raw_spin_unlock(&rsp->fqslock); /* irqs remain disabled */ |
Paul E. McKenney | 46a1e34 | 2010-01-04 15:09:09 -0800 | [diff] [blame] | 1707 | rsp->fqs_need_gp = 0; |
| 1708 | rcu_start_gp(rsp, flags); /* releases rnp->lock */ |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1709 | trace_rcu_utilization("End fqs"); |
Paul E. McKenney | 46a1e34 | 2010-01-04 15:09:09 -0800 | [diff] [blame] | 1710 | return; |
| 1711 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1712 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1713 | unlock_fqs_ret: |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1714 | raw_spin_unlock_irqrestore(&rsp->fqslock, flags); |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1715 | trace_rcu_utilization("End fqs"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1716 | } |
| 1717 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1718 | /* |
Paul E. McKenney | e0f2306 | 2011-06-21 01:29:39 -0700 | [diff] [blame] | 1719 | * This does the RCU core processing work for the specified rcu_state |
| 1720 | * and rcu_data structures. This may be called only from the CPU to |
| 1721 | * whom the rdp belongs. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1722 | */ |
| 1723 | static void |
| 1724 | __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) |
| 1725 | { |
| 1726 | unsigned long flags; |
| 1727 | |
Paul E. McKenney | 2e59755 | 2009-08-15 09:53:48 -0700 | [diff] [blame] | 1728 | WARN_ON_ONCE(rdp->beenonline == 0); |
| 1729 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1730 | /* |
| 1731 | * If an RCU GP has gone long enough, go check for dyntick |
| 1732 | * idle CPUs and, if needed, send resched IPIs. |
| 1733 | */ |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1734 | if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1735 | force_quiescent_state(rsp, 1); |
| 1736 | |
| 1737 | /* |
| 1738 | * Advance callbacks in response to end of earlier grace |
| 1739 | * period that some other CPU ended. |
| 1740 | */ |
| 1741 | rcu_process_gp_end(rsp, rdp); |
| 1742 | |
| 1743 | /* Update RCU state based on any recent quiescent states. */ |
| 1744 | rcu_check_quiescent_state(rsp, rdp); |
| 1745 | |
| 1746 | /* Does this CPU require a not-yet-started grace period? */ |
| 1747 | if (cpu_needs_another_gp(rsp, rdp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1748 | raw_spin_lock_irqsave(&rcu_get_root(rsp)->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1749 | rcu_start_gp(rsp, flags); /* releases above lock */ |
| 1750 | } |
| 1751 | |
| 1752 | /* If there are callbacks ready, invoke them. */ |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 1753 | if (cpu_has_callbacks_ready_to_invoke(rdp)) |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1754 | invoke_rcu_callbacks(rsp, rdp); |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 1755 | } |
| 1756 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1757 | /* |
Paul E. McKenney | e0f2306 | 2011-06-21 01:29:39 -0700 | [diff] [blame] | 1758 | * Do RCU core processing for the current CPU. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1759 | */ |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 1760 | static void rcu_process_callbacks(struct softirq_action *unused) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1761 | { |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1762 | trace_rcu_utilization("Start RCU core"); |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1763 | __rcu_process_callbacks(&rcu_sched_state, |
| 1764 | &__get_cpu_var(rcu_sched_data)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1765 | __rcu_process_callbacks(&rcu_bh_state, &__get_cpu_var(rcu_bh_data)); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1766 | rcu_preempt_process_callbacks(); |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1767 | trace_rcu_utilization("End RCU core"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1768 | } |
| 1769 | |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1770 | /* |
Paul E. McKenney | e0f2306 | 2011-06-21 01:29:39 -0700 | [diff] [blame] | 1771 | * Schedule RCU callback invocation. If the specified type of RCU |
| 1772 | * does not support RCU priority boosting, just do a direct call, |
| 1773 | * otherwise wake up the per-CPU kernel kthread. Note that because we |
| 1774 | * are running on the current CPU with interrupts disabled, the |
| 1775 | * rcu_cpu_kthread_task cannot disappear out from under us. |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1776 | */ |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1777 | 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] | 1778 | { |
Paul E. McKenney | b0d3041 | 2011-07-10 15:57:35 -0700 | [diff] [blame] | 1779 | if (unlikely(!ACCESS_ONCE(rcu_scheduler_fully_active))) |
| 1780 | return; |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1781 | if (likely(!rsp->boost)) { |
| 1782 | rcu_do_batch(rsp, rdp); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1783 | return; |
| 1784 | } |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1785 | invoke_rcu_callbacks_kthread(); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1786 | } |
| 1787 | |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1788 | static void invoke_rcu_core(void) |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 1789 | { |
| 1790 | raise_softirq(RCU_SOFTIRQ); |
| 1791 | } |
| 1792 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1793 | static void |
| 1794 | __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1795 | struct rcu_state *rsp, bool lazy) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1796 | { |
| 1797 | unsigned long flags; |
| 1798 | struct rcu_data *rdp; |
| 1799 | |
Paul E. McKenney | 0bb7b59 | 2012-01-05 14:44:39 -0800 | [diff] [blame] | 1800 | WARN_ON_ONCE((unsigned long)head & 0x3); /* Misaligned rcu_head! */ |
