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 | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 39 | #include <asm/atomic.h> |
| 40 | #include <linux/bitops.h> |
| 41 | #include <linux/module.h> |
| 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> |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 52 | |
Paul E. McKenney | 9f77da9 | 2009-08-22 13:56:45 -0700 | [diff] [blame] | 53 | #include "rcutree.h" |
| 54 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 55 | /* Data structures. */ |
| 56 | |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 57 | static struct lock_class_key rcu_node_class[NUM_RCU_LVLS]; |
Peter Zijlstra | 88b91c7 | 2009-10-26 10:24:31 -0700 | [diff] [blame] | 58 | |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 59 | #define RCU_STATE_INITIALIZER(structname) { \ |
| 60 | .level = { &structname.node[0] }, \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 61 | .levelcnt = { \ |
| 62 | NUM_RCU_LVL_0, /* root of hierarchy. */ \ |
| 63 | NUM_RCU_LVL_1, \ |
| 64 | NUM_RCU_LVL_2, \ |
Paul E. McKenney | cf244dc | 2009-12-02 12:10:14 -0800 | [diff] [blame] | 65 | NUM_RCU_LVL_3, \ |
| 66 | NUM_RCU_LVL_4, /* == MAX_RCU_LVLS */ \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 67 | }, \ |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 68 | .signaled = RCU_GP_IDLE, \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 69 | .gpnum = -300, \ |
| 70 | .completed = -300, \ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 71 | .onofflock = __RAW_SPIN_LOCK_UNLOCKED(&structname.onofflock), \ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 72 | .fqslock = __RAW_SPIN_LOCK_UNLOCKED(&structname.fqslock), \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 73 | .n_force_qs = 0, \ |
| 74 | .n_force_qs_ngp = 0, \ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 75 | .name = #structname, \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 76 | } |
| 77 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 78 | struct rcu_state rcu_sched_state = RCU_STATE_INITIALIZER(rcu_sched_state); |
| 79 | DEFINE_PER_CPU(struct rcu_data, rcu_sched_data); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 80 | |
Ingo Molnar | 6258c4f | 2009-03-25 16:42:24 +0100 | [diff] [blame] | 81 | struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state); |
| 82 | DEFINE_PER_CPU(struct rcu_data, rcu_bh_data); |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 83 | |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 84 | static struct rcu_state *rcu_state; |
| 85 | |
Paul E. McKenney | bbad937 | 2010-04-02 16:17:17 -0700 | [diff] [blame] | 86 | int rcu_scheduler_active __read_mostly; |
| 87 | EXPORT_SYMBOL_GPL(rcu_scheduler_active); |
| 88 | |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 89 | /* |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 90 | * Control variables for per-CPU and per-rcu_node kthreads. These |
| 91 | * handle all flavors of RCU. |
| 92 | */ |
| 93 | static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task); |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 94 | DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status); |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 95 | DEFINE_PER_CPU(int, rcu_cpu_kthread_cpu); |
Paul E. McKenney | 5ece5ba | 2011-04-22 18:08:51 -0700 | [diff] [blame] | 96 | DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 97 | static DEFINE_PER_CPU(wait_queue_head_t, rcu_cpu_wq); |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 98 | DEFINE_PER_CPU(char, rcu_cpu_has_work); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 99 | static char rcu_kthreads_spawnable; |
| 100 | |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 101 | static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu); |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 102 | static void invoke_rcu_cpu_kthread(void); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 103 | |
| 104 | #define RCU_KTHREAD_PRIO 1 /* RT priority for per-CPU kthreads. */ |
| 105 | |
| 106 | /* |
Paul E. McKenney | 4a29865 | 2011-04-03 21:33:51 -0700 | [diff] [blame] | 107 | * Track the rcutorture test sequence number and the update version |
| 108 | * number within a given test. The rcutorture_testseq is incremented |
| 109 | * on every rcutorture module load and unload, so has an odd value |
| 110 | * when a test is running. The rcutorture_vernum is set to zero |
| 111 | * when rcutorture starts and is incremented on each rcutorture update. |
| 112 | * These variables enable correlating rcutorture output with the |
| 113 | * RCU tracing information. |
| 114 | */ |
| 115 | unsigned long rcutorture_testseq; |
| 116 | unsigned long rcutorture_vernum; |
| 117 | |
| 118 | /* |
Paul E. McKenney | fc2219d4 | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 119 | * Return true if an RCU grace period is in progress. The ACCESS_ONCE()s |
| 120 | * permit this function to be invoked without holding the root rcu_node |
| 121 | * structure's ->lock, but of course results can be subject to change. |
| 122 | */ |
| 123 | static int rcu_gp_in_progress(struct rcu_state *rsp) |
| 124 | { |
| 125 | return ACCESS_ONCE(rsp->completed) != ACCESS_ONCE(rsp->gpnum); |
| 126 | } |
| 127 | |
| 128 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 129 | * Note a quiescent state. Because we do not need to know |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 130 | * how many quiescent states passed, just if there was at least |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 131 | * one since the start of the grace period, this just sets a flag. |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 132 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 133 | void rcu_sched_qs(int cpu) |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 134 | { |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 135 | struct rcu_data *rdp = &per_cpu(rcu_sched_data, cpu); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 136 | |
Paul E. McKenney | c64ac3c | 2009-11-10 13:37:22 -0800 | [diff] [blame] | 137 | rdp->passed_quiesc_completed = rdp->gpnum - 1; |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 138 | barrier(); |
| 139 | rdp->passed_quiesc = 1; |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 140 | } |
| 141 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 142 | void rcu_bh_qs(int cpu) |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 143 | { |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 144 | struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 145 | |
Paul E. McKenney | c64ac3c | 2009-11-10 13:37:22 -0800 | [diff] [blame] | 146 | rdp->passed_quiesc_completed = rdp->gpnum - 1; |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 147 | barrier(); |
| 148 | rdp->passed_quiesc = 1; |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 149 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 150 | |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 151 | /* |
| 152 | * Note a context switch. This is a quiescent state for RCU-sched, |
| 153 | * and requires special handling for preemptible RCU. |
| 154 | */ |
| 155 | void rcu_note_context_switch(int cpu) |
| 156 | { |
| 157 | rcu_sched_qs(cpu); |
| 158 | rcu_preempt_note_context_switch(cpu); |
| 159 | } |
| 160 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 161 | #ifdef CONFIG_NO_HZ |
Paul E. McKenney | 90a4d2c | 2009-01-04 11:41:11 -0800 | [diff] [blame] | 162 | DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { |
| 163 | .dynticks_nesting = 1, |
Paul E. McKenney | e59fb31 | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 164 | .dynticks = ATOMIC_INIT(1), |
Paul E. McKenney | 90a4d2c | 2009-01-04 11:41:11 -0800 | [diff] [blame] | 165 | }; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 166 | #endif /* #ifdef CONFIG_NO_HZ */ |
| 167 | |
| 168 | static int blimit = 10; /* Maximum callbacks per softirq. */ |
| 169 | static int qhimark = 10000; /* If this many pending, ignore blimit. */ |
| 170 | static int qlowmark = 100; /* Once only this many pending, use blimit. */ |
| 171 | |
Paul E. McKenney | 3d76c08 | 2009-09-28 07:46:32 -0700 | [diff] [blame] | 172 | module_param(blimit, int, 0); |
| 173 | module_param(qhimark, int, 0); |
| 174 | module_param(qlowmark, int, 0); |
| 175 | |
Paul E. McKenney | a00e0d71 | 2011-02-08 17:14:39 -0800 | [diff] [blame] | 176 | int rcu_cpu_stall_suppress __read_mostly; |
Paul E. McKenney | f2e0dd7 | 2010-07-14 14:38:30 -0700 | [diff] [blame] | 177 | module_param(rcu_cpu_stall_suppress, int, 0644); |
Paul E. McKenney | 742734e | 2010-06-30 11:43:52 -0700 | [diff] [blame] | 178 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 179 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed); |
Paul E. McKenney | a157229 | 2009-08-22 13:56:51 -0700 | [diff] [blame] | 180 | static int rcu_pending(int cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 181 | |
| 182 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 183 | * 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] | 184 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 185 | long rcu_batches_completed_sched(void) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 186 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 187 | return rcu_sched_state.completed; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 188 | } |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 189 | EXPORT_SYMBOL_GPL(rcu_batches_completed_sched); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 190 | |
| 191 | /* |
| 192 | * Return the number of RCU BH batches processed thus far for debug & stats. |
| 193 | */ |
| 194 | long rcu_batches_completed_bh(void) |
| 195 | { |
| 196 | return rcu_bh_state.completed; |
| 197 | } |
| 198 | EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); |
| 199 | |
| 200 | /* |
Paul E. McKenney | bf66f18 | 2010-01-04 15:09:10 -0800 | [diff] [blame] | 201 | * Force a quiescent state for RCU BH. |
| 202 | */ |
| 203 | void rcu_bh_force_quiescent_state(void) |
| 204 | { |
| 205 | force_quiescent_state(&rcu_bh_state, 0); |
| 206 | } |
| 207 | EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state); |
| 208 | |
| 209 | /* |
Paul E. McKenney | 4a29865 | 2011-04-03 21:33:51 -0700 | [diff] [blame] | 210 | * Record the number of times rcutorture tests have been initiated and |
| 211 | * terminated. This information allows the debugfs tracing stats to be |
| 212 | * correlated to the rcutorture messages, even when the rcutorture module |
| 213 | * is being repeatedly loaded and unloaded. In other words, we cannot |
| 214 | * store this state in rcutorture itself. |
| 215 | */ |
| 216 | void rcutorture_record_test_transition(void) |
| 217 | { |
| 218 | rcutorture_testseq++; |
| 219 | rcutorture_vernum = 0; |
| 220 | } |
| 221 | EXPORT_SYMBOL_GPL(rcutorture_record_test_transition); |
| 222 | |
| 223 | /* |
| 224 | * Record the number of writer passes through the current rcutorture test. |
| 225 | * This is also used to correlate debugfs tracing stats with the rcutorture |
| 226 | * messages. |
| 227 | */ |
| 228 | void rcutorture_record_progress(unsigned long vernum) |
| 229 | { |
| 230 | rcutorture_vernum++; |
| 231 | } |
| 232 | EXPORT_SYMBOL_GPL(rcutorture_record_progress); |
| 233 | |
| 234 | /* |
Paul E. McKenney | bf66f18 | 2010-01-04 15:09:10 -0800 | [diff] [blame] | 235 | * Force a quiescent state for RCU-sched. |
| 236 | */ |
| 237 | void rcu_sched_force_quiescent_state(void) |
| 238 | { |
| 239 | force_quiescent_state(&rcu_sched_state, 0); |
| 240 | } |
| 241 | EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state); |
| 242 | |
| 243 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 244 | * Does the CPU have callbacks ready to be invoked? |
| 245 | */ |
| 246 | static int |
| 247 | cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp) |
| 248 | { |
| 249 | return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]; |
| 250 | } |
| 251 | |
| 252 | /* |
| 253 | * Does the current CPU require a yet-as-unscheduled grace period? |
| 254 | */ |
| 255 | static int |
| 256 | cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp) |
| 257 | { |
Paul E. McKenney | fc2219d4 | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 258 | return *rdp->nxttail[RCU_DONE_TAIL] && !rcu_gp_in_progress(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 259 | } |
| 260 | |
| 261 | /* |
| 262 | * Return the root node of the specified rcu_state structure. |
| 263 | */ |
| 264 | static struct rcu_node *rcu_get_root(struct rcu_state *rsp) |
| 265 | { |
| 266 | return &rsp->node[0]; |
| 267 | } |
| 268 | |
| 269 | #ifdef CONFIG_SMP |
| 270 | |
| 271 | /* |
| 272 | * If the specified CPU is offline, tell the caller that it is in |
| 273 | * a quiescent state. Otherwise, whack it with a reschedule IPI. |
| 274 | * Grace periods can end up waiting on an offline CPU when that |
| 275 | * CPU is in the process of coming online -- it will be added to the |
| 276 | * rcu_node bitmasks before it actually makes it online. The same thing |
| 277 | * can happen while a CPU is in the process of coming online. Because this |
| 278 | * race is quite rare, we check for it after detecting that the grace |
| 279 | * period has been delayed rather than checking each and every CPU |
| 280 | * each and every time we start a new grace period. |
| 281 | */ |
| 282 | static int rcu_implicit_offline_qs(struct rcu_data *rdp) |
| 283 | { |
| 284 | /* |
| 285 | * If the CPU is offline, it is in a quiescent state. We can |
| 286 | * trust its state not to change because interrupts are disabled. |
| 287 | */ |
| 288 | if (cpu_is_offline(rdp->cpu)) { |
| 289 | rdp->offline_fqs++; |
| 290 | return 1; |
| 291 | } |
| 292 | |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 293 | /* If preemptible RCU, no point in sending reschedule IPI. */ |
| 294 | if (rdp->preemptible) |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 295 | return 0; |
| 296 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 297 | /* The CPU is online, so send it a reschedule IPI. */ |
| 298 | if (rdp->cpu != smp_processor_id()) |
| 299 | smp_send_reschedule(rdp->cpu); |
| 300 | else |
| 301 | set_need_resched(); |
| 302 | rdp->resched_ipi++; |
| 303 | return 0; |
| 304 | } |
| 305 | |
| 306 | #endif /* #ifdef CONFIG_SMP */ |
| 307 | |
| 308 | #ifdef CONFIG_NO_HZ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 309 | |
| 310 | /** |
| 311 | * rcu_enter_nohz - inform RCU that current CPU is entering nohz |
| 312 | * |
| 313 | * Enter nohz mode, in other words, -leave- the mode in which RCU |
| 314 | * read-side critical sections can occur. (Though RCU read-side |
| 315 | * critical sections can occur in irq handlers in nohz mode, a possibility |
| 316 | * handled by rcu_irq_enter() and rcu_irq_exit()). |
| 317 | */ |
| 318 | void rcu_enter_nohz(void) |
| 319 | { |
| 320 | unsigned long flags; |
| 321 | struct rcu_dynticks *rdtp; |
| 322 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 323 | local_irq_save(flags); |
| 324 | rdtp = &__get_cpu_var(rcu_dynticks); |
Paul E. McKenney | e59fb31 | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 325 | if (--rdtp->dynticks_nesting) { |
| 326 | local_irq_restore(flags); |
| 327 | return; |
| 328 | } |
| 329 | /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ |
| 330 | smp_mb__before_atomic_inc(); /* See above. */ |
| 331 | atomic_inc(&rdtp->dynticks); |
| 332 | smp_mb__after_atomic_inc(); /* Force ordering with next sojourn. */ |
| 333 | WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 334 | local_irq_restore(flags); |
Paul E. McKenney | e59fb31 | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 335 | |
