Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Read-Copy Update mechanism for mutual exclusion |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation; either version 2 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, write to the Free Software |
| 16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 17 | * |
| 18 | * Copyright IBM Corporation, 2008 |
| 19 | * |
| 20 | * Authors: Dipankar Sarma <dipankar@in.ibm.com> |
| 21 | * Manfred Spraul <manfred@colorfullife.com> |
| 22 | * Paul E. McKenney <paulmck@linux.vnet.ibm.com> Hierarchical version |
| 23 | * |
| 24 | * Based on the original work by Paul McKenney <paulmck@us.ibm.com> |
| 25 | * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. |
| 26 | * |
| 27 | * For detailed explanation of Read-Copy Update mechanism see - |
Paul E. McKenney | a71fca5 | 2009-09-18 10:28:19 -0700 | [diff] [blame] | 28 | * Documentation/RCU |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 29 | */ |
| 30 | #include <linux/types.h> |
| 31 | #include <linux/kernel.h> |
| 32 | #include <linux/init.h> |
| 33 | #include <linux/spinlock.h> |
| 34 | #include <linux/smp.h> |
| 35 | #include <linux/rcupdate.h> |
| 36 | #include <linux/interrupt.h> |
| 37 | #include <linux/sched.h> |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 38 | #include <linux/nmi.h> |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 39 | #include <asm/atomic.h> |
| 40 | #include <linux/bitops.h> |
| 41 | #include <linux/module.h> |
| 42 | #include <linux/completion.h> |
| 43 | #include <linux/moduleparam.h> |
| 44 | #include <linux/percpu.h> |
| 45 | #include <linux/notifier.h> |
| 46 | #include <linux/cpu.h> |
| 47 | #include <linux/mutex.h> |
| 48 | #include <linux/time.h> |
Paul E. McKenney | bbad937 | 2010-04-02 16:17:17 -0700 | [diff] [blame] | 49 | #include <linux/kernel_stat.h> |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 50 | |
Paul E. McKenney | 9f77da9 | 2009-08-22 13:56:45 -0700 | [diff] [blame] | 51 | #include "rcutree.h" |
| 52 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 53 | /* Data structures. */ |
| 54 | |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 55 | static struct lock_class_key rcu_node_class[NUM_RCU_LVLS]; |
Peter Zijlstra | 88b91c7 | 2009-10-26 10:24:31 -0700 | [diff] [blame] | 56 | |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 57 | #define RCU_STATE_INITIALIZER(structname) { \ |
| 58 | .level = { &structname.node[0] }, \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 59 | .levelcnt = { \ |
| 60 | NUM_RCU_LVL_0, /* root of hierarchy. */ \ |
| 61 | NUM_RCU_LVL_1, \ |
| 62 | NUM_RCU_LVL_2, \ |
Paul E. McKenney | cf244dc | 2009-12-02 12:10:14 -0800 | [diff] [blame] | 63 | NUM_RCU_LVL_3, \ |
| 64 | NUM_RCU_LVL_4, /* == MAX_RCU_LVLS */ \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 65 | }, \ |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 66 | .signaled = RCU_GP_IDLE, \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 67 | .gpnum = -300, \ |
| 68 | .completed = -300, \ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 69 | .onofflock = __RAW_SPIN_LOCK_UNLOCKED(&structname.onofflock), \ |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 70 | .orphan_cbs_list = NULL, \ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 71 | .orphan_cbs_tail = &structname.orphan_cbs_list, \ |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 72 | .orphan_qlen = 0, \ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 73 | .fqslock = __RAW_SPIN_LOCK_UNLOCKED(&structname.fqslock), \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 74 | .n_force_qs = 0, \ |
| 75 | .n_force_qs_ngp = 0, \ |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 76 | .name = #structname, \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 77 | } |
| 78 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 79 | struct rcu_state rcu_sched_state = RCU_STATE_INITIALIZER(rcu_sched_state); |
| 80 | DEFINE_PER_CPU(struct rcu_data, rcu_sched_data); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 81 | |
Ingo Molnar | 6258c4f | 2009-03-25 16:42:24 +0100 | [diff] [blame] | 82 | struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state); |
| 83 | DEFINE_PER_CPU(struct rcu_data, rcu_bh_data); |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 84 | |
Paul E. McKenney | bbad937 | 2010-04-02 16:17:17 -0700 | [diff] [blame] | 85 | int rcu_scheduler_active __read_mostly; |
