Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Read-Copy Update mechanism for mutual exclusion |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation; either version 2 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, write to the Free Software |
| 16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 17 | * |
| 18 | * Copyright IBM Corporation, 2008 |
| 19 | * |
| 20 | * Authors: Dipankar Sarma <dipankar@in.ibm.com> |
| 21 | * Manfred Spraul <manfred@colorfullife.com> |
| 22 | * Paul E. McKenney <paulmck@linux.vnet.ibm.com> Hierarchical version |
| 23 | * |
| 24 | * Based on the original work by Paul McKenney <paulmck@us.ibm.com> |
| 25 | * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. |
| 26 | * |
| 27 | * For detailed explanation of Read-Copy Update mechanism see - |
Paul E. McKenney | a71fca5 | 2009-09-18 10:28:19 -0700 | [diff] [blame] | 28 | * Documentation/RCU |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 29 | */ |
| 30 | #include <linux/types.h> |
| 31 | #include <linux/kernel.h> |
| 32 | #include <linux/init.h> |
| 33 | #include <linux/spinlock.h> |
| 34 | #include <linux/smp.h> |
| 35 | #include <linux/rcupdate.h> |
| 36 | #include <linux/interrupt.h> |
| 37 | #include <linux/sched.h> |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 38 | #include <linux/nmi.h> |
Paul E. McKenney | 8826f3b | 2011-05-11 05:41:41 -0700 | [diff] [blame] | 39 | #include <linux/atomic.h> |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 40 | #include <linux/bitops.h> |
| 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> |
Linus Torvalds | 268bb0c | 2011-05-20 12:50:29 -0700 | [diff] [blame] | 52 | #include <linux/prefetch.h> |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 53 | |
Paul E. McKenney | 9f77da9 | 2009-08-22 13:56:45 -0700 | [diff] [blame] | 54 | #include "rcutree.h" |
| 55 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 56 | /* Data structures. */ |
| 57 | |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 58 | static struct lock_class_key rcu_node_class[NUM_RCU_LVLS]; |
Peter Zijlstra | 88b91c7 | 2009-10-26 10:24:31 -0700 | [diff] [blame] | 59 | |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 60 | #define RCU_STATE_INITIALIZER(structname) { \ |
| 61 | .level = { &structname.node[0] }, \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 62 | .levelcnt = { \ |
| 63 | NUM_RCU_LVL_0, /* root of hierarchy. */ \ |
| 64 | NUM_RCU_LVL_1, \ |
| 65 | NUM_RCU_LVL_2, \ |
Paul E. McKenney | cf244dc | 2009-12-02 12:10:14 -0800 | [diff] [blame] | 66 | NUM_RCU_LVL_3, \ |
| 67 | NUM_RCU_LVL_4, /* == MAX_RCU_LVLS */ \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 68 | }, \ |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 69 | .signaled = RCU_GP_IDLE, \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 70 | .gpnum = -300, \ |
| 71 | .completed = -300, \ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 72 | .onofflock = __RAW_SPIN_LOCK_UNLOCKED(&structname.onofflock), \ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 73 | .fqslock = __RAW_SPIN_LOCK_UNLOCKED(&structname.fqslock), \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 74 | .n_force_qs = 0, \ |
| 75 | .n_force_qs_ngp = 0, \ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 76 | .name = #structname, \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 77 | } |
| 78 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 79 | struct rcu_state rcu_sched_state = RCU_STATE_INITIALIZER(rcu_sched_state); |
| 80 | DEFINE_PER_CPU(struct rcu_data, rcu_sched_data); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 81 | |
Ingo Molnar | 6258c4f | 2009-03-25 16:42:24 +0100 | [diff] [blame] | 82 | struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state); |
| 83 | DEFINE_PER_CPU(struct rcu_data, rcu_bh_data); |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 84 | |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 85 | static struct rcu_state *rcu_state; |
| 86 | |
Paul E. McKenney | b0d3041 | 2011-07-10 15:57:35 -0700 | [diff] [blame] | 87 | /* |
| 88 | * The rcu_scheduler_active variable transitions from zero to one just |
| 89 | * before the first task is spawned. So when this variable is zero, RCU |
| 90 | * can assume that there is but one task, allowing RCU to (for example) |
| 91 | * optimized synchronize_sched() to a simple barrier(). When this variable |
| 92 | * is one, RCU must actually do all the hard work required to detect real |
| 93 | * grace periods. This variable is also used to suppress boot-time false |
| 94 | * positives from lockdep-RCU error checking. |
| 95 | */ |
Paul E. McKenney | bbad937 | 2010-04-02 16:17:17 -0700 | [diff] [blame] | 96 | int rcu_scheduler_active __read_mostly; |
| 97 | EXPORT_SYMBOL_GPL(rcu_scheduler_active); |
| 98 | |
Paul E. McKenney | b0d3041 | 2011-07-10 15:57:35 -0700 | [diff] [blame] | 99 | /* |
| 100 | * The rcu_scheduler_fully_active variable transitions from zero to one |
| 101 | * during the early_initcall() processing, which is after the scheduler |
| 102 | * is capable of creating new tasks. So RCU processing (for example, |
| 103 | * creating tasks for RCU priority boosting) must be delayed until after |
| 104 | * rcu_scheduler_fully_active transitions from zero to one. We also |
| 105 | * currently delay invocation of any RCU callbacks until after this point. |
| 106 | * |
| 107 | * It might later prove better for people registering RCU callbacks during |
| 108 | * early boot to take responsibility for these callbacks, but one step at |
| 109 | * a time. |
| 110 | */ |
| 111 | static int rcu_scheduler_fully_active __read_mostly; |
| 112 | |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 113 | #ifdef CONFIG_RCU_BOOST |
| 114 | |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 115 | /* |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 116 | * Control variables for per-CPU and per-rcu_node kthreads. These |
| 117 | * handle all flavors of RCU. |
| 118 | */ |
| 119 | static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task); |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 120 | DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status); |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 121 | DEFINE_PER_CPU(int, rcu_cpu_kthread_cpu); |
Paul E. McKenney | 5ece5ba | 2011-04-22 18:08:51 -0700 | [diff] [blame] | 122 | DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 123 | DEFINE_PER_CPU(char, rcu_cpu_has_work); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 124 | |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 125 | #endif /* #ifdef CONFIG_RCU_BOOST */ |
| 126 | |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 127 | static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu); |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 128 | static void invoke_rcu_core(void); |
| 129 | static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 130 | |
| 131 | #define RCU_KTHREAD_PRIO 1 /* RT priority for per-CPU kthreads. */ |
| 132 | |
| 133 | /* |
Paul E. McKenney | 4a29865 | 2011-04-03 21:33:51 -0700 | [diff] [blame] | 134 | * Track the rcutorture test sequence number and the update version |
| 135 | * number within a given test. The rcutorture_testseq is incremented |
| 136 | * on every rcutorture module load and unload, so has an odd value |
| 137 | * when a test is running. The rcutorture_vernum is set to zero |
| 138 | * when rcutorture starts and is incremented on each rcutorture update. |
| 139 | * These variables enable correlating rcutorture output with the |
| 140 | * RCU tracing information. |
| 141 | */ |
| 142 | unsigned long rcutorture_testseq; |
| 143 | unsigned long rcutorture_vernum; |
| 144 | |
| 145 | /* |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 146 | * Return true if an RCU grace period is in progress. The ACCESS_ONCE()s |
| 147 | * permit this function to be invoked without holding the root rcu_node |
| 148 | * structure's ->lock, but of course results can be subject to change. |
| 149 | */ |
| 150 | static int rcu_gp_in_progress(struct rcu_state *rsp) |
| 151 | { |
| 152 | return ACCESS_ONCE(rsp->completed) != ACCESS_ONCE(rsp->gpnum); |
| 153 | } |
| 154 | |
| 155 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 156 | * Note a quiescent state. Because we do not need to know |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 157 | * how many quiescent states passed, just if there was at least |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 158 | * 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] | 159 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 160 | void rcu_sched_qs(int cpu) |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 161 | { |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 162 | struct rcu_data *rdp = &per_cpu(rcu_sched_data, cpu); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 163 | |
Paul E. McKenney | c64ac3c | 2009-11-10 13:37:22 -0800 | [diff] [blame] | 164 | rdp->passed_quiesc_completed = rdp->gpnum - 1; |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 165 | barrier(); |
| 166 | rdp->passed_quiesc = 1; |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 167 | } |
| 168 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 169 | void rcu_bh_qs(int cpu) |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 170 | { |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 171 | struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 172 | |
Paul E. McKenney | c64ac3c | 2009-11-10 13:37:22 -0800 | [diff] [blame] | 173 | rdp->passed_quiesc_completed = rdp->gpnum - 1; |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 174 | barrier(); |
| 175 | rdp->passed_quiesc = 1; |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 176 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 177 | |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 178 | /* |
| 179 | * Note a context switch. This is a quiescent state for RCU-sched, |
| 180 | * and requires special handling for preemptible RCU. |
| 181 | */ |
| 182 | void rcu_note_context_switch(int cpu) |
| 183 | { |
| 184 | rcu_sched_qs(cpu); |
| 185 | rcu_preempt_note_context_switch(cpu); |
| 186 | } |
Gleb Natapov | 29ce831 | 2011-05-04 16:31:03 +0300 | [diff] [blame] | 187 | EXPORT_SYMBOL_GPL(rcu_note_context_switch); |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 188 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 189 | #ifdef CONFIG_NO_HZ |
Paul E. McKenney | 90a4d2c | 2009-01-04 11:41:11 -0800 | [diff] [blame] | 190 | DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { |
| 191 | .dynticks_nesting = 1, |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 192 | .dynticks = ATOMIC_INIT(1), |
Paul E. McKenney | 90a4d2c | 2009-01-04 11:41:11 -0800 | [diff] [blame] | 193 | }; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 194 | #endif /* #ifdef CONFIG_NO_HZ */ |
| 195 | |
| 196 | static int blimit = 10; /* Maximum callbacks per softirq. */ |
| 197 | static int qhimark = 10000; /* If this many pending, ignore blimit. */ |
| 198 | static int qlowmark = 100; /* Once only this many pending, use blimit. */ |
| 199 | |
Paul E. McKenney | 3d76c08 | 2009-09-28 07:46:32 -0700 | [diff] [blame] | 200 | module_param(blimit, int, 0); |
| 201 | module_param(qhimark, int, 0); |
| 202 | module_param(qlowmark, int, 0); |
| 203 | |
Paul E. McKenney | a00e0d71 | 2011-02-08 17:14:39 -0800 | [diff] [blame] | 204 | int rcu_cpu_stall_suppress __read_mostly; |
Paul E. McKenney | f2e0dd7 | 2010-07-14 14:38:30 -0700 | [diff] [blame] | 205 | module_param(rcu_cpu_stall_suppress, int, 0644); |
Paul E. McKenney | 742734e | 2010-06-30 11:43:52 -0700 | [diff] [blame] | 206 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 207 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed); |
Paul E. McKenney | a157229 | 2009-08-22 13:56:51 -0700 | [diff] [blame] | 208 | static int rcu_pending(int cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 209 | |
| 210 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 211 | * 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] | 212 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 213 | long rcu_batches_completed_sched(void) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 214 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 215 | return rcu_sched_state.completed; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 216 | } |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 217 | EXPORT_SYMBOL_GPL(rcu_batches_completed_sched); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 218 | |
| 219 | /* |
| 220 | * Return the number of RCU BH batches processed thus far for debug & stats. |
| 221 | */ |
| 222 | long rcu_batches_completed_bh(void) |
| 223 | { |
| 224 | return rcu_bh_state.completed; |
| 225 | } |
| 226 | EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); |
| 227 | |
| 228 | /* |
Paul E. McKenney | bf66f18 | 2010-01-04 15:09:10 -0800 | [diff] [blame] | 229 | * Force a quiescent state for RCU BH. |
| 230 | */ |
| 231 | void rcu_bh_force_quiescent_state(void) |
| 232 | { |
| 233 | force_quiescent_state(&rcu_bh_state, 0); |
| 234 | } |
| 235 | EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state); |
| 236 | |
| 237 | /* |
Paul E. McKenney | 4a29865 | 2011-04-03 21:33:51 -0700 | [diff] [blame] | 238 | * Record the number of times rcutorture tests have been initiated and |
| 239 | * terminated. This information allows the debugfs tracing stats to be |
| 240 | * correlated to the rcutorture messages, even when the rcutorture module |
| 241 | * is being repeatedly loaded and unloaded. In other words, we cannot |
| 242 | * store this state in rcutorture itself. |
| 243 | */ |
| 244 | void rcutorture_record_test_transition(void) |
| 245 | { |
| 246 | rcutorture_testseq++; |
| 247 | rcutorture_vernum = 0; |
| 248 | } |
| 249 | EXPORT_SYMBOL_GPL(rcutorture_record_test_transition); |
| 250 | |
| 251 | /* |
| 252 | * Record the number of writer passes through the current rcutorture test. |