| 336 | /* If the interrupt queued a callback, get out of dyntick mode. */ |
| 337 | if (in_irq() && |
| 338 | (__get_cpu_var(rcu_sched_data).nxtlist || |
| 339 | __get_cpu_var(rcu_bh_data).nxtlist || |
| 340 | rcu_preempt_needs_cpu(smp_processor_id()))) |
| 341 | set_need_resched(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 342 | } |
| 343 | |
| 344 | /* |
| 345 | * rcu_exit_nohz - inform RCU that current CPU is leaving nohz |
| 346 | * |
| 347 | * Exit nohz mode, in other words, -enter- the mode in which RCU |
| 348 | * read-side critical sections normally occur. |
| 349 | */ |
| 350 | void rcu_exit_nohz(void) |
| 351 | { |
| 352 | unsigned long flags; |
| 353 | struct rcu_dynticks *rdtp; |
| 354 | |
| 355 | local_irq_save(flags); |
| 356 | rdtp = &__get_cpu_var(rcu_dynticks); |
Paul E. McKenney | e59fb31 | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 357 | if (rdtp->dynticks_nesting++) { |
| 358 | local_irq_restore(flags); |
| 359 | return; |
| 360 | } |
| 361 | smp_mb__before_atomic_inc(); /* Force ordering w/previous sojourn. */ |
| 362 | atomic_inc(&rdtp->dynticks); |
| 363 | /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ |
| 364 | smp_mb__after_atomic_inc(); /* See above. */ |
| 365 | WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 366 | local_irq_restore(flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 367 | } |
| 368 | |
| 369 | /** |
| 370 | * rcu_nmi_enter - inform RCU of entry to NMI context |
| 371 | * |
| 372 | * If the CPU was idle with dynamic ticks active, and there is no |
| 373 | * irq handler running, this updates rdtp->dynticks_nmi to let the |
| 374 | * RCU grace-period handling know that the CPU is active. |
| 375 | */ |
| 376 | void rcu_nmi_enter(void) |
| 377 | { |
| 378 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 379 | |
Paul E. McKenney | e59fb31 | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 380 | if (rdtp->dynticks_nmi_nesting == 0 && |
| 381 | (atomic_read(&rdtp->dynticks) & 0x1)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 382 | return; |
Paul E. McKenney | e59fb31 | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 383 | rdtp->dynticks_nmi_nesting++; |
| 384 | smp_mb__before_atomic_inc(); /* Force delay from prior write. */ |
| 385 | atomic_inc(&rdtp->dynticks); |
| 386 | /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ |
| 387 | smp_mb__after_atomic_inc(); /* See above. */ |
| 388 | WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 389 | } |
| 390 | |
| 391 | /** |
| 392 | * rcu_nmi_exit - inform RCU of exit from NMI context |
| 393 | * |
| 394 | * If the CPU was idle with dynamic ticks active, and there is no |
| 395 | * irq handler running, this updates rdtp->dynticks_nmi to let the |
| 396 | * RCU grace-period handling know that the CPU is no longer active. |
| 397 | */ |
| 398 | void rcu_nmi_exit(void) |
| 399 | { |
| 400 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 401 | |
Paul E. McKenney | e59fb31 | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 402 | if (rdtp->dynticks_nmi_nesting == 0 || |
| 403 | --rdtp->dynticks_nmi_nesting != 0) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 404 | return; |
Paul E. McKenney | e59fb31 | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 405 | /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ |
| 406 | smp_mb__before_atomic_inc(); /* See above. */ |
| 407 | atomic_inc(&rdtp->dynticks); |
| 408 | smp_mb__after_atomic_inc(); /* Force delay to next write. */ |
| 409 | WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 410 | } |
| 411 | |
| 412 | /** |
| 413 | * rcu_irq_enter - inform RCU of entry to hard irq context |
| 414 | * |
| 415 | * If the CPU was idle with dynamic ticks active, this updates the |
| 416 | * rdtp->dynticks to let the RCU handling know that the CPU is active. |
| 417 | */ |
| 418 | void rcu_irq_enter(void) |
| 419 | { |
Paul E. McKenney | e59fb31 | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 420 | rcu_exit_nohz(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 421 | } |
| 422 | |
| 423 | /** |
| 424 | * rcu_irq_exit - inform RCU of exit from hard irq context |
| 425 | * |
| 426 | * If the CPU was idle with dynamic ticks active, update the rdp->dynticks |
| 427 | * to put let the RCU handling be aware that the CPU is going back to idle |
| 428 | * with no ticks. |
| 429 | */ |
| 430 | void rcu_irq_exit(void) |
| 431 | { |
Paul E. McKenney | e59fb31 | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 432 | rcu_enter_nohz(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 433 | } |
| 434 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 435 | #ifdef CONFIG_SMP |
| 436 | |
| 437 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 438 | * Snapshot the specified CPU's dynticks counter so that we can later |
| 439 | * 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] | 440 | * is in dynticks idle mode, which is an extended quiescent state. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 441 | */ |
| 442 | static int dyntick_save_progress_counter(struct rcu_data *rdp) |
| 443 | { |
Paul E. McKenney | e59fb31 | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 444 | rdp->dynticks_snap = atomic_add_return(0, &rdp->dynticks->dynticks); |
| 445 | return 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 446 | } |
| 447 | |
| 448 | /* |
| 449 | * Return true if the specified CPU has passed through a quiescent |
| 450 | * state by virtue of being in or having passed through an dynticks |
| 451 | * idle state since the last call to dyntick_save_progress_counter() |
| 452 | * for this same CPU. |
| 453 | */ |
| 454 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) |
| 455 | { |
Paul E. McKenney | e59fb31 | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 456 | unsigned long curr; |
| 457 | unsigned long snap; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 458 | |
Paul E. McKenney | e59fb31 | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 459 | curr = (unsigned long)atomic_add_return(0, &rdp->dynticks->dynticks); |
| 460 | snap = (unsigned long)rdp->dynticks_snap; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 461 | |
| 462 | /* |
| 463 | * If the CPU passed through or entered a dynticks idle phase with |
| 464 | * no active irq/NMI handlers, then we can safely pretend that the CPU |
| 465 | * already acknowledged the request to pass through a quiescent |
| 466 | * state. Either way, that CPU cannot possibly be in an RCU |
| 467 | * read-side critical section that started before the beginning |
| 468 | * of the current RCU grace period. |
| 469 | */ |
Paul E. McKenney | e59fb31 | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 470 | if ((curr & 0x1) == 0 || ULONG_CMP_GE(curr, snap + 2)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 471 | rdp->dynticks_fqs++; |
| 472 | return 1; |
| 473 | } |
| 474 | |
| 475 | /* Go check for the CPU being offline. */ |
| 476 | return rcu_implicit_offline_qs(rdp); |
| 477 | } |
| 478 | |
| 479 | #endif /* #ifdef CONFIG_SMP */ |
| 480 | |
| 481 | #else /* #ifdef CONFIG_NO_HZ */ |
| 482 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 483 | #ifdef CONFIG_SMP |
| 484 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 485 | static int dyntick_save_progress_counter(struct rcu_data *rdp) |
| 486 | { |
| 487 | return 0; |
| 488 | } |
| 489 | |
| 490 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) |
| 491 | { |
| 492 | return rcu_implicit_offline_qs(rdp); |
| 493 | } |
| 494 | |
| 495 | #endif /* #ifdef CONFIG_SMP */ |
| 496 | |
| 497 | #endif /* #else #ifdef CONFIG_NO_HZ */ |
| 498 | |
Paul E. McKenney | 742734e | 2010-06-30 11:43:52 -0700 | [diff] [blame] | 499 | int rcu_cpu_stall_suppress __read_mostly; |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 500 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 501 | static void record_gp_stall_check_time(struct rcu_state *rsp) |
| 502 | { |
| 503 | rsp->gp_start = jiffies; |
| 504 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_CHECK; |
| 505 | } |
| 506 | |
| 507 | static void print_other_cpu_stall(struct rcu_state *rsp) |
| 508 | { |
| 509 | int cpu; |
| 510 | long delta; |
| 511 | unsigned long flags; |
| 512 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 513 | |
| 514 | /* Only let one CPU complain about others per time interval. */ |
| 515 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 516 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 517 | delta = jiffies - rsp->jiffies_stall; |
Paul E. McKenney | fc2219d4 | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 518 | if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 519 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 520 | return; |
| 521 | } |
| 522 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_RECHECK; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 523 | |
| 524 | /* |
| 525 | * Now rat on any tasks that got kicked up to the root rcu_node |
| 526 | * due to CPU offlining. |
| 527 | */ |
| 528 | rcu_print_task_stall(rnp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 529 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 530 | |
Paul E. McKenney | 8cdd32a | 2010-08-09 14:23:03 -0700 | [diff] [blame] | 531 | /* |
| 532 | * OK, time to rat on our buddy... |
| 533 | * See Documentation/RCU/stallwarn.txt for info on how to debug |
| 534 | * RCU CPU stall warnings. |
| 535 | */ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 536 | printk(KERN_ERR "INFO: %s detected stalls on CPUs/tasks: {", |
| 537 | rsp->name); |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 538 | rcu_for_each_leaf_node(rsp, rnp) { |
Paul E. McKenney | 3acd9eb | 2010-02-22 17:05:03 -0800 | [diff] [blame] | 539 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 540 | rcu_print_task_stall(rnp); |
Paul E. McKenney | 3acd9eb | 2010-02-22 17:05:03 -0800 | [diff] [blame] | 541 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 542 | if (rnp->qsmask == 0) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 543 | continue; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 544 | for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++) |
| 545 | if (rnp->qsmask & (1UL << cpu)) |
| 546 | printk(" %d", rnp->grplo + cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 547 | } |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 548 | printk("} (detected by %d, t=%ld jiffies)\n", |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 549 | smp_processor_id(), (long)(jiffies - rsp->gp_start)); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 550 | trigger_all_cpu_backtrace(); |
| 551 | |
Paul E. McKenney | 1ed509a | 2010-02-22 17:05:05 -0800 | [diff] [blame] | 552 | /* If so configured, complain about tasks blocking the grace period. */ |
| 553 | |
| 554 | rcu_print_detail_task_stall(rsp); |
| 555 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 556 | force_quiescent_state(rsp, 0); /* Kick them all. */ |
| 557 | } |
| 558 | |
| 559 | static void print_cpu_stall(struct rcu_state *rsp) |
| 560 | { |
| 561 | unsigned long flags; |
| 562 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 563 | |
Paul E. McKenney | 8cdd32a | 2010-08-09 14:23:03 -0700 | [diff] [blame] | 564 | /* |
| 565 | * OK, time to rat on ourselves... |
| 566 | * See Documentation/RCU/stallwarn.txt for info on how to debug |
| 567 | * RCU CPU stall warnings. |
| 568 | */ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 569 | printk(KERN_ERR "INFO: %s detected stall on CPU %d (t=%lu jiffies)\n", |
| 570 | rsp->name, smp_processor_id(), jiffies - rsp->gp_start); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 571 | trigger_all_cpu_backtrace(); |
| 572 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 573 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 574 | if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 575 | rsp->jiffies_stall = |
| 576 | jiffies + RCU_SECONDS_TILL_STALL_RECHECK; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 577 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 578 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 579 | set_need_resched(); /* kick ourselves to get things going. */ |
| 580 | } |
| 581 | |
| 582 | static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) |
| 583 | { |
| 584 | long delta; |
| 585 | struct rcu_node *rnp; |
| 586 | |
Paul E. McKenney | 742734e | 2010-06-30 11:43:52 -0700 | [diff] [blame] | 587 | if (rcu_cpu_stall_suppress) |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 588 | return; |
Dongdong Deng | 4ee0a60 | 2010-09-28 16:32:43 +0800 | [diff] [blame] | 589 | delta = jiffies - ACCESS_ONCE(rsp->jiffies_stall); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 590 | rnp = rdp->mynode; |
Dongdong Deng | 4ee0a60 | 2010-09-28 16:32:43 +0800 | [diff] [blame] | 591 | if ((ACCESS_ONCE(rnp->qsmask) & rdp->grpmask) && delta >= 0) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 592 | |
| 593 | /* We haven't checked in, so go dump stack. */ |
| 594 | print_cpu_stall(rsp); |
| 595 | |
Paul E. McKenney | fc2219d4 | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 596 | } else if (rcu_gp_in_progress(rsp) && delta >= RCU_STALL_RAT_DELAY) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 597 | |
| 598 | /* They had two time units to dump stack, so complain. */ |
| 599 | print_other_cpu_stall(rsp); |
| 600 | } |
| 601 | } |
| 602 | |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 603 | static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr) |
| 604 | { |
Paul E. McKenney | 742734e | 2010-06-30 11:43:52 -0700 | [diff] [blame] | 605 | rcu_cpu_stall_suppress = 1; |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 606 | return NOTIFY_DONE; |
| 607 | } |
| 608 | |
Paul E. McKenney | 53d84e0 | 2010-08-10 14:28:53 -0700 | [diff] [blame] | 609 | /** |
| 610 | * rcu_cpu_stall_reset - prevent further stall warnings in current grace period |
| 611 | * |
| 612 | * Set the stall-warning timeout way off into the future, thus preventing |
| 613 | * any RCU CPU stall-warning messages from appearing in the current set of |
| 614 | * RCU grace periods. |
| 615 | * |
| 616 | * The caller must disable hard irqs. |
| 617 | */ |
| 618 | void rcu_cpu_stall_reset(void) |
| 619 | { |
| 620 | rcu_sched_state.jiffies_stall = jiffies + ULONG_MAX / 2; |
| 621 | rcu_bh_state.jiffies_stall = jiffies + ULONG_MAX / 2; |
| 622 | rcu_preempt_stall_reset(); |
| 623 | } |
| 624 | |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 625 | static struct notifier_block rcu_panic_block = { |
| 626 | .notifier_call = rcu_panic, |
| 627 | }; |
| 628 | |
| 629 | static void __init check_cpu_stall_init(void) |
| 630 | { |
| 631 | atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block); |
| 632 | } |
| 633 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 634 | /* |
| 635 | * Update CPU-local rcu_data state to record the newly noticed grace period. |
| 636 | * 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] | 637 | * that someone else started the grace period. The caller must hold the |
| 638 | * ->lock of the leaf rcu_node structure corresponding to the current CPU, |
| 639 | * and must have irqs disabled. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 640 | */ |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 641 | static void __note_new_gpnum(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
| 642 | { |
| 643 | if (rdp->gpnum != rnp->gpnum) { |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 644 | /* |
| 645 | * If the current grace period is waiting for this CPU, |
| 646 | * set up to detect a quiescent state, otherwise don't |
| 647 | * go looking for one. |