| 86 | EXPORT_SYMBOL_GPL(rcu_scheduler_active); |
| 87 | |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 88 | /* |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 89 | * Return true if an RCU grace period is in progress. The ACCESS_ONCE()s |
| 90 | * permit this function to be invoked without holding the root rcu_node |
| 91 | * structure's ->lock, but of course results can be subject to change. |
| 92 | */ |
| 93 | static int rcu_gp_in_progress(struct rcu_state *rsp) |
| 94 | { |
| 95 | return ACCESS_ONCE(rsp->completed) != ACCESS_ONCE(rsp->gpnum); |
| 96 | } |
| 97 | |
| 98 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 99 | * Note a quiescent state. Because we do not need to know |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 100 | * how many quiescent states passed, just if there was at least |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 101 | * one since the start of the grace period, this just sets a flag. |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 102 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 103 | void rcu_sched_qs(int cpu) |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 104 | { |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 105 | struct rcu_data *rdp = &per_cpu(rcu_sched_data, cpu); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 106 | |
Paul E. McKenney | c64ac3c | 2009-11-10 13:37:22 -0800 | [diff] [blame] | 107 | rdp->passed_quiesc_completed = rdp->gpnum - 1; |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 108 | barrier(); |
| 109 | rdp->passed_quiesc = 1; |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 110 | } |
| 111 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 112 | void rcu_bh_qs(int cpu) |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 113 | { |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 114 | struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 115 | |
Paul E. McKenney | c64ac3c | 2009-11-10 13:37:22 -0800 | [diff] [blame] | 116 | rdp->passed_quiesc_completed = rdp->gpnum - 1; |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 117 | barrier(); |
| 118 | rdp->passed_quiesc = 1; |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 119 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 120 | |
Paul E. McKenney | 25502a6 | 2010-04-01 17:37:01 -0700 | [diff] [blame] | 121 | /* |
| 122 | * Note a context switch. This is a quiescent state for RCU-sched, |
| 123 | * and requires special handling for preemptible RCU. |
| 124 | */ |
| 125 | void rcu_note_context_switch(int cpu) |
| 126 | { |
| 127 | rcu_sched_qs(cpu); |
| 128 | rcu_preempt_note_context_switch(cpu); |
| 129 | } |
| 130 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 131 | #ifdef CONFIG_NO_HZ |
Paul E. McKenney | 90a4d2c | 2009-01-04 11:41:11 -0800 | [diff] [blame] | 132 | DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { |
| 133 | .dynticks_nesting = 1, |
| 134 | .dynticks = 1, |
| 135 | }; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 136 | #endif /* #ifdef CONFIG_NO_HZ */ |
| 137 | |
| 138 | static int blimit = 10; /* Maximum callbacks per softirq. */ |
| 139 | static int qhimark = 10000; /* If this many pending, ignore blimit. */ |
| 140 | static int qlowmark = 100; /* Once only this many pending, use blimit. */ |
| 141 | |
Paul E. McKenney | 3d76c08 | 2009-09-28 07:46:32 -0700 | [diff] [blame] | 142 | module_param(blimit, int, 0); |
| 143 | module_param(qhimark, int, 0); |
| 144 | module_param(qlowmark, int, 0); |
| 145 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 146 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed); |
Paul E. McKenney | a157229 | 2009-08-22 13:56:51 -0700 | [diff] [blame] | 147 | static int rcu_pending(int cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 148 | |
| 149 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 150 | * 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] | 151 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 152 | long rcu_batches_completed_sched(void) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 153 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 154 | return rcu_sched_state.completed; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 155 | } |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 156 | EXPORT_SYMBOL_GPL(rcu_batches_completed_sched); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 157 | |
