Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Read-Copy Update mechanism for mutual exclusion |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation; either version 2 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, write to the Free Software |
| 16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 17 | * |
| 18 | * Copyright IBM Corporation, 2008 |
| 19 | * |
| 20 | * Authors: Dipankar Sarma <dipankar@in.ibm.com> |
| 21 | * Manfred Spraul <manfred@colorfullife.com> |
| 22 | * Paul E. McKenney <paulmck@linux.vnet.ibm.com> Hierarchical version |
| 23 | * |
| 24 | * Based on the original work by Paul McKenney <paulmck@us.ibm.com> |
| 25 | * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. |
| 26 | * |
| 27 | * For detailed explanation of Read-Copy Update mechanism see - |
Paul E. McKenney | a71fca5 | 2009-09-18 10:28:19 -0700 | [diff] [blame] | 28 | * Documentation/RCU |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 29 | */ |
| 30 | #include <linux/types.h> |
| 31 | #include <linux/kernel.h> |
| 32 | #include <linux/init.h> |
| 33 | #include <linux/spinlock.h> |
| 34 | #include <linux/smp.h> |
| 35 | #include <linux/rcupdate.h> |
| 36 | #include <linux/interrupt.h> |
| 37 | #include <linux/sched.h> |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 38 | #include <linux/nmi.h> |
Paul E. McKenney | 8826f3b | 2011-05-11 05:41:41 -0700 | [diff] [blame] | 39 | #include <linux/atomic.h> |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 40 | #include <linux/bitops.h> |
Paul Gortmaker | 9984de1 | 2011-05-23 14:51:41 -0400 | [diff] [blame] | 41 | #include <linux/export.h> |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 42 | #include <linux/completion.h> |
| 43 | #include <linux/moduleparam.h> |
| 44 | #include <linux/percpu.h> |
| 45 | #include <linux/notifier.h> |
| 46 | #include <linux/cpu.h> |
| 47 | #include <linux/mutex.h> |
| 48 | #include <linux/time.h> |
Paul E. McKenney | bbad937 | 2010-04-02 16:17:17 -0700 | [diff] [blame] | 49 | #include <linux/kernel_stat.h> |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 50 | #include <linux/wait.h> |
| 51 | #include <linux/kthread.h> |
Linus Torvalds | 268bb0c | 2011-05-20 12:50:29 -0700 | [diff] [blame] | 52 | #include <linux/prefetch.h> |
Paul E. McKenney | 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" |
Paul E. McKenney | 29c00b4 | 2011-06-17 15:53:19 -0700 | [diff] [blame] | 55 | #include <trace/events/rcu.h> |
| 56 | |
| 57 | #include "rcu.h" |
Paul E. McKenney | 9f77da9 | 2009-08-22 13:56:45 -0700 | [diff] [blame] | 58 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 59 | /* Data structures. */ |
| 60 | |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 61 | static struct lock_class_key rcu_node_class[NUM_RCU_LVLS]; |
Peter Zijlstra | 88b91c7 | 2009-10-26 10:24:31 -0700 | [diff] [blame] | 62 | |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 63 | #define RCU_STATE_INITIALIZER(structname) { \ |
Paul E. McKenney | e99033c | 2011-06-21 00:13:44 -0700 | [diff] [blame] | 64 | .level = { &structname##_state.node[0] }, \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 65 | .levelcnt = { \ |
| 66 | NUM_RCU_LVL_0, /* root of hierarchy. */ \ |
| 67 | NUM_RCU_LVL_1, \ |
| 68 | NUM_RCU_LVL_2, \ |
Paul E. McKenney | cf244dc | 2009-12-02 12:10:14 -0800 | [diff] [blame] | 69 | NUM_RCU_LVL_3, \ |
| 70 | NUM_RCU_LVL_4, /* == MAX_RCU_LVLS */ \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 71 | }, \ |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 72 | .signaled = RCU_GP_IDLE, \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 73 | .gpnum = -300, \ |
| 74 | .completed = -300, \ |
Paul E. McKenney | e99033c | 2011-06-21 00:13:44 -0700 | [diff] [blame] | 75 | .onofflock = __RAW_SPIN_LOCK_UNLOCKED(&structname##_state.onofflock), \ |
| 76 | .fqslock = __RAW_SPIN_LOCK_UNLOCKED(&structname##_state.fqslock), \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 77 | .n_force_qs = 0, \ |
| 78 | .n_force_qs_ngp = 0, \ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 79 | .name = #structname, \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 80 | } |
| 81 | |
Paul E. McKenney | e99033c | 2011-06-21 00:13:44 -0700 | [diff] [blame] | 82 | struct rcu_state rcu_sched_state = RCU_STATE_INITIALIZER(rcu_sched); |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 83 | DEFINE_PER_CPU(struct rcu_data, rcu_sched_data); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 84 | |
Paul E. McKenney | e99033c | 2011-06-21 00:13:44 -0700 | [diff] [blame] | 85 | struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh); |
Ingo Molnar | 6258c4f | 2009-03-25 16:42:24 +0100 | [diff] [blame] | 86 | DEFINE_PER_CPU(struct rcu_data, rcu_bh_data); |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 87 | |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 88 | static struct rcu_state *rcu_state; |
| 89 | |
Paul E. McKenney | b0d3041 | 2011-07-10 15:57:35 -0700 | [diff] [blame] | 90 | /* |
| 91 | * The rcu_scheduler_active variable transitions from zero to one just |
| 92 | * before the first task is spawned. So when this variable is zero, RCU |
| 93 | * can assume that there is but one task, allowing RCU to (for example) |
| 94 | * optimized synchronize_sched() to a simple barrier(). When this variable |
| 95 | * is one, RCU must actually do all the hard work required to detect real |
| 96 | * grace periods. This variable is also used to suppress boot-time false |
| 97 | * positives from lockdep-RCU error checking. |
| 98 | */ |
Paul E. McKenney | bbad937 | 2010-04-02 16:17:17 -0700 | [diff] [blame] | 99 | int rcu_scheduler_active __read_mostly; |
| 100 | EXPORT_SYMBOL_GPL(rcu_scheduler_active); |
| 101 | |
Paul E. McKenney | b0d3041 | 2011-07-10 15:57:35 -0700 | [diff] [blame] | 102 | /* |
| 103 | * The rcu_scheduler_fully_active variable transitions from zero to one |
| 104 | * during the early_initcall() processing, which is after the scheduler |
| 105 | * is capable of creating new tasks. So RCU processing (for example, |
| 106 | * creating tasks for RCU priority boosting) must be delayed until after |
| 107 | * rcu_scheduler_fully_active transitions from zero to one. We also |
| 108 | * currently delay invocation of any RCU callbacks until after this point. |
| 109 | * |
| 110 | * It might later prove better for people registering RCU callbacks during |
| 111 | * early boot to take responsibility for these callbacks, but one step at |
| 112 | * a time. |
| 113 | */ |
| 114 | static int rcu_scheduler_fully_active __read_mostly; |
| 115 | |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 116 | #ifdef CONFIG_RCU_BOOST |
| 117 | |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 118 | /* |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 119 | * Control variables for per-CPU and per-rcu_node kthreads. These |
| 120 | * handle all flavors of RCU. |
| 121 | */ |
| 122 | static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task); |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 123 | DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status); |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 124 | DEFINE_PER_CPU(int, rcu_cpu_kthread_cpu); |
Paul E. McKenney | 5ece5ba | 2011-04-22 18:08:51 -0700 | [diff] [blame] | 125 | DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); |
Paul E. McKenney | d71df90 | 2011-03-29 17:48:28 -0700 | [diff] [blame] | 126 | DEFINE_PER_CPU(char, rcu_cpu_has_work); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 127 | |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 128 | #endif /* #ifdef CONFIG_RCU_BOOST */ |
| 129 | |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 130 | 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] | 131 | static void invoke_rcu_core(void); |
| 132 | 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] | 133 | |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 134 | /* |
Paul E. McKenney | 4a29865 | 2011-04-03 21:33:51 -0700 | [diff] [blame] | 135 | * Track the rcutorture test sequence number and the update version |
| 136 | * number within a given test. The rcutorture_testseq is incremented |
| 137 | * on every rcutorture module load and unload, so has an odd value |
| 138 | * when a test is running. The rcutorture_vernum is set to zero |
| 139 | * when rcutorture starts and is incremented on each rcutorture update. |
| 140 | * These variables enable correlating rcutorture output with the |
| 141 | * RCU tracing information. |
| 142 | */ |
| 143 | unsigned long rcutorture_testseq; |
| 144 | unsigned long rcutorture_vernum; |
| 145 | |
| 146 | /* |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 147 | * Return true if an RCU grace period is in progress. The ACCESS_ONCE()s |
| 148 | * permit this function to be invoked without holding the root rcu_node |
| 149 | * structure's ->lock, but of course results can be subject to change. |
| 150 | */ |
| 151 | static int rcu_gp_in_progress(struct rcu_state *rsp) |
| 152 | { |
| 153 | return ACCESS_ONCE(rsp->completed) != ACCESS_ONCE(rsp->gpnum); |
| 154 | } |
| 155 | |
| 156 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 157 | * Note a quiescent state. Because we do not need to know |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 158 | * how many quiescent states passed, just if there was at least |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 159 | * one since the start of the grace period, this just sets a flag. |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 160 | * The caller must have disabled preemption. |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 161 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 162 | void rcu_sched_qs(int cpu) |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 163 | { |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 164 | struct rcu_data *rdp = &per_cpu(rcu_sched_data, cpu); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 165 | |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 166 | rdp->passed_quiesce_gpnum = rdp->gpnum; |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 167 | barrier(); |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 168 | if (rdp->passed_quiesce == 0) |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 169 | trace_rcu_grace_period("rcu_sched", rdp->gpnum, "cpuqs"); |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 170 | rdp->passed_quiesce = 1; |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 171 | } |
| 172 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 173 | void rcu_bh_qs(int cpu) |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 174 | { |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 175 | struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 176 | |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 177 | rdp->passed_quiesce_gpnum = rdp->gpnum; |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 178 | barrier(); |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 179 | if (rdp->passed_quiesce == 0) |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 180 | trace_rcu_grace_period("rcu_bh", rdp->gpnum, "cpuqs"); |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 181 | rdp->passed_quiesce = 1; |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 182 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 183 | |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 184 | /* |
| 185 | * Note a context switch. This is a quiescent state for RCU-sched, |
| 186 | * and requires special handling for preemptible RCU. |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 187 | * The caller must have disabled preemption. |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 188 | */ |
| 189 | void rcu_note_context_switch(int cpu) |
| 190 | { |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 191 | trace_rcu_utilization("Start context switch"); |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 192 | rcu_sched_qs(cpu); |
| 193 | rcu_preempt_note_context_switch(cpu); |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 194 | trace_rcu_utilization("End context switch"); |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 195 | } |
Gleb Natapov | 29ce831 | 2011-05-04 16:31:03 +0300 | [diff] [blame] | 196 | EXPORT_SYMBOL_GPL(rcu_note_context_switch); |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 197 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 198 | #ifdef CONFIG_NO_HZ |
Paul E. McKenney | 90a4d2c | 2009-01-04 11:41:11 -0800 | [diff] [blame] | 199 | DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { |
| 200 | .dynticks_nesting = 1, |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 201 | .dynticks = ATOMIC_INIT(1), |
Paul E. McKenney | 90a4d2c | 2009-01-04 11:41:11 -0800 | [diff] [blame] | 202 | }; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 203 | #endif /* #ifdef CONFIG_NO_HZ */ |
| 204 | |
Paul E. McKenney | e0f2306 | 2011-06-21 01:29:39 -0700 | [diff] [blame] | 205 | static int blimit = 10; /* Maximum callbacks per rcu_do_batch. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 206 | static int qhimark = 10000; /* If this many pending, ignore blimit. */ |
| 207 | static int qlowmark = 100; /* Once only this many pending, use blimit. */ |
| 208 | |
Paul E. McKenney | 3d76c08 | 2009-09-28 07:46:32 -0700 | [diff] [blame] | 209 | module_param(blimit, int, 0); |
| 210 | module_param(qhimark, int, 0); |
| 211 | module_param(qlowmark, int, 0); |
| 212 | |
Paul E. McKenney | a00e0d71 | 2011-02-08 17:14:39 -0800 | [diff] [blame] | 213 | int rcu_cpu_stall_suppress __read_mostly; |
Paul E. McKenney | f2e0dd7 | 2010-07-14 14:38:30 -0700 | [diff] [blame] | 214 | module_param(rcu_cpu_stall_suppress, int, 0644); |
Paul E. McKenney | 742734e | 2010-06-30 11:43:52 -0700 | [diff] [blame] | 215 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 216 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed); |
Paul E. McKenney | a157229 | 2009-08-22 13:56:51 -0700 | [diff] [blame] | 217 | static int rcu_pending(int cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 218 | |
| 219 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 220 | * 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] | 221 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 222 | long rcu_batches_completed_sched(void) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 223 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 224 | return rcu_sched_state.completed; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 225 | } |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 226 | EXPORT_SYMBOL_GPL(rcu_batches_completed_sched); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 227 | |
| 228 | /* |
| 229 | * Return the number of RCU BH batches processed thus far for debug & stats. |
| 230 | */ |
| 231 | long rcu_batches_completed_bh(void) |
| 232 | { |
| 233 | return rcu_bh_state.completed; |
| 234 | } |
| 235 | EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); |
| 236 | |
| 237 | /* |
Paul E. McKenney | bf66f18 | 2010-01-04 15:09:10 -0800 | [diff] [blame] | 238 | * Force a quiescent state for RCU BH. |
| 239 | */ |
| 240 | void rcu_bh_force_quiescent_state(void) |
| 241 | { |