| 648 | */ |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 649 | rdp->gpnum = rnp->gpnum; |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 650 | if (rnp->qsmask & rdp->grpmask) { |
| 651 | rdp->qs_pending = 1; |
| 652 | rdp->passed_quiesc = 0; |
| 653 | } else |
| 654 | rdp->qs_pending = 0; |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 655 | } |
| 656 | } |
| 657 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 658 | static void note_new_gpnum(struct rcu_state *rsp, struct rcu_data *rdp) |
| 659 | { |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 660 | unsigned long flags; |
| 661 | struct rcu_node *rnp; |
| 662 | |
| 663 | local_irq_save(flags); |
| 664 | rnp = rdp->mynode; |
| 665 | if (rdp->gpnum == ACCESS_ONCE(rnp->gpnum) || /* outside lock. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 666 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 667 | local_irq_restore(flags); |
| 668 | return; |
| 669 | } |
| 670 | __note_new_gpnum(rsp, rnp, rdp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 671 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 672 | } |
| 673 | |
| 674 | /* |
| 675 | * Did someone else start a new RCU grace period start since we last |
| 676 | * checked? Update local state appropriately if so. Must be called |
| 677 | * on the CPU corresponding to rdp. |
| 678 | */ |
| 679 | static int |
| 680 | check_for_new_grace_period(struct rcu_state *rsp, struct rcu_data *rdp) |
| 681 | { |
| 682 | unsigned long flags; |
| 683 | int ret = 0; |
| 684 | |
| 685 | local_irq_save(flags); |
| 686 | if (rdp->gpnum != rsp->gpnum) { |
| 687 | note_new_gpnum(rsp, rdp); |
| 688 | ret = 1; |
| 689 | } |
| 690 | local_irq_restore(flags); |
| 691 | return ret; |
| 692 | } |
| 693 | |
| 694 | /* |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 695 | * Advance this CPU's callbacks, but only if the current grace period |
| 696 | * has ended. This may be called only from the CPU to whom the rdp |
| 697 | * belongs. In addition, the corresponding leaf rcu_node structure's |
| 698 | * ->lock must be held by the caller, with irqs disabled. |
| 699 | */ |
| 700 | static void |
| 701 | __rcu_process_gp_end(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
| 702 | { |
| 703 | /* Did another grace period end? */ |
| 704 | if (rdp->completed != rnp->completed) { |
| 705 | |
| 706 | /* Advance callbacks. No harm if list empty. */ |
| 707 | rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL]; |
| 708 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL]; |
| 709 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 710 | |
| 711 | /* Remember that we saw this grace-period completion. */ |
| 712 | rdp->completed = rnp->completed; |
Frederic Weisbecker | 20377f3 | 2010-12-10 22:11:10 +0100 | [diff] [blame] | 713 | |
| 714 | /* |
Frederic Weisbecker | 5ff8e6f | 2010-12-10 22:11:11 +0100 | [diff] [blame] | 715 | * If we were in an extended quiescent state, we may have |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 716 | * missed some grace periods that others CPUs handled on |
Frederic Weisbecker | 5ff8e6f | 2010-12-10 22:11:11 +0100 | [diff] [blame] | 717 | * our behalf. Catch up with this state to avoid noting |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 718 | * spurious new grace periods. If another grace period |
| 719 | * has started, then rnp->gpnum will have advanced, so |
| 720 | * we will detect this later on. |
Frederic Weisbecker | 5ff8e6f | 2010-12-10 22:11:11 +0100 | [diff] [blame] | 721 | */ |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 722 | if (ULONG_CMP_LT(rdp->gpnum, rdp->completed)) |
Frederic Weisbecker | 5ff8e6f | 2010-12-10 22:11:11 +0100 | [diff] [blame] | 723 | rdp->gpnum = rdp->completed; |
| 724 | |
| 725 | /* |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 726 | * If RCU does not need a quiescent state from this CPU, |
| 727 | * then make sure that this CPU doesn't go looking for one. |
Frederic Weisbecker | 20377f3 | 2010-12-10 22:11:10 +0100 | [diff] [blame] | 728 | */ |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 729 | if ((rnp->qsmask & rdp->grpmask) == 0) |
Frederic Weisbecker | 20377f3 | 2010-12-10 22:11:10 +0100 | [diff] [blame] | 730 | rdp->qs_pending = 0; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 731 | } |
| 732 | } |
| 733 | |
| 734 | /* |
| 735 | * Advance this CPU's callbacks, but only if the current grace period |
| 736 | * has ended. This may be called only from the CPU to whom the rdp |
| 737 | * belongs. |
| 738 | */ |
| 739 | static void |
| 740 | rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp) |
| 741 | { |
| 742 | unsigned long flags; |
| 743 | struct rcu_node *rnp; |
| 744 | |
| 745 | local_irq_save(flags); |
| 746 | rnp = rdp->mynode; |
| 747 | if (rdp->completed == ACCESS_ONCE(rnp->completed) || /* outside lock. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 748 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 749 | local_irq_restore(flags); |
| 750 | return; |
| 751 | } |
| 752 | __rcu_process_gp_end(rsp, rnp, rdp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 753 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 754 | } |
| 755 | |
| 756 | /* |
| 757 | * Do per-CPU grace-period initialization for running CPU. The caller |
| 758 | * must hold the lock of the leaf rcu_node structure corresponding to |
| 759 | * this CPU. |
| 760 | */ |
| 761 | static void |
| 762 | rcu_start_gp_per_cpu(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
| 763 | { |
| 764 | /* Prior grace period ended, so advance callbacks for current CPU. */ |
| 765 | __rcu_process_gp_end(rsp, rnp, rdp); |
| 766 | |
| 767 | /* |
| 768 | * Because this CPU just now started the new grace period, we know |
| 769 | * that all of its callbacks will be covered by this upcoming grace |
| 770 | * period, even the ones that were registered arbitrarily recently. |
| 771 | * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL. |
| 772 | * |
| 773 | * Other CPUs cannot be sure exactly when the grace period started. |
| 774 | * Therefore, their recently registered callbacks must pass through |
| 775 | * an additional RCU_NEXT_READY stage, so that they will be handled |
| 776 | * by the next RCU grace period. |
| 777 | */ |
| 778 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 779 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 780 | |
| 781 | /* Set state so that this CPU will detect the next quiescent state. */ |
| 782 | __note_new_gpnum(rsp, rnp, rdp); |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 783 | } |
| 784 | |
| 785 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 786 | * Start a new RCU grace period if warranted, re-initializing the hierarchy |
| 787 | * in preparation for detecting the next grace period. The caller must hold |
| 788 | * the root node's ->lock, which is released before return. Hard irqs must |
| 789 | * be disabled. |
| 790 | */ |
| 791 | static void |
| 792 | rcu_start_gp(struct rcu_state *rsp, unsigned long flags) |
| 793 | __releases(rcu_get_root(rsp)->lock) |
| 794 | { |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 795 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 796 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 797 | |
Paul E. McKenney | 07079d5 | 2010-01-04 15:09:02 -0800 | [diff] [blame] | 798 | if (!cpu_needs_another_gp(rsp, rdp) || rsp->fqs_active) { |
Paul E. McKenney | 46a1e34 | 2010-01-04 15:09:09 -0800 | [diff] [blame] | 799 | if (cpu_needs_another_gp(rsp, rdp)) |
| 800 | rsp->fqs_need_gp = 1; |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 801 | if (rnp->completed == rsp->completed) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 802 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 803 | return; |
| 804 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 805 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 806 | |
| 807 | /* |
| 808 | * Propagate new ->completed value to rcu_node structures |
| 809 | * so that other CPUs don't have to wait until the start |
| 810 | * of the next grace period to process their callbacks. |
| 811 | */ |
| 812 | rcu_for_each_node_breadth_first(rsp, rnp) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 813 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 814 | rnp->completed = rsp->completed; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 815 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 816 | } |
| 817 | local_irq_restore(flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 818 | return; |
| 819 | } |
| 820 | |
| 821 | /* Advance to a new grace period and initialize state. */ |
| 822 | rsp->gpnum++; |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 823 | WARN_ON_ONCE(rsp->signaled == RCU_GP_INIT); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 824 | rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */ |
| 825 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 826 | record_gp_stall_check_time(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 827 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 828 | /* Special-case the common single-level case. */ |
| 829 | if (NUM_RCU_NODES == 1) { |
Paul E. McKenney | b0e165c0 | 2009-09-13 09:15:09 -0700 | [diff] [blame] | 830 | rcu_preempt_check_blocked_tasks(rnp); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 831 | rnp->qsmask = rnp->qsmaskinit; |
Paul E. McKenney | de078d8 | 2009-09-08 15:54:36 -0700 | [diff] [blame] | 832 | rnp->gpnum = rsp->gpnum; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 833 | rnp->completed = rsp->completed; |
Paul E. McKenney | c12172c | 2009-01-04 20:30:06 -0800 | [diff] [blame] | 834 | rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state OK. */ |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 835 | rcu_start_gp_per_cpu(rsp, rnp, rdp); |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 836 | rcu_preempt_boost_start_gp(rnp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 837 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 838 | return; |
| 839 | } |
| 840 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 841 | raw_spin_unlock(&rnp->lock); /* leave irqs disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 842 | |
| 843 | |
| 844 | /* Exclude any concurrent CPU-hotplug operations. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 845 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 846 | |
| 847 | /* |
Paul E. McKenney | b835db1 | 2009-09-08 15:54:37 -0700 | [diff] [blame] | 848 | * Set the quiescent-state-needed bits in all the rcu_node |
| 849 | * structures for all currently online CPUs in breadth-first |
| 850 | * order, starting from the root rcu_node structure. This |
| 851 | * operation relies on the layout of the hierarchy within the |
| 852 | * rsp->node[] array. Note that other CPUs will access only |
| 853 | * the leaves of the hierarchy, which still indicate that no |
| 854 | * grace period is in progress, at least until the corresponding |
| 855 | * leaf node has been initialized. In addition, we have excluded |
| 856 | * CPU-hotplug operations. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 857 | * |
| 858 | * Note that the grace period cannot complete until we finish |
| 859 | * the initialization process, as there will be at least one |
| 860 | * 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] | 861 | * one corresponding to this CPU, due to the fact that we have |
| 862 | * irqs disabled. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 863 | */ |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 864 | rcu_for_each_node_breadth_first(rsp, rnp) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 865 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | b0e165c0 | 2009-09-13 09:15:09 -0700 | [diff] [blame] | 866 | rcu_preempt_check_blocked_tasks(rnp); |
Paul E. McKenney | 49e2912 | 2009-09-18 09:50:19 -0700 | [diff] [blame] | 867 | rnp->qsmask = rnp->qsmaskinit; |
Paul E. McKenney | de078d8 | 2009-09-08 15:54:36 -0700 | [diff] [blame] | 868 | rnp->gpnum = rsp->gpnum; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 869 | rnp->completed = rsp->completed; |
| 870 | if (rnp == rdp->mynode) |
| 871 | rcu_start_gp_per_cpu(rsp, rnp, rdp); |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 872 | rcu_preempt_boost_start_gp(rnp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 873 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 874 | } |
| 875 | |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 876 | rnp = rcu_get_root(rsp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 877 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 878 | rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state now OK. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 879 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
| 880 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 881 | } |
| 882 | |
| 883 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 884 | * Report a full set of quiescent states to the specified rcu_state |
| 885 | * data structure. This involves cleaning up after the prior grace |
| 886 | * period and letting rcu_start_gp() start up the next grace period |
| 887 | * if one is needed. Note that the caller must hold rnp->lock, as |
| 888 | * required by rcu_start_gp(), which will release it. |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 889 | */ |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 890 | 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] | 891 | __releases(rcu_get_root(rsp)->lock) |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 892 | { |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 893 | unsigned long gp_duration; |
| 894 | |
Paul E. McKenney | fc2219d4 | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 895 | WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); |
Paul E. McKenney | e59fb31 | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 896 | |
| 897 | /* |
| 898 | * Ensure that all grace-period and pre-grace-period activity |
| 899 | * is seen before the assignment to rsp->completed. |
| 900 | */ |
| 901 | smp_mb(); /* See above block comment. */ |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 902 | gp_duration = jiffies - rsp->gp_start; |
| 903 | if (gp_duration > rsp->gp_max) |
| 904 | rsp->gp_max = gp_duration; |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 905 | rsp->completed = rsp->gpnum; |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 906 | rsp->signaled = RCU_GP_IDLE; |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 907 | rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */ |
| 908 | } |
| 909 | |
| 910 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 911 | * Similar to rcu_report_qs_rdp(), for which it is a helper function. |
| 912 | * Allows quiescent states for a group of CPUs to be reported at one go |
| 913 | * to the specified rcu_node structure, though all the CPUs in the group |
| 914 | * must be represented by the same rcu_node structure (which need not be |
| 915 | * a leaf rcu_node structure, though it often will be). That structure's |
| 916 | * 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] | 917 | */ |
| 918 | static void |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 919 | rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp, |
| 920 | struct rcu_node *rnp, unsigned long flags) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 921 | __releases(rnp->lock) |
| 922 | { |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 923 | struct rcu_node *rnp_c; |
| 924 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 925 | /* Walk up the rcu_node hierarchy. */ |
| 926 | for (;;) { |
| 927 | if (!(rnp->qsmask & mask)) { |
| 928 | |