| 158 | /* |
| 159 | * Return the number of RCU BH batches processed thus far for debug & stats. |
| 160 | */ |
| 161 | long rcu_batches_completed_bh(void) |
| 162 | { |
| 163 | return rcu_bh_state.completed; |
| 164 | } |
| 165 | EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); |
| 166 | |
| 167 | /* |
Paul E. McKenney | bf66f18 | 2010-01-04 15:09:10 -0800 | [diff] [blame] | 168 | * Force a quiescent state for RCU BH. |
| 169 | */ |
| 170 | void rcu_bh_force_quiescent_state(void) |
| 171 | { |
| 172 | force_quiescent_state(&rcu_bh_state, 0); |
| 173 | } |
| 174 | EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state); |
| 175 | |
| 176 | /* |
| 177 | * Force a quiescent state for RCU-sched. |
| 178 | */ |
| 179 | void rcu_sched_force_quiescent_state(void) |
| 180 | { |
| 181 | force_quiescent_state(&rcu_sched_state, 0); |
| 182 | } |
| 183 | EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state); |
| 184 | |
| 185 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 186 | * Does the CPU have callbacks ready to be invoked? |
| 187 | */ |
| 188 | static int |
| 189 | cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp) |
| 190 | { |
| 191 | return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]; |
| 192 | } |
| 193 | |
| 194 | /* |
| 195 | * Does the current CPU require a yet-as-unscheduled grace period? |
| 196 | */ |
| 197 | static int |
| 198 | cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp) |
| 199 | { |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 200 | return *rdp->nxttail[RCU_DONE_TAIL] && !rcu_gp_in_progress(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 201 | } |
| 202 | |
| 203 | /* |
| 204 | * Return the root node of the specified rcu_state structure. |
| 205 | */ |
| 206 | static struct rcu_node *rcu_get_root(struct rcu_state *rsp) |
| 207 | { |
| 208 | return &rsp->node[0]; |
| 209 | } |
| 210 | |
| 211 | #ifdef CONFIG_SMP |
| 212 | |
| 213 | /* |
| 214 | * If the specified CPU is offline, tell the caller that it is in |
| 215 | * a quiescent state. Otherwise, whack it with a reschedule IPI. |
| 216 | * Grace periods can end up waiting on an offline CPU when that |
| 217 | * CPU is in the process of coming online -- it will be added to the |
| 218 | * rcu_node bitmasks before it actually makes it online. The same thing |
| 219 | * can happen while a CPU is in the process of coming online. Because this |
| 220 | * race is quite rare, we check for it after detecting that the grace |
| 221 | * period has been delayed rather than checking each and every CPU |
| 222 | * each and every time we start a new grace period. |
| 223 | */ |
| 224 | static int rcu_implicit_offline_qs(struct rcu_data *rdp) |
| 225 | { |
| 226 | /* |
| 227 | * If the CPU is offline, it is in a quiescent state. We can |
| 228 | * trust its state not to change because interrupts are disabled. |
| 229 | */ |
| 230 | if (cpu_is_offline(rdp->cpu)) { |
| 231 | rdp->offline_fqs++; |
| 232 | return 1; |
| 233 | } |
| 234 | |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 235 | /* If preemptable RCU, no point in sending reschedule IPI. */ |
| 236 | if (rdp->preemptable) |
| 237 | return 0; |
| 238 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 239 | /* The CPU is online, so send it a reschedule IPI. */ |
| 240 | if (rdp->cpu != smp_processor_id()) |
| 241 | smp_send_reschedule(rdp->cpu); |
| 242 | else |
| 243 | set_need_resched(); |
| 244 | rdp->resched_ipi++; |
| 245 | return 0; |
| 246 | } |
| 247 | |
| 248 | #endif /* #ifdef CONFIG_SMP */ |
| 249 | |
| 250 | #ifdef CONFIG_NO_HZ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 251 | |
| 252 | /** |
| 253 | * rcu_enter_nohz - inform RCU that current CPU is entering nohz |
| 254 | * |
| 255 | * Enter nohz mode, in other words, -leave- the mode in which RCU |
| 256 | * read-side critical sections can occur. (Though RCU read-side |
| 257 | * critical sections can occur in irq handlers in nohz mode, a possibility |
| 258 | * handled by rcu_irq_enter() and rcu_irq_exit()). |
| 259 | */ |
| 260 | void rcu_enter_nohz(void) |
| 261 | { |
| 262 | unsigned long flags; |
| 263 | struct rcu_dynticks *rdtp; |
| 264 | |
| 265 | smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ |
| 266 | local_irq_save(flags); |
| 267 | rdtp = &__get_cpu_var(rcu_dynticks); |
| 268 | rdtp->dynticks++; |
| 269 | rdtp->dynticks_nesting--; |