| 242 | force_quiescent_state(&rcu_bh_state, 0); |
| 243 | } |
| 244 | EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state); |
| 245 | |
| 246 | /* |
Paul E. McKenney | 4a29865 | 2011-04-03 21:33:51 -0700 | [diff] [blame] | 247 | * Record the number of times rcutorture tests have been initiated and |
| 248 | * terminated. This information allows the debugfs tracing stats to be |
| 249 | * correlated to the rcutorture messages, even when the rcutorture module |
| 250 | * is being repeatedly loaded and unloaded. In other words, we cannot |
| 251 | * store this state in rcutorture itself. |
| 252 | */ |
| 253 | void rcutorture_record_test_transition(void) |
| 254 | { |
| 255 | rcutorture_testseq++; |
| 256 | rcutorture_vernum = 0; |
| 257 | } |
| 258 | EXPORT_SYMBOL_GPL(rcutorture_record_test_transition); |
| 259 | |
| 260 | /* |
| 261 | * Record the number of writer passes through the current rcutorture test. |
| 262 | * This is also used to correlate debugfs tracing stats with the rcutorture |
| 263 | * messages. |
| 264 | */ |
| 265 | void rcutorture_record_progress(unsigned long vernum) |
| 266 | { |
| 267 | rcutorture_vernum++; |
| 268 | } |
| 269 | EXPORT_SYMBOL_GPL(rcutorture_record_progress); |
| 270 | |
| 271 | /* |
Paul E. McKenney | bf66f18 | 2010-01-04 15:09:10 -0800 | [diff] [blame] | 272 | * Force a quiescent state for RCU-sched. |
| 273 | */ |
| 274 | void rcu_sched_force_quiescent_state(void) |
| 275 | { |
| 276 | force_quiescent_state(&rcu_sched_state, 0); |
| 277 | } |
| 278 | EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state); |
| 279 | |
| 280 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 281 | * Does the CPU have callbacks ready to be invoked? |
| 282 | */ |
| 283 | static int |
| 284 | cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp) |
| 285 | { |
| 286 | return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]; |
| 287 | } |
| 288 | |
| 289 | /* |
| 290 | * Does the current CPU require a yet-as-unscheduled grace period? |
| 291 | */ |
| 292 | static int |
| 293 | cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp) |
| 294 | { |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 295 | return *rdp->nxttail[RCU_DONE_TAIL] && !rcu_gp_in_progress(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 296 | } |
| 297 | |
| 298 | /* |
| 299 | * Return the root node of the specified rcu_state structure. |
| 300 | */ |
| 301 | static struct rcu_node *rcu_get_root(struct rcu_state *rsp) |
| 302 | { |
| 303 | return &rsp->node[0]; |
| 304 | } |
| 305 | |
| 306 | #ifdef CONFIG_SMP |
| 307 | |
| 308 | /* |
| 309 | * If the specified CPU is offline, tell the caller that it is in |
| 310 | * a quiescent state. Otherwise, whack it with a reschedule IPI. |
| 311 | * Grace periods can end up waiting on an offline CPU when that |
| 312 | * CPU is in the process of coming online -- it will be added to the |
| 313 | * rcu_node bitmasks before it actually makes it online. The same thing |
| 314 | * can happen while a CPU is in the process of coming online. Because this |
| 315 | * race is quite rare, we check for it after detecting that the grace |
| 316 | * period has been delayed rather than checking each and every CPU |
| 317 | * each and every time we start a new grace period. |
| 318 | */ |
| 319 | static int rcu_implicit_offline_qs(struct rcu_data *rdp) |
| 320 | { |
| 321 | /* |
| 322 | * If the CPU is offline, it is in a quiescent state. We can |
| 323 | * trust its state not to change because interrupts are disabled. |
| 324 | */ |
| 325 | if (cpu_is_offline(rdp->cpu)) { |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 326 | trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, "ofl"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 327 | rdp->offline_fqs++; |
| 328 | return 1; |
| 329 | } |
| 330 | |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 331 | /* If preemptible RCU, no point in sending reschedule IPI. */ |
| 332 | if (rdp->preemptible) |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 333 | return 0; |
| 334 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 335 | /* The CPU is online, so send it a reschedule IPI. */ |
| 336 | if (rdp->cpu != smp_processor_id()) |
| 337 | smp_send_reschedule(rdp->cpu); |
| 338 | else |
| 339 | set_need_resched(); |
| 340 | rdp->resched_ipi++; |
| 341 | return 0; |
| 342 | } |
| 343 | |
| 344 | #endif /* #ifdef CONFIG_SMP */ |
| 345 | |
| 346 | #ifdef CONFIG_NO_HZ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 347 | |
| 348 | /** |
| 349 | * rcu_enter_nohz - inform RCU that current CPU is entering nohz |
| 350 | * |
| 351 | * Enter nohz mode, in other words, -leave- the mode in which RCU |
| 352 | * read-side critical sections can occur. (Though RCU read-side |
| 353 | * critical sections can occur in irq handlers in nohz mode, a possibility |
| 354 | * handled by rcu_irq_enter() and rcu_irq_exit()). |
| 355 | */ |
| 356 | void rcu_enter_nohz(void) |
| 357 | { |
| 358 | unsigned long flags; |
| 359 | struct rcu_dynticks *rdtp; |
| 360 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 361 | local_irq_save(flags); |
| 362 | rdtp = &__get_cpu_var(rcu_dynticks); |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 363 | if (--rdtp->dynticks_nesting) { |
| 364 | local_irq_restore(flags); |
| 365 | return; |
| 366 | } |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 367 | trace_rcu_dyntick("Start"); |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 368 | /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ |
| 369 | smp_mb__before_atomic_inc(); /* See above. */ |
| 370 | atomic_inc(&rdtp->dynticks); |
| 371 | smp_mb__after_atomic_inc(); /* Force ordering with next sojourn. */ |
| 372 | WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 373 | local_irq_restore(flags); |
| 374 | } |
| 375 | |
| 376 | /* |
| 377 | * rcu_exit_nohz - inform RCU that current CPU is leaving nohz |
| 378 | * |
| 379 | * Exit nohz mode, in other words, -enter- the mode in which RCU |
| 380 | * read-side critical sections normally occur. |
| 381 | */ |
| 382 | void rcu_exit_nohz(void) |
| 383 | { |
| 384 | unsigned long flags; |
| 385 | struct rcu_dynticks *rdtp; |
| 386 | |
| 387 | local_irq_save(flags); |
| 388 | rdtp = &__get_cpu_var(rcu_dynticks); |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 389 | if (rdtp->dynticks_nesting++) { |
| 390 | local_irq_restore(flags); |
| 391 | return; |
| 392 | } |
| 393 | smp_mb__before_atomic_inc(); /* Force ordering w/previous sojourn. */ |
| 394 | atomic_inc(&rdtp->dynticks); |
| 395 | /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ |
| 396 | smp_mb__after_atomic_inc(); /* See above. */ |
| 397 | WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 398 | trace_rcu_dyntick("End"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 399 | local_irq_restore(flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 400 | } |
| 401 | |
| 402 | /** |
| 403 | * rcu_nmi_enter - inform RCU of entry to NMI context |
| 404 | * |
| 405 | * If the CPU was idle with dynamic ticks active, and there is no |
| 406 | * irq handler running, this updates rdtp->dynticks_nmi to let the |
| 407 | * RCU grace-period handling know that the CPU is active. |
| 408 | */ |
| 409 | void rcu_nmi_enter(void) |
| 410 | { |
| 411 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 412 | |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 413 | if (rdtp->dynticks_nmi_nesting == 0 && |
| 414 | (atomic_read(&rdtp->dynticks) & 0x1)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 415 | return; |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 416 | rdtp->dynticks_nmi_nesting++; |
| 417 | smp_mb__before_atomic_inc(); /* Force delay from prior write. */ |
| 418 | atomic_inc(&rdtp->dynticks); |
| 419 | /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ |
| 420 | smp_mb__after_atomic_inc(); /* See above. */ |
| 421 | WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 422 | } |
| 423 | |
| 424 | /** |
| 425 | * rcu_nmi_exit - inform RCU of exit from NMI context |
| 426 | * |
| 427 | * If the CPU was idle with dynamic ticks active, and there is no |
| 428 | * irq handler running, this updates rdtp->dynticks_nmi to let the |
| 429 | * RCU grace-period handling know that the CPU is no longer active. |
| 430 | */ |
| 431 | void rcu_nmi_exit(void) |
| 432 | { |
| 433 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 434 | |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 435 | if (rdtp->dynticks_nmi_nesting == 0 || |
| 436 | --rdtp->dynticks_nmi_nesting != 0) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 437 | return; |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 438 | /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ |
| 439 | smp_mb__before_atomic_inc(); /* See above. */ |
| 440 | atomic_inc(&rdtp->dynticks); |
| 441 | smp_mb__after_atomic_inc(); /* Force delay to next write. */ |
| 442 | WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 443 | } |
| 444 | |
| 445 | /** |
| 446 | * rcu_irq_enter - inform RCU of entry to hard irq context |
| 447 | * |
| 448 | * If the CPU was idle with dynamic ticks active, this updates the |
| 449 | * rdtp->dynticks to let the RCU handling know that the CPU is active. |
| 450 | */ |
| 451 | void rcu_irq_enter(void) |
| 452 | { |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 453 | rcu_exit_nohz(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 454 | } |
| 455 | |
| 456 | /** |
| 457 | * rcu_irq_exit - inform RCU of exit from hard irq context |
| 458 | * |
| 459 | * If the CPU was idle with dynamic ticks active, update the rdp->dynticks |
| 460 | * to put let the RCU handling be aware that the CPU is going back to idle |
| 461 | * with no ticks. |
| 462 | */ |
| 463 | void rcu_irq_exit(void) |
| 464 | { |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 465 | rcu_enter_nohz(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 466 | } |
| 467 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 468 | #ifdef CONFIG_SMP |
| 469 | |
| 470 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 471 | * Snapshot the specified CPU's dynticks counter so that we can later |
| 472 | * 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] | 473 | * is in dynticks idle mode, which is an extended quiescent state. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 474 | */ |
| 475 | static int dyntick_save_progress_counter(struct rcu_data *rdp) |
| 476 | { |
Paul E. McKenney | 23b5c8f | 2010-09-07 10:38:22 -0700 | [diff] [blame] | 477 | rdp->dynticks_snap = atomic_add_return(0, &rdp->dynticks->dynticks); |
| 478 | return 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 479 | } |
| 480 | |
| 481 | /* |
| 482 | * Return true if the specified CPU has passed through a quiescent |
| 483 | * state by virtue of being in or having passed through an dynticks |
| 484 | * idle state since the last call to dyntick_save_progress_counter() |
| 485 | * for this same CPU. |
| 486 | */ |
| 487 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) |
| 488 | { |
Paul E. McKenney | 7eb4f45 | 2011-07-30 07:32:48 -0700 | [diff] [blame] | 489 | unsigned int curr; |
| 490 | unsigned int snap; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 491 | |
Paul E. McKenney | 7eb4f45 | 2011-07-30 07:32:48 -0700 | [diff] [blame] | 492 | curr = (unsigned int)atomic_add_return(0, &rdp->dynticks->dynticks); |
| 493 | snap = (unsigned int)rdp->dynticks_snap; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 494 | |
| 495 | /* |
| 496 | * If the CPU passed through or entered a dynticks idle phase with |
| 497 | * no active irq/NMI handlers, then we can safely pretend that the CPU |
| 498 | * already acknowledged the request to pass through a quiescent |
| 499 | * state. Either way, that CPU cannot possibly be in an RCU |
| 500 | * read-side critical section that started before the beginning |
| 501 | * of the current RCU grace period. |
| 502 | */ |
Paul E. McKenney | 7eb4f45 | 2011-07-30 07:32:48 -0700 | [diff] [blame] | 503 | if ((curr & 0x1) == 0 || UINT_CMP_GE(curr, snap + 2)) { |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 504 | trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, "dti"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 505 | rdp->dynticks_fqs++; |
| 506 | return 1; |
| 507 | } |
| 508 | |
| 509 | /* Go check for the CPU being offline. */ |
| 510 | return rcu_implicit_offline_qs(rdp); |
| 511 | } |
| 512 | |
| 513 | #endif /* #ifdef CONFIG_SMP */ |
| 514 | |
| 515 | #else /* #ifdef CONFIG_NO_HZ */ |
| 516 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 517 | #ifdef CONFIG_SMP |
| 518 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 519 | static int dyntick_save_progress_counter(struct rcu_data *rdp) |
| 520 | { |
| 521 | return 0; |
| 522 | } |
| 523 | |
| 524 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) |
| 525 | { |
| 526 | return rcu_implicit_offline_qs(rdp); |
| 527 | } |
| 528 | |
| 529 | #endif /* #ifdef CONFIG_SMP */ |
| 530 | |
| 531 | #endif /* #else #ifdef CONFIG_NO_HZ */ |
| 532 | |
Paul E. McKenney | 742734e | 2010-06-30 11:43:52 -0700 | [diff] [blame] | 533 | int rcu_cpu_stall_suppress __read_mostly; |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 534 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 535 | static void record_gp_stall_check_time(struct rcu_state *rsp) |
| 536 | { |
| 537 | rsp->gp_start = jiffies; |
| 538 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_CHECK; |
| 539 | } |
| 540 | |
| 541 | static void print_other_cpu_stall(struct rcu_state *rsp) |
| 542 | { |
| 543 | int cpu; |
| 544 | long delta; |
| 545 | unsigned long flags; |
Paul E. McKenney | 9bc8b55 | 2011-08-13 13:31:47 -0700 | [diff] [blame] | 546 | int ndetected; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 547 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 548 | |
| 549 | /* Only let one CPU complain about others per time interval. */ |
| 550 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 551 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 552 | delta = jiffies - rsp->jiffies_stall; |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 553 | if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 554 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 555 | return; |
| 556 | } |
| 557 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_RECHECK; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 558 | |
| 559 | /* |
| 560 | * Now rat on any tasks that got kicked up to the root rcu_node |
| 561 | * due to CPU offlining. |
| 562 | */ |
Paul E. McKenney | 9bc8b55 | 2011-08-13 13:31:47 -0700 | [diff] [blame] | 563 | ndetected = rcu_print_task_stall(rnp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 564 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 565 | |
Paul E. McKenney | 8cdd32a | 2010-08-09 14:23:03 -0700 | [diff] [blame] | 566 | /* |
| 567 | * OK, time to rat on our buddy... |
| 568 | * See Documentation/RCU/stallwarn.txt for info on how to debug |
| 569 | * RCU CPU stall warnings. |
| 570 | */ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 571 | printk(KERN_ERR "INFO: %s detected stalls on CPUs/tasks: {", |