| 253 | * This is also used to correlate debugfs tracing stats with the rcutorture |
| 254 | * messages. |
| 255 | */ |
| 256 | void rcutorture_record_progress(unsigned long vernum) |
| 257 | { |
| 258 | rcutorture_vernum++; |
| 259 | } |
| 260 | EXPORT_SYMBOL_GPL(rcutorture_record_progress); |
| 261 | |
| 262 | /* |
Paul E. McKenney | bf66f18 | 2010-01-04 15:09:10 -0800 | [diff] [blame] | 263 | * Force a quiescent state for RCU-sched. |
| 264 | */ |
| 265 | void rcu_sched_force_quiescent_state(void) |
| 266 | { |
| 267 | force_quiescent_state(&rcu_sched_state, 0); |
| 268 | } |
| 269 | EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state); |
| 270 | |
| 271 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 272 | * Does the CPU have callbacks ready to be invoked? |
| 273 | */ |
| 274 | static int |
| 275 | cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp) |
| 276 | { |
| 277 | return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]; |
| 278 | } |
| 279 | |
| 280 | /* |
| 281 | * Does the current CPU require a yet-as-unscheduled grace period? |
| 282 | */ |
| 283 | static int |
| 284 | cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp) |
| 285 | { |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 286 | return *rdp->nxttail[RCU_DONE_TAIL] && !rcu_gp_in_progress(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 287 | } |
| 288 | |
| 289 | /* |
| 290 | * Return the root node of the specified rcu_state structure. |
| 291 | */ |
| 292 | static struct rcu_node *rcu_get_root(struct rcu_state *rsp) |
| 293 | { |
| 294 | return &rsp->node[0]; |
| 295 | } |
| 296 | |
| 297 | #ifdef CONFIG_SMP |
| 298 | |
| 299 | /* |
| 300 | * If the specified CPU is offline, tell the caller that it is in |
| 301 | * a quiescent state. Otherwise, whack it with a reschedule IPI. |
| 302 | * Grace periods can end up waiting on an offline CPU when that |
| 303 | * CPU is in the process of coming online -- it will be added to the |
| 304 | * rcu_node bitmasks before it actually makes it online. The same thing |
| 305 | * can happen while a CPU is in the process of coming online. Because this |
| 306 | * race is quite rare, we check for it after detecting that the grace |
| 307 | * period has been delayed rather than checking each and every CPU |
| 308 | * each and every time we start a new grace period. |
| 309 | */ |
| 310 | static int rcu_implicit_offline_qs(struct rcu_data *rdp) |
| 311 | { |
| 312 | /* |
| 313 | * If the CPU is offline, it is in a quiescent state. We can |
| 314 | * trust its state not to change because interrupts are disabled. |
| 315 | */ |
| 316 | if (cpu_is_offline(rdp->cpu)) { |
| 317 | rdp->offline_fqs++; |
| 318 | return 1; |
| 319 | } |
| 320 | |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 321 | /* If preemptible RCU, no point in sending reschedule IPI. */ |
| 322 | if (rdp->preemptible) |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 323 | return 0; |
| 324 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 325 | /* The CPU is online, so send it a reschedule IPI. */ |
| 326 | if (rdp->cpu != smp_processor_id()) |
| 327 | smp_send_reschedule(rdp->cpu); |
| 328 | else |
| 329 | set_need_resched(); |
| 330 | rdp->resched_ipi++; |
| 331 | return 0; |
| 332 | } |
| 333 | |
| 334 | #endif /* #ifdef CONFIG_SMP */ |
| 335 | |
| 336 | #ifdef CONFIG_NO_HZ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 337 | |
| 338 | /** |
| 339 | * rcu_enter_nohz - inform RCU that current CPU is entering nohz |
| 340 | * |
| 341 | * Enter nohz mode, in other words, -leave- the mode in which RCU |
| 342 | * read-side critical sections can occur. (Though RCU read-side |
| 343 | * critical sections can occur in irq handlers in nohz mode, a possibility |
| 344 | * handled by rcu_irq_enter() and rcu_irq_exit()). |
| 345 | */ |
| 346 | void rcu_enter_nohz(void) |
| 347 | { |
| 348 | unsigned long flags; |
| 349 | struct rcu_dynticks *rdtp; |
| 350 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 351 | local_irq_save(flags); |
| 352 | rdtp = &__get_cpu_var(rcu_dynticks); |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 353 | if (--rdtp->dynticks_nesting) { |
| 354 | local_irq_restore(flags); |
| 355 | return; |
| 356 | } |
| 357 | /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ |
| 358 | smp_mb__before_atomic_inc(); /* See above. */ |
| 359 | atomic_inc(&rdtp->dynticks); |
| 360 | smp_mb__after_atomic_inc(); /* Force ordering with next sojourn. */ |
| 361 | WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 362 | local_irq_restore(flags); |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 363 | |
| 364 | /* If the interrupt queued a callback, get out of dyntick mode. */ |
| 365 | if (in_irq() && |
| 366 | (__get_cpu_var(rcu_sched_data).nxtlist || |
| 367 | __get_cpu_var(rcu_bh_data).nxtlist || |
| 368 | rcu_preempt_needs_cpu(smp_processor_id()))) |
| 369 | set_need_resched(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 370 | } |
| 371 | |
| 372 | /* |
| 373 | * rcu_exit_nohz - inform RCU that current CPU is leaving nohz |
| 374 | * |
| 375 | * Exit nohz mode, in other words, -enter- the mode in which RCU |
| 376 | * read-side critical sections normally occur. |
| 377 | */ |
| 378 | void rcu_exit_nohz(void) |
| 379 | { |
| 380 | unsigned long flags; |
| 381 | struct rcu_dynticks *rdtp; |
| 382 | |
| 383 | local_irq_save(flags); |
| 384 | rdtp = &__get_cpu_var(rcu_dynticks); |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 385 | if (rdtp->dynticks_nesting++) { |
| 386 | local_irq_restore(flags); |
| 387 | return; |
| 388 | } |
| 389 | smp_mb__before_atomic_inc(); /* Force ordering w/previous sojourn. */ |
| 390 | atomic_inc(&rdtp->dynticks); |
| 391 | /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ |
| 392 | smp_mb__after_atomic_inc(); /* See above. */ |
| 393 | WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 394 | local_irq_restore(flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 395 | } |
| 396 | |
| 397 | /** |
| 398 | * rcu_nmi_enter - inform RCU of entry to NMI context |
| 399 | * |
| 400 | * If the CPU was idle with dynamic ticks active, and there is no |
| 401 | * irq handler running, this updates rdtp->dynticks_nmi to let the |
| 402 | * RCU grace-period handling know that the CPU is active. |
| 403 | */ |
| 404 | void rcu_nmi_enter(void) |
| 405 | { |
| 406 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 407 | |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 408 | if (rdtp->dynticks_nmi_nesting == 0 && |
| 409 | (atomic_read(&rdtp->dynticks) & 0x1)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 410 | return; |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 411 | rdtp->dynticks_nmi_nesting++; |
| 412 | smp_mb__before_atomic_inc(); /* Force delay from prior write. */ |
| 413 | atomic_inc(&rdtp->dynticks); |
| 414 | /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ |
| 415 | smp_mb__after_atomic_inc(); /* See above. */ |
| 416 | WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 417 | } |
| 418 | |
| 419 | /** |
| 420 | * rcu_nmi_exit - inform RCU of exit from NMI context |
| 421 | * |
| 422 | * If the CPU was idle with dynamic ticks active, and there is no |
| 423 | * irq handler running, this updates rdtp->dynticks_nmi to let the |
| 424 | * RCU grace-period handling know that the CPU is no longer active. |
| 425 | */ |
| 426 | void rcu_nmi_exit(void) |
| 427 | { |
| 428 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 429 | |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 430 | if (rdtp->dynticks_nmi_nesting == 0 || |
| 431 | --rdtp->dynticks_nmi_nesting != 0) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 432 | return; |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 433 | /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ |
| 434 | smp_mb__before_atomic_inc(); /* See above. */ |
| 435 | atomic_inc(&rdtp->dynticks); |
| 436 | smp_mb__after_atomic_inc(); /* Force delay to next write. */ |
| 437 | WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 438 | } |
| 439 | |
| 440 | /** |
| 441 | * rcu_irq_enter - inform RCU of entry to hard irq context |
| 442 | * |
| 443 | * If the CPU was idle with dynamic ticks active, this updates the |
| 444 | * rdtp->dynticks to let the RCU handling know that the CPU is active. |
| 445 | */ |
| 446 | void rcu_irq_enter(void) |
| 447 | { |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 448 | rcu_exit_nohz(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 449 | } |
| 450 | |
| 451 | /** |
| 452 | * rcu_irq_exit - inform RCU of exit from hard irq context |
| 453 | * |
| 454 | * If the CPU was idle with dynamic ticks active, update the rdp->dynticks |
| 455 | * to put let the RCU handling be aware that the CPU is going back to idle |
| 456 | * with no ticks. |
| 457 | */ |
| 458 | void rcu_irq_exit(void) |
| 459 | { |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 460 | rcu_enter_nohz(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 461 | } |
| 462 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 463 | #ifdef CONFIG_SMP |
| 464 | |
| 465 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 466 | * Snapshot the specified CPU's dynticks counter so that we can later |
| 467 | * 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] | 468 | * is in dynticks idle mode, which is an extended quiescent state. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 469 | */ |
| 470 | static int dyntick_save_progress_counter(struct rcu_data *rdp) |
| 471 | { |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 472 | rdp->dynticks_snap = atomic_add_return(0, &rdp->dynticks->dynticks); |
| 473 | return 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 474 | } |
| 475 | |
| 476 | /* |
| 477 | * Return true if the specified CPU has passed through a quiescent |
| 478 | * state by virtue of being in or having passed through an dynticks |
| 479 | * idle state since the last call to dyntick_save_progress_counter() |
| 480 | * for this same CPU. |
| 481 | */ |
| 482 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) |
| 483 | { |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 484 | unsigned long curr; |
| 485 | unsigned long snap; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 486 | |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 487 | curr = (unsigned long)atomic_add_return(0, &rdp->dynticks->dynticks); |
| 488 | snap = (unsigned long)rdp->dynticks_snap; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 489 | |
| 490 | /* |
| 491 | * If the CPU passed through or entered a dynticks idle phase with |
| 492 | * no active irq/NMI handlers, then we can safely pretend that the CPU |
| 493 | * already acknowledged the request to pass through a quiescent |
| 494 | * state. Either way, that CPU cannot possibly be in an RCU |
| 495 | * read-side critical section that started before the beginning |
| 496 | * of the current RCU grace period. |
| 497 | */ |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 498 | if ((curr & 0x1) == 0 || ULONG_CMP_GE(curr, snap + 2)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 499 | rdp->dynticks_fqs++; |
| 500 | return 1; |
| 501 | } |
| 502 | |
| 503 | /* Go check for the CPU being offline. */ |
| 504 | return rcu_implicit_offline_qs(rdp); |
| 505 | } |
| 506 | |
| 507 | #endif /* #ifdef CONFIG_SMP */ |
| 508 | |
| 509 | #else /* #ifdef CONFIG_NO_HZ */ |
| 510 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 511 | #ifdef CONFIG_SMP |
| 512 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 513 | static int dyntick_save_progress_counter(struct rcu_data *rdp) |
| 514 | { |
| 515 | return 0; |
| 516 | } |
| 517 | |
| 518 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) |
| 519 | { |
| 520 | return rcu_implicit_offline_qs(rdp); |
| 521 | } |
| 522 | |
| 523 | #endif /* #ifdef CONFIG_SMP */ |
| 524 | |
| 525 | #endif /* #else #ifdef CONFIG_NO_HZ */ |
| 526 | |
Paul E. McKenney | 742734e | 2010-06-30 11:43:52 -0700 | [diff] [blame] | 527 | int rcu_cpu_stall_suppress __read_mostly; |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 528 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 529 | static void record_gp_stall_check_time(struct rcu_state *rsp) |
| 530 | { |
| 531 | rsp->gp_start = jiffies; |
| 532 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_CHECK; |
| 533 | } |
| 534 | |
| 535 | static void print_other_cpu_stall(struct rcu_state *rsp) |
| 536 | { |
| 537 | int cpu; |
| 538 | long delta; |
| 539 | unsigned long flags; |
| 540 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 541 | |
| 542 | /* Only let one CPU complain about others per time interval. */ |
| 543 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 544 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 545 | delta = jiffies - rsp->jiffies_stall; |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 546 | if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 547 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 548 | return; |
| 549 | } |
| 550 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_RECHECK; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 551 | |
| 552 | /* |
| 553 | * Now rat on any tasks that got kicked up to the root rcu_node |
| 554 | * due to CPU offlining. |
| 555 | */ |
| 556 | rcu_print_task_stall(rnp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 557 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 558 | |
Paul E. McKenney | 8cdd32a | 2010-08-09 14:23:03 -0700 | [diff] [blame] | 559 | /* |
| 560 | * OK, time to rat on our buddy... |
| 561 | * See Documentation/RCU/stallwarn.txt for info on how to debug |
| 562 | * RCU CPU stall warnings. |
| 563 | */ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 564 | printk(KERN_ERR "INFO: %s detected stalls on CPUs/tasks: {", |
| 565 | rsp->name); |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 566 | rcu_for_each_leaf_node(rsp, rnp) { |