Mathieu Desnoyers | 551d55a | 2010-04-17 08:48:42 -0400 | [diff] [blame] | 1801 | debug_rcu_head_queue(head); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1802 | head->func = func; |
| 1803 | head->next = NULL; |
| 1804 | |
| 1805 | smp_mb(); /* Ensure RCU update seen before callback registry. */ |
| 1806 | |
| 1807 | /* |
| 1808 | * Opportunistically note grace-period endings and beginnings. |
| 1809 | * Note that we might see a beginning right after we see an |
| 1810 | * end, but never vice versa, since this CPU has to pass through |
| 1811 | * a quiescent state betweentimes. |
| 1812 | */ |
| 1813 | local_irq_save(flags); |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 1814 | WARN_ON_ONCE(cpu_is_offline(smp_processor_id())); |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1815 | rdp = this_cpu_ptr(rsp->rda); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1816 | |
| 1817 | /* Add the callback to our list. */ |
| 1818 | *rdp->nxttail[RCU_NEXT_TAIL] = head; |
| 1819 | rdp->nxttail[RCU_NEXT_TAIL] = &head->next; |
Paul E. McKenney | 2655d57 | 2011-04-07 22:47:23 -0700 | [diff] [blame] | 1820 | rdp->qlen++; |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1821 | if (lazy) |
| 1822 | rdp->qlen_lazy++; |
Paul E. McKenney | 2655d57 | 2011-04-07 22:47:23 -0700 | [diff] [blame] | 1823 | |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 1824 | if (__is_kfree_rcu_offset((unsigned long)func)) |
| 1825 | trace_rcu_kfree_callback(rsp->name, head, (unsigned long)func, |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1826 | rdp->qlen_lazy, rdp->qlen); |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 1827 | else |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1828 | trace_rcu_callback(rsp->name, head, rdp->qlen_lazy, rdp->qlen); |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 1829 | |
Paul E. McKenney | 2655d57 | 2011-04-07 22:47:23 -0700 | [diff] [blame] | 1830 | /* If interrupts were disabled, don't dive into RCU core. */ |
| 1831 | if (irqs_disabled_flags(flags)) { |
| 1832 | local_irq_restore(flags); |
| 1833 | return; |
| 1834 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1835 | |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1836 | /* |
| 1837 | * Force the grace period if too many callbacks or too long waiting. |
| 1838 | * Enforce hysteresis, and don't invoke force_quiescent_state() |
| 1839 | * if some other CPU has recently done so. Also, don't bother |
| 1840 | * invoking force_quiescent_state() if the newly enqueued callback |
| 1841 | * is the only one waiting for a grace period to complete. |
| 1842 | */ |
Paul E. McKenney | 2655d57 | 2011-04-07 22:47:23 -0700 | [diff] [blame] | 1843 | if (unlikely(rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) { |
Paul E. McKenney | b52573d | 2010-12-14 17:36:02 -0800 | [diff] [blame] | 1844 | |
| 1845 | /* Are we ignoring a completed grace period? */ |
| 1846 | rcu_process_gp_end(rsp, rdp); |
| 1847 | check_for_new_grace_period(rsp, rdp); |
| 1848 | |
| 1849 | /* Start a new grace period if one not already started. */ |
| 1850 | if (!rcu_gp_in_progress(rsp)) { |
| 1851 | unsigned long nestflag; |
| 1852 | struct rcu_node *rnp_root = rcu_get_root(rsp); |
| 1853 | |
| 1854 | raw_spin_lock_irqsave(&rnp_root->lock, nestflag); |
| 1855 | rcu_start_gp(rsp, nestflag); /* rlses rnp_root->lock */ |
| 1856 | } else { |
| 1857 | /* Give the grace period a kick. */ |
| 1858 | rdp->blimit = LONG_MAX; |
| 1859 | if (rsp->n_force_qs == rdp->n_force_qs_snap && |
| 1860 | *rdp->nxttail[RCU_DONE_TAIL] != head) |
| 1861 | force_quiescent_state(rsp, 0); |
| 1862 | rdp->n_force_qs_snap = rsp->n_force_qs; |
| 1863 | rdp->qlen_last_fqs_check = rdp->qlen; |
| 1864 | } |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1865 | } else if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1866 | force_quiescent_state(rsp, 1); |
| 1867 | local_irq_restore(flags); |
| 1868 | } |
| 1869 | |
| 1870 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1871 | * Queue an RCU-sched callback for invocation after a grace period. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1872 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1873 | 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] | 1874 | { |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1875 | __call_rcu(head, func, &rcu_sched_state, 0); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1876 | } |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1877 | EXPORT_SYMBOL_GPL(call_rcu_sched); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1878 | |
| 1879 | /* |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1880 | * Queue an RCU callback for invocation after a quicker grace period. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1881 | */ |
| 1882 | void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) |
| 1883 | { |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 1884 | __call_rcu(head, func, &rcu_bh_state, 0); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1885 | } |
| 1886 | EXPORT_SYMBOL_GPL(call_rcu_bh); |
| 1887 | |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1888 | /** |
| 1889 | * synchronize_sched - wait until an rcu-sched grace period has elapsed. |
| 1890 | * |
| 1891 | * Control will return to the caller some time after a full rcu-sched |
| 1892 | * grace period has elapsed, in other words after all currently executing |
| 1893 | * rcu-sched read-side critical sections have completed. These read-side |
| 1894 | * critical sections are delimited by rcu_read_lock_sched() and |
| 1895 | * rcu_read_unlock_sched(), and may be nested. Note that preempt_disable(), |
| 1896 | * local_irq_disable(), and so on may be used in place of |
| 1897 | * rcu_read_lock_sched(). |
| 1898 | * |