| 572 | rsp->name); |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 573 | rcu_for_each_leaf_node(rsp, rnp) { |
Paul E. McKenney | 3acd9eb | 2010-02-22 17:05:03 -0800 | [diff] [blame] | 574 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 9bc8b55 | 2011-08-13 13:31:47 -0700 | [diff] [blame] | 575 | ndetected += rcu_print_task_stall(rnp); |
Paul E. McKenney | 3acd9eb | 2010-02-22 17:05:03 -0800 | [diff] [blame] | 576 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 577 | if (rnp->qsmask == 0) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 578 | continue; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 579 | for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++) |
Paul E. McKenney | 9bc8b55 | 2011-08-13 13:31:47 -0700 | [diff] [blame] | 580 | if (rnp->qsmask & (1UL << cpu)) { |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 581 | printk(" %d", rnp->grplo + cpu); |
Paul E. McKenney | 9bc8b55 | 2011-08-13 13:31:47 -0700 | [diff] [blame] | 582 | ndetected++; |
| 583 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 584 | } |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 585 | printk("} (detected by %d, t=%ld jiffies)\n", |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 586 | smp_processor_id(), (long)(jiffies - rsp->gp_start)); |
Paul E. McKenney | 9bc8b55 | 2011-08-13 13:31:47 -0700 | [diff] [blame] | 587 | if (ndetected == 0) |
| 588 | printk(KERN_ERR "INFO: Stall ended before state dump start\n"); |
| 589 | else if (!trigger_all_cpu_backtrace()) |
Paul E. McKenney | 4627e24 | 2011-08-03 03:34:24 -0700 | [diff] [blame] | 590 | dump_stack(); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 591 | |
Paul E. McKenney | 1ed509a | 2010-02-22 17:05:05 -0800 | [diff] [blame] | 592 | /* If so configured, complain about tasks blocking the grace period. */ |
| 593 | |
| 594 | rcu_print_detail_task_stall(rsp); |
| 595 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 596 | force_quiescent_state(rsp, 0); /* Kick them all. */ |
| 597 | } |
| 598 | |
| 599 | static void print_cpu_stall(struct rcu_state *rsp) |
| 600 | { |
| 601 | unsigned long flags; |
| 602 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 603 | |
Paul E. McKenney | 8cdd32a | 2010-08-09 14:23:03 -0700 | [diff] [blame] | 604 | /* |
| 605 | * OK, time to rat on ourselves... |
| 606 | * See Documentation/RCU/stallwarn.txt for info on how to debug |
| 607 | * RCU CPU stall warnings. |
| 608 | */ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 609 | printk(KERN_ERR "INFO: %s detected stall on CPU %d (t=%lu jiffies)\n", |
| 610 | rsp->name, smp_processor_id(), jiffies - rsp->gp_start); |
Paul E. McKenney | 4627e24 | 2011-08-03 03:34:24 -0700 | [diff] [blame] | 611 | if (!trigger_all_cpu_backtrace()) |
| 612 | dump_stack(); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 613 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 614 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 615 | if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 616 | rsp->jiffies_stall = |
| 617 | jiffies + RCU_SECONDS_TILL_STALL_RECHECK; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 618 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 619 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 620 | set_need_resched(); /* kick ourselves to get things going. */ |
| 621 | } |
| 622 | |
| 623 | static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) |
| 624 | { |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 625 | unsigned long j; |
| 626 | unsigned long js; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 627 | struct rcu_node *rnp; |
| 628 | |
Paul E. McKenney | 742734e | 2010-06-30 11:43:52 -0700 | [diff] [blame] | 629 | if (rcu_cpu_stall_suppress) |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 630 | return; |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 631 | j = ACCESS_ONCE(jiffies); |
| 632 | js = ACCESS_ONCE(rsp->jiffies_stall); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 633 | rnp = rdp->mynode; |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 634 | 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] | 635 | |
| 636 | /* We haven't checked in, so go dump stack. */ |
| 637 | print_cpu_stall(rsp); |
| 638 | |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 639 | } else if (rcu_gp_in_progress(rsp) && |
| 640 | ULONG_CMP_GE(j, js + RCU_STALL_RAT_DELAY)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 641 | |
Paul E. McKenney | bad6e13 | 2011-05-02 23:40:04 -0700 | [diff] [blame] | 642 | /* They had a few time units to dump stack, so complain. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 643 | print_other_cpu_stall(rsp); |
| 644 | } |
| 645 | } |
| 646 | |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 647 | static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr) |
| 648 | { |
Paul E. McKenney | 742734e | 2010-06-30 11:43:52 -0700 | [diff] [blame] | 649 | rcu_cpu_stall_suppress = 1; |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 650 | return NOTIFY_DONE; |
| 651 | } |
| 652 | |
Paul E. McKenney | 53d84e0 | 2010-08-10 14:28:53 -0700 | [diff] [blame] | 653 | /** |
| 654 | * rcu_cpu_stall_reset - prevent further stall warnings in current grace period |
| 655 | * |
| 656 | * Set the stall-warning timeout way off into the future, thus preventing |
| 657 | * any RCU CPU stall-warning messages from appearing in the current set of |
| 658 | * RCU grace periods. |
| 659 | * |
| 660 | * The caller must disable hard irqs. |
| 661 | */ |
| 662 | void rcu_cpu_stall_reset(void) |
| 663 | { |
| 664 | rcu_sched_state.jiffies_stall = jiffies + ULONG_MAX / 2; |
| 665 | rcu_bh_state.jiffies_stall = jiffies + ULONG_MAX / 2; |
| 666 | rcu_preempt_stall_reset(); |
| 667 | } |
| 668 | |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 669 | static struct notifier_block rcu_panic_block = { |
| 670 | .notifier_call = rcu_panic, |
| 671 | }; |
| 672 | |
| 673 | static void __init check_cpu_stall_init(void) |
| 674 | { |
| 675 | atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block); |
| 676 | } |
| 677 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 678 | /* |
| 679 | * Update CPU-local rcu_data state to record the newly noticed grace period. |
| 680 | * 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] | 681 | * that someone else started the grace period. The caller must hold the |
| 682 | * ->lock of the leaf rcu_node structure corresponding to the current CPU, |
| 683 | * and must have irqs disabled. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 684 | */ |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 685 | static void __note_new_gpnum(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
| 686 | { |
| 687 | if (rdp->gpnum != rnp->gpnum) { |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 688 | /* |
| 689 | * If the current grace period is waiting for this CPU, |
| 690 | * set up to detect a quiescent state, otherwise don't |
| 691 | * go looking for one. |
| 692 | */ |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 693 | rdp->gpnum = rnp->gpnum; |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 694 | trace_rcu_grace_period(rsp->name, rdp->gpnum, "cpustart"); |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 695 | if (rnp->qsmask & rdp->grpmask) { |
| 696 | rdp->qs_pending = 1; |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 697 | rdp->passed_quiesce = 0; |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 698 | } else |
| 699 | rdp->qs_pending = 0; |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 700 | } |
| 701 | } |
| 702 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 703 | static void note_new_gpnum(struct rcu_state *rsp, struct rcu_data *rdp) |
| 704 | { |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 705 | unsigned long flags; |
| 706 | struct rcu_node *rnp; |
| 707 | |
| 708 | local_irq_save(flags); |
| 709 | rnp = rdp->mynode; |
| 710 | if (rdp->gpnum == ACCESS_ONCE(rnp->gpnum) || /* outside lock. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 711 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 712 | local_irq_restore(flags); |
| 713 | return; |
| 714 | } |
| 715 | __note_new_gpnum(rsp, rnp, rdp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 716 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 717 | } |
| 718 | |
| 719 | /* |
| 720 | * Did someone else start a new RCU grace period start since we last |
| 721 | * checked? Update local state appropriately if so. Must be called |
| 722 | * on the CPU corresponding to rdp. |
| 723 | */ |
| 724 | static int |
| 725 | check_for_new_grace_period(struct rcu_state *rsp, struct rcu_data *rdp) |
| 726 | { |
| 727 | unsigned long flags; |
| 728 | int ret = 0; |
| 729 | |
| 730 | local_irq_save(flags); |
| 731 | if (rdp->gpnum != rsp->gpnum) { |
| 732 | note_new_gpnum(rsp, rdp); |
| 733 | ret = 1; |
| 734 | } |
| 735 | local_irq_restore(flags); |
| 736 | return ret; |
| 737 | } |
| 738 | |
| 739 | /* |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 740 | * Advance this CPU's callbacks, but only if the current grace period |
| 741 | * has ended. This may be called only from the CPU to whom the rdp |
| 742 | * belongs. In addition, the corresponding leaf rcu_node structure's |
| 743 | * ->lock must be held by the caller, with irqs disabled. |
| 744 | */ |
| 745 | static void |
| 746 | __rcu_process_gp_end(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
| 747 | { |
| 748 | /* Did another grace period end? */ |
| 749 | if (rdp->completed != rnp->completed) { |
| 750 | |
| 751 | /* Advance callbacks. No harm if list empty. */ |
| 752 | rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL]; |
| 753 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL]; |
| 754 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 755 | |
| 756 | /* Remember that we saw this grace-period completion. */ |
| 757 | rdp->completed = rnp->completed; |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 758 | trace_rcu_grace_period(rsp->name, rdp->gpnum, "cpuend"); |
Frederic Weisbecker | 20377f3 | 2010-12-10 22:11:10 +0100 | [diff] [blame] | 759 | |
| 760 | /* |
Frederic Weisbecker | 5ff8e6f | 2010-12-10 22:11:11 +0100 | [diff] [blame] | 761 | * If we were in an extended quiescent state, we may have |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 762 | * missed some grace periods that others CPUs handled on |
Frederic Weisbecker | 5ff8e6f | 2010-12-10 22:11:11 +0100 | [diff] [blame] | 763 | * our behalf. Catch up with this state to avoid noting |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 764 | * spurious new grace periods. If another grace period |
| 765 | * has started, then rnp->gpnum will have advanced, so |
| 766 | * we will detect this later on. |
Frederic Weisbecker | 5ff8e6f | 2010-12-10 22:11:11 +0100 | [diff] [blame] | 767 | */ |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 768 | if (ULONG_CMP_LT(rdp->gpnum, rdp->completed)) |
Frederic Weisbecker | 5ff8e6f | 2010-12-10 22:11:11 +0100 | [diff] [blame] | 769 | rdp->gpnum = rdp->completed; |
| 770 | |
| 771 | /* |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 772 | * If RCU does not need a quiescent state from this CPU, |
| 773 | * then make sure that this CPU doesn't go looking for one. |
Frederic Weisbecker | 20377f3 | 2010-12-10 22:11:10 +0100 | [diff] [blame] | 774 | */ |
Paul E. McKenney | 121dfc4 | 2010-12-10 15:02:47 -0800 | [diff] [blame] | 775 | if ((rnp->qsmask & rdp->grpmask) == 0) |
Frederic Weisbecker | 20377f3 | 2010-12-10 22:11:10 +0100 | [diff] [blame] | 776 | rdp->qs_pending = 0; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 777 | } |
| 778 | } |
| 779 | |
| 780 | /* |
| 781 | * Advance this CPU's callbacks, but only if the current grace period |
| 782 | * has ended. This may be called only from the CPU to whom the rdp |
| 783 | * belongs. |
| 784 | */ |
| 785 | static void |
| 786 | rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp) |
| 787 | { |
| 788 | unsigned long flags; |
| 789 | struct rcu_node *rnp; |
| 790 | |
| 791 | local_irq_save(flags); |
| 792 | rnp = rdp->mynode; |
| 793 | if (rdp->completed == ACCESS_ONCE(rnp->completed) || /* outside lock. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 794 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 795 | local_irq_restore(flags); |
| 796 | return; |
| 797 | } |
| 798 | __rcu_process_gp_end(rsp, rnp, rdp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 799 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 800 | } |
| 801 | |
| 802 | /* |
| 803 | * Do per-CPU grace-period initialization for running CPU. The caller |
| 804 | * must hold the lock of the leaf rcu_node structure corresponding to |
| 805 | * this CPU. |
| 806 | */ |
| 807 | static void |
| 808 | rcu_start_gp_per_cpu(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
| 809 | { |
| 810 | /* Prior grace period ended, so advance callbacks for current CPU. */ |
| 811 | __rcu_process_gp_end(rsp, rnp, rdp); |
| 812 | |
| 813 | /* |
| 814 | * Because this CPU just now started the new grace period, we know |
| 815 | * that all of its callbacks will be covered by this upcoming grace |
| 816 | * period, even the ones that were registered arbitrarily recently. |
| 817 | * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL. |
| 818 | * |
| 819 | * Other CPUs cannot be sure exactly when the grace period started. |
| 820 | * Therefore, their recently registered callbacks must pass through |
| 821 | * an additional RCU_NEXT_READY stage, so that they will be handled |
| 822 | * by the next RCU grace period. |
| 823 | */ |
| 824 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 825 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 826 | |
| 827 | /* Set state so that this CPU will detect the next quiescent state. */ |
| 828 | __note_new_gpnum(rsp, rnp, rdp); |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 829 | } |
| 830 | |
| 831 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 832 | * Start a new RCU grace period if warranted, re-initializing the hierarchy |
| 833 | * in preparation for detecting the next grace period. The caller must hold |
| 834 | * the root node's ->lock, which is released before return. Hard irqs must |
| 835 | * be disabled. |
| 836 | */ |
| 837 | static void |
| 838 | rcu_start_gp(struct rcu_state *rsp, unsigned long flags) |
| 839 | __releases(rcu_get_root(rsp)->lock) |
| 840 | { |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 841 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 842 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 843 | |
Paul E. McKenney | 037067a | 2011-08-07 20:26:31 -0700 | [diff] [blame] | 844 | if (!rcu_scheduler_fully_active || |
Paul E. McKenney | afe24b1 | 2011-08-24 16:52:09 -0700 | [diff] [blame] | 845 | !cpu_needs_another_gp(rsp, rdp)) { |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 846 | /* |
Paul E. McKenney | afe24b1 | 2011-08-24 16:52:09 -0700 | [diff] [blame] | 847 | * Either the scheduler hasn't yet spawned the first |
| 848 | * non-idle task or this CPU does not need another |
| 849 | * grace period. Either way, don't start a new grace |
| 850 | * period. |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 851 | */ |