| 929 | /* Our bit has already been cleared, so done. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 930 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 931 | return; |
| 932 | } |
| 933 | rnp->qsmask &= ~mask; |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 934 | if (rnp->qsmask != 0 || rcu_preempt_blocked_readers_cgp(rnp)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 935 | |
| 936 | /* Other bits still set at this level, so done. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 937 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 938 | return; |
| 939 | } |
| 940 | mask = rnp->grpmask; |
| 941 | if (rnp->parent == NULL) { |
| 942 | |
| 943 | /* No more levels. Exit loop holding root lock. */ |
| 944 | |
| 945 | break; |
| 946 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 947 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 948 | rnp_c = rnp; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 949 | rnp = rnp->parent; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 950 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 951 | WARN_ON_ONCE(rnp_c->qsmask); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 952 | } |
| 953 | |
| 954 | /* |
| 955 | * 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] | 956 | * state for this grace period. Invoke rcu_report_qs_rsp() |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 957 | * 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] | 958 | */ |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 959 | rcu_report_qs_rsp(rsp, flags); /* releases rnp->lock. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 960 | } |
| 961 | |
| 962 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 963 | * Record a quiescent state for the specified CPU to that CPU's rcu_data |
| 964 | * structure. This must be either called from the specified CPU, or |
| 965 | * called when the specified CPU is known to be offline (and when it is |
| 966 | * also known that no other CPU is concurrently trying to help the offline |
| 967 | * CPU). The lastcomp argument is used to make sure we are still in the |
| 968 | * grace period of interest. We don't want to end the current grace period |
| 969 | * based on quiescent states detected in an earlier grace period! |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 970 | */ |
| 971 | static void |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 972 | rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 973 | { |
| 974 | unsigned long flags; |
| 975 | unsigned long mask; |
| 976 | struct rcu_node *rnp; |
| 977 | |
| 978 | rnp = rdp->mynode; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 979 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 560d4bc | 2009-11-13 19:51:38 -0800 | [diff] [blame] | 980 | if (lastcomp != rnp->completed) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 981 | |
| 982 | /* |
| 983 | * Someone beat us to it for this grace period, so leave. |
| 984 | * The race with GP start is resolved by the fact that we |
| 985 | * hold the leaf rcu_node lock, so that the per-CPU bits |
| 986 | * cannot yet be initialized -- so we would simply find our |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 987 | * CPU's bit already cleared in rcu_report_qs_rnp() if this |
| 988 | * race occurred. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 989 | */ |
| 990 | rdp->passed_quiesc = 0; /* try again later! */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 991 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 992 | return; |
| 993 | } |
| 994 | mask = rdp->grpmask; |
| 995 | if ((rnp->qsmask & mask) == 0) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 996 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 997 | } else { |
| 998 | rdp->qs_pending = 0; |
| 999 | |
| 1000 | /* |
| 1001 | * This GP can't end until cpu checks in, so all of our |
| 1002 | * callbacks can be processed during the next GP. |
| 1003 | */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1004 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 1005 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1006 | rcu_report_qs_rnp(mask, rsp, rnp, flags); /* rlses rnp->lock */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1007 | } |
| 1008 | } |
| 1009 | |
| 1010 | /* |
| 1011 | * Check to see if there is a new grace period of which this CPU |
| 1012 | * is not yet aware, and if so, set up local rcu_data state for it. |
| 1013 | * Otherwise, see if this CPU has just passed through its first |
| 1014 | * quiescent state for this grace period, and record that fact if so. |
| 1015 | */ |
| 1016 | static void |
| 1017 | rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp) |
| 1018 | { |
| 1019 | /* If there is now a new grace period, record and return. */ |
| 1020 | if (check_for_new_grace_period(rsp, rdp)) |
| 1021 | return; |
| 1022 | |
| 1023 | /* |
| 1024 | * Does this CPU still need to do its part for current grace period? |
| 1025 | * If no, return and let the other CPUs do their part as well. |
| 1026 | */ |
| 1027 | if (!rdp->qs_pending) |
| 1028 | return; |
| 1029 | |
| 1030 | /* |
| 1031 | * Was there a quiescent state since the beginning of the grace |
| 1032 | * period? If no, then exit and wait for the next call. |
| 1033 | */ |
| 1034 | if (!rdp->passed_quiesc) |
| 1035 | return; |
| 1036 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1037 | /* |
| 1038 | * Tell RCU we are done (but rcu_report_qs_rdp() will be the |
| 1039 | * judge of that). |
| 1040 | */ |
| 1041 | rcu_report_qs_rdp(rdp->cpu, rsp, rdp, rdp->passed_quiesc_completed); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1042 | } |
| 1043 | |
| 1044 | #ifdef CONFIG_HOTPLUG_CPU |
| 1045 | |
| 1046 | /* |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1047 | * Move a dying CPU's RCU callbacks to online CPU's callback list. |
| 1048 | * Synchronization is not required because this function executes |
| 1049 | * in stop_machine() context. |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1050 | */ |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1051 | static void rcu_send_cbs_to_online(struct rcu_state *rsp) |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1052 | { |
| 1053 | int i; |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1054 | /* current DYING CPU is cleared in the cpu_online_mask */ |
| 1055 | int receive_cpu = cpumask_any(cpu_online_mask); |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1056 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1057 | struct rcu_data *receive_rdp = per_cpu_ptr(rsp->rda, receive_cpu); |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1058 | |
| 1059 | if (rdp->nxtlist == NULL) |
| 1060 | return; /* irqs disabled, so comparison is stable. */ |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1061 | |
| 1062 | *receive_rdp->nxttail[RCU_NEXT_TAIL] = rdp->nxtlist; |
| 1063 | receive_rdp->nxttail[RCU_NEXT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 1064 | receive_rdp->qlen += rdp->qlen; |
| 1065 | receive_rdp->n_cbs_adopted += rdp->qlen; |
| 1066 | rdp->n_cbs_orphaned += rdp->qlen; |
| 1067 | |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1068 | rdp->nxtlist = NULL; |
| 1069 | for (i = 0; i < RCU_NEXT_SIZE; i++) |
| 1070 | rdp->nxttail[i] = &rdp->nxtlist; |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1071 | rdp->qlen = 0; |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1072 | } |
| 1073 | |
| 1074 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1075 | * Remove the outgoing CPU from the bitmasks in the rcu_node hierarchy |
| 1076 | * and move all callbacks from the outgoing CPU to the current one. |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1077 | * There can only be one CPU hotplug operation at a time, so no other |
| 1078 | * CPU can be attempting to update rcu_cpu_kthread_task. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1079 | */ |
| 1080 | static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) |
| 1081 | { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1082 | unsigned long flags; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1083 | unsigned long mask; |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1084 | int need_report = 0; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1085 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1086 | struct rcu_node *rnp; |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1087 | struct task_struct *t; |
| 1088 | |
| 1089 | /* Stop the CPU's kthread. */ |
| 1090 | t = per_cpu(rcu_cpu_kthread_task, cpu); |
| 1091 | if (t != NULL) { |
| 1092 | per_cpu(rcu_cpu_kthread_task, cpu) = NULL; |
| 1093 | kthread_stop(t); |
| 1094 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1095 | |
| 1096 | /* Exclude any attempts to start a new grace period. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1097 | raw_spin_lock_irqsave(&rsp->onofflock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1098 | |
| 1099 | /* Remove the outgoing CPU from the masks in the rcu_node hierarchy. */ |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 1100 | rnp = rdp->mynode; /* this is the outgoing CPU's rnp. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1101 | mask = rdp->grpmask; /* rnp->grplo is constant. */ |
| 1102 | do { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1103 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1104 | rnp->qsmaskinit &= ~mask; |
| 1105 | if (rnp->qsmaskinit != 0) { |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1106 | if (rnp != rdp->mynode) |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1107 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1108 | break; |
| 1109 | } |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1110 | if (rnp == rdp->mynode) |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1111 | need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp); |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1112 | else |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1113 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1114 | mask = rnp->grpmask; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1115 | rnp = rnp->parent; |
| 1116 | } while (rnp != NULL); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1117 | |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1118 | /* |
| 1119 | * We still hold the leaf rcu_node structure lock here, and |
| 1120 | * irqs are still disabled. The reason for this subterfuge is |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1121 | * because invoking rcu_report_unblock_qs_rnp() with ->onofflock |
| 1122 | * held leads to deadlock. |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1123 | */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1124 | raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1125 | rnp = rdp->mynode; |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1126 | if (need_report & RCU_OFL_TASKS_NORM_GP) |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1127 | rcu_report_unblock_qs_rnp(rnp, flags); |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1128 | else |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1129 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1130 | if (need_report & RCU_OFL_TASKS_EXP_GP) |
| 1131 | rcu_report_exp_rnp(rsp, rnp); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1132 | |
| 1133 | /* |
| 1134 | * If there are no more online CPUs for this rcu_node structure, |
| 1135 | * kill the rcu_node structure's kthread. Otherwise, adjust its |
| 1136 | * affinity. |
| 1137 | */ |
| 1138 | t = rnp->node_kthread_task; |
| 1139 | if (t != NULL && |
| 1140 | rnp->qsmaskinit == 0) { |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1141 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1142 | rnp->node_kthread_task = NULL; |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1143 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
| 1144 | kthread_stop(t); |
| 1145 | rcu_stop_boost_kthread(rnp); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1146 | } else |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 1147 | rcu_node_kthread_setaffinity(rnp, -1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1148 | } |
| 1149 | |
| 1150 | /* |
| 1151 | * Remove the specified CPU from the RCU hierarchy and move any pending |
| 1152 | * callbacks that it might have to the current CPU. This code assumes |
| 1153 | * that at least one CPU in the system will remain running at all times. |
| 1154 | * Any attempt to offline -all- CPUs is likely to strand RCU callbacks. |
| 1155 | */ |
| 1156 | static void rcu_offline_cpu(int cpu) |
| 1157 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1158 | __rcu_offline_cpu(cpu, &rcu_sched_state); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1159 | __rcu_offline_cpu(cpu, &rcu_bh_state); |
Paul E. McKenney | 33f7614 | 2009-08-24 09:42:01 -0700 | [diff] [blame] | 1160 | rcu_preempt_offline_cpu(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1161 | } |
| 1162 | |
| 1163 | #else /* #ifdef CONFIG_HOTPLUG_CPU */ |
| 1164 | |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1165 | static void rcu_send_cbs_to_online(struct rcu_state *rsp) |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1166 | { |
| 1167 | } |
| 1168 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1169 | static void rcu_offline_cpu(int cpu) |
| 1170 | { |
| 1171 | } |
| 1172 | |
| 1173 | #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */ |
| 1174 | |
| 1175 | /* |
| 1176 | * Invoke any RCU callbacks that have made it to the end of their grace |
| 1177 | * period. Thottle as specified by rdp->blimit. |
| 1178 | */ |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1179 | 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] | 1180 | { |
| 1181 | unsigned long flags; |
| 1182 | struct rcu_head *next, *list, **tail; |
| 1183 | int count; |
| 1184 | |
| 1185 | /* If no callbacks are ready, just return.*/ |
| 1186 | if (!cpu_has_callbacks_ready_to_invoke(rdp)) |
| 1187 | return; |
| 1188 | |
| 1189 | /* |
| 1190 | * Extract the list of ready callbacks, disabling to prevent |
| 1191 | * races with call_rcu() from interrupt handlers. |
| 1192 | */ |
| 1193 | local_irq_save(flags); |
| 1194 | list = rdp->nxtlist; |
| 1195 | rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL]; |
| 1196 | *rdp->nxttail[RCU_DONE_TAIL] = NULL; |
| 1197 | tail = rdp->nxttail[RCU_DONE_TAIL]; |
| 1198 | for (count = RCU_NEXT_SIZE - 1; count >= 0; count--) |
| 1199 | if (rdp->nxttail[count] == rdp->nxttail[RCU_DONE_TAIL]) |
| 1200 | rdp->nxttail[count] = &rdp->nxtlist; |
| 1201 | local_irq_restore(flags); |
| 1202 | |
| 1203 | /* Invoke callbacks. */ |
| 1204 | count = 0; |
| 1205 | while (list) { |
| 1206 | next = list->next; |
| 1207 | prefetch(next); |
Mathieu Desnoyers | 551d55a | 2010-04-17 08:48:42 -0400 | [diff] [blame] | 1208 | debug_rcu_head_unqueue(list); |
Lai Jiangshan | 9ab1544 | 2011-03-18 11:15:47 +0800 | [diff] [blame] | 1209 | __rcu_reclaim(list); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1210 | list = next; |
| 1211 | if (++count >= rdp->blimit) |
| 1212 | break; |
| 1213 | } |
| 1214 | |
| 1215 | local_irq_save(flags); |
| 1216 | |
| 1217 | /* Update count, and requeue any remaining callbacks. */ |
| 1218 | rdp->qlen -= count; |
Paul E. McKenney | 269dcc1 | 2010-09-07 14:23:09 -0700 | [diff] [blame] | 1219 | rdp->n_cbs_invoked += count; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1220 | if (list != NULL) { |
| 1221 | *tail = rdp->nxtlist; |
| 1222 | rdp->nxtlist = list; |
| 1223 | for (count = 0; count < RCU_NEXT_SIZE; count++) |
| 1224 | if (&rdp->nxtlist == rdp->nxttail[count]) |
| 1225 | rdp->nxttail[count] = tail; |
| 1226 | else |