| 1899 | * This means that all preempt_disable code sequences, including NMI and |
| 1900 | * hardware-interrupt handlers, in progress on entry will have completed |
| 1901 | * before this primitive returns. However, this does not guarantee that |
| 1902 | * softirq handlers will have completed, since in some kernels, these |
| 1903 | * handlers can run in process context, and can block. |
| 1904 | * |
| 1905 | * This primitive provides the guarantees made by the (now removed) |
| 1906 | * synchronize_kernel() API. In contrast, synchronize_rcu() only |
| 1907 | * guarantees that rcu_read_lock() sections will have completed. |
| 1908 | * In "classic RCU", these two guarantees happen to be one and |
| 1909 | * the same, but can differ in realtime RCU implementations. |
| 1910 | */ |
| 1911 | void synchronize_sched(void) |
| 1912 | { |
Paul E. McKenney | fe15d70 | 2012-01-04 13:30:33 -0800 | [diff] [blame] | 1913 | rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) && |
| 1914 | !lock_is_held(&rcu_lock_map) && |
| 1915 | !lock_is_held(&rcu_sched_lock_map), |
| 1916 | "Illegal synchronize_sched() in RCU-sched read-side critical section"); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1917 | if (rcu_blocking_is_gp()) |
| 1918 | return; |
Paul E. McKenney | 2c42818 | 2011-05-26 22:14:36 -0700 | [diff] [blame] | 1919 | wait_rcu_gp(call_rcu_sched); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1920 | } |
| 1921 | EXPORT_SYMBOL_GPL(synchronize_sched); |
| 1922 | |
| 1923 | /** |
| 1924 | * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed. |
| 1925 | * |
| 1926 | * Control will return to the caller some time after a full rcu_bh grace |
| 1927 | * period has elapsed, in other words after all currently executing rcu_bh |
| 1928 | * read-side critical sections have completed. RCU read-side critical |
| 1929 | * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(), |
| 1930 | * and may be nested. |
| 1931 | */ |
| 1932 | void synchronize_rcu_bh(void) |
| 1933 | { |
Paul E. McKenney | fe15d70 | 2012-01-04 13:30:33 -0800 | [diff] [blame] | 1934 | rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) && |
| 1935 | !lock_is_held(&rcu_lock_map) && |
| 1936 | !lock_is_held(&rcu_sched_lock_map), |
| 1937 | "Illegal synchronize_rcu_bh() in RCU-bh read-side critical section"); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1938 | if (rcu_blocking_is_gp()) |
| 1939 | return; |
Paul E. McKenney | 2c42818 | 2011-05-26 22:14:36 -0700 | [diff] [blame] | 1940 | wait_rcu_gp(call_rcu_bh); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1941 | } |
| 1942 | EXPORT_SYMBOL_GPL(synchronize_rcu_bh); |
| 1943 | |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 1944 | static atomic_t sync_sched_expedited_started = ATOMIC_INIT(0); |
| 1945 | static atomic_t sync_sched_expedited_done = ATOMIC_INIT(0); |
| 1946 | |
| 1947 | static int synchronize_sched_expedited_cpu_stop(void *data) |
| 1948 | { |
| 1949 | /* |
| 1950 | * There must be a full memory barrier on each affected CPU |
| 1951 | * between the time that try_stop_cpus() is called and the |
| 1952 | * time that it returns. |
| 1953 | * |
| 1954 | * In the current initial implementation of cpu_stop, the |
| 1955 | * above condition is already met when the control reaches |
| 1956 | * this point and the following smp_mb() is not strictly |
| 1957 | * necessary. Do smp_mb() anyway for documentation and |
| 1958 | * robustness against future implementation changes. |
| 1959 | */ |
| 1960 | smp_mb(); /* See above comment block. */ |
| 1961 | return 0; |
| 1962 | } |
| 1963 | |
Paul E. McKenney | 236fefa | 2012-01-31 14:00:41 -0800 | [diff] [blame^] | 1964 | /** |
| 1965 | * synchronize_sched_expedited - Brute-force RCU-sched grace period |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 1966 | * |
Paul E. McKenney | 236fefa | 2012-01-31 14:00:41 -0800 | [diff] [blame^] | 1967 | * Wait for an RCU-sched grace period to elapse, but use a "big hammer" |
| 1968 | * approach to force the grace period to end quickly. This consumes |
| 1969 | * significant time on all CPUs and is unfriendly to real-time workloads, |
| 1970 | * so is thus not recommended for any sort of common-case code. In fact, |
| 1971 | * if you are using synchronize_sched_expedited() in a loop, please |
| 1972 | * restructure your code to batch your updates, and then use a single |
| 1973 | * synchronize_sched() instead. |
| 1974 | * |
| 1975 | * Note that it is illegal to call this function while holding any lock |
| 1976 | * that is acquired by a CPU-hotplug notifier. And yes, it is also illegal |
| 1977 | * to call this function from a CPU-hotplug notifier. Failing to observe |
| 1978 | * these restriction will result in deadlock. |
Paul E. McKenney | 3d3b7db | 2012-01-23 17:05:46 -0800 | [diff] [blame] | 1979 | * |
| 1980 | * This implementation can be thought of as an application of ticket |
| 1981 | * locking to RCU, with sync_sched_expedited_started and |
| 1982 | * sync_sched_expedited_done taking on the roles of the halves |
| 1983 | * of the ticket-lock word. Each task atomically increments |
| 1984 | * sync_sched_expedited_started upon entry, snapshotting the old value, |
| 1985 | * then attempts to stop all the CPUs. If this succeeds, then each |
| 1986 | * CPU will have executed a context switch, resulting in an RCU-sched |
| 1987 | * grace period. We are then done, so we use atomic_cmpxchg() to |
| 1988 | * update sync_sched_expedited_done to match our snapshot -- but |
| 1989 | * only if someone else has not already advanced past our snapshot. |
| 1990 | * |
| 1991 | * On the other hand, if try_stop_cpus() fails, we check the value |
| 1992 | * of sync_sched_expedited_done. If it has advanced past our |
| 1993 | * initial snapshot, then someone else must have forced a grace period |