Paul E. McKenney | afe24b1 | 2011-08-24 16:52:09 -0700 | [diff] [blame] | 852 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
| 853 | return; |
| 854 | } |
| 855 | |
| 856 | if (rsp->fqs_active) { |
| 857 | /* |
| 858 | * This CPU needs a grace period, but force_quiescent_state() |
| 859 | * is running. Tell it to start one on this CPU's behalf. |
| 860 | */ |
| 861 | rsp->fqs_need_gp = 1; |
| 862 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 863 | return; |
| 864 | } |
| 865 | |
| 866 | /* Advance to a new grace period and initialize state. */ |
| 867 | rsp->gpnum++; |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 868 | trace_rcu_grace_period(rsp->name, rsp->gpnum, "start"); |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 869 | WARN_ON_ONCE(rsp->signaled == RCU_GP_INIT); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 870 | rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */ |
| 871 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 872 | record_gp_stall_check_time(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 873 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 874 | /* Special-case the common single-level case. */ |
| 875 | if (NUM_RCU_NODES == 1) { |
Paul E. McKenney | b0e165c | 2009-09-13 09:15:09 -0700 | [diff] [blame] | 876 | rcu_preempt_check_blocked_tasks(rnp); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 877 | rnp->qsmask = rnp->qsmaskinit; |
Paul E. McKenney | de078d8 | 2009-09-08 15:54:36 -0700 | [diff] [blame] | 878 | rnp->gpnum = rsp->gpnum; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 879 | rnp->completed = rsp->completed; |
Paul E. McKenney | c12172c | 2009-01-04 20:30:06 -0800 | [diff] [blame] | 880 | rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state OK. */ |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 881 | rcu_start_gp_per_cpu(rsp, rnp, rdp); |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 882 | rcu_preempt_boost_start_gp(rnp); |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 883 | trace_rcu_grace_period_init(rsp->name, rnp->gpnum, |
| 884 | rnp->level, rnp->grplo, |
| 885 | rnp->grphi, rnp->qsmask); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 886 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 887 | return; |
| 888 | } |
| 889 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 890 | raw_spin_unlock(&rnp->lock); /* leave irqs disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 891 | |
| 892 | |
| 893 | /* Exclude any concurrent CPU-hotplug operations. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 894 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 895 | |
| 896 | /* |
Paul E. McKenney | b835db1 | 2009-09-08 15:54:37 -0700 | [diff] [blame] | 897 | * Set the quiescent-state-needed bits in all the rcu_node |
| 898 | * structures for all currently online CPUs in breadth-first |
| 899 | * order, starting from the root rcu_node structure. This |
| 900 | * operation relies on the layout of the hierarchy within the |
| 901 | * rsp->node[] array. Note that other CPUs will access only |
| 902 | * the leaves of the hierarchy, which still indicate that no |
| 903 | * grace period is in progress, at least until the corresponding |
| 904 | * leaf node has been initialized. In addition, we have excluded |
| 905 | * CPU-hotplug operations. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 906 | * |
| 907 | * Note that the grace period cannot complete until we finish |
| 908 | * the initialization process, as there will be at least one |
| 909 | * 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] | 910 | * one corresponding to this CPU, due to the fact that we have |
| 911 | * irqs disabled. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 912 | */ |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 913 | rcu_for_each_node_breadth_first(rsp, rnp) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 914 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | b0e165c | 2009-09-13 09:15:09 -0700 | [diff] [blame] | 915 | rcu_preempt_check_blocked_tasks(rnp); |
Paul E. McKenney | 49e2912 | 2009-09-18 09:50:19 -0700 | [diff] [blame] | 916 | rnp->qsmask = rnp->qsmaskinit; |
Paul E. McKenney | de078d8 | 2009-09-08 15:54:36 -0700 | [diff] [blame] | 917 | rnp->gpnum = rsp->gpnum; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 918 | rnp->completed = rsp->completed; |
| 919 | if (rnp == rdp->mynode) |
| 920 | rcu_start_gp_per_cpu(rsp, rnp, rdp); |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 921 | rcu_preempt_boost_start_gp(rnp); |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 922 | trace_rcu_grace_period_init(rsp->name, rnp->gpnum, |
| 923 | rnp->level, rnp->grplo, |
| 924 | rnp->grphi, rnp->qsmask); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 925 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 926 | } |
| 927 | |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 928 | rnp = rcu_get_root(rsp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 929 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 930 | rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state now OK. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 931 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
| 932 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 933 | } |
| 934 | |
| 935 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 936 | * Report a full set of quiescent states to the specified rcu_state |
| 937 | * data structure. This involves cleaning up after the prior grace |
| 938 | * period and letting rcu_start_gp() start up the next grace period |
| 939 | * if one is needed. Note that the caller must hold rnp->lock, as |
| 940 | * required by rcu_start_gp(), which will release it. |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 941 | */ |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 942 | 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] | 943 | __releases(rcu_get_root(rsp)->lock) |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 944 | { |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 945 | unsigned long gp_duration; |
Paul E. McKenney | afe24b1 | 2011-08-24 16:52:09 -0700 | [diff] [blame] | 946 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 947 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 948 | |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 949 | WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); |
Paul E. McKenney | 0bbcc52 | 2011-05-16 02:24:04 -0700 | [diff] [blame] | 950 | |
| 951 | /* |
| 952 | * Ensure that all grace-period and pre-grace-period activity |
| 953 | * is seen before the assignment to rsp->completed. |
| 954 | */ |
| 955 | smp_mb(); /* See above block comment. */ |
Paul E. McKenney | 15ba0ba | 2011-04-06 16:01:16 -0700 | [diff] [blame] | 956 | gp_duration = jiffies - rsp->gp_start; |
| 957 | if (gp_duration > rsp->gp_max) |
| 958 | rsp->gp_max = gp_duration; |
Paul E. McKenney | afe24b1 | 2011-08-24 16:52:09 -0700 | [diff] [blame] | 959 | |
| 960 | /* |
| 961 | * We know the grace period is complete, but to everyone else |
| 962 | * it appears to still be ongoing. But it is also the case |
| 963 | * that to everyone else it looks like there is nothing that |
| 964 | * they can do to advance the grace period. It is therefore |
| 965 | * safe for us to drop the lock in order to mark the grace |
| 966 | * period as completed in all of the rcu_node structures. |
| 967 | * |
| 968 | * But if this CPU needs another grace period, it will take |
| 969 | * care of this while initializing the next grace period. |
| 970 | * We use RCU_WAIT_TAIL instead of the usual RCU_DONE_TAIL |
| 971 | * because the callbacks have not yet been advanced: Those |
| 972 | * callbacks are waiting on the grace period that just now |
| 973 | * completed. |
| 974 | */ |
| 975 | if (*rdp->nxttail[RCU_WAIT_TAIL] == NULL) { |
| 976 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
| 977 | |
| 978 | /* |
| 979 | * Propagate new ->completed value to rcu_node structures |
| 980 | * so that other CPUs don't have to wait until the start |
| 981 | * of the next grace period to process their callbacks. |
| 982 | */ |
| 983 | rcu_for_each_node_breadth_first(rsp, rnp) { |
| 984 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
| 985 | rnp->completed = rsp->gpnum; |
| 986 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
| 987 | } |
| 988 | rnp = rcu_get_root(rsp); |
| 989 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
| 990 | } |
| 991 | |
| 992 | rsp->completed = rsp->gpnum; /* Declare the grace period complete. */ |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 993 | trace_rcu_grace_period(rsp->name, rsp->completed, "end"); |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 994 | rsp->signaled = RCU_GP_IDLE; |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 995 | rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */ |
| 996 | } |
| 997 | |
| 998 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 999 | * Similar to rcu_report_qs_rdp(), for which it is a helper function. |
| 1000 | * Allows quiescent states for a group of CPUs to be reported at one go |
| 1001 | * to the specified rcu_node structure, though all the CPUs in the group |
| 1002 | * must be represented by the same rcu_node structure (which need not be |
| 1003 | * a leaf rcu_node structure, though it often will be). That structure's |
| 1004 | * 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] | 1005 | */ |
| 1006 | static void |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1007 | rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp, |
| 1008 | struct rcu_node *rnp, unsigned long flags) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1009 | __releases(rnp->lock) |
| 1010 | { |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 1011 | struct rcu_node *rnp_c; |
| 1012 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1013 | /* Walk up the rcu_node hierarchy. */ |
| 1014 | for (;;) { |
| 1015 | if (!(rnp->qsmask & mask)) { |
| 1016 | |
| 1017 | /* Our bit has already been cleared, so done. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1018 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1019 | return; |
| 1020 | } |
| 1021 | rnp->qsmask &= ~mask; |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 1022 | trace_rcu_quiescent_state_report(rsp->name, rnp->gpnum, |
| 1023 | mask, rnp->qsmask, rnp->level, |
| 1024 | rnp->grplo, rnp->grphi, |
| 1025 | !!rnp->gp_tasks); |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1026 | if (rnp->qsmask != 0 || rcu_preempt_blocked_readers_cgp(rnp)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1027 | |
| 1028 | /* Other bits still set at this level, so done. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1029 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1030 | return; |
| 1031 | } |
| 1032 | mask = rnp->grpmask; |
| 1033 | if (rnp->parent == NULL) { |
| 1034 | |
| 1035 | /* No more levels. Exit loop holding root lock. */ |
| 1036 | |
| 1037 | break; |
| 1038 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1039 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 1040 | rnp_c = rnp; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1041 | rnp = rnp->parent; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1042 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 1043 | WARN_ON_ONCE(rnp_c->qsmask); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1044 | } |
| 1045 | |
| 1046 | /* |
| 1047 | * 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] | 1048 | * state for this grace period. Invoke rcu_report_qs_rsp() |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1049 | * 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] | 1050 | */ |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1051 | rcu_report_qs_rsp(rsp, flags); /* releases rnp->lock. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1052 | } |
| 1053 | |
| 1054 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1055 | * Record a quiescent state for the specified CPU to that CPU's rcu_data |
| 1056 | * structure. This must be either called from the specified CPU, or |
| 1057 | * called when the specified CPU is known to be offline (and when it is |
| 1058 | * also known that no other CPU is concurrently trying to help the offline |
| 1059 | * CPU). The lastcomp argument is used to make sure we are still in the |
| 1060 | * grace period of interest. We don't want to end the current grace period |
| 1061 | * based on quiescent states detected in an earlier grace period! |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1062 | */ |
| 1063 | static void |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1064 | rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastgp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1065 | { |
| 1066 | unsigned long flags; |
| 1067 | unsigned long mask; |
| 1068 | struct rcu_node *rnp; |
| 1069 | |
| 1070 | rnp = rdp->mynode; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1071 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1072 | if (lastgp != rnp->gpnum || rnp->completed == rnp->gpnum) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1073 | |
| 1074 | /* |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1075 | * The grace period in which this quiescent state was |
| 1076 | * recorded has ended, so don't report it upwards. |
| 1077 | * We will instead need a new quiescent state that lies |
| 1078 | * within the current grace period. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1079 | */ |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1080 | rdp->passed_quiesce = 0; /* need qs for new gp. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1081 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1082 | return; |
| 1083 | } |
| 1084 | mask = rdp->grpmask; |
| 1085 | if ((rnp->qsmask & mask) == 0) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1086 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1087 | } else { |
| 1088 | rdp->qs_pending = 0; |
| 1089 | |
| 1090 | /* |
| 1091 | * This GP can't end until cpu checks in, so all of our |
| 1092 | * callbacks can be processed during the next GP. |
| 1093 | */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1094 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 1095 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1096 | rcu_report_qs_rnp(mask, rsp, rnp, flags); /* rlses rnp->lock */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1097 | } |
| 1098 | } |
| 1099 | |
| 1100 | /* |
| 1101 | * Check to see if there is a new grace period of which this CPU |
| 1102 | * is not yet aware, and if so, set up local rcu_data state for it. |
| 1103 | * Otherwise, see if this CPU has just passed through its first |
| 1104 | * quiescent state for this grace period, and record that fact if so. |
| 1105 | */ |
| 1106 | static void |
| 1107 | rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp) |
| 1108 | { |
| 1109 | /* If there is now a new grace period, record and return. */ |
| 1110 | if (check_for_new_grace_period(rsp, rdp)) |
| 1111 | return; |
| 1112 | |
| 1113 | /* |
| 1114 | * Does this CPU still need to do its part for current grace period? |