Paul E. McKenney | 3acd9eb | 2010-02-22 17:05:03 -0800 | [diff] [blame] | 567 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 568 | rcu_print_task_stall(rnp); |
Paul E. McKenney | 3acd9eb | 2010-02-22 17:05:03 -0800 | [diff] [blame] | 569 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 570 | if (rnp->qsmask == 0) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 571 | continue; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 572 | for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++) |
| 573 | if (rnp->qsmask & (1UL << cpu)) |
| 574 | printk(" %d", rnp->grplo + cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 575 | } |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 576 | printk("} (detected by %d, t=%ld jiffies)\n", |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 577 | smp_processor_id(), (long)(jiffies - rsp->gp_start)); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 578 | trigger_all_cpu_backtrace(); |
| 579 | |
Paul E. McKenney | 1ed509a | 2010-02-22 17:05:05 -0800 | [diff] [blame] | 580 | /* If so configured, complain about tasks blocking the grace period. */ |
| 581 | |
| 582 | rcu_print_detail_task_stall(rsp); |
| 583 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 584 | force_quiescent_state(rsp, 0); /* Kick them all. */ |
| 585 | } |
| 586 | |
| 587 | static void print_cpu_stall(struct rcu_state *rsp) |
| 588 | { |
| 589 | unsigned long flags; |
| 590 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 591 | |
Paul E. McKenney | 8cdd32a | 2010-08-09 14:23:03 -0700 | [diff] [blame] | 592 | /* |
| 593 | * OK, time to rat on ourselves... |
| 594 | * See Documentation/RCU/stallwarn.txt for info on how to debug |
| 595 | * RCU CPU stall warnings. |
| 596 | */ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 597 | printk(KERN_ERR "INFO: %s detected stall on CPU %d (t=%lu jiffies)\n", |
| 598 | rsp->name, smp_processor_id(), jiffies - rsp->gp_start); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 599 | trigger_all_cpu_backtrace(); |
| 600 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 601 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 602 | if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 603 | rsp->jiffies_stall = |
| 604 | jiffies + RCU_SECONDS_TILL_STALL_RECHECK; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 605 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 606 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 607 | set_need_resched(); /* kick ourselves to get things going. */ |
| 608 | } |
| 609 | |
| 610 | static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) |
| 611 | { |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 612 | unsigned long j; |
| 613 | unsigned long js; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 614 | struct rcu_node *rnp; |
| 615 | |
Paul E. McKenney | 742734e | 2010-06-30 11:43:52 -0700 | [diff] [blame] | 616 | if (rcu_cpu_stall_suppress) |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 617 | return; |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 618 | j = ACCESS_ONCE(jiffies); |
| 619 | js = ACCESS_ONCE(rsp->jiffies_stall); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 620 | rnp = rdp->mynode; |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 621 | if ((ACCESS_ONCE(rnp->qsmask) & rdp->grpmask) && ULONG_CMP_GE(j, js)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 622 | |
| 623 | /* We haven't checked in, so go dump stack. */ |
| 624 | print_cpu_stall(rsp); |
| 625 | |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 626 | } else if (rcu_gp_in_progress(rsp) && |
| 627 | ULONG_CMP_GE(j, js + RCU_STALL_RAT_DELAY)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 628 | |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 629 | /* They had a few time units to dump stack, so complain. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 630 | print_other_cpu_stall(rsp); |
| 631 | } |
| 632 | } |
| 633 | |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 634 | static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr) |
| 635 | { |
Paul E. McKenney | 742734e | 2010-06-30 11:43:52 -0700 | [diff] [blame] | 636 | rcu_cpu_stall_suppress = 1; |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 637 | return NOTIFY_DONE; |
| 638 | } |
| 639 | |
Paul E. McKenney | 53d84e0 | 2010-08-10 14:28:53 -0700 | [diff] [blame] | 640 | /** |
| 641 | * rcu_cpu_stall_reset - prevent further stall warnings in current grace period |
| 642 | * |
| 643 | * Set the stall-warning timeout way off into the future, thus preventing |
| 644 | * any RCU CPU stall-warning messages from appearing in the current set of |
| 645 | * RCU grace periods. |
| 646 | * |
| 647 | * The caller must disable hard irqs. |
| 648 | */ |
| 649 | void rcu_cpu_stall_reset(void) |
| 650 | { |
| 651 | rcu_sched_state.jiffies_stall = jiffies + ULONG_MAX / 2; |
| 652 | rcu_bh_state.jiffies_stall = jiffies + ULONG_MAX / 2; |
| 653 | rcu_preempt_stall_reset(); |
| 654 | } |
| 655 | |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 656 | static struct notifier_block rcu_panic_block = { |
| 657 | .notifier_call = rcu_panic, |
| 658 | }; |
| 659 | |
| 660 | static void __init check_cpu_stall_init(void) |
| 661 | { |
| 662 | atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block); |
| 663 | } |
| 664 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 665 | /* |
| 666 | * Update CPU-local rcu_data state to record the newly noticed grace period. |
| 667 | * 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] | 668 | * that someone else started the grace period. The caller must hold the |
| 669 | * ->lock of the leaf rcu_node structure corresponding to the current CPU, |
| 670 | * and must have irqs disabled. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 671 | */ |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 672 | static void __note_new_gpnum(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
| 673 | { |
| 674 | if (rdp->gpnum != rnp->gpnum) { |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 675 | /* |
| 676 | * If the current grace period is waiting for this CPU, |
| 677 | * set up to detect a quiescent state, otherwise don't |
| 678 | * go looking for one. |
| 679 | */ |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 680 | rdp->gpnum = rnp->gpnum; |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 681 | if (rnp->qsmask & rdp->grpmask) { |
| 682 | rdp->qs_pending = 1; |
| 683 | rdp->passed_quiesc = 0; |
| 684 | } else |
| 685 | rdp->qs_pending = 0; |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 686 | } |
| 687 | } |
| 688 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 689 | static void note_new_gpnum(struct rcu_state *rsp, struct rcu_data *rdp) |
| 690 | { |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 691 | unsigned long flags; |
| 692 | struct rcu_node *rnp; |
| 693 | |
| 694 | local_irq_save(flags); |
| 695 | rnp = rdp->mynode; |
| 696 | if (rdp->gpnum == ACCESS_ONCE(rnp->gpnum) || /* outside lock. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 697 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 698 | local_irq_restore(flags); |
| 699 | return; |
| 700 | } |
| 701 | __note_new_gpnum(rsp, rnp, rdp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 702 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 703 | } |
| 704 | |
| 705 | /* |
| 706 | * Did someone else start a new RCU grace period start since we last |
| 707 | * checked? Update local state appropriately if so. Must be called |
| 708 | * on the CPU corresponding to rdp. |
| 709 | */ |
| 710 | static int |
| 711 | check_for_new_grace_period(struct rcu_state *rsp, struct rcu_data *rdp) |
| 712 | { |
| 713 | unsigned long flags; |
| 714 | int ret = 0; |
| 715 | |
| 716 | local_irq_save(flags); |
| 717 | if (rdp->gpnum != rsp->gpnum) { |
| 718 | note_new_gpnum(rsp, rdp); |
| 719 | ret = 1; |
| 720 | } |
| 721 | local_irq_restore(flags); |
| 722 | return ret; |
| 723 | } |
| 724 | |
| 725 | /* |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 726 | * Advance this CPU's callbacks, but only if the current grace period |
| 727 | * has ended. This may be called only from the CPU to whom the rdp |
| 728 | * belongs. In addition, the corresponding leaf rcu_node structure's |
| 729 | * ->lock must be held by the caller, with irqs disabled. |
| 730 | */ |
| 731 | static void |
| 732 | __rcu_process_gp_end(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
| 733 | { |
| 734 | /* Did another grace period end? */ |
| 735 | if (rdp->completed != rnp->completed) { |
| 736 | |
| 737 | /* Advance callbacks. No harm if list empty. */ |
| 738 | rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL]; |
| 739 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL]; |
| 740 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 741 | |
| 742 | /* Remember that we saw this grace-period completion. */ |
| 743 | rdp->completed = rnp->completed; |
Frederic Weisbecker | 20377f3 | 2010-12-10 22:11:10 +0100 | [diff] [blame] | 744 | |
| 745 | /* |
Frederic Weisbecker | 5ff8e6f | 2010-12-10 22:11:11 +0100 | [diff] [blame] | 746 | * If we were in an extended quiescent state, we may have |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 747 | * missed some grace periods that others CPUs handled on |
Frederic Weisbecker | 5ff8e6f | 2010-12-10 22:11:11 +0100 | [diff] [blame] | 748 | * our behalf. Catch up with this state to avoid noting |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 749 | * spurious new grace periods. If another grace period |
| 750 | * has started, then rnp->gpnum will have advanced, so |
| 751 | * we will detect this later on. |
Frederic Weisbecker | 5ff8e6f | 2010-12-10 22:11:11 +0100 | [diff] [blame] | 752 | */ |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 753 | if (ULONG_CMP_LT(rdp->gpnum, rdp->completed)) |
Frederic Weisbecker | 5ff8e6f | 2010-12-10 22:11:11 +0100 | [diff] [blame] | 754 | rdp->gpnum = rdp->completed; |
| 755 | |
| 756 | /* |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 757 | * If RCU does not need a quiescent state from this CPU, |
| 758 | * then make sure that this CPU doesn't go looking for one. |
Frederic Weisbecker | 20377f3 | 2010-12-10 22:11:10 +0100 | [diff] [blame] | 759 | */ |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 760 | if ((rnp->qsmask & rdp->grpmask) == 0) |
Frederic Weisbecker | 20377f3 | 2010-12-10 22:11:10 +0100 | [diff] [blame] | 761 | rdp->qs_pending = 0; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 762 | } |
| 763 | } |
| 764 | |
| 765 | /* |
| 766 | * Advance this CPU's callbacks, but only if the current grace period |
| 767 | * has ended. This may be called only from the CPU to whom the rdp |
| 768 | * belongs. |
| 769 | */ |
| 770 | static void |
| 771 | rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp) |
| 772 | { |
| 773 | unsigned long flags; |
| 774 | struct rcu_node *rnp; |
| 775 | |
| 776 | local_irq_save(flags); |
| 777 | rnp = rdp->mynode; |
| 778 | if (rdp->completed == ACCESS_ONCE(rnp->completed) || /* outside lock. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 779 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 780 | local_irq_restore(flags); |
| 781 | return; |
| 782 | } |
| 783 | __rcu_process_gp_end(rsp, rnp, rdp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 784 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 785 | } |
| 786 | |
| 787 | /* |
| 788 | * Do per-CPU grace-period initialization for running CPU. The caller |
| 789 | * must hold the lock of the leaf rcu_node structure corresponding to |
| 790 | * this CPU. |
| 791 | */ |
| 792 | static void |
| 793 | rcu_start_gp_per_cpu(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
| 794 | { |
| 795 | /* Prior grace period ended, so advance callbacks for current CPU. */ |
| 796 | __rcu_process_gp_end(rsp, rnp, rdp); |
| 797 | |
| 798 | /* |
| 799 | * Because this CPU just now started the new grace period, we know |
| 800 | * that all of its callbacks will be covered by this upcoming grace |
| 801 | * period, even the ones that were registered arbitrarily recently. |
| 802 | * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL. |
| 803 | * |
| 804 | * Other CPUs cannot be sure exactly when the grace period started. |
| 805 | * Therefore, their recently registered callbacks must pass through |
| 806 | * an additional RCU_NEXT_READY stage, so that they will be handled |
| 807 | * by the next RCU grace period. |
| 808 | */ |
| 809 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 810 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 811 | |
| 812 | /* Set state so that this CPU will detect the next quiescent state. */ |
| 813 | __note_new_gpnum(rsp, rnp, rdp); |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 814 | } |
| 815 | |
| 816 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 817 | * Start a new RCU grace period if warranted, re-initializing the hierarchy |
| 818 | * in preparation for detecting the next grace period. The caller must hold |
| 819 | * the root node's ->lock, which is released before return. Hard irqs must |
| 820 | * be disabled. |
| 821 | */ |
| 822 | static void |
| 823 | rcu_start_gp(struct rcu_state *rsp, unsigned long flags) |
| 824 | __releases(rcu_get_root(rsp)->lock) |
| 825 | { |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 826 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 827 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 828 | |
Paul E. McKenney | 07079d5 | 2010-01-04 15:09:02 -0800 | [diff] [blame] | 829 | if (!cpu_needs_another_gp(rsp, rdp) || rsp->fqs_active) { |
Paul E. McKenney | 46a1e34 | 2010-01-04 15:09:09 -0800 | [diff] [blame] | 830 | if (cpu_needs_another_gp(rsp, rdp)) |
| 831 | rsp->fqs_need_gp = 1; |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 832 | if (rnp->completed == rsp->completed) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 833 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 834 | return; |