| 1227 | break; |
| 1228 | } |
| 1229 | |
| 1230 | /* Reinstate batch limit if we have worked down the excess. */ |
| 1231 | if (rdp->blimit == LONG_MAX && rdp->qlen <= qlowmark) |
| 1232 | rdp->blimit = blimit; |
| 1233 | |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1234 | /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */ |
| 1235 | if (rdp->qlen == 0 && rdp->qlen_last_fqs_check != 0) { |
| 1236 | rdp->qlen_last_fqs_check = 0; |
| 1237 | rdp->n_force_qs_snap = rsp->n_force_qs; |
| 1238 | } else if (rdp->qlen < rdp->qlen_last_fqs_check - qhimark) |
| 1239 | rdp->qlen_last_fqs_check = rdp->qlen; |
| 1240 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1241 | local_irq_restore(flags); |
| 1242 | |
| 1243 | /* Re-raise the RCU softirq if there are callbacks remaining. */ |
| 1244 | if (cpu_has_callbacks_ready_to_invoke(rdp)) |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1245 | invoke_rcu_cpu_kthread(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1246 | } |
| 1247 | |
| 1248 | /* |
| 1249 | * Check to see if this CPU is in a non-context-switch quiescent state |
| 1250 | * (user mode or idle loop for rcu, non-softirq execution for rcu_bh). |
| 1251 | * Also schedule the RCU softirq handler. |
| 1252 | * |
| 1253 | * This function must be called with hardirqs disabled. It is normally |
| 1254 | * invoked from the scheduling-clock interrupt. If rcu_pending returns |
| 1255 | * false, there is no point in invoking rcu_check_callbacks(). |
| 1256 | */ |
| 1257 | void rcu_check_callbacks(int cpu, int user) |
| 1258 | { |
| 1259 | if (user || |
Paul E. McKenney | a682604 | 2009-02-25 18:03:42 -0800 | [diff] [blame] | 1260 | (idle_cpu(cpu) && rcu_scheduler_active && |
| 1261 | !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1262 | |
| 1263 | /* |
| 1264 | * Get here if this CPU took its interrupt from user |
| 1265 | * mode or from the idle loop, and if this is not a |
| 1266 | * nested interrupt. In this case, the CPU is in |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1267 | * a quiescent state, so note it. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1268 | * |
| 1269 | * No memory barrier is required here because both |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1270 | * rcu_sched_qs() and rcu_bh_qs() reference only CPU-local |
| 1271 | * variables that other CPUs neither access nor modify, |
| 1272 | * at least not while the corresponding CPU is online. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1273 | */ |
| 1274 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1275 | rcu_sched_qs(cpu); |
| 1276 | rcu_bh_qs(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1277 | |
| 1278 | } else if (!in_softirq()) { |
| 1279 | |
| 1280 | /* |
| 1281 | * Get here if this CPU did not take its interrupt from |
| 1282 | * softirq, in other words, if it is not interrupting |
| 1283 | * a rcu_bh read-side critical section. This is an _bh |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1284 | * critical section, so note it. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1285 | */ |
| 1286 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1287 | rcu_bh_qs(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1288 | } |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1289 | rcu_preempt_check_callbacks(cpu); |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 1290 | if (rcu_pending(cpu)) |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1291 | invoke_rcu_cpu_kthread(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1292 | } |
| 1293 | |
| 1294 | #ifdef CONFIG_SMP |
| 1295 | |
| 1296 | /* |
| 1297 | * Scan the leaf rcu_node structures, processing dyntick state for any that |
| 1298 | * have not yet encountered a quiescent state, using the function specified. |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1299 | * Also initiate boosting for any threads blocked on the root rcu_node. |
| 1300 | * |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1301 | * The caller must have suppressed start of new grace periods. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1302 | */ |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1303 | 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] | 1304 | { |
| 1305 | unsigned long bit; |
| 1306 | int cpu; |
| 1307 | unsigned long flags; |
| 1308 | unsigned long mask; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1309 | struct rcu_node *rnp; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1310 | |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1311 | rcu_for_each_leaf_node(rsp, rnp) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1312 | mask = 0; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1313 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1314 | if (!rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1315 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 0f10dc82 | 2010-01-04 15:09:06 -0800 | [diff] [blame] | 1316 | return; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1317 | } |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1318 | if (rnp->qsmask == 0) { |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1319 | rcu_initiate_boost(rnp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1320 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1321 | continue; |
| 1322 | } |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1323 | cpu = rnp->grplo; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1324 | bit = 1; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1325 | for (; cpu <= rnp->grphi; cpu++, bit <<= 1) { |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1326 | if ((rnp->qsmask & bit) != 0 && |
| 1327 | f(per_cpu_ptr(rsp->rda, cpu))) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1328 | mask |= bit; |
| 1329 | } |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1330 | if (mask != 0) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1331 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1332 | /* rcu_report_qs_rnp() releases rnp->lock. */ |
| 1333 | rcu_report_qs_rnp(mask, rsp, rnp, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1334 | continue; |
| 1335 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1336 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1337 | } |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1338 | rnp = rcu_get_root(rsp); |
| 1339 | raw_spin_lock_irqsave(&rnp->lock, flags); |
| 1340 | if (rnp->qsmask == 0) |
| 1341 | rcu_initiate_boost(rnp); |
| 1342 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1343 | } |
| 1344 | |
| 1345 | /* |
| 1346 | * Force quiescent states on reluctant CPUs, and also detect which |
| 1347 | * CPUs are in dyntick-idle mode. |
| 1348 | */ |
| 1349 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) |
| 1350 | { |
| 1351 | unsigned long flags; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1352 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1353 | |
Paul E. McKenney | fc2219d4 | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 1354 | if (!rcu_gp_in_progress(rsp)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1355 | return; /* No grace period in progress, nothing to force. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1356 | if (!raw_spin_trylock_irqsave(&rsp->fqslock, flags)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1357 | rsp->n_force_qs_lh++; /* Inexact, can lose counts. Tough! */ |
| 1358 | return; /* Someone else is already on the job. */ |
| 1359 | } |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1360 | if (relaxed && ULONG_CMP_GE(rsp->jiffies_force_qs, jiffies)) |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1361 | goto unlock_fqs_ret; /* no emergency and done recently. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1362 | rsp->n_force_qs++; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1363 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1364 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
Paul E. McKenney | 560d4bc | 2009-11-13 19:51:38 -0800 | [diff] [blame] | 1365 | if(!rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1366 | rsp->n_force_qs_ngp++; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1367 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1368 | goto unlock_fqs_ret; /* no GP in progress, time updated. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1369 | } |
Paul E. McKenney | 07079d5 | 2010-01-04 15:09:02 -0800 | [diff] [blame] | 1370 | rsp->fqs_active = 1; |
Paul E. McKenney | f3a8b5c | 2010-01-04 15:09:03 -0800 | [diff] [blame] | 1371 | switch (rsp->signaled) { |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 1372 | case RCU_GP_IDLE: |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1373 | case RCU_GP_INIT: |
| 1374 | |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 1375 | break; /* grace period idle or initializing, ignore. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1376 | |
| 1377 | case RCU_SAVE_DYNTICK: |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1378 | if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK) |
| 1379 | break; /* So gcc recognizes the dead code. */ |
| 1380 | |
Lai Jiangshan | f261414 | 2010-03-28 11:15:20 +0800 | [diff] [blame] | 1381 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
| 1382 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1383 | /* Record dyntick-idle state. */ |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1384 | force_qs_rnp(rsp, dyntick_save_progress_counter); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1385 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1386 | if (rcu_gp_in_progress(rsp)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1387 | rsp->signaled = RCU_FORCE_QS; |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1388 | break; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1389 | |
| 1390 | case RCU_FORCE_QS: |
| 1391 | |
| 1392 | /* Check dyntick-idle state, send IPI to laggarts. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1393 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1394 | force_qs_rnp(rsp, rcu_implicit_dynticks_qs); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1395 | |
| 1396 | /* Leave state in case more forcing is required. */ |
| 1397 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1398 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1399 | break; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1400 | } |
Paul E. McKenney | 07079d5 | 2010-01-04 15:09:02 -0800 | [diff] [blame] | 1401 | rsp->fqs_active = 0; |
Paul E. McKenney | 46a1e34 | 2010-01-04 15:09:09 -0800 | [diff] [blame] | 1402 | if (rsp->fqs_need_gp) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1403 | raw_spin_unlock(&rsp->fqslock); /* irqs remain disabled */ |
Paul E. McKenney | 46a1e34 | 2010-01-04 15:09:09 -0800 | [diff] [blame] | 1404 | rsp->fqs_need_gp = 0; |
| 1405 | rcu_start_gp(rsp, flags); /* releases rnp->lock */ |
| 1406 | return; |
| 1407 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1408 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1409 | unlock_fqs_ret: |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1410 | raw_spin_unlock_irqrestore(&rsp->fqslock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1411 | } |
| 1412 | |
| 1413 | #else /* #ifdef CONFIG_SMP */ |
| 1414 | |
| 1415 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) |
| 1416 | { |
| 1417 | set_need_resched(); |
| 1418 | } |
| 1419 | |
| 1420 | #endif /* #else #ifdef CONFIG_SMP */ |
| 1421 | |
| 1422 | /* |
| 1423 | * This does the RCU processing work from softirq context for the |
| 1424 | * specified rcu_state and rcu_data structures. This may be called |
| 1425 | * only from the CPU to whom the rdp belongs. |
| 1426 | */ |
| 1427 | static void |
| 1428 | __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) |
| 1429 | { |
| 1430 | unsigned long flags; |
| 1431 | |
Paul E. McKenney | 2e59755 | 2009-08-15 09:53:48 -0700 | [diff] [blame] | 1432 | WARN_ON_ONCE(rdp->beenonline == 0); |
| 1433 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1434 | /* |
| 1435 | * If an RCU GP has gone long enough, go check for dyntick |
| 1436 | * idle CPUs and, if needed, send resched IPIs. |
| 1437 | */ |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1438 | if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1439 | force_quiescent_state(rsp, 1); |
| 1440 | |
| 1441 | /* |
| 1442 | * Advance callbacks in response to end of earlier grace |
| 1443 | * period that some other CPU ended. |
| 1444 | */ |
| 1445 | rcu_process_gp_end(rsp, rdp); |
| 1446 | |
| 1447 | /* Update RCU state based on any recent quiescent states. */ |
| 1448 | rcu_check_quiescent_state(rsp, rdp); |
| 1449 | |
| 1450 | /* Does this CPU require a not-yet-started grace period? */ |
| 1451 | if (cpu_needs_another_gp(rsp, rdp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1452 | raw_spin_lock_irqsave(&rcu_get_root(rsp)->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1453 | rcu_start_gp(rsp, flags); /* releases above lock */ |
| 1454 | } |
| 1455 | |
| 1456 | /* If there are callbacks ready, invoke them. */ |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1457 | rcu_do_batch(rsp, rdp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1458 | } |
| 1459 | |
| 1460 | /* |
| 1461 | * Do softirq processing for the current CPU. |
| 1462 | */ |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1463 | static void rcu_process_callbacks(void) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1464 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1465 | __rcu_process_callbacks(&rcu_sched_state, |
| 1466 | &__get_cpu_var(rcu_sched_data)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1467 | __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] | 1468 | rcu_preempt_process_callbacks(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1469 | |
Paul E. McKenney | a47cd88 | 2010-02-26 16:38:56 -0800 | [diff] [blame] | 1470 | /* If we are last CPU on way to dyntick-idle mode, accelerate it. */ |
| 1471 | rcu_needs_cpu_flush(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1472 | } |
| 1473 | |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1474 | /* |
| 1475 | * Wake up the current CPU's kthread. This replaces raise_softirq() |
| 1476 | * in earlier versions of RCU. Note that because we are running on |
| 1477 | * the current CPU with interrupts disabled, the rcu_cpu_kthread_task |
| 1478 | * cannot disappear out from under us. |
| 1479 | */ |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1480 | static void invoke_rcu_cpu_kthread(void) |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1481 | { |
| 1482 | unsigned long flags; |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1483 | |
| 1484 | local_irq_save(flags); |
Paul E. McKenney | f0a07ae | 2011-02-23 11:10:52 -0800 | [diff] [blame] | 1485 | __this_cpu_write(rcu_cpu_has_work, 1); |
| 1486 | if (__this_cpu_read(rcu_cpu_kthread_task) == NULL) { |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1487 | local_irq_restore(flags); |
| 1488 | return; |
| 1489 | } |
Paul E. McKenney | f0a07ae | 2011-02-23 11:10:52 -0800 | [diff] [blame] | 1490 | wake_up(&__get_cpu_var(rcu_cpu_wq)); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1491 | local_irq_restore(flags); |
| 1492 | } |
| 1493 | |
| 1494 | /* |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1495 | * Wake up the specified per-rcu_node-structure kthread. |
| 1496 | * The caller must hold ->lock. |
| 1497 | */ |
| 1498 | static void invoke_rcu_node_kthread(struct rcu_node *rnp) |
| 1499 | { |
| 1500 | struct task_struct *t; |
| 1501 | |
| 1502 | t = rnp->node_kthread_task; |
| 1503 | if (t != NULL) |
| 1504 | wake_up_process(t); |