| 1115 | * If no, return and let the other CPUs do their part as well. |
| 1116 | */ |
| 1117 | if (!rdp->qs_pending) |
| 1118 | return; |
| 1119 | |
| 1120 | /* |
| 1121 | * Was there a quiescent state since the beginning of the grace |
| 1122 | * period? If no, then exit and wait for the next call. |
| 1123 | */ |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1124 | if (!rdp->passed_quiesce) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1125 | return; |
| 1126 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1127 | /* |
| 1128 | * Tell RCU we are done (but rcu_report_qs_rdp() will be the |
| 1129 | * judge of that). |
| 1130 | */ |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1131 | rcu_report_qs_rdp(rdp->cpu, rsp, rdp, rdp->passed_quiesce_gpnum); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1132 | } |
| 1133 | |
| 1134 | #ifdef CONFIG_HOTPLUG_CPU |
| 1135 | |
| 1136 | /* |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1137 | * Move a dying CPU's RCU callbacks to online CPU's callback list. |
| 1138 | * Synchronization is not required because this function executes |
| 1139 | * in stop_machine() context. |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1140 | */ |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1141 | static void rcu_send_cbs_to_online(struct rcu_state *rsp) |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1142 | { |
| 1143 | int i; |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1144 | /* current DYING CPU is cleared in the cpu_online_mask */ |
| 1145 | int receive_cpu = cpumask_any(cpu_online_mask); |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1146 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1147 | 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] | 1148 | |
| 1149 | if (rdp->nxtlist == NULL) |
| 1150 | return; /* irqs disabled, so comparison is stable. */ |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1151 | |
| 1152 | *receive_rdp->nxttail[RCU_NEXT_TAIL] = rdp->nxtlist; |
| 1153 | receive_rdp->nxttail[RCU_NEXT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 1154 | receive_rdp->qlen += rdp->qlen; |
| 1155 | receive_rdp->n_cbs_adopted += rdp->qlen; |
| 1156 | rdp->n_cbs_orphaned += rdp->qlen; |
| 1157 | |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1158 | rdp->nxtlist = NULL; |
| 1159 | for (i = 0; i < RCU_NEXT_SIZE; i++) |
| 1160 | rdp->nxttail[i] = &rdp->nxtlist; |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1161 | rdp->qlen = 0; |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1162 | } |
| 1163 | |
| 1164 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1165 | * Remove the outgoing CPU from the bitmasks in the rcu_node hierarchy |
| 1166 | * 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] | 1167 | * There can only be one CPU hotplug operation at a time, so no other |
| 1168 | * CPU can be attempting to update rcu_cpu_kthread_task. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1169 | */ |
| 1170 | static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) |
| 1171 | { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1172 | unsigned long flags; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1173 | unsigned long mask; |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1174 | int need_report = 0; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1175 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1176 | struct rcu_node *rnp; |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1177 | |
Paul E. McKenney | f8b7fc6 | 2011-06-16 08:26:32 -0700 | [diff] [blame] | 1178 | rcu_stop_cpu_kthread(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1179 | |
| 1180 | /* Exclude any attempts to start a new grace period. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1181 | raw_spin_lock_irqsave(&rsp->onofflock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1182 | |
| 1183 | /* 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] | 1184 | rnp = rdp->mynode; /* this is the outgoing CPU's rnp. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1185 | mask = rdp->grpmask; /* rnp->grplo is constant. */ |
| 1186 | do { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1187 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1188 | rnp->qsmaskinit &= ~mask; |
| 1189 | if (rnp->qsmaskinit != 0) { |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1190 | if (rnp != rdp->mynode) |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1191 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 1192 | else |
| 1193 | trace_rcu_grace_period(rsp->name, |
| 1194 | rnp->gpnum + 1 - |
| 1195 | !!(rnp->qsmask & mask), |
| 1196 | "cpuofl"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1197 | break; |
| 1198 | } |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 1199 | if (rnp == rdp->mynode) { |
| 1200 | trace_rcu_grace_period(rsp->name, |
| 1201 | rnp->gpnum + 1 - |
| 1202 | !!(rnp->qsmask & mask), |
| 1203 | "cpuofl"); |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1204 | need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp); |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 1205 | } else |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1206 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1207 | mask = rnp->grpmask; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1208 | rnp = rnp->parent; |
| 1209 | } while (rnp != NULL); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1210 | |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1211 | /* |
| 1212 | * We still hold the leaf rcu_node structure lock here, and |
| 1213 | * irqs are still disabled. The reason for this subterfuge is |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1214 | * because invoking rcu_report_unblock_qs_rnp() with ->onofflock |
| 1215 | * held leads to deadlock. |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1216 | */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1217 | raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1218 | rnp = rdp->mynode; |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1219 | if (need_report & RCU_OFL_TASKS_NORM_GP) |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1220 | rcu_report_unblock_qs_rnp(rnp, flags); |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1221 | else |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1222 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1223 | if (need_report & RCU_OFL_TASKS_EXP_GP) |
| 1224 | rcu_report_exp_rnp(rsp, rnp); |
Paul E. McKenney | 1217ed1 | 2011-05-04 21:43:49 -0700 | [diff] [blame] | 1225 | rcu_node_kthread_setaffinity(rnp, -1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1226 | } |
| 1227 | |
| 1228 | /* |
| 1229 | * Remove the specified CPU from the RCU hierarchy and move any pending |
| 1230 | * callbacks that it might have to the current CPU. This code assumes |
| 1231 | * that at least one CPU in the system will remain running at all times. |
| 1232 | * Any attempt to offline -all- CPUs is likely to strand RCU callbacks. |
| 1233 | */ |
| 1234 | static void rcu_offline_cpu(int cpu) |
| 1235 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1236 | __rcu_offline_cpu(cpu, &rcu_sched_state); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1237 | __rcu_offline_cpu(cpu, &rcu_bh_state); |
Paul E. McKenney | 33f7614 | 2009-08-24 09:42:01 -0700 | [diff] [blame] | 1238 | rcu_preempt_offline_cpu(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1239 | } |
| 1240 | |
| 1241 | #else /* #ifdef CONFIG_HOTPLUG_CPU */ |
| 1242 | |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 1243 | static void rcu_send_cbs_to_online(struct rcu_state *rsp) |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1244 | { |
| 1245 | } |
| 1246 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1247 | static void rcu_offline_cpu(int cpu) |
| 1248 | { |
| 1249 | } |
| 1250 | |
| 1251 | #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */ |
| 1252 | |
| 1253 | /* |
| 1254 | * Invoke any RCU callbacks that have made it to the end of their grace |
| 1255 | * period. Thottle as specified by rdp->blimit. |
| 1256 | */ |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1257 | 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] | 1258 | { |
| 1259 | unsigned long flags; |
| 1260 | struct rcu_head *next, *list, **tail; |
Paul E. McKenney | 29c00b4 | 2011-06-17 15:53:19 -0700 | [diff] [blame] | 1261 | int bl, count; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1262 | |
| 1263 | /* If no callbacks are ready, just return.*/ |
Paul E. McKenney | 29c00b4 | 2011-06-17 15:53:19 -0700 | [diff] [blame] | 1264 | if (!cpu_has_callbacks_ready_to_invoke(rdp)) { |
Paul E. McKenney | 72fe701 | 2011-06-21 01:14:54 -0700 | [diff] [blame] | 1265 | trace_rcu_batch_start(rsp->name, 0, 0); |
| 1266 | trace_rcu_batch_end(rsp->name, 0); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1267 | return; |
Paul E. McKenney | 29c00b4 | 2011-06-17 15:53:19 -0700 | [diff] [blame] | 1268 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1269 | |
| 1270 | /* |
| 1271 | * Extract the list of ready callbacks, disabling to prevent |
| 1272 | * races with call_rcu() from interrupt handlers. |
| 1273 | */ |
| 1274 | local_irq_save(flags); |
Paul E. McKenney | 29c00b4 | 2011-06-17 15:53:19 -0700 | [diff] [blame] | 1275 | bl = rdp->blimit; |
Paul E. McKenney | 72fe701 | 2011-06-21 01:14:54 -0700 | [diff] [blame] | 1276 | trace_rcu_batch_start(rsp->name, rdp->qlen, bl); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1277 | list = rdp->nxtlist; |
| 1278 | rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL]; |
| 1279 | *rdp->nxttail[RCU_DONE_TAIL] = NULL; |
| 1280 | tail = rdp->nxttail[RCU_DONE_TAIL]; |
| 1281 | for (count = RCU_NEXT_SIZE - 1; count >= 0; count--) |
| 1282 | if (rdp->nxttail[count] == rdp->nxttail[RCU_DONE_TAIL]) |
| 1283 | rdp->nxttail[count] = &rdp->nxtlist; |
| 1284 | local_irq_restore(flags); |
| 1285 | |
| 1286 | /* Invoke callbacks. */ |
| 1287 | count = 0; |
| 1288 | while (list) { |
| 1289 | next = list->next; |
| 1290 | prefetch(next); |
Mathieu Desnoyers | 551d55a | 2010-04-17 08:48:42 -0400 | [diff] [blame] | 1291 | debug_rcu_head_unqueue(list); |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 1292 | __rcu_reclaim(rsp->name, list); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1293 | list = next; |
Paul E. McKenney | 29c00b4 | 2011-06-17 15:53:19 -0700 | [diff] [blame] | 1294 | if (++count >= bl) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1295 | break; |
| 1296 | } |
| 1297 | |
| 1298 | local_irq_save(flags); |
Paul E. McKenney | 72fe701 | 2011-06-21 01:14:54 -0700 | [diff] [blame] | 1299 | trace_rcu_batch_end(rsp->name, count); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1300 | |
| 1301 | /* Update count, and requeue any remaining callbacks. */ |
| 1302 | rdp->qlen -= count; |
Paul E. McKenney | 269dcc1 | 2010-09-07 14:23:09 -0700 | [diff] [blame] | 1303 | rdp->n_cbs_invoked += count; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1304 | if (list != NULL) { |
| 1305 | *tail = rdp->nxtlist; |
| 1306 | rdp->nxtlist = list; |
| 1307 | for (count = 0; count < RCU_NEXT_SIZE; count++) |
| 1308 | if (&rdp->nxtlist == rdp->nxttail[count]) |
| 1309 | rdp->nxttail[count] = tail; |
| 1310 | else |
| 1311 | break; |
| 1312 | } |
| 1313 | |
| 1314 | /* Reinstate batch limit if we have worked down the excess. */ |
| 1315 | if (rdp->blimit == LONG_MAX && rdp->qlen <= qlowmark) |
| 1316 | rdp->blimit = blimit; |
| 1317 | |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1318 | /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */ |
| 1319 | if (rdp->qlen == 0 && rdp->qlen_last_fqs_check != 0) { |
| 1320 | rdp->qlen_last_fqs_check = 0; |
| 1321 | rdp->n_force_qs_snap = rsp->n_force_qs; |
| 1322 | } else if (rdp->qlen < rdp->qlen_last_fqs_check - qhimark) |
| 1323 | rdp->qlen_last_fqs_check = rdp->qlen; |
| 1324 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1325 | local_irq_restore(flags); |
| 1326 | |
Paul E. McKenney | e0f2306 | 2011-06-21 01:29:39 -0700 | [diff] [blame] | 1327 | /* Re-invoke RCU core processing if there are callbacks remaining. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1328 | if (cpu_has_callbacks_ready_to_invoke(rdp)) |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1329 | invoke_rcu_core(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1330 | } |
| 1331 | |
| 1332 | /* |
| 1333 | * Check to see if this CPU is in a non-context-switch quiescent state |
| 1334 | * (user mode or idle loop for rcu, non-softirq execution for rcu_bh). |
Paul E. McKenney | e0f2306 | 2011-06-21 01:29:39 -0700 | [diff] [blame] | 1335 | * Also schedule RCU core processing. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1336 | * |
| 1337 | * This function must be called with hardirqs disabled. It is normally |
| 1338 | * invoked from the scheduling-clock interrupt. If rcu_pending returns |
| 1339 | * false, there is no point in invoking rcu_check_callbacks(). |
| 1340 | */ |
| 1341 | void rcu_check_callbacks(int cpu, int user) |
| 1342 | { |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1343 | trace_rcu_utilization("Start scheduler-tick"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1344 | if (user || |
Paul E. McKenney | a682604 | 2009-02-25 18:03:42 -0800 | [diff] [blame] | 1345 | (idle_cpu(cpu) && rcu_scheduler_active && |
| 1346 | !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1347 | |
| 1348 | /* |
| 1349 | * Get here if this CPU took its interrupt from user |
| 1350 | * mode or from the idle loop, and if this is not a |
| 1351 | * nested interrupt. In this case, the CPU is in |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1352 | * a quiescent state, so note it. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1353 | * |
| 1354 | * No memory barrier is required here because both |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1355 | * rcu_sched_qs() and rcu_bh_qs() reference only CPU-local |
| 1356 | * variables that other CPUs neither access nor modify, |
| 1357 | * at least not while the corresponding CPU is online. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1358 | */ |
| 1359 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1360 | rcu_sched_qs(cpu); |
| 1361 | rcu_bh_qs(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1362 | |
| 1363 | } else if (!in_softirq()) { |
| 1364 | |
| 1365 | /* |
| 1366 | * Get here if this CPU did not take its interrupt from |
| 1367 | * softirq, in other words, if it is not interrupting |
| 1368 | * a rcu_bh read-side critical section. This is an _bh |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1369 | * critical section, so note it. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1370 | */ |
| 1371 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1372 | rcu_bh_qs(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1373 | } |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1374 | rcu_preempt_check_callbacks(cpu); |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 1375 | if (rcu_pending(cpu)) |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1376 | invoke_rcu_core(); |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1377 | trace_rcu_utilization("End scheduler-tick"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1378 | } |