| 835 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 836 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 837 | |
| 838 | /* |
| 839 | * Propagate new ->completed value to rcu_node structures |
| 840 | * so that other CPUs don't have to wait until the start |
| 841 | * of the next grace period to process their callbacks. |
| 842 | */ |
| 843 | rcu_for_each_node_breadth_first(rsp, rnp) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 844 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 845 | rnp->completed = rsp->completed; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 846 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 847 | } |
| 848 | local_irq_restore(flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 849 | return; |
| 850 | } |
| 851 | |
| 852 | /* Advance to a new grace period and initialize state. */ |
| 853 | rsp->gpnum++; |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 854 | WARN_ON_ONCE(rsp->signaled == RCU_GP_INIT); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 855 | rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */ |
| 856 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 857 | record_gp_stall_check_time(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 858 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 859 | /* Special-case the common single-level case. */ |
| 860 | if (NUM_RCU_NODES == 1) { |
Paul E. McKenney | b0e165c | 2009-09-13 09:15:09 -0700 | [diff] [blame] | 861 | rcu_preempt_check_blocked_tasks(rnp); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 862 | rnp->qsmask = rnp->qsmaskinit; |
Paul E. McKenney | de078d8 | 2009-09-08 15:54:36 -0700 | [diff] [blame] | 863 | rnp->gpnum = rsp->gpnum; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 864 | rnp->completed = rsp->completed; |
Paul E. McKenney | c12172c | 2009-01-04 20:30:06 -0800 | [diff] [blame] | 865 | rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state OK. */ |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 866 | rcu_start_gp_per_cpu(rsp, rnp, rdp); |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 867 | rcu_preempt_boost_start_gp(rnp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 868 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 869 | return; |
| 870 | } |
| 871 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 872 | raw_spin_unlock(&rnp->lock); /* leave irqs disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 873 | |
| 874 | |
| 875 | /* Exclude any concurrent CPU-hotplug operations. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 876 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 877 | |
| 878 | /* |
Paul E. McKenney | b835db1 | 2009-09-08 15:54:37 -0700 | [diff] [blame] | 879 | * Set the quiescent-state-needed bits in all the rcu_node |
| 880 | * structures for all currently online CPUs in breadth-first |
| 881 | * order, starting from the root rcu_node structure. This |
| 882 | * operation relies on the layout of the hierarchy within the |
| 883 | * rsp->node[] array. Note that other CPUs will access only |
| 884 | * the leaves of the hierarchy, which still indicate that no |
| 885 | * grace period is in progress, at least until the corresponding |
| 886 | * leaf node has been initialized. In addition, we have excluded |
| 887 | * CPU-hotplug operations. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 888 | * |
| 889 | * Note that the grace period cannot complete until we finish |
| 890 | * the initialization process, as there will be at least one |
| 891 | * 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] | 892 | * one corresponding to this CPU, due to the fact that we have |
| 893 | * irqs disabled. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 894 | */ |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 895 | rcu_for_each_node_breadth_first(rsp, rnp) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 896 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | b0e165c | 2009-09-13 09:15:09 -0700 | [diff] [blame] | 897 | rcu_preempt_check_blocked_tasks(rnp); |
Paul E. McKenney | 49e2912 | 2009-09-18 09:50:19 -0700 | [diff] [blame] | 898 | rnp->qsmask = rnp->qsmaskinit; |
Paul E. McKenney | de078d8 | 2009-09-08 15:54:36 -0700 | [diff] [blame] | 899 | rnp->gpnum = rsp->gpnum; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 900 | rnp->completed = rsp->completed; |
| 901 | if (rnp == rdp->mynode) |
| 902 | rcu_start_gp_per_cpu(rsp, rnp, rdp); |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 903 | rcu_preempt_boost_start_gp(rnp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 904 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 905 | } |
| 906 | |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 907 | rnp = rcu_get_root(rsp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 908 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 909 | rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state now OK. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 910 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
| 911 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 912 | } |
| 913 | |
| 914 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 915 | * Report a full set of quiescent states to the specified rcu_state |
| 916 | * data structure. This involves cleaning up after the prior grace |
| 917 | * period and letting rcu_start_gp() start up the next grace period |
| 918 | * if one is needed. Note that the caller must hold rnp->lock, as |
| 919 | * required by rcu_start_gp(), which will release it. |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 920 | */ |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 921 | static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags) |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 922 | __releases(rcu_get_root(rsp)->lock) |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 923 | { |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 924 | unsigned long gp_duration; |
| 925 | |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 926 | WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); |
Paul E. McKenney | 0bbcc52 | 2011-05-16 02:24:04 -0700 | [diff] [blame] | 927 | |
| 928 | /* |
| 929 | * Ensure that all grace-period and pre-grace-period activity |
| 930 | * is seen before the assignment to rsp->completed. |
| 931 | */ |
| 932 | smp_mb(); /* See above block comment. */ |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 933 | gp_duration = jiffies - rsp->gp_start; |
| 934 | if (gp_duration > rsp->gp_max) |
| 935 | rsp->gp_max = gp_duration; |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 936 | rsp->completed = rsp->gpnum; |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 937 | rsp->signaled = RCU_GP_IDLE; |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 938 | rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */ |
| 939 | } |
| 940 | |
| 941 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 942 | * Similar to rcu_report_qs_rdp(), for which it is a helper function. |
| 943 | * Allows quiescent states for a group of CPUs to be reported at one go |
| 944 | * to the specified rcu_node structure, though all the CPUs in the group |
| 945 | * must be represented by the same rcu_node structure (which need not be |
| 946 | * a leaf rcu_node structure, though it often will be). That structure's |
| 947 | * 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] | 948 | */ |
| 949 | static void |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 950 | rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp, |
| 951 | struct rcu_node *rnp, unsigned long flags) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 952 | __releases(rnp->lock) |
| 953 | { |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 954 | struct rcu_node *rnp_c; |
| 955 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 956 | /* Walk up the rcu_node hierarchy. */ |
| 957 | for (;;) { |
| 958 | if (!(rnp->qsmask & mask)) { |
| 959 | |
| 960 | /* Our bit has already been cleared, so done. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 961 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 962 | return; |
| 963 | } |
| 964 | rnp->qsmask &= ~mask; |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 965 | if (rnp->qsmask != 0 || rcu_preempt_blocked_readers_cgp(rnp)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 966 | |
| 967 | /* Other bits still set at this level, so done. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 968 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 969 | return; |
| 970 | } |
| 971 | mask = rnp->grpmask; |
| 972 | if (rnp->parent == NULL) { |
| 973 | |
| 974 | /* No more levels. Exit loop holding root lock. */ |
| 975 | |
| 976 | break; |
| 977 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 978 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 979 | rnp_c = rnp; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 980 | rnp = rnp->parent; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 981 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 982 | WARN_ON_ONCE(rnp_c->qsmask); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 983 | } |
| 984 | |
| 985 | /* |
| 986 | * 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] | 987 | * state for this grace period. Invoke rcu_report_qs_rsp() |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 988 | * 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] | 989 | */ |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 990 | rcu_report_qs_rsp(rsp, flags); /* releases rnp->lock. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 991 | } |
| 992 | |
| 993 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 994 | * Record a quiescent state for the specified CPU to that CPU's rcu_data |
| 995 | * structure. This must be either called from the specified CPU, or |
| 996 | * called when the specified CPU is known to be offline (and when it is |
| 997 | * also known that no other CPU is concurrently trying to help the offline |
| 998 | * CPU). The lastcomp argument is used to make sure we are still in the |
| 999 | * grace period of interest. We don't want to end the current grace period |
| 1000 | * based on quiescent states detected in an earlier grace period! |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1001 | */ |
| 1002 | static void |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1003 | 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] | 1004 | { |
| 1005 | unsigned long flags; |
| 1006 | unsigned long mask; |
| 1007 | struct rcu_node *rnp; |
| 1008 | |
| 1009 | rnp = rdp->mynode; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1010 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 560d4bc | 2009-11-13 19:51:38 -0800 | [diff] [blame] | 1011 | if (lastcomp != rnp->completed) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1012 | |
| 1013 | /* |
| 1014 | * Someone beat us to it for this grace period, so leave. |
| 1015 | * The race with GP start is resolved by the fact that we |
| 1016 | * hold the leaf rcu_node lock, so that the per-CPU bits |
| 1017 | * cannot yet be initialized -- so we would simply find our |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1018 | * CPU's bit already cleared in rcu_report_qs_rnp() if this |
| 1019 | * race occurred. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1020 | */ |
| 1021 | rdp->passed_quiesc = 0; /* try again later! */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1022 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1023 | return; |
| 1024 | } |
| 1025 | mask = rdp->grpmask; |
| 1026 | if ((rnp->qsmask & mask) == 0) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1027 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1028 | } else { |
| 1029 | rdp->qs_pending = 0; |
| 1030 | |
| 1031 | /* |
| 1032 | * This GP can't end until cpu checks in, so all of our |
| 1033 | * callbacks can be processed during the next GP. |
| 1034 | */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1035 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 1036 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1037 | rcu_report_qs_rnp(mask, rsp, rnp, flags); /* rlses rnp->lock */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1038 | } |
| 1039 | } |
| 1040 | |
| 1041 | /* |
| 1042 | * Check to see if there is a new grace period of which this CPU |
| 1043 | * is not yet aware, and if so, set up local rcu_data state for it. |
| 1044 | * Otherwise, see if this CPU has just passed through its first |
| 1045 | * quiescent state for this grace period, and record that fact if so. |
| 1046 | */ |
| 1047 | static void |
| 1048 | rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp) |
| 1049 | { |
| 1050 | /* If there is now a new grace period, record and return. */ |
| 1051 | if (check_for_new_grace_period(rsp, rdp)) |
| 1052 | return; |
| 1053 | |
| 1054 | /* |
| 1055 | * Does this CPU still need to do its part for current grace period? |
| 1056 | * If no, return and let the other CPUs do their part as well. |
| 1057 | */ |
| 1058 | if (!rdp->qs_pending) |
| 1059 | return; |
| 1060 | |
| 1061 | /* |
| 1062 | * Was there a quiescent state since the beginning of the grace |
| 1063 | * period? If no, then exit and wait for the next call. |
| 1064 | */ |
| 1065 | if (!rdp->passed_quiesc) |
| 1066 | return; |
| 1067 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1068 | /* |
| 1069 | * Tell RCU we are done (but rcu_report_qs_rdp() will be the |
| 1070 | * judge of that). |
| 1071 | */ |
| 1072 | 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] | 1073 | } |
| 1074 | |
| 1075 | #ifdef CONFIG_HOTPLUG_CPU |
| 1076 | |
| 1077 | /* |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1078 | * Move a dying CPU's RCU callbacks to online CPU's callback list. |
| 1079 | * Synchronization is not required because this function executes |