| 1505 | } |
| 1506 | |
| 1507 | /* |
Paul E. McKenney | e3995a2 | 2011-04-18 15:31:26 -0700 | [diff] [blame] | 1508 | * Set the specified CPU's kthread to run RT or not, as specified by |
| 1509 | * the to_rt argument. The CPU-hotplug locks are held, so the task |
| 1510 | * is not going away. |
| 1511 | */ |
| 1512 | static void rcu_cpu_kthread_setrt(int cpu, int to_rt) |
| 1513 | { |
| 1514 | int policy; |
| 1515 | struct sched_param sp; |
| 1516 | struct task_struct *t; |
| 1517 | |
| 1518 | t = per_cpu(rcu_cpu_kthread_task, cpu); |
| 1519 | if (t == NULL) |
| 1520 | return; |
| 1521 | if (to_rt) { |
| 1522 | policy = SCHED_FIFO; |
| 1523 | sp.sched_priority = RCU_KTHREAD_PRIO; |
| 1524 | } else { |
| 1525 | policy = SCHED_NORMAL; |
| 1526 | sp.sched_priority = 0; |
| 1527 | } |
| 1528 | sched_setscheduler_nocheck(t, policy, &sp); |
| 1529 | } |
| 1530 | |
| 1531 | /* |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1532 | * Timer handler to initiate the waking up of per-CPU kthreads that |
| 1533 | * have yielded the CPU due to excess numbers of RCU callbacks. |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1534 | * We wake up the per-rcu_node kthread, which in turn will wake up |
| 1535 | * the booster kthread. |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1536 | */ |
| 1537 | static void rcu_cpu_kthread_timer(unsigned long arg) |
| 1538 | { |
| 1539 | unsigned long flags; |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1540 | struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, arg); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1541 | struct rcu_node *rnp = rdp->mynode; |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1542 | |
| 1543 | raw_spin_lock_irqsave(&rnp->lock, flags); |
| 1544 | rnp->wakemask |= rdp->grpmask; |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1545 | invoke_rcu_node_kthread(rnp); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1546 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
| 1547 | } |
| 1548 | |
| 1549 | /* |
| 1550 | * Drop to non-real-time priority and yield, but only after posting a |
| 1551 | * timer that will cause us to regain our real-time priority if we |
| 1552 | * remain preempted. Either way, we restore our real-time priority |
| 1553 | * before returning. |
| 1554 | */ |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1555 | static void rcu_yield(void (*f)(unsigned long), unsigned long arg) |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1556 | { |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1557 | struct sched_param sp; |
| 1558 | struct timer_list yield_timer; |
| 1559 | |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1560 | setup_timer_on_stack(&yield_timer, f, arg); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1561 | mod_timer(&yield_timer, jiffies + 2); |
| 1562 | sp.sched_priority = 0; |
| 1563 | sched_setscheduler_nocheck(current, SCHED_NORMAL, &sp); |
Paul E. McKenney | baa1ae0 | 2011-03-26 22:01:35 -0700 | [diff] [blame^] | 1564 | set_user_nice(current, 19); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1565 | schedule(); |
| 1566 | sp.sched_priority = RCU_KTHREAD_PRIO; |
| 1567 | sched_setscheduler_nocheck(current, SCHED_FIFO, &sp); |
| 1568 | del_timer(&yield_timer); |
| 1569 | } |
| 1570 | |
| 1571 | /* |
| 1572 | * Handle cases where the rcu_cpu_kthread() ends up on the wrong CPU. |
| 1573 | * This can happen while the corresponding CPU is either coming online |
| 1574 | * or going offline. We cannot wait until the CPU is fully online |
| 1575 | * before starting the kthread, because the various notifier functions |
| 1576 | * can wait for RCU grace periods. So we park rcu_cpu_kthread() until |
| 1577 | * the corresponding CPU is online. |
| 1578 | * |
| 1579 | * Return 1 if the kthread needs to stop, 0 otherwise. |
| 1580 | * |
| 1581 | * Caller must disable bh. This function can momentarily enable it. |
| 1582 | */ |
| 1583 | static int rcu_cpu_kthread_should_stop(int cpu) |
| 1584 | { |
| 1585 | while (cpu_is_offline(cpu) || |
| 1586 | !cpumask_equal(¤t->cpus_allowed, cpumask_of(cpu)) || |
| 1587 | smp_processor_id() != cpu) { |
| 1588 | if (kthread_should_stop()) |
| 1589 | return 1; |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 1590 | per_cpu(rcu_cpu_kthread_status, cpu) = RCU_KTHREAD_OFFCPU; |
| 1591 | per_cpu(rcu_cpu_kthread_cpu, cpu) = raw_smp_processor_id(); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1592 | local_bh_enable(); |
| 1593 | schedule_timeout_uninterruptible(1); |
| 1594 | if (!cpumask_equal(¤t->cpus_allowed, cpumask_of(cpu))) |
| 1595 | set_cpus_allowed_ptr(current, cpumask_of(cpu)); |
| 1596 | local_bh_disable(); |
| 1597 | } |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 1598 | per_cpu(rcu_cpu_kthread_cpu, cpu) = cpu; |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1599 | return 0; |
| 1600 | } |
| 1601 | |
| 1602 | /* |
| 1603 | * Per-CPU kernel thread that invokes RCU callbacks. This replaces the |
| 1604 | * earlier RCU softirq. |
| 1605 | */ |
| 1606 | static int rcu_cpu_kthread(void *arg) |
| 1607 | { |
| 1608 | int cpu = (int)(long)arg; |
| 1609 | unsigned long flags; |
| 1610 | int spincnt = 0; |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 1611 | unsigned int *statusp = &per_cpu(rcu_cpu_kthread_status, cpu); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1612 | wait_queue_head_t *wqp = &per_cpu(rcu_cpu_wq, cpu); |
| 1613 | char work; |
| 1614 | char *workp = &per_cpu(rcu_cpu_has_work, cpu); |
| 1615 | |
| 1616 | for (;;) { |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 1617 | *statusp = RCU_KTHREAD_WAITING; |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1618 | wait_event_interruptible(*wqp, |
| 1619 | *workp != 0 || kthread_should_stop()); |
| 1620 | local_bh_disable(); |
| 1621 | if (rcu_cpu_kthread_should_stop(cpu)) { |
| 1622 | local_bh_enable(); |
| 1623 | break; |
| 1624 | } |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 1625 | *statusp = RCU_KTHREAD_RUNNING; |
Paul E. McKenney | 5ece5ba | 2011-04-22 18:08:51 -0700 | [diff] [blame] | 1626 | per_cpu(rcu_cpu_kthread_loops, cpu)++; |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1627 | local_irq_save(flags); |
| 1628 | work = *workp; |
| 1629 | *workp = 0; |
| 1630 | local_irq_restore(flags); |
| 1631 | if (work) |
| 1632 | rcu_process_callbacks(); |
| 1633 | local_bh_enable(); |
| 1634 | if (*workp != 0) |
| 1635 | spincnt++; |
| 1636 | else |
| 1637 | spincnt = 0; |
| 1638 | if (spincnt > 10) { |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 1639 | *statusp = RCU_KTHREAD_YIELDING; |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1640 | rcu_yield(rcu_cpu_kthread_timer, (unsigned long)cpu); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1641 | spincnt = 0; |
| 1642 | } |
| 1643 | } |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 1644 | *statusp = RCU_KTHREAD_STOPPED; |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1645 | return 0; |
| 1646 | } |
| 1647 | |
| 1648 | /* |
| 1649 | * Spawn a per-CPU kthread, setting up affinity and priority. |
| 1650 | * Because the CPU hotplug lock is held, no other CPU will be attempting |
| 1651 | * to manipulate rcu_cpu_kthread_task. There might be another CPU |
| 1652 | * attempting to access it during boot, but the locking in kthread_bind() |
| 1653 | * will enforce sufficient ordering. |
| 1654 | */ |
| 1655 | static int __cpuinit rcu_spawn_one_cpu_kthread(int cpu) |
| 1656 | { |
| 1657 | struct sched_param sp; |
| 1658 | struct task_struct *t; |
| 1659 | |
| 1660 | if (!rcu_kthreads_spawnable || |
| 1661 | per_cpu(rcu_cpu_kthread_task, cpu) != NULL) |
| 1662 | return 0; |
| 1663 | t = kthread_create(rcu_cpu_kthread, (void *)(long)cpu, "rcuc%d", cpu); |
| 1664 | if (IS_ERR(t)) |
| 1665 | return PTR_ERR(t); |
| 1666 | kthread_bind(t, cpu); |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 1667 | per_cpu(rcu_cpu_kthread_cpu, cpu) = cpu; |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1668 | WARN_ON_ONCE(per_cpu(rcu_cpu_kthread_task, cpu) != NULL); |
| 1669 | per_cpu(rcu_cpu_kthread_task, cpu) = t; |
| 1670 | wake_up_process(t); |
| 1671 | sp.sched_priority = RCU_KTHREAD_PRIO; |
| 1672 | sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); |
| 1673 | return 0; |
| 1674 | } |
| 1675 | |
| 1676 | /* |
| 1677 | * Per-rcu_node kthread, which is in charge of waking up the per-CPU |
| 1678 | * kthreads when needed. We ignore requests to wake up kthreads |
| 1679 | * for offline CPUs, which is OK because force_quiescent_state() |
| 1680 | * takes care of this case. |
| 1681 | */ |
| 1682 | static int rcu_node_kthread(void *arg) |
| 1683 | { |
| 1684 | int cpu; |
| 1685 | unsigned long flags; |
| 1686 | unsigned long mask; |
| 1687 | struct rcu_node *rnp = (struct rcu_node *)arg; |
| 1688 | struct sched_param sp; |
| 1689 | struct task_struct *t; |
| 1690 | |
| 1691 | for (;;) { |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 1692 | rnp->node_kthread_status = RCU_KTHREAD_WAITING; |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1693 | wait_event_interruptible(rnp->node_wq, rnp->wakemask != 0 || |
| 1694 | kthread_should_stop()); |
| 1695 | if (kthread_should_stop()) |
| 1696 | break; |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 1697 | rnp->node_kthread_status = RCU_KTHREAD_RUNNING; |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1698 | raw_spin_lock_irqsave(&rnp->lock, flags); |
| 1699 | mask = rnp->wakemask; |
| 1700 | rnp->wakemask = 0; |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1701 | rcu_initiate_boost(rnp); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1702 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
| 1703 | for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1) { |
| 1704 | if ((mask & 0x1) == 0) |
| 1705 | continue; |
| 1706 | preempt_disable(); |
| 1707 | t = per_cpu(rcu_cpu_kthread_task, cpu); |
| 1708 | if (!cpu_online(cpu) || t == NULL) { |
| 1709 | preempt_enable(); |
| 1710 | continue; |
| 1711 | } |
| 1712 | per_cpu(rcu_cpu_has_work, cpu) = 1; |
| 1713 | sp.sched_priority = RCU_KTHREAD_PRIO; |
| 1714 | sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); |
| 1715 | preempt_enable(); |
| 1716 | } |
| 1717 | } |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 1718 | rnp->node_kthread_status = RCU_KTHREAD_STOPPED; |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1719 | return 0; |
| 1720 | } |
| 1721 | |
| 1722 | /* |
| 1723 | * Set the per-rcu_node kthread's affinity to cover all CPUs that are |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1724 | * served by the rcu_node in question. The CPU hotplug lock is still |
| 1725 | * held, so the value of rnp->qsmaskinit will be stable. |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 1726 | * |
| 1727 | * We don't include outgoingcpu in the affinity set, use -1 if there is |
| 1728 | * no outgoing CPU. If there are no CPUs left in the affinity set, |
| 1729 | * this function allows the kthread to execute on any CPU. |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1730 | */ |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 1731 | static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu) |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1732 | { |
| 1733 | cpumask_var_t cm; |
| 1734 | int cpu; |
| 1735 | unsigned long mask = rnp->qsmaskinit; |
| 1736 | |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1737 | if (rnp->node_kthread_task == NULL || mask == 0) |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1738 | return; |
| 1739 | if (!alloc_cpumask_var(&cm, GFP_KERNEL)) |
| 1740 | return; |
| 1741 | cpumask_clear(cm); |
| 1742 | for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1) |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 1743 | if ((mask & 0x1) && cpu != outgoingcpu) |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1744 | cpumask_set_cpu(cpu, cm); |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 1745 | if (cpumask_weight(cm) == 0) { |
| 1746 | cpumask_setall(cm); |
| 1747 | for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++) |
| 1748 | cpumask_clear_cpu(cpu, cm); |
| 1749 | WARN_ON_ONCE(cpumask_weight(cm) == 0); |
| 1750 | } |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1751 | set_cpus_allowed_ptr(rnp->node_kthread_task, cm); |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1752 | rcu_boost_kthread_setaffinity(rnp, cm); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1753 | free_cpumask_var(cm); |
| 1754 | } |
| 1755 | |
| 1756 | /* |
| 1757 | * Spawn a per-rcu_node kthread, setting priority and affinity. |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1758 | * Called during boot before online/offline can happen, or, if |
| 1759 | * during runtime, with the main CPU-hotplug locks held. So only |
| 1760 | * one of these can be executing at a time. |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1761 | */ |
| 1762 | static int __cpuinit rcu_spawn_one_node_kthread(struct rcu_state *rsp, |
| 1763 | struct rcu_node *rnp) |
| 1764 | { |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1765 | unsigned long flags; |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1766 | int rnp_index = rnp - &rsp->node[0]; |
| 1767 | struct sched_param sp; |
| 1768 | struct task_struct *t; |
| 1769 | |
| 1770 | if (!rcu_kthreads_spawnable || |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1771 | rnp->qsmaskinit == 0) |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1772 | return 0; |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1773 | if (rnp->node_kthread_task == NULL) { |
| 1774 | t = kthread_create(rcu_node_kthread, (void *)rnp, |
| 1775 | "rcun%d", rnp_index); |
| 1776 | if (IS_ERR(t)) |
| 1777 | return PTR_ERR(t); |
| 1778 | raw_spin_lock_irqsave(&rnp->lock, flags); |
| 1779 | rnp->node_kthread_task = t; |
| 1780 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
| 1781 | wake_up_process(t); |
| 1782 | sp.sched_priority = 99; |
| 1783 | sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); |
| 1784 | } |
| 1785 | return rcu_spawn_one_boost_kthread(rsp, rnp, rnp_index); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1786 | } |
| 1787 | |
| 1788 | /* |
| 1789 | * Spawn all kthreads -- called as soon as the scheduler is running. |
| 1790 | */ |
| 1791 | static int __init rcu_spawn_kthreads(void) |
| 1792 | { |
| 1793 | int cpu; |
| 1794 | struct rcu_node *rnp; |
| 1795 | |
| 1796 | rcu_kthreads_spawnable = 1; |
| 1797 | for_each_possible_cpu(cpu) { |
| 1798 | init_waitqueue_head(&per_cpu(rcu_cpu_wq, cpu)); |
| 1799 | per_cpu(rcu_cpu_has_work, cpu) = 0; |
| 1800 | if (cpu_online(cpu)) |
| 1801 | (void)rcu_spawn_one_cpu_kthread(cpu); |
| 1802 | } |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1803 | rnp = rcu_get_root(rcu_state); |
| 1804 | init_waitqueue_head(&rnp->node_wq); |
| 1805 | rcu_init_boost_waitqueue(rnp); |
| 1806 | (void)rcu_spawn_one_node_kthread(rcu_state, rnp); |
| 1807 | if (NUM_RCU_NODES > 1) |
| 1808 | rcu_for_each_leaf_node(rcu_state, rnp) { |
| 1809 | init_waitqueue_head(&rnp->node_wq); |
| 1810 | rcu_init_boost_waitqueue(rnp); |
| 1811 | (void)rcu_spawn_one_node_kthread(rcu_state, rnp); |
| 1812 | } |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1813 | return 0; |
| 1814 | } |
| 1815 | early_initcall(rcu_spawn_kthreads); |
| 1816 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1817 | static void |
| 1818 | __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), |
| 1819 | struct rcu_state *rsp) |
| 1820 | { |
| 1821 | unsigned long flags; |
| 1822 | struct rcu_data *rdp; |
| 1823 | |