Paul E. McKenney | 8684896 | 2009-08-27 15:00:12 -0700 | [diff] [blame] | 270 | WARN_ON_ONCE(rdtp->dynticks & 0x1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 271 | local_irq_restore(flags); |
| 272 | } |
| 273 | |
| 274 | /* |
| 275 | * rcu_exit_nohz - inform RCU that current CPU is leaving nohz |
| 276 | * |
| 277 | * Exit nohz mode, in other words, -enter- the mode in which RCU |
| 278 | * read-side critical sections normally occur. |
| 279 | */ |
| 280 | void rcu_exit_nohz(void) |
| 281 | { |
| 282 | unsigned long flags; |
| 283 | struct rcu_dynticks *rdtp; |
| 284 | |
| 285 | local_irq_save(flags); |
| 286 | rdtp = &__get_cpu_var(rcu_dynticks); |
| 287 | rdtp->dynticks++; |
| 288 | rdtp->dynticks_nesting++; |
Paul E. McKenney | 8684896 | 2009-08-27 15:00:12 -0700 | [diff] [blame] | 289 | WARN_ON_ONCE(!(rdtp->dynticks & 0x1)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 290 | local_irq_restore(flags); |
| 291 | smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ |
| 292 | } |
| 293 | |
| 294 | /** |
| 295 | * rcu_nmi_enter - inform RCU of entry to NMI context |
| 296 | * |
| 297 | * If the CPU was idle with dynamic ticks active, and there is no |
| 298 | * irq handler running, this updates rdtp->dynticks_nmi to let the |
| 299 | * RCU grace-period handling know that the CPU is active. |
| 300 | */ |
| 301 | void rcu_nmi_enter(void) |
| 302 | { |
| 303 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 304 | |
| 305 | if (rdtp->dynticks & 0x1) |
| 306 | return; |
| 307 | rdtp->dynticks_nmi++; |
Paul E. McKenney | 8684896 | 2009-08-27 15:00:12 -0700 | [diff] [blame] | 308 | WARN_ON_ONCE(!(rdtp->dynticks_nmi & 0x1)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 309 | smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ |
| 310 | } |
| 311 | |
| 312 | /** |
| 313 | * rcu_nmi_exit - inform RCU of exit from NMI context |
| 314 | * |
| 315 | * If the CPU was idle with dynamic ticks active, and there is no |
| 316 | * irq handler running, this updates rdtp->dynticks_nmi to let the |
| 317 | * RCU grace-period handling know that the CPU is no longer active. |
| 318 | */ |
| 319 | void rcu_nmi_exit(void) |
| 320 | { |
| 321 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 322 | |
| 323 | if (rdtp->dynticks & 0x1) |
| 324 | return; |
| 325 | smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ |
| 326 | rdtp->dynticks_nmi++; |
Paul E. McKenney | 8684896 | 2009-08-27 15:00:12 -0700 | [diff] [blame] | 327 | WARN_ON_ONCE(rdtp->dynticks_nmi & 0x1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 328 | } |
| 329 | |
| 330 | /** |
| 331 | * rcu_irq_enter - inform RCU of entry to hard irq context |
| 332 | * |
| 333 | * If the CPU was idle with dynamic ticks active, this updates the |
| 334 | * rdtp->dynticks to let the RCU handling know that the CPU is active. |
| 335 | */ |
| 336 | void rcu_irq_enter(void) |
| 337 | { |
| 338 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 339 | |
| 340 | if (rdtp->dynticks_nesting++) |
| 341 | return; |
| 342 | rdtp->dynticks++; |
Paul E. McKenney | 8684896 | 2009-08-27 15:00:12 -0700 | [diff] [blame] | 343 | WARN_ON_ONCE(!(rdtp->dynticks & 0x1)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 344 | smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ |
| 345 | } |
| 346 | |
| 347 | /** |
| 348 | * rcu_irq_exit - inform RCU of exit from hard irq context |
| 349 | * |
| 350 | * If the CPU was idle with dynamic ticks active, update the rdp->dynticks |
| 351 | * to put let the RCU handling be aware that the CPU is going back to idle |
| 352 | * with no ticks. |
| 353 | */ |
| 354 | void rcu_irq_exit(void) |
| 355 | { |
| 356 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 357 | |
| 358 | if (--rdtp->dynticks_nesting) |
| 359 | return; |
| 360 | smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ |
| 361 | rdtp->dynticks++; |
Paul E. McKenney | 8684896 | 2009-08-27 15:00:12 -0700 | [diff] [blame] | 362 | WARN_ON_ONCE(rdtp->dynticks & 0x1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 363 | |
| 364 | /* If the interrupt queued a callback, get out of dyntick mode. */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 365 | if (__get_cpu_var(rcu_sched_data).nxtlist || |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 366 | __get_cpu_var(rcu_bh_data).nxtlist) |
| 367 | set_need_resched(); |
| 368 | } |