| 1379 | |
| 1380 | #ifdef CONFIG_SMP |
| 1381 | |
| 1382 | /* |
| 1383 | * Scan the leaf rcu_node structures, processing dyntick state for any that |
| 1384 | * have not yet encountered a quiescent state, using the function specified. |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1385 | * Also initiate boosting for any threads blocked on the root rcu_node. |
| 1386 | * |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1387 | * The caller must have suppressed start of new grace periods. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1388 | */ |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1389 | 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] | 1390 | { |
| 1391 | unsigned long bit; |
| 1392 | int cpu; |
| 1393 | unsigned long flags; |
| 1394 | unsigned long mask; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1395 | struct rcu_node *rnp; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1396 | |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1397 | rcu_for_each_leaf_node(rsp, rnp) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1398 | mask = 0; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1399 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1400 | if (!rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1401 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 0f10dc82 | 2010-01-04 15:09:06 -0800 | [diff] [blame] | 1402 | return; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1403 | } |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1404 | if (rnp->qsmask == 0) { |
Paul E. McKenney | 1217ed1 | 2011-05-04 21:43:49 -0700 | [diff] [blame] | 1405 | rcu_initiate_boost(rnp, flags); /* releases rnp->lock */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1406 | continue; |
| 1407 | } |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1408 | cpu = rnp->grplo; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1409 | bit = 1; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1410 | for (; cpu <= rnp->grphi; cpu++, bit <<= 1) { |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1411 | if ((rnp->qsmask & bit) != 0 && |
| 1412 | f(per_cpu_ptr(rsp->rda, cpu))) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1413 | mask |= bit; |
| 1414 | } |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1415 | if (mask != 0) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1416 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1417 | /* rcu_report_qs_rnp() releases rnp->lock. */ |
| 1418 | rcu_report_qs_rnp(mask, rsp, rnp, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1419 | continue; |
| 1420 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1421 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1422 | } |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1423 | rnp = rcu_get_root(rsp); |
Paul E. McKenney | 1217ed1 | 2011-05-04 21:43:49 -0700 | [diff] [blame] | 1424 | if (rnp->qsmask == 0) { |
| 1425 | raw_spin_lock_irqsave(&rnp->lock, flags); |
| 1426 | rcu_initiate_boost(rnp, flags); /* releases rnp->lock. */ |
| 1427 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1428 | } |
| 1429 | |
| 1430 | /* |
| 1431 | * Force quiescent states on reluctant CPUs, and also detect which |
| 1432 | * CPUs are in dyntick-idle mode. |
| 1433 | */ |
| 1434 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) |
| 1435 | { |
| 1436 | unsigned long flags; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1437 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1438 | |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1439 | trace_rcu_utilization("Start fqs"); |
| 1440 | if (!rcu_gp_in_progress(rsp)) { |
| 1441 | trace_rcu_utilization("End fqs"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1442 | return; /* No grace period in progress, nothing to force. */ |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1443 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1444 | if (!raw_spin_trylock_irqsave(&rsp->fqslock, flags)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1445 | rsp->n_force_qs_lh++; /* Inexact, can lose counts. Tough! */ |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1446 | trace_rcu_utilization("End fqs"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1447 | return; /* Someone else is already on the job. */ |
| 1448 | } |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1449 | if (relaxed && ULONG_CMP_GE(rsp->jiffies_force_qs, jiffies)) |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1450 | goto unlock_fqs_ret; /* no emergency and done recently. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1451 | rsp->n_force_qs++; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1452 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1453 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
Paul E. McKenney | 560d4bc | 2009-11-13 19:51:38 -0800 | [diff] [blame] | 1454 | if(!rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1455 | rsp->n_force_qs_ngp++; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1456 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1457 | goto unlock_fqs_ret; /* no GP in progress, time updated. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1458 | } |
Paul E. McKenney | 07079d5 | 2010-01-04 15:09:02 -0800 | [diff] [blame] | 1459 | rsp->fqs_active = 1; |
Paul E. McKenney | f3a8b5c | 2010-01-04 15:09:03 -0800 | [diff] [blame] | 1460 | switch (rsp->signaled) { |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 1461 | case RCU_GP_IDLE: |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1462 | case RCU_GP_INIT: |
| 1463 | |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 1464 | break; /* grace period idle or initializing, ignore. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1465 | |
| 1466 | case RCU_SAVE_DYNTICK: |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1467 | if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK) |
| 1468 | break; /* So gcc recognizes the dead code. */ |
| 1469 | |
Lai Jiangshan | f261414 | 2010-03-28 11:15:20 +0800 | [diff] [blame] | 1470 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
| 1471 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1472 | /* Record dyntick-idle state. */ |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1473 | force_qs_rnp(rsp, dyntick_save_progress_counter); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1474 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1475 | if (rcu_gp_in_progress(rsp)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1476 | rsp->signaled = RCU_FORCE_QS; |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1477 | break; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1478 | |
| 1479 | case RCU_FORCE_QS: |
| 1480 | |
| 1481 | /* Check dyntick-idle state, send IPI to laggarts. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1482 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1483 | force_qs_rnp(rsp, rcu_implicit_dynticks_qs); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1484 | |
| 1485 | /* Leave state in case more forcing is required. */ |
| 1486 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1487 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1488 | break; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1489 | } |
Paul E. McKenney | 07079d5 | 2010-01-04 15:09:02 -0800 | [diff] [blame] | 1490 | rsp->fqs_active = 0; |
Paul E. McKenney | 46a1e34 | 2010-01-04 15:09:09 -0800 | [diff] [blame] | 1491 | if (rsp->fqs_need_gp) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1492 | raw_spin_unlock(&rsp->fqslock); /* irqs remain disabled */ |
Paul E. McKenney | 46a1e34 | 2010-01-04 15:09:09 -0800 | [diff] [blame] | 1493 | rsp->fqs_need_gp = 0; |
| 1494 | rcu_start_gp(rsp, flags); /* releases rnp->lock */ |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1495 | trace_rcu_utilization("End fqs"); |
Paul E. McKenney | 46a1e34 | 2010-01-04 15:09:09 -0800 | [diff] [blame] | 1496 | return; |
| 1497 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1498 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1499 | unlock_fqs_ret: |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1500 | raw_spin_unlock_irqrestore(&rsp->fqslock, flags); |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1501 | trace_rcu_utilization("End fqs"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1502 | } |
| 1503 | |
| 1504 | #else /* #ifdef CONFIG_SMP */ |
| 1505 | |
| 1506 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) |
| 1507 | { |
| 1508 | set_need_resched(); |
| 1509 | } |
| 1510 | |
| 1511 | #endif /* #else #ifdef CONFIG_SMP */ |
| 1512 | |
| 1513 | /* |
Paul E. McKenney | e0f2306 | 2011-06-21 01:29:39 -0700 | [diff] [blame] | 1514 | * This does the RCU core processing work for the specified rcu_state |
| 1515 | * and rcu_data structures. This may be called only from the CPU to |
| 1516 | * whom the rdp belongs. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1517 | */ |
| 1518 | static void |
| 1519 | __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) |
| 1520 | { |
| 1521 | unsigned long flags; |
| 1522 | |
Paul E. McKenney | 2e59755 | 2009-08-15 09:53:48 -0700 | [diff] [blame] | 1523 | WARN_ON_ONCE(rdp->beenonline == 0); |
| 1524 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1525 | /* |
| 1526 | * If an RCU GP has gone long enough, go check for dyntick |
| 1527 | * idle CPUs and, if needed, send resched IPIs. |
| 1528 | */ |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1529 | if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1530 | force_quiescent_state(rsp, 1); |
| 1531 | |
| 1532 | /* |
| 1533 | * Advance callbacks in response to end of earlier grace |
| 1534 | * period that some other CPU ended. |
| 1535 | */ |
| 1536 | rcu_process_gp_end(rsp, rdp); |
| 1537 | |
| 1538 | /* Update RCU state based on any recent quiescent states. */ |
| 1539 | rcu_check_quiescent_state(rsp, rdp); |
| 1540 | |
| 1541 | /* Does this CPU require a not-yet-started grace period? */ |
| 1542 | if (cpu_needs_another_gp(rsp, rdp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1543 | raw_spin_lock_irqsave(&rcu_get_root(rsp)->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1544 | rcu_start_gp(rsp, flags); /* releases above lock */ |
| 1545 | } |
| 1546 | |
| 1547 | /* If there are callbacks ready, invoke them. */ |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 1548 | if (cpu_has_callbacks_ready_to_invoke(rdp)) |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1549 | invoke_rcu_callbacks(rsp, rdp); |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 1550 | } |
| 1551 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1552 | /* |
Paul E. McKenney | e0f2306 | 2011-06-21 01:29:39 -0700 | [diff] [blame] | 1553 | * Do RCU core processing for the current CPU. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1554 | */ |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 1555 | static void rcu_process_callbacks(struct softirq_action *unused) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1556 | { |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1557 | trace_rcu_utilization("Start RCU core"); |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1558 | __rcu_process_callbacks(&rcu_sched_state, |
| 1559 | &__get_cpu_var(rcu_sched_data)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1560 | __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] | 1561 | rcu_preempt_process_callbacks(); |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 1562 | trace_rcu_utilization("End RCU core"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1563 | } |
| 1564 | |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1565 | /* |
Paul E. McKenney | e0f2306 | 2011-06-21 01:29:39 -0700 | [diff] [blame] | 1566 | * Schedule RCU callback invocation. If the specified type of RCU |
| 1567 | * does not support RCU priority boosting, just do a direct call, |
| 1568 | * otherwise wake up the per-CPU kernel kthread. Note that because we |
| 1569 | * are running on the current CPU with interrupts disabled, the |
| 1570 | * rcu_cpu_kthread_task cannot disappear out from under us. |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1571 | */ |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1572 | 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] | 1573 | { |
Paul E. McKenney | b0d3041 | 2011-07-10 15:57:35 -0700 | [diff] [blame] | 1574 | if (unlikely(!ACCESS_ONCE(rcu_scheduler_fully_active))) |
| 1575 | return; |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1576 | if (likely(!rsp->boost)) { |
| 1577 | rcu_do_batch(rsp, rdp); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1578 | return; |
| 1579 | } |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1580 | invoke_rcu_callbacks_kthread(); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1581 | } |
| 1582 | |
Paul E. McKenney | a46e089 | 2011-06-15 15:47:09 -0700 | [diff] [blame] | 1583 | static void invoke_rcu_core(void) |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 1584 | { |
| 1585 | raise_softirq(RCU_SOFTIRQ); |
| 1586 | } |
| 1587 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1588 | static void |
| 1589 | __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), |
| 1590 | struct rcu_state *rsp) |
| 1591 | { |
| 1592 | unsigned long flags; |
| 1593 | struct rcu_data *rdp; |
| 1594 | |
Mathieu Desnoyers | 551d55a | 2010-04-17 08:48:42 -0400 | [diff] [blame] | 1595 | debug_rcu_head_queue(head); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1596 | head->func = func; |
| 1597 | head->next = NULL; |
| 1598 | |
| 1599 | smp_mb(); /* Ensure RCU update seen before callback registry. */ |
| 1600 | |
| 1601 | /* |
| 1602 | * Opportunistically note grace-period endings and beginnings. |
| 1603 | * Note that we might see a beginning right after we see an |
| 1604 | * end, but never vice versa, since this CPU has to pass through |
| 1605 | * a quiescent state betweentimes. |
| 1606 | */ |
| 1607 | local_irq_save(flags); |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1608 | rdp = this_cpu_ptr(rsp->rda); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1609 | |
| 1610 | /* Add the callback to our list. */ |
| 1611 | *rdp->nxttail[RCU_NEXT_TAIL] = head; |
| 1612 | rdp->nxttail[RCU_NEXT_TAIL] = &head->next; |
Paul E. McKenney | 2655d57 | 2011-04-07 22:47:23 -0700 | [diff] [blame] | 1613 | rdp->qlen++; |
| 1614 | |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 1615 | if (__is_kfree_rcu_offset((unsigned long)func)) |
| 1616 | trace_rcu_kfree_callback(rsp->name, head, (unsigned long)func, |
| 1617 | rdp->qlen); |
| 1618 | else |
| 1619 | trace_rcu_callback(rsp->name, head, rdp->qlen); |
| 1620 | |
Paul E. McKenney | 2655d57 | 2011-04-07 22:47:23 -0700 | [diff] [blame] | 1621 | /* If interrupts were disabled, don't dive into RCU core. */ |
| 1622 | if (irqs_disabled_flags(flags)) { |
| 1623 | local_irq_restore(flags); |
| 1624 | return; |
| 1625 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1626 | |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1627 | /* |