Mathieu Desnoyers | 551d55a | 2010-04-17 08:48:42 -0400 | [diff] [blame] | 1824 | debug_rcu_head_queue(head); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1825 | head->func = func; |
| 1826 | head->next = NULL; |
| 1827 | |
| 1828 | smp_mb(); /* Ensure RCU update seen before callback registry. */ |
| 1829 | |
| 1830 | /* |
| 1831 | * Opportunistically note grace-period endings and beginnings. |
| 1832 | * Note that we might see a beginning right after we see an |
| 1833 | * end, but never vice versa, since this CPU has to pass through |
| 1834 | * a quiescent state betweentimes. |
| 1835 | */ |
| 1836 | local_irq_save(flags); |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1837 | rdp = this_cpu_ptr(rsp->rda); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1838 | |
| 1839 | /* Add the callback to our list. */ |
| 1840 | *rdp->nxttail[RCU_NEXT_TAIL] = head; |
| 1841 | rdp->nxttail[RCU_NEXT_TAIL] = &head->next; |
| 1842 | |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1843 | /* |
| 1844 | * Force the grace period if too many callbacks or too long waiting. |
| 1845 | * Enforce hysteresis, and don't invoke force_quiescent_state() |
| 1846 | * if some other CPU has recently done so. Also, don't bother |
| 1847 | * invoking force_quiescent_state() if the newly enqueued callback |
| 1848 | * is the only one waiting for a grace period to complete. |
| 1849 | */ |
| 1850 | if (unlikely(++rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) { |
Paul E. McKenney | b52573d | 2010-12-14 17:36:02 -0800 | [diff] [blame] | 1851 | |
| 1852 | /* Are we ignoring a completed grace period? */ |
| 1853 | rcu_process_gp_end(rsp, rdp); |
| 1854 | check_for_new_grace_period(rsp, rdp); |
| 1855 | |
| 1856 | /* Start a new grace period if one not already started. */ |
| 1857 | if (!rcu_gp_in_progress(rsp)) { |
| 1858 | unsigned long nestflag; |
| 1859 | struct rcu_node *rnp_root = rcu_get_root(rsp); |
| 1860 | |
| 1861 | raw_spin_lock_irqsave(&rnp_root->lock, nestflag); |
| 1862 | rcu_start_gp(rsp, nestflag); /* rlses rnp_root->lock */ |
| 1863 | } else { |
| 1864 | /* Give the grace period a kick. */ |
| 1865 | rdp->blimit = LONG_MAX; |
| 1866 | if (rsp->n_force_qs == rdp->n_force_qs_snap && |
| 1867 | *rdp->nxttail[RCU_DONE_TAIL] != head) |
| 1868 | force_quiescent_state(rsp, 0); |
| 1869 | rdp->n_force_qs_snap = rsp->n_force_qs; |
| 1870 | rdp->qlen_last_fqs_check = rdp->qlen; |
| 1871 | } |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1872 | } 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] | 1873 | force_quiescent_state(rsp, 1); |
| 1874 | local_irq_restore(flags); |
| 1875 | } |
| 1876 | |
| 1877 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1878 | * Queue an RCU-sched callback for invocation after a grace period. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1879 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1880 | 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] | 1881 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1882 | __call_rcu(head, func, &rcu_sched_state); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1883 | } |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1884 | EXPORT_SYMBOL_GPL(call_rcu_sched); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1885 | |
| 1886 | /* |
| 1887 | * Queue an RCU for invocation after a quicker grace period. |
| 1888 | */ |
| 1889 | void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) |
| 1890 | { |
| 1891 | __call_rcu(head, func, &rcu_bh_state); |
| 1892 | } |
| 1893 | EXPORT_SYMBOL_GPL(call_rcu_bh); |
| 1894 | |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1895 | /** |
| 1896 | * synchronize_sched - wait until an rcu-sched grace period has elapsed. |
| 1897 | * |
| 1898 | * Control will return to the caller some time after a full rcu-sched |
| 1899 | * grace period has elapsed, in other words after all currently executing |
| 1900 | * rcu-sched read-side critical sections have completed. These read-side |
| 1901 | * critical sections are delimited by rcu_read_lock_sched() and |
| 1902 | * rcu_read_unlock_sched(), and may be nested. Note that preempt_disable(), |
| 1903 | * local_irq_disable(), and so on may be used in place of |
| 1904 | * rcu_read_lock_sched(). |
| 1905 | * |
| 1906 | * This means that all preempt_disable code sequences, including NMI and |
| 1907 | * hardware-interrupt handlers, in progress on entry will have completed |
| 1908 | * before this primitive returns. However, this does not guarantee that |
| 1909 | * softirq handlers will have completed, since in some kernels, these |
| 1910 | * handlers can run in process context, and can block. |
| 1911 | * |
| 1912 | * This primitive provides the guarantees made by the (now removed) |
| 1913 | * synchronize_kernel() API. In contrast, synchronize_rcu() only |
| 1914 | * guarantees that rcu_read_lock() sections will have completed. |
| 1915 | * In "classic RCU", these two guarantees happen to be one and |
| 1916 | * the same, but can differ in realtime RCU implementations. |
| 1917 | */ |
| 1918 | void synchronize_sched(void) |
| 1919 | { |
| 1920 | struct rcu_synchronize rcu; |
| 1921 | |
| 1922 | if (rcu_blocking_is_gp()) |
| 1923 | return; |
| 1924 | |
Paul E. McKenney | 72d5a9f | 2010-05-10 17:12:17 -0700 | [diff] [blame] | 1925 | init_rcu_head_on_stack(&rcu.head); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1926 | init_completion(&rcu.completion); |
| 1927 | /* Will wake me after RCU finished. */ |
| 1928 | call_rcu_sched(&rcu.head, wakeme_after_rcu); |
| 1929 | /* Wait for it. */ |
| 1930 | wait_for_completion(&rcu.completion); |
Paul E. McKenney | 72d5a9f | 2010-05-10 17:12:17 -0700 | [diff] [blame] | 1931 | destroy_rcu_head_on_stack(&rcu.head); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1932 | } |
| 1933 | EXPORT_SYMBOL_GPL(synchronize_sched); |
| 1934 | |
| 1935 | /** |
| 1936 | * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed. |
| 1937 | * |
| 1938 | * Control will return to the caller some time after a full rcu_bh grace |
| 1939 | * period has elapsed, in other words after all currently executing rcu_bh |
| 1940 | * read-side critical sections have completed. RCU read-side critical |
| 1941 | * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(), |
| 1942 | * and may be nested. |
| 1943 | */ |
| 1944 | void synchronize_rcu_bh(void) |
| 1945 | { |
| 1946 | struct rcu_synchronize rcu; |
| 1947 | |
| 1948 | if (rcu_blocking_is_gp()) |
| 1949 | return; |
| 1950 | |
Paul E. McKenney | 72d5a9f | 2010-05-10 17:12:17 -0700 | [diff] [blame] | 1951 | init_rcu_head_on_stack(&rcu.head); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1952 | init_completion(&rcu.completion); |
| 1953 | /* Will wake me after RCU finished. */ |
| 1954 | call_rcu_bh(&rcu.head, wakeme_after_rcu); |
| 1955 | /* Wait for it. */ |
| 1956 | wait_for_completion(&rcu.completion); |
Paul E. McKenney | 72d5a9f | 2010-05-10 17:12:17 -0700 | [diff] [blame] | 1957 | destroy_rcu_head_on_stack(&rcu.head); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1958 | } |
| 1959 | EXPORT_SYMBOL_GPL(synchronize_rcu_bh); |
| 1960 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1961 | /* |
| 1962 | * Check to see if there is any immediate RCU-related work to be done |
| 1963 | * by the current CPU, for the specified type of RCU, returning 1 if so. |
| 1964 | * The checks are in order of increasing expense: checks that can be |
| 1965 | * carried out against CPU-local state are performed first. However, |
| 1966 | * we must check for CPU stalls first, else we might not get a chance. |
| 1967 | */ |
| 1968 | static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) |
| 1969 | { |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 1970 | struct rcu_node *rnp = rdp->mynode; |
| 1971 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1972 | rdp->n_rcu_pending++; |
| 1973 | |
| 1974 | /* Check for CPU stalls, if enabled. */ |
| 1975 | check_cpu_stall(rsp, rdp); |
| 1976 | |
| 1977 | /* Is the RCU core waiting for a quiescent state from this CPU? */ |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 1978 | if (rdp->qs_pending && !rdp->passed_quiesc) { |
Paul E. McKenney | d25eb94 | 2010-03-18 21:36:51 -0700 | [diff] [blame] | 1979 | |
| 1980 | /* |
| 1981 | * If force_quiescent_state() coming soon and this CPU |
| 1982 | * needs a quiescent state, and this is either RCU-sched |
| 1983 | * or RCU-bh, force a local reschedule. |
| 1984 | */ |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 1985 | rdp->n_rp_qs_pending++; |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 1986 | if (!rdp->preemptible && |
Paul E. McKenney | d25eb94 | 2010-03-18 21:36:51 -0700 | [diff] [blame] | 1987 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs) - 1, |
| 1988 | jiffies)) |
| 1989 | set_need_resched(); |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 1990 | } else if (rdp->qs_pending && rdp->passed_quiesc) { |
| 1991 | rdp->n_rp_report_qs++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1992 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1993 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1994 | |
| 1995 | /* Does this CPU have callbacks ready to invoke? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1996 | if (cpu_has_callbacks_ready_to_invoke(rdp)) { |
| 1997 | rdp->n_rp_cb_ready++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1998 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1999 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2000 | |
| 2001 | /* Has RCU gone idle with this CPU needing another grace period? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2002 | if (cpu_needs_another_gp(rsp, rdp)) { |
| 2003 | rdp->n_rp_cpu_needs_gp++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2004 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2005 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2006 | |
| 2007 | /* Has another RCU grace period completed? */ |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 2008 | if (ACCESS_ONCE(rnp->completed) != rdp->completed) { /* outside lock */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2009 | rdp->n_rp_gp_completed++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2010 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2011 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2012 | |
| 2013 | /* Has a new RCU grace period started? */ |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 2014 | if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum) { /* outside lock */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2015 | rdp->n_rp_gp_started++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2016 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2017 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2018 | |
| 2019 | /* 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] | 2020 | if (rcu_gp_in_progress(rsp) && |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 2021 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) { |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2022 | rdp->n_rp_need_fqs++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2023 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2024 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2025 | |
| 2026 | /* nothing to do */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 2027 | rdp->n_rp_need_nothing++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2028 | return 0; |
| 2029 | } |
| 2030 | |
| 2031 | /* |
| 2032 | * Check to see if there is any immediate RCU-related work to be done |
| 2033 | * by the current CPU, returning 1 if so. This function is part of the |
| 2034 | * RCU implementation; it is -not- an exported member of the RCU API. |
| 2035 | */ |
Paul E. McKenney | a157229 | 2009-08-22 13:56:51 -0700 | [diff] [blame] | 2036 | static int rcu_pending(int cpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2037 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 2038 | 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] | 2039 | __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu)) || |
| 2040 | rcu_preempt_pending(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2041 | } |
| 2042 | |
| 2043 | /* |
| 2044 | * Check to see if any future RCU-related work will need to be done |
| 2045 | * 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] | 2046 | * 1 if so. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2047 | */ |
Paul E. McKenney | 8bd93a2 | 2010-02-22 17:04:59 -0800 | [diff] [blame] | 2048 | static int rcu_needs_cpu_quick_check(int cpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2049 | { |
| 2050 | /* RCU callbacks either ready or pending? */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 2051 | return per_cpu(rcu_sched_data, cpu).nxtlist || |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2052 | per_cpu(rcu_bh_data, cpu).nxtlist || |
| 2053 | rcu_preempt_needs_cpu(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2054 | } |
| 2055 | |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2056 | static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL}; |
| 2057 | static atomic_t rcu_barrier_cpu_count; |
| 2058 | static DEFINE_MUTEX(rcu_barrier_mutex); |
| 2059 | static struct completion rcu_barrier_completion; |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2060 | |
| 2061 | static void rcu_barrier_callback(struct rcu_head *notused) |
| 2062 | { |
| 2063 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) |
| 2064 | complete(&rcu_barrier_completion); |
| 2065 | } |
| 2066 | |
| 2067 | /* |
| 2068 | * Called with preemption disabled, and from cross-cpu IRQ context. |
| 2069 | */ |
| 2070 | static void rcu_barrier_func(void *type) |
| 2071 | { |
| 2072 | int cpu = smp_processor_id(); |
| 2073 | struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu); |
| 2074 | void (*call_rcu_func)(struct rcu_head *head, |
| 2075 | void (*func)(struct rcu_head *head)); |
| 2076 | |
| 2077 | atomic_inc(&rcu_barrier_cpu_count); |
| 2078 | call_rcu_func = type; |
| 2079 | call_rcu_func(head, rcu_barrier_callback); |
| 2080 | } |
| 2081 | |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2082 | /* |
| 2083 | * Orchestrate the specified type of RCU barrier, waiting for all |
| 2084 | * RCU callbacks of the specified type to complete. |
| 2085 | */ |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 2086 | static void _rcu_barrier(struct rcu_state *rsp, |
| 2087 | void (*call_rcu_func)(struct rcu_head *head, |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2088 | void (*func)(struct rcu_head *head))) |
| 2089 | { |
| 2090 | BUG_ON(in_interrupt()); |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 2091 | /* Take mutex to serialize concurrent rcu_barrier() requests. */ |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2092 | mutex_lock(&rcu_barrier_mutex); |
| 2093 | init_completion(&rcu_barrier_completion); |
| 2094 | /* |
| 2095 | * Initialize rcu_barrier_cpu_count to 1, then invoke |
| 2096 | * rcu_barrier_func() on each CPU, so that each CPU also has |
| 2097 | * incremented rcu_barrier_cpu_count. Only then is it safe to |
| 2098 | * decrement rcu_barrier_cpu_count -- otherwise the first CPU |
| 2099 | * might complete its grace period before all of the other CPUs |
| 2100 | * did their increment, causing this function to return too |
Paul E. McKenney | 2d999e0 | 2010-10-20 12:06:18 -0700 | [diff] [blame] | 2101 | * early. Note that on_each_cpu() disables irqs, which prevents |
| 2102 | * any CPUs from coming online or going offline until each online |
| 2103 | * CPU has queued its RCU-barrier callback. |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2104 | */ |
| 2105 | atomic_set(&rcu_barrier_cpu_count, 1); |
| 2106 | on_each_cpu(rcu_barrier_func, (void *)call_rcu_func, 1); |