| 369 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 370 | #ifdef CONFIG_SMP |
| 371 | |
| 372 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 373 | * Snapshot the specified CPU's dynticks counter so that we can later |
| 374 | * 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] | 375 | * is in dynticks idle mode, which is an extended quiescent state. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 376 | */ |
| 377 | static int dyntick_save_progress_counter(struct rcu_data *rdp) |
| 378 | { |
| 379 | int ret; |
| 380 | int snap; |
| 381 | int snap_nmi; |
| 382 | |
| 383 | snap = rdp->dynticks->dynticks; |
| 384 | snap_nmi = rdp->dynticks->dynticks_nmi; |
| 385 | smp_mb(); /* Order sampling of snap with end of grace period. */ |
| 386 | rdp->dynticks_snap = snap; |
| 387 | rdp->dynticks_nmi_snap = snap_nmi; |
| 388 | ret = ((snap & 0x1) == 0) && ((snap_nmi & 0x1) == 0); |
| 389 | if (ret) |
| 390 | rdp->dynticks_fqs++; |
| 391 | return ret; |
| 392 | } |
| 393 | |
| 394 | /* |
| 395 | * Return true if the specified CPU has passed through a quiescent |
| 396 | * state by virtue of being in or having passed through an dynticks |
| 397 | * idle state since the last call to dyntick_save_progress_counter() |
| 398 | * for this same CPU. |
| 399 | */ |
| 400 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) |
| 401 | { |
| 402 | long curr; |
| 403 | long curr_nmi; |
| 404 | long snap; |
| 405 | long snap_nmi; |
| 406 | |
| 407 | curr = rdp->dynticks->dynticks; |
| 408 | snap = rdp->dynticks_snap; |
| 409 | curr_nmi = rdp->dynticks->dynticks_nmi; |
| 410 | snap_nmi = rdp->dynticks_nmi_snap; |
| 411 | smp_mb(); /* force ordering with cpu entering/leaving dynticks. */ |
| 412 | |
| 413 | /* |
| 414 | * If the CPU passed through or entered a dynticks idle phase with |
| 415 | * no active irq/NMI handlers, then we can safely pretend that the CPU |
| 416 | * already acknowledged the request to pass through a quiescent |
| 417 | * state. Either way, that CPU cannot possibly be in an RCU |
| 418 | * read-side critical section that started before the beginning |
| 419 | * of the current RCU grace period. |
| 420 | */ |
| 421 | if ((curr != snap || (curr & 0x1) == 0) && |
| 422 | (curr_nmi != snap_nmi || (curr_nmi & 0x1) == 0)) { |
| 423 | rdp->dynticks_fqs++; |
| 424 | return 1; |
| 425 | } |
| 426 | |
| 427 | /* Go check for the CPU being offline. */ |
| 428 | return rcu_implicit_offline_qs(rdp); |
| 429 | } |
| 430 | |
| 431 | #endif /* #ifdef CONFIG_SMP */ |
| 432 | |
| 433 | #else /* #ifdef CONFIG_NO_HZ */ |
| 434 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 435 | #ifdef CONFIG_SMP |
| 436 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 437 | static int dyntick_save_progress_counter(struct rcu_data *rdp) |
| 438 | { |
| 439 | return 0; |
| 440 | } |
| 441 | |
| 442 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) |
| 443 | { |
| 444 | return rcu_implicit_offline_qs(rdp); |
| 445 | } |
| 446 | |
| 447 | #endif /* #ifdef CONFIG_SMP */ |
| 448 | |
| 449 | #endif /* #else #ifdef CONFIG_NO_HZ */ |
| 450 | |
| 451 | #ifdef CONFIG_RCU_CPU_STALL_DETECTOR |
| 452 | |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 453 | int rcu_cpu_stall_panicking __read_mostly; |
| 454 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 455 | static void record_gp_stall_check_time(struct rcu_state *rsp) |
| 456 | { |
| 457 | rsp->gp_start = jiffies; |
| 458 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_CHECK; |
| 459 | } |
| 460 | |
| 461 | static void print_other_cpu_stall(struct rcu_state *rsp) |
| 462 | { |
| 463 | int cpu; |
| 464 | long delta; |
| 465 | unsigned long flags; |
| 466 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 467 | |
| 468 | /* Only let one CPU complain about others per time interval. */ |
| 469 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 470 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 471 | delta = jiffies - rsp->jiffies_stall; |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 472 | if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 473 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 474 | return; |
| 475 | } |
| 476 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_RECHECK; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 477 | |
| 478 | /* |
| 479 | * Now rat on any tasks that got kicked up to the root rcu_node |
| 480 | * due to CPU offlining. |
| 481 | */ |