| 1994 | * some time after we took our snapshot. In this case, our work is |
| 1995 | * done for us, and we can simply return. Otherwise, we try again, |
| 1996 | * but keep our initial snapshot for purposes of checking for someone |
| 1997 | * doing our work for us. |
| 1998 | * |
| 1999 | * If we fail too many times in a row, we fall back to synchronize_sched(). |
| 2000 | */ |
| 2001 | void synchronize_sched_expedited(void) |
| 2002 | { |
| 2003 | int firstsnap, s, snap, trycount = 0; |
| 2004 | |
| 2005 | /* Note that atomic_inc_return() implies full memory barrier. */ |
| 2006 | firstsnap = snap = atomic_inc_return(&sync_sched_expedited_started); |
| 2007 | get_online_cpus(); |
| 2008 | WARN_ON_ONCE(cpu_is_offline(smp_processor_id())); |
| 2009 | |
| 2010 | /* |
| 2011 | * Each pass through the following loop attempts to force a |
| 2012 | * context switch on each CPU. |
| 2013 | */ |
| 2014 | while (try_stop_cpus(cpu_online_mask, |
| 2015 | synchronize_sched_expedited_cpu_stop, |
| 2016 | NULL) == -EAGAIN) { |
| 2017 | put_online_cpus(); |
| 2018 | |
| 2019 | /* No joy, try again later. Or just synchronize_sched(). */ |
| 2020 | if (trycount++ < 10) |
| 2021 | udelay(trycount * num_online_cpus()); |
| 2022 | else { |
| 2023 | synchronize_sched(); |
| 2024 | return; |
| 2025 | } |
| 2026 | |
| 2027 | /* Check to see if someone else did our work for us. */ |
| 2028 | s = atomic_read(&sync_sched_expedited_done); |
| 2029 | if (UINT_CMP_GE((unsigned)s, (unsigned)firstsnap)) { |
| 2030 | smp_mb(); /* ensure test happens before caller kfree */ |
| 2031 | return; |
| 2032 | } |
| 2033 | |
| 2034 | /* |
| 2035 | * Refetching sync_sched_expedited_started allows later |
| 2036 | * callers to piggyback on our grace period. We subtract |
| 2037 | * 1 to get the same token that the last incrementer got. |
| 2038 | * We retry after they started, so our grace period works |
| 2039 | * for them, and they started after our first try, so their |
| 2040 | * grace period works for us. |
| 2041 | */ |
| 2042 | get_online_cpus(); |
| 2043 | snap = atomic_read(&sync_sched_expedited_started); |
| 2044 | smp_mb(); /* ensure read is before try_stop_cpus(). */ |
| 2045 | } |
| 2046 | |
| 2047 | /* |
| 2048 | * Everyone up to our most recent fetch is covered by our grace |
| 2049 | * period. Update the counter, but only if our work is still |
| 2050 | * relevant -- which it won't be if someone who started later |
| 2051 | * than we did beat us to the punch. |
| 2052 | */ |
| 2053 | do { |
| 2054 | s = atomic_read(&sync_sched_expedited_done); |
| 2055 | if (UINT_CMP_GE((unsigned)s, (unsigned)snap)) { |
| 2056 | smp_mb(); /* ensure test happens before caller kfree */ |
| 2057 | break; |
| 2058 | } |
| 2059 | } while (atomic_cmpxchg(&sync_sched_expedited_done, s, snap) != s); |
| 2060 | |
| 2061 | put_online_cpus(); |
| 2062 | } |
| 2063 | EXPORT_SYMBOL_GPL(synchronize_sched_expedited); |
| 2064 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2065 | /* |
| 2066 | * Check to see if there is any immediate RCU-related work to be done |
| 2067 | * by the current CPU, for the specified type of RCU, returning 1 if so. |
| 2068 | * The checks are in order of increasing expense: checks that can be |
| 2069 | * carried out against CPU-local state are performed first. However, |
| 2070 | * we must check for CPU stalls first, else we might not get a chance. |
| 2071 | */ |
| 2072 | static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) |
| 2073 | { |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 2074 | struct rcu_node *rnp = rdp->mynode; |
| 2075 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2076 | rdp->n_rcu_pending++; |
| 2077 | |
| 2078 | /* Check for CPU stalls, if enabled. */ |
| 2079 | check_cpu_stall(rsp, rdp); |
| 2080 | |
| 2081 | /* 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] | 2082 | if (rcu_scheduler_fully_active && |
| 2083 | rdp->qs_pending && !rdp->passed_quiesce) { |
Paul E. McKenney | d25eb94 | 2010-03-18 21:36:51 -0700 | [diff] [blame] | 2084 | |
| 2085 | /* |
| 2086 | * If force_quiescent_state() coming soon and this CPU |
| 2087 | * needs a quiescent state, and this is either RCU-sched |
| 2088 | * or RCU-bh, force a local reschedule. |
| 2089 | */ |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 2090 | rdp->n_rp_qs_pending++; |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 2091 | if (!rdp->preemptible && |
Paul E. McKenney | d25eb94 | 2010-03-18 21:36:51 -0700 | [diff] [blame] | 2092 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs) - 1, |
| 2093 | jiffies)) |
| 2094 | set_need_resched(); |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 2095 | } else if (rdp->qs_pending && rdp->passed_quiesce) { |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 2096 | rdp->n_rp_report_qs++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2097 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2098 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2099 | |
| 2100 | /* Does this CPU have callbacks ready to invoke? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2101 | if (cpu_has_callbacks_ready_to_invoke(rdp)) { |
| 2102 | rdp->n_rp_cb_ready++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2103 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2104 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2105 | |
| 2106 | /* Has RCU gone idle with this CPU needing another grace period? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2107 | if (cpu_needs_another_gp(rsp, rdp)) { |
| 2108 | rdp->n_rp_cpu_needs_gp++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2109 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2110 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2111 | |