| 1628 | * Force the grace period if too many callbacks or too long waiting. |
| 1629 | * Enforce hysteresis, and don't invoke force_quiescent_state() |
| 1630 | * if some other CPU has recently done so. Also, don't bother |
| 1631 | * invoking force_quiescent_state() if the newly enqueued callback |
| 1632 | * is the only one waiting for a grace period to complete. |
| 1633 | */ |
Paul E. McKenney | 2655d57 | 2011-04-07 22:47:23 -0700 | [diff] [blame] | 1634 | if (unlikely(rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) { |
Paul E. McKenney | b52573d | 2010-12-14 17:36:02 -0800 | [diff] [blame] | 1635 | |
| 1636 | /* Are we ignoring a completed grace period? */ |
| 1637 | rcu_process_gp_end(rsp, rdp); |
| 1638 | check_for_new_grace_period(rsp, rdp); |
| 1639 | |
| 1640 | /* Start a new grace period if one not already started. */ |
| 1641 | if (!rcu_gp_in_progress(rsp)) { |
| 1642 | unsigned long nestflag; |
| 1643 | struct rcu_node *rnp_root = rcu_get_root(rsp); |
| 1644 | |
| 1645 | raw_spin_lock_irqsave(&rnp_root->lock, nestflag); |
| 1646 | rcu_start_gp(rsp, nestflag); /* rlses rnp_root->lock */ |
| 1647 | } else { |
| 1648 | /* Give the grace period a kick. */ |
| 1649 | rdp->blimit = LONG_MAX; |
| 1650 | if (rsp->n_force_qs == rdp->n_force_qs_snap && |
| 1651 | *rdp->nxttail[RCU_DONE_TAIL] != head) |
| 1652 | force_quiescent_state(rsp, 0); |
| 1653 | rdp->n_force_qs_snap = rsp->n_force_qs; |
| 1654 | rdp->qlen_last_fqs_check = rdp->qlen; |
| 1655 | } |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1656 | } 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] | 1657 | force_quiescent_state(rsp, 1); |
| 1658 | local_irq_restore(flags); |
| 1659 | } |
| 1660 | |
| 1661 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1662 | * Queue an RCU-sched callback for invocation after a grace period. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1663 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1664 | 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] | 1665 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1666 | __call_rcu(head, func, &rcu_sched_state); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1667 | } |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1668 | EXPORT_SYMBOL_GPL(call_rcu_sched); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1669 | |
| 1670 | /* |
| 1671 | * Queue an RCU for invocation after a quicker grace period. |
| 1672 | */ |
| 1673 | void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) |
| 1674 | { |
| 1675 | __call_rcu(head, func, &rcu_bh_state); |
| 1676 | } |
| 1677 | EXPORT_SYMBOL_GPL(call_rcu_bh); |
| 1678 | |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1679 | /** |
| 1680 | * synchronize_sched - wait until an rcu-sched grace period has elapsed. |
| 1681 | * |
| 1682 | * Control will return to the caller some time after a full rcu-sched |
| 1683 | * grace period has elapsed, in other words after all currently executing |
| 1684 | * rcu-sched read-side critical sections have completed. These read-side |
| 1685 | * critical sections are delimited by rcu_read_lock_sched() and |
| 1686 | * rcu_read_unlock_sched(), and may be nested. Note that preempt_disable(), |
| 1687 | * local_irq_disable(), and so on may be used in place of |
| 1688 | * rcu_read_lock_sched(). |
| 1689 | * |
| 1690 | * This means that all preempt_disable code sequences, including NMI and |
| 1691 | * hardware-interrupt handlers, in progress on entry will have completed |
| 1692 | * before this primitive returns. However, this does not guarantee that |
| 1693 | * softirq handlers will have completed, since in some kernels, these |
| 1694 | * handlers can run in process context, and can block. |
| 1695 | * |
| 1696 | * This primitive provides the guarantees made by the (now removed) |
| 1697 | * synchronize_kernel() API. In contrast, synchronize_rcu() only |
| 1698 | * guarantees that rcu_read_lock() sections will have completed. |
| 1699 | * In "classic RCU", these two guarantees happen to be one and |
| 1700 | * the same, but can differ in realtime RCU implementations. |
| 1701 | */ |
| 1702 | void synchronize_sched(void) |
| 1703 | { |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1704 | if (rcu_blocking_is_gp()) |
| 1705 | return; |
Paul E. McKenney | 2c42818 | 2011-05-26 22:14:36 -0700 | [diff] [blame] | 1706 | wait_rcu_gp(call_rcu_sched); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1707 | } |
| 1708 | EXPORT_SYMBOL_GPL(synchronize_sched); |
| 1709 | |
| 1710 | /** |
| 1711 | * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed. |
| 1712 | * |
| 1713 | * Control will return to the caller some time after a full rcu_bh grace |
| 1714 | * period has elapsed, in other words after all currently executing rcu_bh |
| 1715 | * read-side critical sections have completed. RCU read-side critical |
| 1716 | * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(), |
| 1717 | * and may be nested. |
| 1718 | */ |
| 1719 | void synchronize_rcu_bh(void) |
| 1720 | { |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1721 | if (rcu_blocking_is_gp()) |
| 1722 | return; |
Paul E. McKenney | 2c42818 | 2011-05-26 22:14:36 -0700 | [diff] [blame] | 1723 | wait_rcu_gp(call_rcu_bh); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1724 | } |
| 1725 | EXPORT_SYMBOL_GPL(synchronize_rcu_bh); |
| 1726 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1727 | /* |
| 1728 | * Check to see if there is any immediate RCU-related work to be done |
| 1729 | * by the current CPU, for the specified type of RCU, returning 1 if so. |
| 1730 | * The checks are in order of increasing expense: checks that can be |
| 1731 | * carried out against CPU-local state are performed first. However, |
| 1732 | * we must check for CPU stalls first, else we might not get a chance. |
| 1733 | */ |
| 1734 | static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) |
| 1735 | { |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 1736 | struct rcu_node *rnp = rdp->mynode; |
| 1737 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1738 | rdp->n_rcu_pending++; |
| 1739 | |
| 1740 | /* Check for CPU stalls, if enabled. */ |
| 1741 | check_cpu_stall(rsp, rdp); |
| 1742 | |
| 1743 | /* Is the RCU core waiting for a quiescent state from this CPU? */ |
Paul E. McKenney | 5c51dd7 | 2011-08-04 06:59:03 -0700 | [diff] [blame] | 1744 | if (rcu_scheduler_fully_active && |
| 1745 | rdp->qs_pending && !rdp->passed_quiesce) { |
Paul E. McKenney | d25eb94 | 2010-03-18 21:36:51 -0700 | [diff] [blame] | 1746 | |
| 1747 | /* |
| 1748 | * If force_quiescent_state() coming soon and this CPU |
| 1749 | * needs a quiescent state, and this is either RCU-sched |
| 1750 | * or RCU-bh, force a local reschedule. |
| 1751 | */ |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 1752 | rdp->n_rp_qs_pending++; |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 1753 | if (!rdp->preemptible && |
Paul E. McKenney | d25eb94 | 2010-03-18 21:36:51 -0700 | [diff] [blame] | 1754 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs) - 1, |
| 1755 | jiffies)) |
| 1756 | set_need_resched(); |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1757 | } else if (rdp->qs_pending && rdp->passed_quiesce) { |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 1758 | rdp->n_rp_report_qs++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1759 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1760 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1761 | |
| 1762 | /* Does this CPU have callbacks ready to invoke? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1763 | if (cpu_has_callbacks_ready_to_invoke(rdp)) { |
| 1764 | rdp->n_rp_cb_ready++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1765 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1766 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1767 | |
| 1768 | /* Has RCU gone idle with this CPU needing another grace period? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1769 | if (cpu_needs_another_gp(rsp, rdp)) { |
| 1770 | rdp->n_rp_cpu_needs_gp++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1771 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1772 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1773 | |
| 1774 | /* Has another RCU grace period completed? */ |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 1775 | if (ACCESS_ONCE(rnp->completed) != rdp->completed) { /* outside lock */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1776 | rdp->n_rp_gp_completed++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1777 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1778 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1779 | |
| 1780 | /* Has a new RCU grace period started? */ |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 1781 | if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum) { /* outside lock */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1782 | rdp->n_rp_gp_started++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1783 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1784 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1785 | |
| 1786 | /* 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] | 1787 | if (rcu_gp_in_progress(rsp) && |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1788 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) { |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1789 | rdp->n_rp_need_fqs++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1790 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1791 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1792 | |
| 1793 | /* nothing to do */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1794 | rdp->n_rp_need_nothing++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1795 | return 0; |
| 1796 | } |
| 1797 | |
| 1798 | /* |
| 1799 | * Check to see if there is any immediate RCU-related work to be done |
| 1800 | * by the current CPU, returning 1 if so. This function is part of the |
| 1801 | * RCU implementation; it is -not- an exported member of the RCU API. |
| 1802 | */ |
Paul E. McKenney | a157229 | 2009-08-22 13:56:51 -0700 | [diff] [blame] | 1803 | static int rcu_pending(int cpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1804 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1805 | 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] | 1806 | __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu)) || |
| 1807 | rcu_preempt_pending(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1808 | } |
| 1809 | |
| 1810 | /* |
| 1811 | * Check to see if any future RCU-related work will need to be done |
| 1812 | * 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] | 1813 | * 1 if so. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1814 | */ |
Paul E. McKenney | 8bd93a2 | 2010-02-22 17:04:59 -0800 | [diff] [blame] | 1815 | static int rcu_needs_cpu_quick_check(int cpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1816 | { |
| 1817 | /* RCU callbacks either ready or pending? */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1818 | return per_cpu(rcu_sched_data, cpu).nxtlist || |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1819 | per_cpu(rcu_bh_data, cpu).nxtlist || |
| 1820 | rcu_preempt_needs_cpu(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1821 | } |
| 1822 | |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1823 | static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL}; |
| 1824 | static atomic_t rcu_barrier_cpu_count; |
| 1825 | static DEFINE_MUTEX(rcu_barrier_mutex); |
| 1826 | static struct completion rcu_barrier_completion; |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1827 | |
| 1828 | static void rcu_barrier_callback(struct rcu_head *notused) |
| 1829 | { |
| 1830 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) |
| 1831 | complete(&rcu_barrier_completion); |
| 1832 | } |
| 1833 | |
| 1834 | /* |
| 1835 | * Called with preemption disabled, and from cross-cpu IRQ context. |
| 1836 | */ |
| 1837 | static void rcu_barrier_func(void *type) |
| 1838 | { |
| 1839 | int cpu = smp_processor_id(); |
| 1840 | struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu); |
| 1841 | void (*call_rcu_func)(struct rcu_head *head, |
| 1842 | void (*func)(struct rcu_head *head)); |
| 1843 | |
| 1844 | atomic_inc(&rcu_barrier_cpu_count); |
| 1845 | call_rcu_func = type; |
| 1846 | call_rcu_func(head, rcu_barrier_callback); |
| 1847 | } |
| 1848 | |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1849 | /* |
| 1850 | * Orchestrate the specified type of RCU barrier, waiting for all |
| 1851 | * RCU callbacks of the specified type to complete. |
| 1852 | */ |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1853 | static void _rcu_barrier(struct rcu_state *rsp, |
| 1854 | void (*call_rcu_func)(struct rcu_head *head, |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1855 | void (*func)(struct rcu_head *head))) |
| 1856 | { |
| 1857 | BUG_ON(in_interrupt()); |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1858 | /* Take mutex to serialize concurrent rcu_barrier() requests. */ |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1859 | mutex_lock(&rcu_barrier_mutex); |
| 1860 | init_completion(&rcu_barrier_completion); |
| 1861 | /* |
| 1862 | * Initialize rcu_barrier_cpu_count to 1, then invoke |
| 1863 | * rcu_barrier_func() on each CPU, so that each CPU also has |
| 1864 | * incremented rcu_barrier_cpu_count. Only then is it safe to |
| 1865 | * decrement rcu_barrier_cpu_count -- otherwise the first CPU |
| 1866 | * might complete its grace period before all of the other CPUs |
| 1867 | * did their increment, causing this function to return too |
Paul E. McKenney | 2d999e0 | 2010-10-20 12:06:18 -0700 | [diff] [blame] | 1868 | * early. Note that on_each_cpu() disables irqs, which prevents |
| 1869 | * any CPUs from coming online or going offline until each online |
| 1870 | * CPU has queued its RCU-barrier callback. |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1871 | */ |
| 1872 | atomic_set(&rcu_barrier_cpu_count, 1); |
| 1873 | on_each_cpu(rcu_barrier_func, (void *)call_rcu_func, 1); |
| 1874 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) |
| 1875 | complete(&rcu_barrier_completion); |
| 1876 | wait_for_completion(&rcu_barrier_completion); |
| 1877 | mutex_unlock(&rcu_barrier_mutex); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1878 | } |
| 1879 | |
| 1880 | /** |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1881 | * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete. |
| 1882 | */ |
| 1883 | void rcu_barrier_bh(void) |
| 1884 | { |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1885 | _rcu_barrier(&rcu_bh_state, call_rcu_bh); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1886 | } |
| 1887 | EXPORT_SYMBOL_GPL(rcu_barrier_bh); |
| 1888 | |
| 1889 | /** |
| 1890 | * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks. |
| 1891 | */ |
| 1892 | void rcu_barrier_sched(void) |
| 1893 | { |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1894 | _rcu_barrier(&rcu_sched_state, call_rcu_sched); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1895 | } |