| 2107 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) |
| 2108 | complete(&rcu_barrier_completion); |
| 2109 | wait_for_completion(&rcu_barrier_completion); |
| 2110 | mutex_unlock(&rcu_barrier_mutex); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2111 | } |
| 2112 | |
| 2113 | /** |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2114 | * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete. |
| 2115 | */ |
| 2116 | void rcu_barrier_bh(void) |
| 2117 | { |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 2118 | _rcu_barrier(&rcu_bh_state, call_rcu_bh); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2119 | } |
| 2120 | EXPORT_SYMBOL_GPL(rcu_barrier_bh); |
| 2121 | |
| 2122 | /** |
| 2123 | * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks. |
| 2124 | */ |
| 2125 | void rcu_barrier_sched(void) |
| 2126 | { |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 2127 | _rcu_barrier(&rcu_sched_state, call_rcu_sched); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2128 | } |
| 2129 | EXPORT_SYMBOL_GPL(rcu_barrier_sched); |
| 2130 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2131 | /* |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2132 | * 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] | 2133 | */ |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2134 | static void __init |
| 2135 | rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2136 | { |
| 2137 | unsigned long flags; |
| 2138 | int i; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2139 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2140 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 2141 | |
| 2142 | /* Set up local state, ensuring consistent view of global state. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2143 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2144 | rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo); |
| 2145 | rdp->nxtlist = NULL; |
| 2146 | for (i = 0; i < RCU_NEXT_SIZE; i++) |
| 2147 | rdp->nxttail[i] = &rdp->nxtlist; |
| 2148 | rdp->qlen = 0; |
| 2149 | #ifdef CONFIG_NO_HZ |
| 2150 | rdp->dynticks = &per_cpu(rcu_dynticks, cpu); |
| 2151 | #endif /* #ifdef CONFIG_NO_HZ */ |
| 2152 | rdp->cpu = cpu; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2153 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 2154 | } |
| 2155 | |
| 2156 | /* |
| 2157 | * Initialize a CPU's per-CPU RCU data. Note that only one online or |
| 2158 | * offline event can be happening at a given time. Note also that we |
| 2159 | * can accept some slop in the rsp->completed access due to the fact |
| 2160 | * 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] | 2161 | */ |
| 2162 | static void __cpuinit |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 2163 | 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] | 2164 | { |
| 2165 | unsigned long flags; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2166 | unsigned long mask; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2167 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2168 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 2169 | |
| 2170 | /* Set up local state, ensuring consistent view of global state. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2171 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2172 | rdp->passed_quiesc = 0; /* We could be racing with new GP, */ |
| 2173 | rdp->qs_pending = 1; /* so set up to respond to current GP. */ |
| 2174 | rdp->beenonline = 1; /* We have now been online. */ |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 2175 | rdp->preemptible = preemptible; |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 2176 | rdp->qlen_last_fqs_check = 0; |
| 2177 | rdp->n_force_qs_snap = rsp->n_force_qs; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2178 | rdp->blimit = blimit; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2179 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2180 | |
| 2181 | /* |
| 2182 | * A new grace period might start here. If so, we won't be part |
| 2183 | * of it, but that is OK, as we are currently in a quiescent state. |
| 2184 | */ |
| 2185 | |
| 2186 | /* Exclude any attempts to start a new GP on large systems. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2187 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2188 | |
| 2189 | /* Add CPU to rcu_node bitmasks. */ |
| 2190 | rnp = rdp->mynode; |
| 2191 | mask = rdp->grpmask; |
| 2192 | do { |
| 2193 | /* Exclude any attempts to start a new GP on small systems. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2194 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2195 | rnp->qsmaskinit |= mask; |
| 2196 | mask = rnp->grpmask; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 2197 | if (rnp == rdp->mynode) { |
| 2198 | rdp->gpnum = rnp->completed; /* if GP in progress... */ |
| 2199 | rdp->completed = rnp->completed; |
| 2200 | rdp->passed_quiesc_completed = rnp->completed - 1; |
| 2201 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2202 | raw_spin_unlock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2203 | rnp = rnp->parent; |
| 2204 | } while (rnp != NULL && !(rnp->qsmaskinit & mask)); |
| 2205 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2206 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2207 | } |
| 2208 | |
| 2209 | static void __cpuinit rcu_online_cpu(int cpu) |
| 2210 | { |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2211 | rcu_init_percpu_data(cpu, &rcu_sched_state, 0); |
| 2212 | rcu_init_percpu_data(cpu, &rcu_bh_state, 0); |
| 2213 | rcu_preempt_init_percpu_data(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2214 | } |
| 2215 | |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 2216 | static void __cpuinit rcu_online_kthreads(int cpu) |
| 2217 | { |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 2218 | struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 2219 | struct rcu_node *rnp = rdp->mynode; |
| 2220 | |
| 2221 | /* Fire up the incoming CPU's kthread and leaf rcu_node kthread. */ |
| 2222 | if (rcu_kthreads_spawnable) { |
| 2223 | (void)rcu_spawn_one_cpu_kthread(cpu); |
| 2224 | if (rnp->node_kthread_task == NULL) |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 2225 | (void)rcu_spawn_one_node_kthread(rcu_state, rnp); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 2226 | } |
| 2227 | } |
| 2228 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2229 | /* |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2230 | * Handle CPU online/offline notification events. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2231 | */ |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 2232 | static int __cpuinit rcu_cpu_notify(struct notifier_block *self, |
| 2233 | unsigned long action, void *hcpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2234 | { |
| 2235 | long cpu = (long)hcpu; |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 2236 | struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 2237 | struct rcu_node *rnp = rdp->mynode; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2238 | |
| 2239 | switch (action) { |
| 2240 | case CPU_UP_PREPARE: |
| 2241 | case CPU_UP_PREPARE_FROZEN: |
| 2242 | rcu_online_cpu(cpu); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 2243 | rcu_online_kthreads(cpu); |
| 2244 | break; |
| 2245 | case CPU_ONLINE: |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 2246 | case CPU_DOWN_FAILED: |
| 2247 | rcu_node_kthread_setaffinity(rnp, -1); |
Paul E. McKenney | e3995a2 | 2011-04-18 15:31:26 -0700 | [diff] [blame] | 2248 | rcu_cpu_kthread_setrt(cpu, 1); |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 2249 | break; |
| 2250 | case CPU_DOWN_PREPARE: |
| 2251 | rcu_node_kthread_setaffinity(rnp, cpu); |
Paul E. McKenney | e3995a2 | 2011-04-18 15:31:26 -0700 | [diff] [blame] | 2252 | rcu_cpu_kthread_setrt(cpu, 0); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2253 | break; |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2254 | case CPU_DYING: |
| 2255 | case CPU_DYING_FROZEN: |
| 2256 | /* |
Paul E. McKenney | 2d999e0 | 2010-10-20 12:06:18 -0700 | [diff] [blame] | 2257 | * The whole machine is "stopped" except this CPU, so we can |
| 2258 | * touch any data without introducing corruption. We send the |
| 2259 | * dying CPU's callbacks to an arbitrarily chosen online CPU. |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2260 | */ |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 2261 | rcu_send_cbs_to_online(&rcu_bh_state); |
| 2262 | rcu_send_cbs_to_online(&rcu_sched_state); |
| 2263 | rcu_preempt_send_cbs_to_online(); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2264 | break; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2265 | case CPU_DEAD: |
| 2266 | case CPU_DEAD_FROZEN: |
| 2267 | case CPU_UP_CANCELED: |
| 2268 | case CPU_UP_CANCELED_FROZEN: |
| 2269 | rcu_offline_cpu(cpu); |
| 2270 | break; |
| 2271 | default: |
| 2272 | break; |
| 2273 | } |
| 2274 | return NOTIFY_OK; |
| 2275 | } |
| 2276 | |
| 2277 | /* |
Paul E. McKenney | bbad937 | 2010-04-02 16:17:17 -0700 | [diff] [blame] | 2278 | * This function is invoked towards the end of the scheduler's initialization |
| 2279 | * process. Before this is called, the idle task might contain |
| 2280 | * RCU read-side critical sections (during which time, this idle |
| 2281 | * task is booting the system). After this function is called, the |
| 2282 | * idle tasks are prohibited from containing RCU read-side critical |
| 2283 | * sections. This function also enables RCU lockdep checking. |
| 2284 | */ |
| 2285 | void rcu_scheduler_starting(void) |
| 2286 | { |
| 2287 | WARN_ON(num_online_cpus() != 1); |
| 2288 | WARN_ON(nr_context_switches() > 0); |
| 2289 | rcu_scheduler_active = 1; |
| 2290 | } |
| 2291 | |
| 2292 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2293 | * Compute the per-level fanout, either using the exact fanout specified |
| 2294 | * or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT. |
| 2295 | */ |
| 2296 | #ifdef CONFIG_RCU_FANOUT_EXACT |
| 2297 | static void __init rcu_init_levelspread(struct rcu_state *rsp) |
| 2298 | { |
| 2299 | int i; |
| 2300 | |
Paul E. McKenney | 0209f64 | 2010-12-14 16:07:52 -0800 | [diff] [blame] | 2301 | for (i = NUM_RCU_LVLS - 1; i > 0; i--) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2302 | rsp->levelspread[i] = CONFIG_RCU_FANOUT; |
Paul E. McKenney | 0209f64 | 2010-12-14 16:07:52 -0800 | [diff] [blame] | 2303 | rsp->levelspread[0] = RCU_FANOUT_LEAF; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2304 | } |
| 2305 | #else /* #ifdef CONFIG_RCU_FANOUT_EXACT */ |
| 2306 | static void __init rcu_init_levelspread(struct rcu_state *rsp) |
| 2307 | { |
| 2308 | int ccur; |
| 2309 | int cprv; |
| 2310 | int i; |
| 2311 | |
| 2312 | cprv = NR_CPUS; |
| 2313 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { |
| 2314 | ccur = rsp->levelcnt[i]; |
| 2315 | rsp->levelspread[i] = (cprv + ccur - 1) / ccur; |
| 2316 | cprv = ccur; |
| 2317 | } |
| 2318 | } |
| 2319 | #endif /* #else #ifdef CONFIG_RCU_FANOUT_EXACT */ |
| 2320 | |
| 2321 | /* |
| 2322 | * Helper function for rcu_init() that initializes one rcu_state structure. |
| 2323 | */ |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2324 | static void __init rcu_init_one(struct rcu_state *rsp, |
| 2325 | struct rcu_data __percpu *rda) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2326 | { |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 2327 | static char *buf[] = { "rcu_node_level_0", |
| 2328 | "rcu_node_level_1", |
| 2329 | "rcu_node_level_2", |
| 2330 | "rcu_node_level_3" }; /* Match MAX_RCU_LVLS */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2331 | int cpustride = 1; |
| 2332 | int i; |
| 2333 | int j; |
| 2334 | struct rcu_node *rnp; |
| 2335 | |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 2336 | BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */ |
| 2337 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2338 | /* Initialize the level-tracking arrays. */ |
| 2339 | |
| 2340 | for (i = 1; i < NUM_RCU_LVLS; i++) |
| 2341 | rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1]; |
| 2342 | rcu_init_levelspread(rsp); |
| 2343 | |
| 2344 | /* Initialize the elements themselves, starting from the leaves. */ |
| 2345 | |
| 2346 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { |
| 2347 | cpustride *= rsp->levelspread[i]; |
| 2348 | rnp = rsp->level[i]; |
| 2349 | for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2350 | raw_spin_lock_init(&rnp->lock); |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 2351 | lockdep_set_class_and_name(&rnp->lock, |
| 2352 | &rcu_node_class[i], buf[i]); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2353 | rnp->gpnum = 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2354 | rnp->qsmask = 0; |
| 2355 | rnp->qsmaskinit = 0; |
| 2356 | rnp->grplo = j * cpustride; |
| 2357 | rnp->grphi = (j + 1) * cpustride - 1; |
| 2358 | if (rnp->grphi >= NR_CPUS) |
| 2359 | rnp->grphi = NR_CPUS - 1; |
| 2360 | if (i == 0) { |
| 2361 | rnp->grpnum = 0; |
| 2362 | rnp->grpmask = 0; |
| 2363 | rnp->parent = NULL; |
| 2364 | } else { |
| 2365 | rnp->grpnum = j % rsp->levelspread[i - 1]; |
| 2366 | rnp->grpmask = 1UL << rnp->grpnum; |
| 2367 | rnp->parent = rsp->level[i - 1] + |
| 2368 | j / rsp->levelspread[i - 1]; |
| 2369 | } |
| 2370 | rnp->level = i; |
Paul E. McKenney | 12f5f52 | 2010-11-29 21:56:39 -0800 | [diff] [blame] | 2371 | INIT_LIST_HEAD(&rnp->blkd_tasks); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2372 | } |
| 2373 | } |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 2374 | |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2375 | rsp->rda = rda; |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 2376 | rnp = rsp->level[NUM_RCU_LVLS - 1]; |
| 2377 | for_each_possible_cpu(i) { |
Paul E. McKenney | 4a90a06 | 2010-04-14 16:48:11 -0700 | [diff] [blame] | 2378 | while (i > rnp->grphi) |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 2379 | rnp++; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2380 | per_cpu_ptr(rsp->rda, i)->mynode = rnp; |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 2381 | rcu_boot_init_percpu_data(i, rsp); |
| 2382 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2383 | } |
| 2384 | |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 2385 | void __init rcu_init(void) |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2386 | { |
Paul E. McKenney | 017c426 | 2010-01-14 16:10:58 -0800 | [diff] [blame] | 2387 | int cpu; |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 2388 | |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2389 | rcu_bootup_announce(); |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2390 | rcu_init_one(&rcu_sched_state, &rcu_sched_data); |
| 2391 | rcu_init_one(&rcu_bh_state, &rcu_bh_data); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2392 | __rcu_init_preempt(); |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 2393 | |
| 2394 | /* |
| 2395 | * We don't need protection against CPU-hotplug here because |
| 2396 | * this is called early in boot, before either interrupts |
| 2397 | * or the scheduler are operational. |
| 2398 | */ |
| 2399 | cpu_notifier(rcu_cpu_notify, 0); |
Paul E. McKenney | 017c426 | 2010-01-14 16:10:58 -0800 | [diff] [blame] | 2400 | for_each_online_cpu(cpu) |
| 2401 | rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu); |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 2402 | check_cpu_stall_init(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2403 | } |
| 2404 | |
Paul E. McKenney | 1eba8f8 | 2009-09-23 09:50:42 -0700 | [diff] [blame] | 2405 | #include "rcutree_plugin.h" |