| 2112 | /* Has another RCU grace period completed? */ |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 2113 | if (ACCESS_ONCE(rnp->completed) != rdp->completed) { /* outside lock */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2114 | rdp->n_rp_gp_completed++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2115 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2116 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2117 | |
| 2118 | /* Has a new RCU grace period started? */ |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 2119 | if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum) { /* outside lock */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2120 | rdp->n_rp_gp_started++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2121 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2122 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2123 | |
| 2124 | /* Has an RCU GP gone long enough to send resched IPIs &c? */ |
Paul E. McKenney | fc2219d4 | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 2125 | if (rcu_gp_in_progress(rsp) && |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 2126 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) { |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2127 | rdp->n_rp_need_fqs++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2128 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2129 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2130 | |
| 2131 | /* nothing to do */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2132 | rdp->n_rp_need_nothing++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2133 | return 0; |
| 2134 | } |
| 2135 | |
| 2136 | /* |
| 2137 | * Check to see if there is any immediate RCU-related work to be done |
| 2138 | * by the current CPU, returning 1 if so. This function is part of the |
| 2139 | * RCU implementation; it is -not- an exported member of the RCU API. |
| 2140 | */ |
Paul E. McKenney | a157229 | 2009-08-22 13:56:51 -0700 | [diff] [blame] | 2141 | static int rcu_pending(int cpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2142 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 2143 | return __rcu_pending(&rcu_sched_state, &per_cpu(rcu_sched_data, cpu)) || |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2144 | __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu)) || |
| 2145 | rcu_preempt_pending(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2146 | } |
| 2147 | |
| 2148 | /* |
| 2149 | * Check to see if any future RCU-related work will need to be done |
| 2150 | * by the current CPU, even if none need be done immediately, returning |
Paul E. McKenney | 8bd93a2 | 2010-02-22 17:04:59 -0800 | [diff] [blame] | 2151 | * 1 if so. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2152 | */ |
Paul E. McKenney | aea1b35 | 2011-11-02 06:54:54 -0700 | [diff] [blame] | 2153 | static int rcu_cpu_has_callbacks(int cpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2154 | { |
| 2155 | /* RCU callbacks either ready or pending? */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 2156 | return per_cpu(rcu_sched_data, cpu).nxtlist || |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2157 | per_cpu(rcu_bh_data, cpu).nxtlist || |
Paul E. McKenney | 30fbcc9 | 2012-01-12 11:01:14 -0800 | [diff] [blame] | 2158 | rcu_preempt_cpu_has_callbacks(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2159 | } |
| 2160 | |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2161 | static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL}; |
| 2162 | static atomic_t rcu_barrier_cpu_count; |
| 2163 | static DEFINE_MUTEX(rcu_barrier_mutex); |
| 2164 | static struct completion rcu_barrier_completion; |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2165 | |
| 2166 | static void rcu_barrier_callback(struct rcu_head *notused) |
| 2167 | { |
| 2168 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) |
| 2169 | complete(&rcu_barrier_completion); |
| 2170 | } |
| 2171 | |
| 2172 | /* |
| 2173 | * Called with preemption disabled, and from cross-cpu IRQ context. |
| 2174 | */ |
| 2175 | static void rcu_barrier_func(void *type) |
| 2176 | { |
| 2177 | int cpu = smp_processor_id(); |
| 2178 | struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu); |
| 2179 | void (*call_rcu_func)(struct rcu_head *head, |
| 2180 | void (*func)(struct rcu_head *head)); |
| 2181 | |
| 2182 | atomic_inc(&rcu_barrier_cpu_count); |
| 2183 | call_rcu_func = type; |
| 2184 | call_rcu_func(head, rcu_barrier_callback); |
| 2185 | } |
| 2186 | |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2187 | /* |
| 2188 | * Orchestrate the specified type of RCU barrier, waiting for all |
| 2189 | * RCU callbacks of the specified type to complete. |
| 2190 | */ |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 2191 | static void _rcu_barrier(struct rcu_state *rsp, |
| 2192 | void (*call_rcu_func)(struct rcu_head *head, |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2193 | void (*func)(struct rcu_head *head))) |
| 2194 | { |
| 2195 | BUG_ON(in_interrupt()); |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 2196 | /* Take mutex to serialize concurrent rcu_barrier() requests. */ |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2197 | mutex_lock(&rcu_barrier_mutex); |
| 2198 | init_completion(&rcu_barrier_completion); |
| 2199 | /* |
| 2200 | * Initialize rcu_barrier_cpu_count to 1, then invoke |
| 2201 | * rcu_barrier_func() on each CPU, so that each CPU also has |
| 2202 | * incremented rcu_barrier_cpu_count. Only then is it safe to |
| 2203 | * decrement rcu_barrier_cpu_count -- otherwise the first CPU |
| 2204 | * might complete its grace period before all of the other CPUs |
| 2205 | * did their increment, causing this function to return too |
Paul E. McKenney | 2d999e0 | 2010-10-20 12:06:18 -0700 | [diff] [blame] | 2206 | * early. Note that on_each_cpu() disables irqs, which prevents |