| 482 | rcu_print_task_stall(rnp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 483 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 484 | |
| 485 | /* OK, time to rat on our buddy... */ |
| 486 | |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 487 | printk(KERN_ERR "INFO: %s detected stalls on CPUs/tasks: {", |
| 488 | rsp->name); |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 489 | rcu_for_each_leaf_node(rsp, rnp) { |
Paul E. McKenney | 3acd9eb | 2010-02-22 17:05:03 -0800 | [diff] [blame] | 490 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 491 | rcu_print_task_stall(rnp); |
Paul E. McKenney | 3acd9eb | 2010-02-22 17:05:03 -0800 | [diff] [blame] | 492 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 493 | if (rnp->qsmask == 0) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 494 | continue; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 495 | for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++) |
| 496 | if (rnp->qsmask & (1UL << cpu)) |
| 497 | printk(" %d", rnp->grplo + cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 498 | } |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 499 | printk("} (detected by %d, t=%ld jiffies)\n", |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 500 | smp_processor_id(), (long)(jiffies - rsp->gp_start)); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 501 | trigger_all_cpu_backtrace(); |
| 502 | |
Paul E. McKenney | 1ed509a | 2010-02-22 17:05:05 -0800 | [diff] [blame] | 503 | /* If so configured, complain about tasks blocking the grace period. */ |
| 504 | |
| 505 | rcu_print_detail_task_stall(rsp); |
| 506 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 507 | force_quiescent_state(rsp, 0); /* Kick them all. */ |
| 508 | } |
| 509 | |
| 510 | static void print_cpu_stall(struct rcu_state *rsp) |
| 511 | { |
| 512 | unsigned long flags; |
| 513 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 514 | |
Paul E. McKenney | 4300aa6 | 2010-04-13 16:18:22 -0700 | [diff] [blame] | 515 | printk(KERN_ERR "INFO: %s detected stall on CPU %d (t=%lu jiffies)\n", |
| 516 | rsp->name, smp_processor_id(), jiffies - rsp->gp_start); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 517 | trigger_all_cpu_backtrace(); |
| 518 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 519 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 520 | if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 521 | rsp->jiffies_stall = |
| 522 | jiffies + RCU_SECONDS_TILL_STALL_RECHECK; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 523 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 524 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 525 | set_need_resched(); /* kick ourselves to get things going. */ |
| 526 | } |
| 527 | |
| 528 | static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) |
| 529 | { |
| 530 | long delta; |
| 531 | struct rcu_node *rnp; |
| 532 | |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 533 | if (rcu_cpu_stall_panicking) |
| 534 | return; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 535 | delta = jiffies - rsp->jiffies_stall; |
| 536 | rnp = rdp->mynode; |
| 537 | if ((rnp->qsmask & rdp->grpmask) && delta >= 0) { |
| 538 | |
| 539 | /* We haven't checked in, so go dump stack. */ |
| 540 | print_cpu_stall(rsp); |
| 541 | |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 542 | } else if (rcu_gp_in_progress(rsp) && delta >= RCU_STALL_RAT_DELAY) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 543 | |
| 544 | /* They had two time units to dump stack, so complain. */ |
| 545 | print_other_cpu_stall(rsp); |
| 546 | } |
| 547 | } |
| 548 | |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 549 | static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr) |
| 550 | { |
| 551 | rcu_cpu_stall_panicking = 1; |
| 552 | return NOTIFY_DONE; |
| 553 | } |
| 554 | |
| 555 | static struct notifier_block rcu_panic_block = { |
| 556 | .notifier_call = rcu_panic, |
| 557 | }; |
| 558 | |
| 559 | static void __init check_cpu_stall_init(void) |
| 560 | { |
| 561 | atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block); |
| 562 | } |
| 563 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 564 | #else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ |
| 565 | |
| 566 | static void record_gp_stall_check_time(struct rcu_state *rsp) |
| 567 | { |
| 568 | } |
| 569 | |