| 1080 | * in stop_machine() context. |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1081 | */ |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1082 | static void rcu_send_cbs_to_online(struct rcu_state *rsp) |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1083 | { |
| 1084 | int i; |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1085 | /* current DYING CPU is cleared in the cpu_online_mask */ |
| 1086 | int receive_cpu = cpumask_any(cpu_online_mask); |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1087 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1088 | 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] | 1089 | |
| 1090 | if (rdp->nxtlist == NULL) |
| 1091 | return; /* irqs disabled, so comparison is stable. */ |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1092 | |
| 1093 | *receive_rdp->nxttail[RCU_NEXT_TAIL] = rdp->nxtlist; |
| 1094 | receive_rdp->nxttail[RCU_NEXT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 1095 | receive_rdp->qlen += rdp->qlen; |
| 1096 | receive_rdp->n_cbs_adopted += rdp->qlen; |
| 1097 | rdp->n_cbs_orphaned += rdp->qlen; |
| 1098 | |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1099 | rdp->nxtlist = NULL; |
| 1100 | for (i = 0; i < RCU_NEXT_SIZE; i++) |
| 1101 | rdp->nxttail[i] = &rdp->nxtlist; |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1102 | rdp->qlen = 0; |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1103 | } |
| 1104 | |
| 1105 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1106 | * Remove the outgoing CPU from the bitmasks in the rcu_node hierarchy |
| 1107 | * 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] | 1108 | * There can only be one CPU hotplug operation at a time, so no other |
| 1109 | * CPU can be attempting to update rcu_cpu_kthread_task. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1110 | */ |
| 1111 | static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) |
| 1112 | { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1113 | unsigned long flags; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1114 | unsigned long mask; |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1115 | int need_report = 0; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1116 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1117 | struct rcu_node *rnp; |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1118 | |
Paul E. McKenney | f8b7fc6 | 2011-06-16 08:26:32 -0700 | [diff] [blame] | 1119 | rcu_stop_cpu_kthread(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1120 | |
| 1121 | /* Exclude any attempts to start a new grace period. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1122 | raw_spin_lock_irqsave(&rsp->onofflock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1123 | |
| 1124 | /* 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] | 1125 | rnp = rdp->mynode; /* this is the outgoing CPU's rnp. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1126 | mask = rdp->grpmask; /* rnp->grplo is constant. */ |
| 1127 | do { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1128 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1129 | rnp->qsmaskinit &= ~mask; |
| 1130 | if (rnp->qsmaskinit != 0) { |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1131 | if (rnp != rdp->mynode) |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1132 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1133 | break; |
| 1134 | } |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1135 | if (rnp == rdp->mynode) |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1136 | need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp); |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1137 | else |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1138 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1139 | mask = rnp->grpmask; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1140 | rnp = rnp->parent; |
| 1141 | } while (rnp != NULL); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1142 | |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1143 | /* |
| 1144 | * We still hold the leaf rcu_node structure lock here, and |
| 1145 | * irqs are still disabled. The reason for this subterfuge is |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1146 | * because invoking rcu_report_unblock_qs_rnp() with ->onofflock |
| 1147 | * held leads to deadlock. |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1148 | */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1149 | raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1150 | rnp = rdp->mynode; |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1151 | if (need_report & RCU_OFL_TASKS_NORM_GP) |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1152 | rcu_report_unblock_qs_rnp(rnp, flags); |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1153 | else |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1154 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1155 | if (need_report & RCU_OFL_TASKS_EXP_GP) |
| 1156 | rcu_report_exp_rnp(rsp, rnp); |
Paul E. McKenney | 1217ed1 | 2011-05-04 21:43:49 -0700 | [diff] [blame] | 1157 | rcu_node_kthread_setaffinity(rnp, -1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1158 | } |
| 1159 | |
| 1160 | /* |
| 1161 | * Remove the specified CPU from the RCU hierarchy and move any pending |
| 1162 | * callbacks that it might have to the current CPU. This code assumes |
| 1163 | * that at least one CPU in the system will remain running at all times. |
| 1164 | * Any attempt to offline -all- CPUs is likely to strand RCU callbacks. |
| 1165 | */ |
| 1166 | static void rcu_offline_cpu(int cpu) |
| 1167 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1168 | __rcu_offline_cpu(cpu, &rcu_sched_state); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1169 | __rcu_offline_cpu(cpu, &rcu_bh_state); |
Paul E. McKenney | 33f7614 | 2009-08-24 09:42:01 -0700 | [diff] [blame] | 1170 | rcu_preempt_offline_cpu(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1171 | } |
| 1172 | |
| 1173 | #else /* #ifdef CONFIG_HOTPLUG_CPU */ |
| 1174 | |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1175 | static void rcu_send_cbs_to_online(struct rcu_state *rsp) |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1176 | { |
| 1177 | } |
| 1178 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1179 | static void rcu_offline_cpu(int cpu) |
| 1180 | { |
| 1181 | } |
| 1182 | |
| 1183 | #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */ |
| 1184 | |
| 1185 | /* |
| 1186 | * Invoke any RCU callbacks that have made it to the end of their grace |
| 1187 | * period. Thottle as specified by rdp->blimit. |
| 1188 | */ |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1189 | 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] | 1190 | { |
| 1191 | unsigned long flags; |
| 1192 | struct rcu_head *next, *list, **tail; |
| 1193 | int count; |
| 1194 | |
| 1195 | /* If no callbacks are ready, just return.*/ |
| 1196 | if (!cpu_has_callbacks_ready_to_invoke(rdp)) |
| 1197 | return; |
| 1198 | |
| 1199 | /* |
| 1200 | * Extract the list of ready callbacks, disabling to prevent |
| 1201 | * races with call_rcu() from interrupt handlers. |
| 1202 | */ |
| 1203 | local_irq_save(flags); |
| 1204 | list = rdp->nxtlist; |
| 1205 | rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL]; |
| 1206 | *rdp->nxttail[RCU_DONE_TAIL] = NULL; |
| 1207 | tail = rdp->nxttail[RCU_DONE_TAIL]; |
| 1208 | for (count = RCU_NEXT_SIZE - 1; count >= 0; count--) |
| 1209 | if (rdp->nxttail[count] == rdp->nxttail[RCU_DONE_TAIL]) |
| 1210 | rdp->nxttail[count] = &rdp->nxtlist; |
| 1211 | local_irq_restore(flags); |
| 1212 | |
| 1213 | /* Invoke callbacks. */ |
| 1214 | count = 0; |
| 1215 | while (list) { |
| 1216 | next = list->next; |
| 1217 | prefetch(next); |
Mathieu Desnoyers | 551d55a | 2010-04-17 08:48:42 -0400 | [diff] [blame] | 1218 | debug_rcu_head_unqueue(list); |
Lai Jiangshan | 9ab1544 | 2011-03-18 11:15:47 +0800 | [diff] [blame] | 1219 | __rcu_reclaim(list); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1220 | list = next; |
| 1221 | if (++count >= rdp->blimit) |
| 1222 | break; |
| 1223 | } |
| 1224 | |
| 1225 | local_irq_save(flags); |
| 1226 | |
| 1227 | /* Update count, and requeue any remaining callbacks. */ |
| 1228 | rdp->qlen -= count; |
Paul E. McKenney | 269dcc1 | 2010-09-07 14:23:09 -0700 | [diff] [blame] | 1229 | rdp->n_cbs_invoked += count; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1230 | if (list != NULL) { |
| 1231 | *tail = rdp->nxtlist; |
| 1232 | rdp->nxtlist = list; |
| 1233 | for (count = 0; count < RCU_NEXT_SIZE; count++) |
| 1234 | if (&rdp->nxtlist == rdp->nxttail[count]) |
| 1235 | rdp->nxttail[count] = tail; |
| 1236 | else |
| 1237 | break; |
| 1238 | } |
| 1239 | |
| 1240 | /* Reinstate batch limit if we have worked down the excess. */ |
| 1241 | if (rdp->blimit == LONG_MAX && rdp->qlen <= qlowmark) |
| 1242 | rdp->blimit = blimit; |
| 1243 | |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1244 | /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */ |
| 1245 | if (rdp->qlen == 0 && rdp->qlen_last_fqs_check != 0) { |
| 1246 | rdp->qlen_last_fqs_check = 0; |
| 1247 | rdp->n_force_qs_snap = rsp->n_force_qs; |
| 1248 | } else if (rdp->qlen < rdp->qlen_last_fqs_check - qhimark) |
| 1249 | rdp->qlen_last_fqs_check = rdp->qlen; |
| 1250 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1251 | local_irq_restore(flags); |
| 1252 | |
| 1253 | /* Re-raise the RCU softirq if there are callbacks remaining. */ |
| 1254 | if (cpu_has_callbacks_ready_to_invoke(rdp)) |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1255 | invoke_rcu_core(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1256 | } |
| 1257 | |
| 1258 | /* |
| 1259 | * Check to see if this CPU is in a non-context-switch quiescent state |
| 1260 | * (user mode or idle loop for rcu, non-softirq execution for rcu_bh). |
| 1261 | * Also schedule the RCU softirq handler. |
| 1262 | * |
| 1263 | * This function must be called with hardirqs disabled. It is normally |
| 1264 | * invoked from the scheduling-clock interrupt. If rcu_pending returns |
| 1265 | * false, there is no point in invoking rcu_check_callbacks(). |
| 1266 | */ |
| 1267 | void rcu_check_callbacks(int cpu, int user) |
| 1268 | { |
| 1269 | if (user || |
Paul E. McKenney | a682604 | 2009-02-25 18:03:42 -0800 | [diff] [blame] | 1270 | (idle_cpu(cpu) && rcu_scheduler_active && |
| 1271 | !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1272 | |
| 1273 | /* |
| 1274 | * Get here if this CPU took its interrupt from user |
| 1275 | * mode or from the idle loop, and if this is not a |
| 1276 | * nested interrupt. In this case, the CPU is in |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1277 | * a quiescent state, so note it. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1278 | * |
| 1279 | * No memory barrier is required here because both |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1280 | * rcu_sched_qs() and rcu_bh_qs() reference only CPU-local |
| 1281 | * variables that other CPUs neither access nor modify, |
| 1282 | * at least not while the corresponding CPU is online. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1283 | */ |
| 1284 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1285 | rcu_sched_qs(cpu); |
| 1286 | rcu_bh_qs(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1287 | |
| 1288 | } else if (!in_softirq()) { |
| 1289 | |
| 1290 | /* |
| 1291 | * Get here if this CPU did not take its interrupt from |
| 1292 | * softirq, in other words, if it is not interrupting |
| 1293 | * a rcu_bh read-side critical section. This is an _bh |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1294 | * critical section, so note it. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1295 | */ |
| 1296 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1297 | rcu_bh_qs(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1298 | } |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1299 | rcu_preempt_check_callbacks(cpu); |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 1300 | if (rcu_pending(cpu)) |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1301 | invoke_rcu_core(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1302 | } |
| 1303 | |
| 1304 | #ifdef CONFIG_SMP |
| 1305 | |
| 1306 | /* |
| 1307 | * Scan the leaf rcu_node structures, processing dyntick state for any that |
| 1308 | * have not yet encountered a quiescent state, using the function specified. |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1309 | * Also initiate boosting for any threads blocked on the root rcu_node. |
| 1310 | * |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1311 | * The caller must have suppressed start of new grace periods. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1312 | */ |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1313 | 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] | 1314 | { |
| 1315 | unsigned long bit; |
| 1316 | int cpu; |
| 1317 | unsigned long flags; |
| 1318 | unsigned long mask; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1319 | struct rcu_node *rnp; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1320 | |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1321 | rcu_for_each_leaf_node(rsp, rnp) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1322 | mask = 0; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1323 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1324 | if (!rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1325 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 0f10dc82 | 2010-01-04 15:09:06 -0800 | [diff] [blame] | 1326 | return; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1327 | } |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1328 | if (rnp->qsmask == 0) { |
Paul E. McKenney | 1217ed1 | 2011-05-04 21:43:49 -0700 | [diff] [blame] | 1329 | rcu_initiate_boost(rnp, flags); /* releases rnp->lock */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1330 | continue; |