| 2207 | * any CPUs from coming online or going offline until each online |
| 2208 | * CPU has queued its RCU-barrier callback. |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2209 | */ |
| 2210 | atomic_set(&rcu_barrier_cpu_count, 1); |
| 2211 | on_each_cpu(rcu_barrier_func, (void *)call_rcu_func, 1); |
| 2212 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) |
| 2213 | complete(&rcu_barrier_completion); |
| 2214 | wait_for_completion(&rcu_barrier_completion); |
| 2215 | mutex_unlock(&rcu_barrier_mutex); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2216 | } |
| 2217 | |
| 2218 | /** |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2219 | * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete. |
| 2220 | */ |
| 2221 | void rcu_barrier_bh(void) |
| 2222 | { |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 2223 | _rcu_barrier(&rcu_bh_state, call_rcu_bh); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2224 | } |
| 2225 | EXPORT_SYMBOL_GPL(rcu_barrier_bh); |
| 2226 | |
| 2227 | /** |
| 2228 | * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks. |
| 2229 | */ |
| 2230 | void rcu_barrier_sched(void) |
| 2231 | { |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 2232 | _rcu_barrier(&rcu_sched_state, call_rcu_sched); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2233 | } |
| 2234 | EXPORT_SYMBOL_GPL(rcu_barrier_sched); |
| 2235 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2236 | /* |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2237 | * 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] | 2238 | */ |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2239 | static void __init |
| 2240 | rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2241 | { |
| 2242 | unsigned long flags; |
| 2243 | int i; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2244 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2245 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 2246 | |
| 2247 | /* Set up local state, ensuring consistent view of global state. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2248 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2249 | rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo); |
| 2250 | rdp->nxtlist = NULL; |
| 2251 | for (i = 0; i < RCU_NEXT_SIZE; i++) |
| 2252 | rdp->nxttail[i] = &rdp->nxtlist; |
Paul E. McKenney | 486e259 | 2012-01-06 14:11:30 -0800 | [diff] [blame] | 2253 | rdp->qlen_lazy = 0; |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2254 | rdp->qlen = 0; |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2255 | rdp->dynticks = &per_cpu(rcu_dynticks, cpu); |
Paul E. McKenney | 4145fa7 | 2011-10-31 15:01:54 -0700 | [diff] [blame] | 2256 | WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_NESTING); |
Paul E. McKenney | 9b2e4f1 | 2011-09-30 12:10:22 -0700 | [diff] [blame] | 2257 | WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2258 | rdp->cpu = cpu; |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 2259 | rdp->rsp = rsp; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2260 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2261 | } |
| 2262 | |
| 2263 | /* |
| 2264 | * Initialize a CPU's per-CPU RCU data. Note that only one online or |
| 2265 | * offline event can be happening at a given time. Note also that we |
| 2266 | * can accept some slop in the rsp->completed access due to the fact |
| 2267 | * 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] | 2268 | */ |
| 2269 | static void __cpuinit |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 2270 | 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] | 2271 | { |
| 2272 | unsigned long flags; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2273 | unsigned long mask; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2274 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2275 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 2276 | |
| 2277 | /* Set up local state, ensuring consistent view of global state. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2278 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2279 | rdp->beenonline = 1; /* We have now been online. */ |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 2280 | rdp->preemptible = preemptible; |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 2281 | rdp->qlen_last_fqs_check = 0; |
| 2282 | rdp->n_force_qs_snap = rsp->n_force_qs; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2283 | rdp->blimit = blimit; |
Paul E. McKenney | c92b131 | 2011-11-23 13:38:58 -0800 | [diff] [blame] | 2284 | rdp->dynticks->dynticks_nesting = DYNTICK_TASK_NESTING; |
| 2285 | atomic_set(&rdp->dynticks->dynticks, |
| 2286 | (atomic_read(&rdp->dynticks->dynticks) & ~0x1) + 1); |
Paul E. McKenney | 7cb9249 | 2011-11-28 12:28:34 -0800 | [diff] [blame] | 2287 | rcu_prepare_for_idle_init(cpu); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2288 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2289 | |
| 2290 | /* |
| 2291 | * A new grace period might start here. If so, we won't be part |
| 2292 | * of it, but that is OK, as we are currently in a quiescent state. |
| 2293 | */ |
| 2294 | |
| 2295 | /* Exclude any attempts to start a new GP on large systems. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2296 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2297 | |
| 2298 | /* Add CPU to rcu_node bitmasks. */ |
| 2299 | rnp = rdp->mynode; |
| 2300 | mask = rdp->grpmask; |
| 2301 | do { |
| 2302 | /* Exclude any attempts to start a new GP on small systems. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2303 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2304 | rnp->qsmaskinit |= mask; |
| 2305 | mask = rnp->grpmask; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 2306 | if (rnp == rdp->mynode) { |