| 1896 | EXPORT_SYMBOL_GPL(rcu_barrier_sched); |
| 1897 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1898 | /* |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1899 | * 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] | 1900 | */ |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1901 | static void __init |
| 1902 | rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1903 | { |
| 1904 | unsigned long flags; |
| 1905 | int i; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1906 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1907 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 1908 | |
| 1909 | /* Set up local state, ensuring consistent view of global state. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1910 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1911 | rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo); |
| 1912 | rdp->nxtlist = NULL; |
| 1913 | for (i = 0; i < RCU_NEXT_SIZE; i++) |
| 1914 | rdp->nxttail[i] = &rdp->nxtlist; |
| 1915 | rdp->qlen = 0; |
| 1916 | #ifdef CONFIG_NO_HZ |
| 1917 | rdp->dynticks = &per_cpu(rcu_dynticks, cpu); |
| 1918 | #endif /* #ifdef CONFIG_NO_HZ */ |
| 1919 | rdp->cpu = cpu; |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 1920 | rdp->rsp = rsp; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1921 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1922 | } |
| 1923 | |
| 1924 | /* |
| 1925 | * Initialize a CPU's per-CPU RCU data. Note that only one online or |
| 1926 | * offline event can be happening at a given time. Note also that we |
| 1927 | * can accept some slop in the rsp->completed access due to the fact |
| 1928 | * 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] | 1929 | */ |
| 1930 | static void __cpuinit |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 1931 | 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] | 1932 | { |
| 1933 | unsigned long flags; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1934 | unsigned long mask; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 1935 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1936 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 1937 | |
| 1938 | /* Set up local state, ensuring consistent view of global state. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1939 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1940 | rdp->beenonline = 1; /* We have now been online. */ |
Paul E. McKenney | 6cc6879 | 2011-03-02 13:15:15 -0800 | [diff] [blame] | 1941 | rdp->preemptible = preemptible; |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1942 | rdp->qlen_last_fqs_check = 0; |
| 1943 | rdp->n_force_qs_snap = rsp->n_force_qs; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1944 | rdp->blimit = blimit; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1945 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1946 | |
| 1947 | /* |
| 1948 | * A new grace period might start here. If so, we won't be part |
| 1949 | * of it, but that is OK, as we are currently in a quiescent state. |
| 1950 | */ |
| 1951 | |
| 1952 | /* Exclude any attempts to start a new GP on large systems. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1953 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1954 | |
| 1955 | /* Add CPU to rcu_node bitmasks. */ |
| 1956 | rnp = rdp->mynode; |
| 1957 | mask = rdp->grpmask; |
| 1958 | do { |
| 1959 | /* Exclude any attempts to start a new GP on small systems. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1960 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1961 | rnp->qsmaskinit |= mask; |
| 1962 | mask = rnp->grpmask; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 1963 | if (rnp == rdp->mynode) { |
Paul E. McKenney | 06ae115a | 2011-08-14 15:56:54 -0700 | [diff] [blame] | 1964 | /* |
| 1965 | * If there is a grace period in progress, we will |
| 1966 | * set up to wait for it next time we run the |
| 1967 | * RCU core code. |
| 1968 | */ |
| 1969 | rdp->gpnum = rnp->completed; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 1970 | rdp->completed = rnp->completed; |
Paul E. McKenney | 06ae115a | 2011-08-14 15:56:54 -0700 | [diff] [blame] | 1971 | rdp->passed_quiesce = 0; |
| 1972 | rdp->qs_pending = 0; |
Paul E. McKenney | e4cc1f2 | 2011-06-27 00:17:43 -0700 | [diff] [blame] | 1973 | rdp->passed_quiesce_gpnum = rnp->gpnum - 1; |
Paul E. McKenney | d4c08f2 | 2011-06-25 06:36:56 -0700 | [diff] [blame] | 1974 | trace_rcu_grace_period(rsp->name, rdp->gpnum, "cpuonl"); |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 1975 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1976 | raw_spin_unlock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1977 | rnp = rnp->parent; |
| 1978 | } while (rnp != NULL && !(rnp->qsmaskinit & mask)); |
| 1979 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1980 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1981 | } |
| 1982 | |
Peter Zijlstra | d72bce0 | 2011-05-30 13:34:51 +0200 | [diff] [blame] | 1983 | static void __cpuinit rcu_prepare_cpu(int cpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1984 | { |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1985 | rcu_init_percpu_data(cpu, &rcu_sched_state, 0); |
| 1986 | rcu_init_percpu_data(cpu, &rcu_bh_state, 0); |
| 1987 | rcu_preempt_init_percpu_data(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1988 | } |
| 1989 | |
| 1990 | /* |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1991 | * Handle CPU online/offline notification events. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1992 | */ |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 1993 | static int __cpuinit rcu_cpu_notify(struct notifier_block *self, |
| 1994 | unsigned long action, void *hcpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1995 | { |
| 1996 | long cpu = (long)hcpu; |
Paul E. McKenney | 27f4d28 | 2011-02-07 12:47:15 -0800 | [diff] [blame] | 1997 | struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 1998 | struct rcu_node *rnp = rdp->mynode; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1999 | |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 2000 | trace_rcu_utilization("Start CPU hotplug"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2001 | switch (action) { |
| 2002 | case CPU_UP_PREPARE: |
| 2003 | case CPU_UP_PREPARE_FROZEN: |
Peter Zijlstra | d72bce0 | 2011-05-30 13:34:51 +0200 | [diff] [blame] | 2004 | rcu_prepare_cpu(cpu); |
| 2005 | rcu_prepare_kthreads(cpu); |
Paul E. McKenney | a26ac24 | 2011-01-12 14:10:23 -0800 | [diff] [blame] | 2006 | break; |
| 2007 | case CPU_ONLINE: |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 2008 | case CPU_DOWN_FAILED: |
| 2009 | rcu_node_kthread_setaffinity(rnp, -1); |
Paul E. McKenney | e3995a2 | 2011-04-18 15:31:26 -0700 | [diff] [blame] | 2010 | rcu_cpu_kthread_setrt(cpu, 1); |
Paul E. McKenney | 0f962a5 | 2011-04-14 12:13:53 -0700 | [diff] [blame] | 2011 | break; |
| 2012 | case CPU_DOWN_PREPARE: |
| 2013 | rcu_node_kthread_setaffinity(rnp, cpu); |
Paul E. McKenney | e3995a2 | 2011-04-18 15:31:26 -0700 | [diff] [blame] | 2014 | rcu_cpu_kthread_setrt(cpu, 0); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2015 | break; |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2016 | case CPU_DYING: |
| 2017 | case CPU_DYING_FROZEN: |
| 2018 | /* |
Paul E. McKenney | 2d999e0 | 2010-10-20 12:06:18 -0700 | [diff] [blame] | 2019 | * The whole machine is "stopped" except this CPU, so we can |
| 2020 | * touch any data without introducing corruption. We send the |
| 2021 | * dying CPU's callbacks to an arbitrarily chosen online CPU. |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2022 | */ |
Lai Jiangshan | 29494be | 2010-10-20 14:13:06 +0800 | [diff] [blame] | 2023 | rcu_send_cbs_to_online(&rcu_bh_state); |
| 2024 | rcu_send_cbs_to_online(&rcu_sched_state); |
| 2025 | rcu_preempt_send_cbs_to_online(); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 2026 | break; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2027 | case CPU_DEAD: |
| 2028 | case CPU_DEAD_FROZEN: |
| 2029 | case CPU_UP_CANCELED: |
| 2030 | case CPU_UP_CANCELED_FROZEN: |
| 2031 | rcu_offline_cpu(cpu); |
| 2032 | break; |
| 2033 | default: |
| 2034 | break; |
| 2035 | } |
Paul E. McKenney | 300df91 | 2011-06-18 22:26:31 -0700 | [diff] [blame] | 2036 | trace_rcu_utilization("End CPU hotplug"); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2037 | return NOTIFY_OK; |
| 2038 | } |
| 2039 | |
| 2040 | /* |
Paul E. McKenney | bbad937 | 2010-04-02 16:17:17 -0700 | [diff] [blame] | 2041 | * This function is invoked towards the end of the scheduler's initialization |
| 2042 | * process. Before this is called, the idle task might contain |
| 2043 | * RCU read-side critical sections (during which time, this idle |
| 2044 | * task is booting the system). After this function is called, the |
| 2045 | * idle tasks are prohibited from containing RCU read-side critical |
| 2046 | * sections. This function also enables RCU lockdep checking. |
| 2047 | */ |
| 2048 | void rcu_scheduler_starting(void) |
| 2049 | { |
| 2050 | WARN_ON(num_online_cpus() != 1); |
| 2051 | WARN_ON(nr_context_switches() > 0); |
| 2052 | rcu_scheduler_active = 1; |
| 2053 | } |
| 2054 | |
| 2055 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2056 | * Compute the per-level fanout, either using the exact fanout specified |
| 2057 | * or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT. |
| 2058 | */ |
| 2059 | #ifdef CONFIG_RCU_FANOUT_EXACT |
| 2060 | static void __init rcu_init_levelspread(struct rcu_state *rsp) |
| 2061 | { |
| 2062 | int i; |
| 2063 | |
Paul E. McKenney | 0209f64 | 2010-12-14 16:07:52 -0800 | [diff] [blame] | 2064 | for (i = NUM_RCU_LVLS - 1; i > 0; i--) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2065 | rsp->levelspread[i] = CONFIG_RCU_FANOUT; |
Paul E. McKenney | 0209f64 | 2010-12-14 16:07:52 -0800 | [diff] [blame] | 2066 | rsp->levelspread[0] = RCU_FANOUT_LEAF; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2067 | } |
| 2068 | #else /* #ifdef CONFIG_RCU_FANOUT_EXACT */ |
| 2069 | static void __init rcu_init_levelspread(struct rcu_state *rsp) |
| 2070 | { |
| 2071 | int ccur; |
| 2072 | int cprv; |
| 2073 | int i; |
| 2074 | |
| 2075 | cprv = NR_CPUS; |
| 2076 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { |
| 2077 | ccur = rsp->levelcnt[i]; |
| 2078 | rsp->levelspread[i] = (cprv + ccur - 1) / ccur; |
| 2079 | cprv = ccur; |
| 2080 | } |
| 2081 | } |
| 2082 | #endif /* #else #ifdef CONFIG_RCU_FANOUT_EXACT */ |
| 2083 | |
| 2084 | /* |
| 2085 | * Helper function for rcu_init() that initializes one rcu_state structure. |
| 2086 | */ |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2087 | static void __init rcu_init_one(struct rcu_state *rsp, |
| 2088 | struct rcu_data __percpu *rda) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2089 | { |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 2090 | static char *buf[] = { "rcu_node_level_0", |
| 2091 | "rcu_node_level_1", |
| 2092 | "rcu_node_level_2", |
| 2093 | "rcu_node_level_3" }; /* Match MAX_RCU_LVLS */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2094 | int cpustride = 1; |
| 2095 | int i; |
| 2096 | int j; |
| 2097 | struct rcu_node *rnp; |
| 2098 | |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 2099 | BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */ |
| 2100 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2101 | /* Initialize the level-tracking arrays. */ |
| 2102 | |
| 2103 | for (i = 1; i < NUM_RCU_LVLS; i++) |
| 2104 | rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1]; |
| 2105 | rcu_init_levelspread(rsp); |
| 2106 | |
| 2107 | /* Initialize the elements themselves, starting from the leaves. */ |
| 2108 | |
| 2109 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { |
| 2110 | cpustride *= rsp->levelspread[i]; |
| 2111 | rnp = rsp->level[i]; |
| 2112 | for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 2113 | raw_spin_lock_init(&rnp->lock); |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 2114 | lockdep_set_class_and_name(&rnp->lock, |
| 2115 | &rcu_node_class[i], buf[i]); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2116 | rnp->gpnum = 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2117 | rnp->qsmask = 0; |
| 2118 | rnp->qsmaskinit = 0; |
| 2119 | rnp->grplo = j * cpustride; |
| 2120 | rnp->grphi = (j + 1) * cpustride - 1; |
| 2121 | if (rnp->grphi >= NR_CPUS) |
| 2122 | rnp->grphi = NR_CPUS - 1; |
| 2123 | if (i == 0) { |
| 2124 | rnp->grpnum = 0; |
| 2125 | rnp->grpmask = 0; |
| 2126 | rnp->parent = NULL; |
| 2127 | } else { |
| 2128 | rnp->grpnum = j % rsp->levelspread[i - 1]; |
| 2129 | rnp->grpmask = 1UL << rnp->grpnum; |
| 2130 | rnp->parent = rsp->level[i - 1] + |
| 2131 | j / rsp->levelspread[i - 1]; |
| 2132 | } |
| 2133 | rnp->level = i; |
Paul E. McKenney | 12f5f52 | 2010-11-29 21:56:39 -0800 | [diff] [blame] | 2134 | INIT_LIST_HEAD(&rnp->blkd_tasks); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2135 | } |
| 2136 | } |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 2137 | |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2138 | rsp->rda = rda; |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 2139 | rnp = rsp->level[NUM_RCU_LVLS - 1]; |
| 2140 | for_each_possible_cpu(i) { |
Paul E. McKenney | 4a90a06 | 2010-04-14 16:48:11 -0700 | [diff] [blame] | 2141 | while (i > rnp->grphi) |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 2142 | rnp++; |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2143 | per_cpu_ptr(rsp->rda, i)->mynode = rnp; |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 2144 | rcu_boot_init_percpu_data(i, rsp); |
| 2145 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2146 | } |
| 2147 | |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 2148 | void __init rcu_init(void) |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2149 | { |
Paul E. McKenney | 017c426 | 2010-01-14 16:10:58 -0800 | [diff] [blame] | 2150 | int cpu; |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 2151 | |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2152 | rcu_bootup_announce(); |
Lai Jiangshan | 394f99a | 2010-06-28 16:25:04 +0800 | [diff] [blame] | 2153 | rcu_init_one(&rcu_sched_state, &rcu_sched_data); |
| 2154 | rcu_init_one(&rcu_bh_state, &rcu_bh_data); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 2155 | __rcu_init_preempt(); |
Shaohua Li | 0922337 | 2011-06-14 13:26:25 +0800 | [diff] [blame] | 2156 | open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 2157 | |
| 2158 | /* |
| 2159 | * We don't need protection against CPU-hotplug here because |
| 2160 | * this is called early in boot, before either interrupts |
| 2161 | * or the scheduler are operational. |
| 2162 | */ |
| 2163 | cpu_notifier(rcu_cpu_notify, 0); |
Paul E. McKenney | 017c426 | 2010-01-14 16:10:58 -0800 | [diff] [blame] | 2164 | for_each_online_cpu(cpu) |
| 2165 | rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu); |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 2166 | check_cpu_stall_init(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 2167 | } |
| 2168 | |
Paul E. McKenney | 1eba8f8 | 2009-09-23 09:50:42 -0700 | [diff] [blame] | 2169 | #include "rcutree_plugin.h" |