| 1331 | } |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1332 | cpu = rnp->grplo; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1333 | bit = 1; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1334 | for (; cpu <= rnp->grphi; cpu++, bit <<= 1) { |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1335 | if ((rnp->qsmask & bit) != 0 && |
| 1336 | f(per_cpu_ptr(rsp->rda, cpu))) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1337 | mask |= bit; |
| 1338 | } |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1339 | if (mask != 0) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1340 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1341 | /* rcu_report_qs_rnp() releases rnp->lock. */ |
| 1342 | rcu_report_qs_rnp(mask, rsp, rnp, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1343 | continue; |
| 1344 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1345 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1346 | } |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1347 | rnp = rcu_get_root(rsp); |
Paul E. McKenney | 1217ed1 | 2011-05-04 21:43:49 -0700 | [diff] [blame] | 1348 | if (rnp->qsmask == 0) { |
| 1349 | raw_spin_lock_irqsave(&rnp->lock, flags); |
| 1350 | rcu_initiate_boost(rnp, flags); /* releases rnp->lock. */ |
| 1351 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1352 | } |
| 1353 | |
| 1354 | /* |
| 1355 | * Force quiescent states on reluctant CPUs, and also detect which |
| 1356 | * CPUs are in dyntick-idle mode. |
| 1357 | */ |
| 1358 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) |
| 1359 | { |
| 1360 | unsigned long flags; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1361 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1362 | |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 1363 | if (!rcu_gp_in_progress(rsp)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1364 | return; /* No grace period in progress, nothing to force. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1365 | if (!raw_spin_trylock_irqsave(&rsp->fqslock, flags)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1366 | rsp->n_force_qs_lh++; /* Inexact, can lose counts. Tough! */ |
| 1367 | return; /* Someone else is already on the job. */ |
| 1368 | } |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1369 | if (relaxed && ULONG_CMP_GE(rsp->jiffies_force_qs, jiffies)) |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1370 | goto unlock_fqs_ret; /* no emergency and done recently. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1371 | rsp->n_force_qs++; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1372 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1373 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
Paul E. McKenney | 560d4bc | 2009-11-13 19:51:38 -0800 | [diff] [blame] | 1374 | if(!rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1375 | rsp->n_force_qs_ngp++; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1376 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1377 | goto unlock_fqs_ret; /* no GP in progress, time updated. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1378 | } |
Paul E. McKenney | 07079d5 | 2010-01-04 15:09:02 -0800 | [diff] [blame] | 1379 | rsp->fqs_active = 1; |
Paul E. McKenney | f3a8b5c | 2010-01-04 15:09:03 -0800 | [diff] [blame] | 1380 | switch (rsp->signaled) { |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 1381 | case RCU_GP_IDLE: |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1382 | case RCU_GP_INIT: |
| 1383 | |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 1384 | break; /* grace period idle or initializing, ignore. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1385 | |
| 1386 | case RCU_SAVE_DYNTICK: |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1387 | if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK) |
| 1388 | break; /* So gcc recognizes the dead code. */ |
| 1389 | |
Lai Jiangshan | f261414 | 2010-03-28 11:15:20 +0800 | [diff] [blame] | 1390 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
| 1391 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1392 | /* Record dyntick-idle state. */ |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1393 | force_qs_rnp(rsp, dyntick_save_progress_counter); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1394 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1395 | if (rcu_gp_in_progress(rsp)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1396 | rsp->signaled = RCU_FORCE_QS; |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1397 | break; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1398 | |
| 1399 | case RCU_FORCE_QS: |
| 1400 | |
| 1401 | /* Check dyntick-idle state, send IPI to laggarts. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1402 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1403 | force_qs_rnp(rsp, rcu_implicit_dynticks_qs); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1404 | |
| 1405 | /* Leave state in case more forcing is required. */ |
| 1406 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1407 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1408 | break; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1409 | } |
Paul E. McKenney | 07079d5 | 2010-01-04 15:09:02 -0800 | [diff] [blame] | 1410 | rsp->fqs_active = 0; |
Paul E. McKenney | 46a1e34 | 2010-01-04 15:09:09 -0800 | [diff] [blame] | 1411 | if (rsp->fqs_need_gp) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1412 | raw_spin_unlock(&rsp->fqslock); /* irqs remain disabled */ |
Paul E. McKenney | 46a1e34 | 2010-01-04 15:09:09 -0800 | [diff] [blame] | 1413 | rsp->fqs_need_gp = 0; |
| 1414 | rcu_start_gp(rsp, flags); /* releases rnp->lock */ |
| 1415 | return; |
| 1416 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1417 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1418 | unlock_fqs_ret: |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1419 | raw_spin_unlock_irqrestore(&rsp->fqslock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1420 | } |
| 1421 | |
| 1422 | #else /* #ifdef CONFIG_SMP */ |
| 1423 | |
| 1424 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) |
| 1425 | { |
| 1426 | set_need_resched(); |
| 1427 | } |
| 1428 | |
| 1429 | #endif /* #else #ifdef CONFIG_SMP */ |
| 1430 | |
| 1431 | /* |
| 1432 | * This does the RCU processing work from softirq context for the |
| 1433 | * specified rcu_state and rcu_data structures. This may be called |
| 1434 | * only from the CPU to whom the rdp belongs. |
| 1435 | */ |
| 1436 | static void |
| 1437 | __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) |
| 1438 | { |
| 1439 | unsigned long flags; |
| 1440 | |
Paul E. McKenney | 2e59755 | 2009-08-15 09:53:48 -0700 | [diff] [blame] | 1441 | WARN_ON_ONCE(rdp->beenonline == 0); |
| 1442 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1443 | /* |
| 1444 | * If an RCU GP has gone long enough, go check for dyntick |
| 1445 | * idle CPUs and, if needed, send resched IPIs. |
| 1446 | */ |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1447 | if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1448 | force_quiescent_state(rsp, 1); |
| 1449 | |
| 1450 | /* |
| 1451 | * Advance callbacks in response to end of earlier grace |
| 1452 | * period that some other CPU ended. |
| 1453 | */ |
| 1454 | rcu_process_gp_end(rsp, rdp); |
| 1455 | |
| 1456 | /* Update RCU state based on any recent quiescent states. */ |
| 1457 | rcu_check_quiescent_state(rsp, rdp); |
| 1458 | |
| 1459 | /* Does this CPU require a not-yet-started grace period? */ |
| 1460 | if (cpu_needs_another_gp(rsp, rdp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1461 | raw_spin_lock_irqsave(&rcu_get_root(rsp)->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1462 | rcu_start_gp(rsp, flags); /* releases above lock */ |
| 1463 | } |
| 1464 | |
| 1465 | /* If there are callbacks ready, invoke them. */ |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 1466 | if (cpu_has_callbacks_ready_to_invoke(rdp)) |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1467 | invoke_rcu_callbacks(rsp, rdp); |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 1468 | } |
| 1469 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1470 | /* |
| 1471 | * Do softirq processing for the current CPU. |
| 1472 | */ |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 1473 | static void rcu_process_callbacks(struct softirq_action *unused) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1474 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1475 | __rcu_process_callbacks(&rcu_sched_state, |
| 1476 | &__get_cpu_var(rcu_sched_data)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1477 | __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] | 1478 | rcu_preempt_process_callbacks(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1479 | |
Paul E. McKenney | a47cd88 | 2010-02-26 16:38:56 -0800 | [diff] [blame] | 1480 | /* If we are last CPU on way to dyntick-idle mode, accelerate it. */ |
| 1481 | rcu_needs_cpu_flush(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1482 | } |
| 1483 | |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1484 | /* |
| 1485 | * Wake up the current CPU's kthread. This replaces raise_softirq() |
| 1486 | * in earlier versions of RCU. Note that because we are running on |
| 1487 | * the current CPU with interrupts disabled, the rcu_cpu_kthread_task |
| 1488 | * cannot disappear out from under us. |
| 1489 | */ |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1490 | static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1491 | { |
Paul E. McKenney | b0d3041 | 2011-07-10 15:57:35 -0700 | [diff] [blame] | 1492 | if (unlikely(!ACCESS_ONCE(rcu_scheduler_fully_active))) |
| 1493 | return; |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1494 | if (likely(!rsp->boost)) { |
| 1495 | rcu_do_batch(rsp, rdp); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1496 | return; |
| 1497 | } |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1498 | invoke_rcu_callbacks_kthread(); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1499 | } |
| 1500 | |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1501 | static void invoke_rcu_core(void) |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 1502 | { |
| 1503 | raise_softirq(RCU_SOFTIRQ); |
| 1504 | } |
| 1505 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1506 | static void |
| 1507 | __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), |
| 1508 | struct rcu_state *rsp) |
| 1509 | { |
| 1510 | unsigned long flags; |
| 1511 | struct rcu_data *rdp; |
| 1512 | |
Mathieu Desnoyers | 551d55a | 2010-04-17 08:48:42 -0400 | [diff] [blame] | 1513 | debug_rcu_head_queue(head); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1514 | head->func = func; |
| 1515 | head->next = NULL; |
| 1516 | |
| 1517 | smp_mb(); /* Ensure RCU update seen before callback registry. */ |
| 1518 | |
| 1519 | /* |
| 1520 | * Opportunistically note grace-period endings and beginnings. |
| 1521 | * Note that we might see a beginning right after we see an |
| 1522 | * end, but never vice versa, since this CPU has to pass through |
| 1523 | * a quiescent state betweentimes. |
| 1524 | */ |
| 1525 | local_irq_save(flags); |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1526 | rdp = this_cpu_ptr(rsp->rda); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1527 | |
| 1528 | /* Add the callback to our list. */ |
| 1529 | *rdp->nxttail[RCU_NEXT_TAIL] = head; |
| 1530 | rdp->nxttail[RCU_NEXT_TAIL] = &head->next; |
Paul E. McKenney | 2655d57 | 2011-04-07 22:47:23 -0700 | [diff] [blame] | 1531 | rdp->qlen++; |
| 1532 | |
| 1533 | /* If interrupts were disabled, don't dive into RCU core. */ |
| 1534 | if (irqs_disabled_flags(flags)) { |
| 1535 | local_irq_restore(flags); |
| 1536 | return; |
| 1537 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1538 | |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1539 | /* |
| 1540 | * Force the grace period if too many callbacks or too long waiting. |
| 1541 | * Enforce hysteresis, and don't invoke force_quiescent_state() |
| 1542 | * if some other CPU has recently done so. Also, don't bother |
| 1543 | * invoking force_quiescent_state() if the newly enqueued callback |
| 1544 | * is the only one waiting for a grace period to complete. |
| 1545 | */ |
Paul E. McKenney | 2655d57 | 2011-04-07 22:47:23 -0700 | [diff] [blame] | 1546 | if (unlikely(rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) { |
Paul E. McKenney | b52573d | 2010-12-14 17:36:02 -0800 | [diff] [blame] | 1547 | |
| 1548 | /* Are we ignoring a completed grace period? */ |
| 1549 | rcu_process_gp_end(rsp, rdp); |
| 1550 | check_for_new_grace_period(rsp, rdp); |
| 1551 | |
| 1552 | /* Start a new grace period if one not already started. */ |
| 1553 | if (!rcu_gp_in_progress(rsp)) { |
| 1554 | unsigned long nestflag; |
| 1555 | struct rcu_node *rnp_root = rcu_get_root(rsp); |
| 1556 | |
| 1557 | raw_spin_lock_irqsave(&rnp_root->lock, nestflag); |
| 1558 | rcu_start_gp(rsp, nestflag); /* rlses rnp_root->lock */ |
| 1559 | } else { |
| 1560 | /* Give the grace period a kick. */ |
| 1561 | rdp->blimit = LONG_MAX; |
| 1562 | if (rsp->n_force_qs == rdp->n_force_qs_snap && |
| 1563 | *rdp->nxttail[RCU_DONE_TAIL] != head) |
| 1564 | force_quiescent_state(rsp, 0); |
| 1565 | rdp->n_force_qs_snap = rsp->n_force_qs; |
| 1566 | rdp->qlen_last_fqs_check = rdp->qlen; |
| 1567 | } |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1568 | } 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] | 1569 | force_quiescent_state(rsp, 1); |
| 1570 | local_irq_restore(flags); |
| 1571 | } |
| 1572 | |
| 1573 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1574 | * Queue an RCU-sched callback for invocation after a grace period. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1575 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1576 | 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] | 1577 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1578 | __call_rcu(head, func, &rcu_sched_state); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1579 | } |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1580 | EXPORT_SYMBOL_GPL(call_rcu_sched); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1581 | |