Paul E. McKenney | 06ae115a | 2011-08-14 15:56:54 -0700 | [diff] [blame] | 2307 | /* |
| 2308 | * If there is a grace period in progress, we will |
| 2309 | * set up to wait for it next time we run the |
| 2310 | * RCU core code. |
| 2311 | */ |
| 2312 | rdp->gpnum = rnp->completed; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 2313 | rdp->completed = rnp->completed; |
Paul E. McKenney | 06ae115a | 2011-08-14 15:56:54 -0700 | [diff] [blame] | 2314 | rdp->passed_quiesce = 0; |
| 2315 | rdp->qs_pending = 0; |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 2316 | rdp->passed_quiesce_gpnum = rnp->gpnum - 1; |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 2317 | trace_rcu_grace_period(rsp->name, rdp->gpnum, "cpuonl"); |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 2318 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2319 | raw_spin_unlock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2320 | rnp = rnp->parent; |
| 2321 | } while (rnp != NULL && !(rnp->qsmaskinit & mask)); |
| 2322 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2323 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2324 | } |
| 2325 | |
Peter Zijlstra | d72bce0 | 2011-05-30 13:34:51 +0200 | [diff] [blame] | 2326 | static void __cpuinit rcu_prepare_cpu(int cpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2327 | { |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2328 | rcu_init_percpu_data(cpu, &rcu_sched_state, 0); |
| 2329 | rcu_init_percpu_data(cpu, &rcu_bh_state, 0); |
| 2330 | rcu_preempt_init_percpu_data(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2331 | } |
| 2332 | |
| 2333 | /* |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2334 | * Handle CPU online/offline notification events. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2335 | */ |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 2336 | static int __cpuinit rcu_cpu_notify(struct notifier_block *self, |
| 2337 | unsigned long action, void *hcpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2338 | { |
| 2339 | long cpu = (long)hcpu; |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 2340 | struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 2341 | struct rcu_node *rnp = rdp->mynode; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2342 | |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 2343 | trace_rcu_utilization("Start CPU hotplug"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2344 | switch (action) { |
| 2345 | case CPU_UP_PREPARE: |
| 2346 | case CPU_UP_PREPARE_FROZEN: |
Peter Zijlstra | d72bce0 | 2011-05-30 13:34:51 +0200 | [diff] [blame] | 2347 | rcu_prepare_cpu(cpu); |
| 2348 | rcu_prepare_kthreads(cpu); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 2349 | break; |
| 2350 | case CPU_ONLINE: |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 2351 | case CPU_DOWN_FAILED: |
| 2352 | rcu_node_kthread_setaffinity(rnp, -1); |
Paul E. McKenney | e3995a2 | 2011-04-18 15:31:26 -0700 | [diff] [blame] | 2353 | rcu_cpu_kthread_setrt(cpu, 1); |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 2354 | break; |
| 2355 | case CPU_DOWN_PREPARE: |
| 2356 | rcu_node_kthread_setaffinity(rnp, cpu); |
Paul E. McKenney | e3995a2 | 2011-04-18 15:31:26 -0700 | [diff] [blame] | 2357 | rcu_cpu_kthread_setrt(cpu, 0); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2358 | break; |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2359 | case CPU_DYING: |
| 2360 | case CPU_DYING_FROZEN: |
| 2361 | /* |
Paul E. McKenney | 2d999e0 | 2010-10-20 12:06:18 -0700 | [diff] [blame] | 2362 | * The whole machine is "stopped" except this CPU, so we can |
| 2363 | * touch any data without introducing corruption. We send the |
| 2364 | * dying CPU's callbacks to an arbitrarily chosen online CPU. |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2365 | */ |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 2366 | rcu_cleanup_dying_cpu(&rcu_bh_state); |
| 2367 | rcu_cleanup_dying_cpu(&rcu_sched_state); |
| 2368 | rcu_preempt_cleanup_dying_cpu(); |
Paul E. McKenney | 7cb9249 | 2011-11-28 12:28:34 -0800 | [diff] [blame] | 2369 | rcu_cleanup_after_idle(cpu); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2370 | break; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2371 | case CPU_DEAD: |
| 2372 | case CPU_DEAD_FROZEN: |
| 2373 | case CPU_UP_CANCELED: |
| 2374 | case CPU_UP_CANCELED_FROZEN: |
Paul E. McKenney | e560140 | 2012-01-07 11:03:57 -0800 | [diff] [blame] | 2375 | rcu_cleanup_dead_cpu(cpu, &rcu_bh_state); |
| 2376 | rcu_cleanup_dead_cpu(cpu, &rcu_sched_state); |
| 2377 | rcu_preempt_cleanup_dead_cpu(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2378 | break; |
| 2379 | default: |
| 2380 | break; |
| 2381 | } |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 2382 | trace_rcu_utilization("End CPU hotplug"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2383 | return NOTIFY_OK; |
| 2384 | } |
| 2385 | |
| 2386 | /* |
Paul E. McKenney | bbad937 | 2010-04-02 16:17:17 -0700 | [diff] [blame] | 2387 | * This function is invoked towards the end of the scheduler's initialization |
| 2388 | * process. Before this is called, the idle task might contain |
| 2389 | * RCU read-side critical sections (during which time, this idle |
| 2390 | * task is booting the system). After this function is called, the |
| 2391 | * idle tasks are prohibited from containing RCU read-side critical |
| 2392 | * sections. This function also enables RCU lockdep checking. |
| 2393 | */ |
| 2394 | void rcu_scheduler_starting(void) |
| 2395 | { |
| 2396 | WARN_ON(num_online_cpus() != 1); |
| 2397 | WARN_ON(nr_context_switches() > 0); |
| 2398 | rcu_scheduler_active = 1; |
| 2399 | } |
| 2400 | |
| 2401 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2402 | * Compute the per-level fanout, either using the exact fanout specified |