| 570 | static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) |
| 571 | { |
| 572 | } |
| 573 | |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 574 | static void __init check_cpu_stall_init(void) |
| 575 | { |
| 576 | } |
| 577 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 578 | #endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ |
| 579 | |
| 580 | /* |
| 581 | * Update CPU-local rcu_data state to record the newly noticed grace period. |
| 582 | * 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] | 583 | * that someone else started the grace period. The caller must hold the |
| 584 | * ->lock of the leaf rcu_node structure corresponding to the current CPU, |
| 585 | * and must have irqs disabled. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 586 | */ |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 587 | static void __note_new_gpnum(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
| 588 | { |
| 589 | if (rdp->gpnum != rnp->gpnum) { |
| 590 | rdp->qs_pending = 1; |
| 591 | rdp->passed_quiesc = 0; |
| 592 | rdp->gpnum = rnp->gpnum; |
| 593 | } |
| 594 | } |
| 595 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 596 | static void note_new_gpnum(struct rcu_state *rsp, struct rcu_data *rdp) |
| 597 | { |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 598 | unsigned long flags; |
| 599 | struct rcu_node *rnp; |
| 600 | |
| 601 | local_irq_save(flags); |
| 602 | rnp = rdp->mynode; |
| 603 | if (rdp->gpnum == ACCESS_ONCE(rnp->gpnum) || /* outside lock. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 604 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 605 | local_irq_restore(flags); |
| 606 | return; |
| 607 | } |
| 608 | __note_new_gpnum(rsp, rnp, rdp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 609 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 610 | } |
| 611 | |
| 612 | /* |
| 613 | * Did someone else start a new RCU grace period start since we last |
| 614 | * checked? Update local state appropriately if so. Must be called |
| 615 | * on the CPU corresponding to rdp. |
| 616 | */ |
| 617 | static int |
| 618 | check_for_new_grace_period(struct rcu_state *rsp, struct rcu_data *rdp) |
| 619 | { |
| 620 | unsigned long flags; |
| 621 | int ret = 0; |
| 622 | |
| 623 | local_irq_save(flags); |
| 624 | if (rdp->gpnum != rsp->gpnum) { |
| 625 | note_new_gpnum(rsp, rdp); |
| 626 | ret = 1; |
| 627 | } |
| 628 | local_irq_restore(flags); |
| 629 | return ret; |
| 630 | } |
| 631 | |
| 632 | /* |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 633 | * Advance this CPU's callbacks, but only if the current grace period |
| 634 | * has ended. This may be called only from the CPU to whom the rdp |
| 635 | * belongs. In addition, the corresponding leaf rcu_node structure's |
| 636 | * ->lock must be held by the caller, with irqs disabled. |
| 637 | */ |
| 638 | static void |
| 639 | __rcu_process_gp_end(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
| 640 | { |
| 641 | /* Did another grace period end? */ |
| 642 | if (rdp->completed != rnp->completed) { |
| 643 | |
| 644 | /* Advance callbacks. No harm if list empty. */ |
| 645 | rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL]; |
| 646 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL]; |
| 647 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 648 | |
| 649 | /* Remember that we saw this grace-period completion. */ |
| 650 | rdp->completed = rnp->completed; |
| 651 | } |
| 652 | } |
| 653 | |
| 654 | /* |
| 655 | * Advance this CPU's callbacks, but only if the current grace period |
| 656 | * has ended. This may be called only from the CPU to whom the rdp |
| 657 | * belongs. |
| 658 | */ |
| 659 | static void |
| 660 | rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp) |
| 661 | { |
| 662 | unsigned long flags; |
| 663 | struct rcu_node *rnp; |
| 664 | |
| 665 | local_irq_save(flags); |
| 666 | rnp = rdp->mynode; |
| 667 | if (rdp->completed == ACCESS_ONCE(rnp->completed) || /* outside lock. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 668 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 669 | local_irq_restore(flags); |
| 670 | return; |
| 671 | } |
| 672 | __rcu_process_gp_end(rsp, rnp, rdp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 673 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 674 | } |
| 675 | |
| 676 | /* |