| 1582 | /* |
| 1583 | * Queue an RCU for invocation after a quicker grace period. |
| 1584 | */ |
| 1585 | void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) |
| 1586 | { |
| 1587 | __call_rcu(head, func, &rcu_bh_state); |
| 1588 | } |
| 1589 | EXPORT_SYMBOL_GPL(call_rcu_bh); |
| 1590 | |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1591 | /** |
| 1592 | * synchronize_sched - wait until an rcu-sched grace period has elapsed. |
| 1593 | * |
| 1594 | * Control will return to the caller some time after a full rcu-sched |
| 1595 | * grace period has elapsed, in other words after all currently executing |
| 1596 | * rcu-sched read-side critical sections have completed. These read-side |
| 1597 | * critical sections are delimited by rcu_read_lock_sched() and |
| 1598 | * rcu_read_unlock_sched(), and may be nested. Note that preempt_disable(), |
| 1599 | * local_irq_disable(), and so on may be used in place of |
| 1600 | * rcu_read_lock_sched(). |
| 1601 | * |
| 1602 | * This means that all preempt_disable code sequences, including NMI and |
| 1603 | * hardware-interrupt handlers, in progress on entry will have completed |
| 1604 | * before this primitive returns. However, this does not guarantee that |
| 1605 | * softirq handlers will have completed, since in some kernels, these |
| 1606 | * handlers can run in process context, and can block. |
| 1607 | * |
| 1608 | * This primitive provides the guarantees made by the (now removed) |
| 1609 | * synchronize_kernel() API. In contrast, synchronize_rcu() only |
| 1610 | * guarantees that rcu_read_lock() sections will have completed. |
| 1611 | * In "classic RCU", these two guarantees happen to be one and |
| 1612 | * the same, but can differ in realtime RCU implementations. |
| 1613 | */ |
| 1614 | void synchronize_sched(void) |
| 1615 | { |
| 1616 | struct rcu_synchronize rcu; |
| 1617 | |
| 1618 | if (rcu_blocking_is_gp()) |
| 1619 | return; |
| 1620 | |
Paul E. McKenney | 72d5a9f | 2010-05-10 17:12:17 -0700 | [diff] [blame] | 1621 | init_rcu_head_on_stack(&rcu.head); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1622 | init_completion(&rcu.completion); |
| 1623 | /* Will wake me after RCU finished. */ |
| 1624 | call_rcu_sched(&rcu.head, wakeme_after_rcu); |
| 1625 | /* Wait for it. */ |
| 1626 | wait_for_completion(&rcu.completion); |
Paul E. McKenney | 72d5a9f | 2010-05-10 17:12:17 -0700 | [diff] [blame] | 1627 | destroy_rcu_head_on_stack(&rcu.head); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1628 | } |
| 1629 | EXPORT_SYMBOL_GPL(synchronize_sched); |
| 1630 | |
| 1631 | /** |
| 1632 | * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed. |
| 1633 | * |
| 1634 | * Control will return to the caller some time after a full rcu_bh grace |
| 1635 | * period has elapsed, in other words after all currently executing rcu_bh |
| 1636 | * read-side critical sections have completed. RCU read-side critical |
| 1637 | * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(), |
| 1638 | * and may be nested. |
| 1639 | */ |
| 1640 | void synchronize_rcu_bh(void) |
| 1641 | { |
| 1642 | struct rcu_synchronize rcu; |
| 1643 | |
| 1644 | if (rcu_blocking_is_gp()) |
| 1645 | return; |
| 1646 | |
Paul E. McKenney | 72d5a9f | 2010-05-10 17:12:17 -0700 | [diff] [blame] | 1647 | init_rcu_head_on_stack(&rcu.head); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1648 | init_completion(&rcu.completion); |
| 1649 | /* Will wake me after RCU finished. */ |
| 1650 | call_rcu_bh(&rcu.head, wakeme_after_rcu); |
| 1651 | /* Wait for it. */ |
| 1652 | wait_for_completion(&rcu.completion); |
Paul E. McKenney | 72d5a9f | 2010-05-10 17:12:17 -0700 | [diff] [blame] | 1653 | destroy_rcu_head_on_stack(&rcu.head); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1654 | } |
| 1655 | EXPORT_SYMBOL_GPL(synchronize_rcu_bh); |
| 1656 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1657 | /* |
| 1658 | * Check to see if there is any immediate RCU-related work to be done |
| 1659 | * by the current CPU, for the specified type of RCU, returning 1 if so. |
| 1660 | * The checks are in order of increasing expense: checks that can be |
| 1661 | * carried out against CPU-local state are performed first. However, |
| 1662 | * we must check for CPU stalls first, else we might not get a chance. |
| 1663 | */ |
| 1664 | static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) |
| 1665 | { |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 1666 | struct rcu_node *rnp = rdp->mynode; |
| 1667 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1668 | rdp->n_rcu_pending++; |
| 1669 | |
| 1670 | /* Check for CPU stalls, if enabled. */ |
| 1671 | check_cpu_stall(rsp, rdp); |
| 1672 | |
| 1673 | /* 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] | 1674 | if (rdp->qs_pending && !rdp->passed_quiesc) { |
Paul E. McKenney | d25eb94 | 2010-03-18 21:36:51 -0700 | [diff] [blame] | 1675 | |
| 1676 | /* |
| 1677 | * If force_quiescent_state() coming soon and this CPU |
| 1678 | * needs a quiescent state, and this is either RCU-sched |
| 1679 | * or RCU-bh, force a local reschedule. |
| 1680 | */ |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 1681 | rdp->n_rp_qs_pending++; |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 1682 | if (!rdp->preemptible && |
Paul E. McKenney | d25eb94 | 2010-03-18 21:36:51 -0700 | [diff] [blame] | 1683 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs) - 1, |
| 1684 | jiffies)) |
| 1685 | set_need_resched(); |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 1686 | } else if (rdp->qs_pending && rdp->passed_quiesc) { |
| 1687 | rdp->n_rp_report_qs++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1688 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1689 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1690 | |
| 1691 | /* Does this CPU have callbacks ready to invoke? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1692 | if (cpu_has_callbacks_ready_to_invoke(rdp)) { |
| 1693 | rdp->n_rp_cb_ready++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1694 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1695 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1696 | |
| 1697 | /* Has RCU gone idle with this CPU needing another grace period? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1698 | if (cpu_needs_another_gp(rsp, rdp)) { |
| 1699 | rdp->n_rp_cpu_needs_gp++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1700 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1701 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1702 | |
| 1703 | /* Has another RCU grace period completed? */ |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 1704 | if (ACCESS_ONCE(rnp->completed) != rdp->completed) { /* outside lock */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1705 | rdp->n_rp_gp_completed++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1706 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1707 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1708 | |
| 1709 | /* Has a new RCU grace period started? */ |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 1710 | if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum) { /* outside lock */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1711 | rdp->n_rp_gp_started++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1712 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1713 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1714 | |
| 1715 | /* Has an RCU GP gone long enough to send resched IPIs &c? */ |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 1716 | if (rcu_gp_in_progress(rsp) && |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1717 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) { |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1718 | rdp->n_rp_need_fqs++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1719 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1720 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1721 | |
| 1722 | /* nothing to do */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1723 | rdp->n_rp_need_nothing++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1724 | return 0; |
| 1725 | } |
| 1726 | |
| 1727 | /* |
| 1728 | * Check to see if there is any immediate RCU-related work to be done |
| 1729 | * by the current CPU, returning 1 if so. This function is part of the |
| 1730 | * RCU implementation; it is -not- an exported member of the RCU API. |
| 1731 | */ |
Paul E. McKenney | a157229 | 2009-08-22 13:56:51 -0700 | [diff] [blame] | 1732 | static int rcu_pending(int cpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1733 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1734 | 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] | 1735 | __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu)) || |
| 1736 | rcu_preempt_pending(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1737 | } |
| 1738 | |
| 1739 | /* |
| 1740 | * Check to see if any future RCU-related work will need to be done |
| 1741 | * 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] | 1742 | * 1 if so. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1743 | */ |
Paul E. McKenney | 8bd93a2 | 2010-02-22 17:04:59 -0800 | [diff] [blame] | 1744 | static int rcu_needs_cpu_quick_check(int cpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1745 | { |
| 1746 | /* RCU callbacks either ready or pending? */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1747 | return per_cpu(rcu_sched_data, cpu).nxtlist || |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1748 | per_cpu(rcu_bh_data, cpu).nxtlist || |
| 1749 | rcu_preempt_needs_cpu(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1750 | } |
| 1751 | |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1752 | static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL}; |
| 1753 | static atomic_t rcu_barrier_cpu_count; |
| 1754 | static DEFINE_MUTEX(rcu_barrier_mutex); |
| 1755 | static struct completion rcu_barrier_completion; |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1756 | |
| 1757 | static void rcu_barrier_callback(struct rcu_head *notused) |
| 1758 | { |
| 1759 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) |
| 1760 | complete(&rcu_barrier_completion); |
| 1761 | } |
| 1762 | |
| 1763 | /* |
| 1764 | * Called with preemption disabled, and from cross-cpu IRQ context. |
| 1765 | */ |
| 1766 | static void rcu_barrier_func(void *type) |
| 1767 | { |
| 1768 | int cpu = smp_processor_id(); |
| 1769 | struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu); |
| 1770 | void (*call_rcu_func)(struct rcu_head *head, |
| 1771 | void (*func)(struct rcu_head *head)); |
| 1772 | |
| 1773 | atomic_inc(&rcu_barrier_cpu_count); |
| 1774 | call_rcu_func = type; |
| 1775 | call_rcu_func(head, rcu_barrier_callback); |
| 1776 | } |
| 1777 | |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1778 | /* |
| 1779 | * Orchestrate the specified type of RCU barrier, waiting for all |
| 1780 | * RCU callbacks of the specified type to complete. |
| 1781 | */ |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1782 | static void _rcu_barrier(struct rcu_state *rsp, |
| 1783 | void (*call_rcu_func)(struct rcu_head *head, |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1784 | void (*func)(struct rcu_head *head))) |
| 1785 | { |
| 1786 | BUG_ON(in_interrupt()); |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1787 | /* Take mutex to serialize concurrent rcu_barrier() requests. */ |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1788 | mutex_lock(&rcu_barrier_mutex); |
| 1789 | init_completion(&rcu_barrier_completion); |
| 1790 | /* |
| 1791 | * Initialize rcu_barrier_cpu_count to 1, then invoke |
| 1792 | * rcu_barrier_func() on each CPU, so that each CPU also has |
| 1793 | * incremented rcu_barrier_cpu_count. Only then is it safe to |
| 1794 | * decrement rcu_barrier_cpu_count -- otherwise the first CPU |
| 1795 | * might complete its grace period before all of the other CPUs |
| 1796 | * did their increment, causing this function to return too |
Paul E. McKenney | 2d999e0 | 2010-10-20 12:06:18 -0700 | [diff] [blame] | 1797 | * early. Note that on_each_cpu() disables irqs, which prevents |
| 1798 | * any CPUs from coming online or going offline until each online |
| 1799 | * CPU has queued its RCU-barrier callback. |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1800 | */ |
| 1801 | atomic_set(&rcu_barrier_cpu_count, 1); |
| 1802 | on_each_cpu(rcu_barrier_func, (void *)call_rcu_func, 1); |
| 1803 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) |
| 1804 | complete(&rcu_barrier_completion); |
| 1805 | wait_for_completion(&rcu_barrier_completion); |
| 1806 | mutex_unlock(&rcu_barrier_mutex); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1807 | } |
| 1808 | |
| 1809 | /** |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1810 | * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete. |
| 1811 | */ |
| 1812 | void rcu_barrier_bh(void) |
| 1813 | { |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1814 | _rcu_barrier(&rcu_bh_state, call_rcu_bh); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1815 | } |
| 1816 | EXPORT_SYMBOL_GPL(rcu_barrier_bh); |
| 1817 | |
| 1818 | /** |
| 1819 | * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks. |
| 1820 | */ |
| 1821 | void rcu_barrier_sched(void) |
| 1822 | { |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1823 | _rcu_barrier(&rcu_sched_state, call_rcu_sched); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1824 | } |
| 1825 | EXPORT_SYMBOL_GPL(rcu_barrier_sched); |