| 2403 | * or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT. |
| 2404 | */ |
| 2405 | #ifdef CONFIG_RCU_FANOUT_EXACT |
| 2406 | static void __init rcu_init_levelspread(struct rcu_state *rsp) |
| 2407 | { |
| 2408 | int i; |
| 2409 | |
Paul E. McKenney | 0209f64 | 2010-12-14 16:07:52 -0800 | [diff] [blame] | 2410 | for (i = NUM_RCU_LVLS - 1; i > 0; i--) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2411 | rsp->levelspread[i] = CONFIG_RCU_FANOUT; |
Paul E. McKenney | 0209f64 | 2010-12-14 16:07:52 -0800 | [diff] [blame] | 2412 | rsp->levelspread[0] = RCU_FANOUT_LEAF; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2413 | } |
| 2414 | #else /* #ifdef CONFIG_RCU_FANOUT_EXACT */ |
| 2415 | static void __init rcu_init_levelspread(struct rcu_state *rsp) |
| 2416 | { |
| 2417 | int ccur; |
| 2418 | int cprv; |
| 2419 | int i; |
| 2420 | |
| 2421 | cprv = NR_CPUS; |
| 2422 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { |
| 2423 | ccur = rsp->levelcnt[i]; |
| 2424 | rsp->levelspread[i] = (cprv + ccur - 1) / ccur; |
| 2425 | cprv = ccur; |
| 2426 | } |
| 2427 | } |
| 2428 | #endif /* #else #ifdef CONFIG_RCU_FANOUT_EXACT */ |
| 2429 | |
| 2430 | /* |
| 2431 | * Helper function for rcu_init() that initializes one rcu_state structure. |
| 2432 | */ |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2433 | static void __init rcu_init_one(struct rcu_state *rsp, |
| 2434 | struct rcu_data __percpu *rda) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2435 | { |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 2436 | static char *buf[] = { "rcu_node_level_0", |
| 2437 | "rcu_node_level_1", |
| 2438 | "rcu_node_level_2", |
| 2439 | "rcu_node_level_3" }; /* Match MAX_RCU_LVLS */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2440 | int cpustride = 1; |
| 2441 | int i; |
| 2442 | int j; |
| 2443 | struct rcu_node *rnp; |
| 2444 | |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 2445 | BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */ |
| 2446 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2447 | /* Initialize the level-tracking arrays. */ |
| 2448 | |
| 2449 | for (i = 1; i < NUM_RCU_LVLS; i++) |
| 2450 | rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1]; |
| 2451 | rcu_init_levelspread(rsp); |
| 2452 | |
| 2453 | /* Initialize the elements themselves, starting from the leaves. */ |
| 2454 | |
| 2455 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { |
| 2456 | cpustride *= rsp->levelspread[i]; |
| 2457 | rnp = rsp->level[i]; |
| 2458 | for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2459 | raw_spin_lock_init(&rnp->lock); |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 2460 | lockdep_set_class_and_name(&rnp->lock, |
| 2461 | &rcu_node_class[i], buf[i]); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2462 | rnp->gpnum = 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2463 | rnp->qsmask = 0; |
| 2464 | rnp->qsmaskinit = 0; |
| 2465 | rnp->grplo = j * cpustride; |
| 2466 | rnp->grphi = (j + 1) * cpustride - 1; |
| 2467 | if (rnp->grphi >= NR_CPUS) |
| 2468 | rnp->grphi = NR_CPUS - 1; |
| 2469 | if (i == 0) { |
| 2470 | rnp->grpnum = 0; |
| 2471 | rnp->grpmask = 0; |
| 2472 | rnp->parent = NULL; |
| 2473 | } else { |
| 2474 | rnp->grpnum = j % rsp->levelspread[i - 1]; |
| 2475 | rnp->grpmask = 1UL << rnp->grpnum; |
| 2476 | rnp->parent = rsp->level[i - 1] + |
| 2477 | j / rsp->levelspread[i - 1]; |
| 2478 | } |
| 2479 | rnp->level = i; |
Paul E. McKenney | 12f5f52 | 2010-11-29 21:56:39 -0800 | [diff] [blame] | 2480 | INIT_LIST_HEAD(&rnp->blkd_tasks); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2481 | } |
| 2482 | } |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 2483 | |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2484 | rsp->rda = rda; |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 2485 | rnp = rsp->level[NUM_RCU_LVLS - 1]; |
| 2486 | for_each_possible_cpu(i) { |
Paul E. McKenney | 4a90a06 | 2010-04-14 16:48:11 -0700 | [diff] [blame] | 2487 | while (i > rnp->grphi) |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 2488 | rnp++; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2489 | per_cpu_ptr(rsp->rda, i)->mynode = rnp; |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 2490 | rcu_boot_init_percpu_data(i, rsp); |
| 2491 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2492 | } |
| 2493 | |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 2494 | void __init rcu_init(void) |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2495 | { |
Paul E. McKenney | 017c426 | 2010-01-14 16:10:58 -0800 | [diff] [blame] | 2496 | int cpu; |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 2497 | |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2498 | rcu_bootup_announce(); |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2499 | rcu_init_one(&rcu_sched_state, &rcu_sched_data); |
| 2500 | rcu_init_one(&rcu_bh_state, &rcu_bh_data); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2501 | __rcu_init_preempt(); |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 2502 | open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 2503 | |
| 2504 | /* |
| 2505 | * We don't need protection against CPU-hotplug here because |
| 2506 | * this is called early in boot, before either interrupts |
| 2507 | * or the scheduler are operational. |
| 2508 | */ |
| 2509 | cpu_notifier(rcu_cpu_notify, 0); |
Paul E. McKenney | 017c426 | 2010-01-14 16:10:58 -0800 | [diff] [blame] | 2510 | for_each_online_cpu(cpu) |
| 2511 | rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu); |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 2512 | check_cpu_stall_init(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2513 | } |
| 2514 | |
Paul E. McKenney | 1eba8f8 | 2009-09-23 09:50:42 -0700 | [diff] [blame] | 2515 | #include "rcutree_plugin.h" |