| 1826 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1827 | /* |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1828 | * 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] | 1829 | */ |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1830 | static void __init |
| 1831 | rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1832 | { |
| 1833 | unsigned long flags; |
| 1834 | int i; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1835 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1836 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 1837 | |
| 1838 | /* Set up local state, ensuring consistent view of global state. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1839 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1840 | rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo); |
| 1841 | rdp->nxtlist = NULL; |
| 1842 | for (i = 0; i < RCU_NEXT_SIZE; i++) |
| 1843 | rdp->nxttail[i] = &rdp->nxtlist; |
| 1844 | rdp->qlen = 0; |
| 1845 | #ifdef CONFIG_NO_HZ |
| 1846 | rdp->dynticks = &per_cpu(rcu_dynticks, cpu); |
| 1847 | #endif /* #ifdef CONFIG_NO_HZ */ |
| 1848 | rdp->cpu = cpu; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1849 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1850 | } |
| 1851 | |
| 1852 | /* |
| 1853 | * Initialize a CPU's per-CPU RCU data. Note that only one online or |
| 1854 | * offline event can be happening at a given time. Note also that we |
| 1855 | * can accept some slop in the rsp->completed access due to the fact |
| 1856 | * 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] | 1857 | */ |
| 1858 | static void __cpuinit |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 1859 | 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] | 1860 | { |
| 1861 | unsigned long flags; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1862 | unsigned long mask; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1863 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1864 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 1865 | |
| 1866 | /* Set up local state, ensuring consistent view of global state. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1867 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1868 | rdp->passed_quiesc = 0; /* We could be racing with new GP, */ |
| 1869 | rdp->qs_pending = 1; /* so set up to respond to current GP. */ |
| 1870 | rdp->beenonline = 1; /* We have now been online. */ |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 1871 | rdp->preemptible = preemptible; |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1872 | rdp->qlen_last_fqs_check = 0; |
| 1873 | rdp->n_force_qs_snap = rsp->n_force_qs; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1874 | rdp->blimit = blimit; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1875 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1876 | |
| 1877 | /* |
| 1878 | * A new grace period might start here. If so, we won't be part |
| 1879 | * of it, but that is OK, as we are currently in a quiescent state. |
| 1880 | */ |
| 1881 | |
| 1882 | /* Exclude any attempts to start a new GP on large systems. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1883 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1884 | |
| 1885 | /* Add CPU to rcu_node bitmasks. */ |
| 1886 | rnp = rdp->mynode; |
| 1887 | mask = rdp->grpmask; |
| 1888 | do { |
| 1889 | /* Exclude any attempts to start a new GP on small systems. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1890 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1891 | rnp->qsmaskinit |= mask; |
| 1892 | mask = rnp->grpmask; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 1893 | if (rnp == rdp->mynode) { |
| 1894 | rdp->gpnum = rnp->completed; /* if GP in progress... */ |
| 1895 | rdp->completed = rnp->completed; |
| 1896 | rdp->passed_quiesc_completed = rnp->completed - 1; |
| 1897 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1898 | raw_spin_unlock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1899 | rnp = rnp->parent; |
| 1900 | } while (rnp != NULL && !(rnp->qsmaskinit & mask)); |
| 1901 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1902 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1903 | } |
| 1904 | |
Peter Zijlstra | d72bce0 | 2011-05-30 13:34:51 +0200 | [diff] [blame] | 1905 | static void __cpuinit rcu_prepare_cpu(int cpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1906 | { |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1907 | rcu_init_percpu_data(cpu, &rcu_sched_state, 0); |
| 1908 | rcu_init_percpu_data(cpu, &rcu_bh_state, 0); |
| 1909 | rcu_preempt_init_percpu_data(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1910 | } |
| 1911 | |
| 1912 | /* |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1913 | * Handle CPU online/offline notification events. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1914 | */ |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 1915 | static int __cpuinit rcu_cpu_notify(struct notifier_block *self, |
| 1916 | unsigned long action, void *hcpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1917 | { |
| 1918 | long cpu = (long)hcpu; |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1919 | struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1920 | struct rcu_node *rnp = rdp->mynode; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1921 | |
| 1922 | switch (action) { |
| 1923 | case CPU_UP_PREPARE: |
| 1924 | case CPU_UP_PREPARE_FROZEN: |
Peter Zijlstra | d72bce0 | 2011-05-30 13:34:51 +0200 | [diff] [blame] | 1925 | rcu_prepare_cpu(cpu); |
| 1926 | rcu_prepare_kthreads(cpu); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1927 | break; |
| 1928 | case CPU_ONLINE: |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 1929 | case CPU_DOWN_FAILED: |
| 1930 | rcu_node_kthread_setaffinity(rnp, -1); |
Paul E. McKenney | e3995a2 | 2011-04-18 15:31:26 -0700 | [diff] [blame] | 1931 | rcu_cpu_kthread_setrt(cpu, 1); |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 1932 | break; |
| 1933 | case CPU_DOWN_PREPARE: |
| 1934 | rcu_node_kthread_setaffinity(rnp, cpu); |
Paul E. McKenney | e3995a2 | 2011-04-18 15:31:26 -0700 | [diff] [blame] | 1935 | rcu_cpu_kthread_setrt(cpu, 0); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1936 | break; |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1937 | case CPU_DYING: |
| 1938 | case CPU_DYING_FROZEN: |
| 1939 | /* |
Paul E. McKenney | 2d999e0 | 2010-10-20 12:06:18 -0700 | [diff] [blame] | 1940 | * The whole machine is "stopped" except this CPU, so we can |
| 1941 | * touch any data without introducing corruption. We send the |
| 1942 | * dying CPU's callbacks to an arbitrarily chosen online CPU. |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1943 | */ |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1944 | rcu_send_cbs_to_online(&rcu_bh_state); |
| 1945 | rcu_send_cbs_to_online(&rcu_sched_state); |
| 1946 | rcu_preempt_send_cbs_to_online(); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1947 | break; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1948 | case CPU_DEAD: |
| 1949 | case CPU_DEAD_FROZEN: |
| 1950 | case CPU_UP_CANCELED: |
| 1951 | case CPU_UP_CANCELED_FROZEN: |
| 1952 | rcu_offline_cpu(cpu); |
| 1953 | break; |
| 1954 | default: |
| 1955 | break; |
| 1956 | } |
| 1957 | return NOTIFY_OK; |
| 1958 | } |
| 1959 | |
| 1960 | /* |
Paul E. McKenney | bbad937 | 2010-04-02 16:17:17 -0700 | [diff] [blame] | 1961 | * This function is invoked towards the end of the scheduler's initialization |
| 1962 | * process. Before this is called, the idle task might contain |
| 1963 | * RCU read-side critical sections (during which time, this idle |
| 1964 | * task is booting the system). After this function is called, the |
| 1965 | * idle tasks are prohibited from containing RCU read-side critical |
| 1966 | * sections. This function also enables RCU lockdep checking. |
| 1967 | */ |
| 1968 | void rcu_scheduler_starting(void) |
| 1969 | { |
| 1970 | WARN_ON(num_online_cpus() != 1); |
| 1971 | WARN_ON(nr_context_switches() > 0); |
| 1972 | rcu_scheduler_active = 1; |
| 1973 | } |
| 1974 | |
| 1975 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1976 | * Compute the per-level fanout, either using the exact fanout specified |
| 1977 | * or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT. |
| 1978 | */ |
| 1979 | #ifdef CONFIG_RCU_FANOUT_EXACT |
| 1980 | static void __init rcu_init_levelspread(struct rcu_state *rsp) |
| 1981 | { |
| 1982 | int i; |
| 1983 | |
Paul E. McKenney | 0209f64 | 2010-12-14 16:07:52 -0800 | [diff] [blame] | 1984 | for (i = NUM_RCU_LVLS - 1; i > 0; i--) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1985 | rsp->levelspread[i] = CONFIG_RCU_FANOUT; |
Paul E. McKenney | 0209f64 | 2010-12-14 16:07:52 -0800 | [diff] [blame] | 1986 | rsp->levelspread[0] = RCU_FANOUT_LEAF; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1987 | } |
| 1988 | #else /* #ifdef CONFIG_RCU_FANOUT_EXACT */ |
| 1989 | static void __init rcu_init_levelspread(struct rcu_state *rsp) |
| 1990 | { |
| 1991 | int ccur; |
| 1992 | int cprv; |
| 1993 | int i; |
| 1994 | |
| 1995 | cprv = NR_CPUS; |
| 1996 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { |
| 1997 | ccur = rsp->levelcnt[i]; |
| 1998 | rsp->levelspread[i] = (cprv + ccur - 1) / ccur; |
| 1999 | cprv = ccur; |
| 2000 | } |
| 2001 | } |
| 2002 | #endif /* #else #ifdef CONFIG_RCU_FANOUT_EXACT */ |
| 2003 | |
| 2004 | /* |
| 2005 | * Helper function for rcu_init() that initializes one rcu_state structure. |
| 2006 | */ |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2007 | static void __init rcu_init_one(struct rcu_state *rsp, |
| 2008 | struct rcu_data __percpu *rda) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2009 | { |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 2010 | static char *buf[] = { "rcu_node_level_0", |
| 2011 | "rcu_node_level_1", |
| 2012 | "rcu_node_level_2", |
| 2013 | "rcu_node_level_3" }; /* Match MAX_RCU_LVLS */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2014 | int cpustride = 1; |
| 2015 | int i; |
| 2016 | int j; |
| 2017 | struct rcu_node *rnp; |
| 2018 | |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 2019 | BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */ |
| 2020 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2021 | /* Initialize the level-tracking arrays. */ |
| 2022 | |
| 2023 | for (i = 1; i < NUM_RCU_LVLS; i++) |
| 2024 | rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1]; |
| 2025 | rcu_init_levelspread(rsp); |
| 2026 | |
| 2027 | /* Initialize the elements themselves, starting from the leaves. */ |
| 2028 | |
| 2029 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { |
| 2030 | cpustride *= rsp->levelspread[i]; |
| 2031 | rnp = rsp->level[i]; |
| 2032 | for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2033 | raw_spin_lock_init(&rnp->lock); |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 2034 | lockdep_set_class_and_name(&rnp->lock, |
| 2035 | &rcu_node_class[i], buf[i]); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2036 | rnp->gpnum = 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2037 | rnp->qsmask = 0; |
| 2038 | rnp->qsmaskinit = 0; |
| 2039 | rnp->grplo = j * cpustride; |
| 2040 | rnp->grphi = (j + 1) * cpustride - 1; |
| 2041 | if (rnp->grphi >= NR_CPUS) |
| 2042 | rnp->grphi = NR_CPUS - 1; |
| 2043 | if (i == 0) { |
| 2044 | rnp->grpnum = 0; |
| 2045 | rnp->grpmask = 0; |
| 2046 | rnp->parent = NULL; |
| 2047 | } else { |
| 2048 | rnp->grpnum = j % rsp->levelspread[i - 1]; |
| 2049 | rnp->grpmask = 1UL << rnp->grpnum; |
| 2050 | rnp->parent = rsp->level[i - 1] + |
| 2051 | j / rsp->levelspread[i - 1]; |
| 2052 | } |
| 2053 | rnp->level = i; |
Paul E. McKenney | 12f5f52 | 2010-11-29 21:56:39 -0800 | [diff] [blame] | 2054 | INIT_LIST_HEAD(&rnp->blkd_tasks); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2055 | } |
| 2056 | } |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 2057 | |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2058 | rsp->rda = rda; |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 2059 | rnp = rsp->level[NUM_RCU_LVLS - 1]; |
| 2060 | for_each_possible_cpu(i) { |
Paul E. McKenney | 4a90a06 | 2010-04-14 16:48:11 -0700 | [diff] [blame] | 2061 | while (i > rnp->grphi) |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 2062 | rnp++; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2063 | per_cpu_ptr(rsp->rda, i)->mynode = rnp; |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 2064 | rcu_boot_init_percpu_data(i, rsp); |
| 2065 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2066 | } |
| 2067 | |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 2068 | void __init rcu_init(void) |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2069 | { |
Paul E. McKenney | 017c426 | 2010-01-14 16:10:58 -0800 | [diff] [blame] | 2070 | int cpu; |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 2071 | |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2072 | rcu_bootup_announce(); |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2073 | rcu_init_one(&rcu_sched_state, &rcu_sched_data); |
| 2074 | rcu_init_one(&rcu_bh_state, &rcu_bh_data); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2075 | __rcu_init_preempt(); |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 2076 | open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 2077 | |
| 2078 | /* |
| 2079 | * We don't need protection against CPU-hotplug here because |
| 2080 | * this is called early in boot, before either interrupts |
| 2081 | * or the scheduler are operational. |
| 2082 | */ |
| 2083 | cpu_notifier(rcu_cpu_notify, 0); |
Paul E. McKenney | 017c426 | 2010-01-14 16:10:58 -0800 | [diff] [blame] | 2084 | for_each_online_cpu(cpu) |
| 2085 | rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu); |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 2086 | check_cpu_stall_init(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2087 | } |
| 2088 | |
Paul E. McKenney | 1eba8f8 | 2009-09-23 09:50:42 -0700 | [diff] [blame] | 2089 | #include "rcutree_plugin.h" |