| 677 | * Do per-CPU grace-period initialization for running CPU. The caller |
| 678 | * must hold the lock of the leaf rcu_node structure corresponding to |
| 679 | * this CPU. |
| 680 | */ |
| 681 | static void |
| 682 | rcu_start_gp_per_cpu(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
| 683 | { |
| 684 | /* Prior grace period ended, so advance callbacks for current CPU. */ |
| 685 | __rcu_process_gp_end(rsp, rnp, rdp); |
| 686 | |
| 687 | /* |
| 688 | * Because this CPU just now started the new grace period, we know |
| 689 | * that all of its callbacks will be covered by this upcoming grace |
| 690 | * period, even the ones that were registered arbitrarily recently. |
| 691 | * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL. |
| 692 | * |
| 693 | * Other CPUs cannot be sure exactly when the grace period started. |
| 694 | * Therefore, their recently registered callbacks must pass through |
| 695 | * an additional RCU_NEXT_READY stage, so that they will be handled |
| 696 | * by the next RCU grace period. |
| 697 | */ |
| 698 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 699 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
Paul E. McKenney | 9160306 | 2009-11-02 13:52:29 -0800 | [diff] [blame] | 700 | |
| 701 | /* Set state so that this CPU will detect the next quiescent state. */ |
| 702 | __note_new_gpnum(rsp, rnp, rdp); |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 703 | } |
| 704 | |
| 705 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 706 | * Start a new RCU grace period if warranted, re-initializing the hierarchy |
| 707 | * in preparation for detecting the next grace period. The caller must hold |
| 708 | * the root node's ->lock, which is released before return. Hard irqs must |
| 709 | * be disabled. |
| 710 | */ |
| 711 | static void |
| 712 | rcu_start_gp(struct rcu_state *rsp, unsigned long flags) |
| 713 | __releases(rcu_get_root(rsp)->lock) |
| 714 | { |
| 715 | struct rcu_data *rdp = rsp->rda[smp_processor_id()]; |
| 716 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 717 | |
Paul E. McKenney | 07079d5 | 2010-01-04 15:09:02 -0800 | [diff] [blame] | 718 | if (!cpu_needs_another_gp(rsp, rdp) || rsp->fqs_active) { |
Paul E. McKenney | 46a1e34 | 2010-01-04 15:09:09 -0800 | [diff] [blame] | 719 | if (cpu_needs_another_gp(rsp, rdp)) |
| 720 | rsp->fqs_need_gp = 1; |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 721 | if (rnp->completed == rsp->completed) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 722 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 723 | return; |
| 724 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 725 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 726 | |
| 727 | /* |
| 728 | * Propagate new ->completed value to rcu_node structures |
| 729 | * so that other CPUs don't have to wait until the start |
| 730 | * of the next grace period to process their callbacks. |
| 731 | */ |
| 732 | rcu_for_each_node_breadth_first(rsp, rnp) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 733 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 734 | rnp->completed = rsp->completed; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 735 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | b32e9eb | 2009-11-12 22:35:03 -0800 | [diff] [blame] | 736 | } |
| 737 | local_irq_restore(flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 738 | return; |
| 739 | } |
| 740 | |
| 741 | /* Advance to a new grace period and initialize state. */ |
| 742 | rsp->gpnum++; |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 743 | WARN_ON_ONCE(rsp->signaled == RCU_GP_INIT); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 744 | rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */ |
| 745 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 746 | record_gp_stall_check_time(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 747 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 748 | /* Special-case the common single-level case. */ |
| 749 | if (NUM_RCU_NODES == 1) { |
Paul E. McKenney | b0e165c | 2009-09-13 09:15:09 -0700 | [diff] [blame] | 750 | rcu_preempt_check_blocked_tasks(rnp); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 751 | rnp->qsmask = rnp->qsmaskinit; |
Paul E. McKenney | de078d8 | 2009-09-08 15:54:36 -0700 | [diff] [blame] | 752 | rnp->gpnum = rsp->gpnum; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 753 | rnp->completed = rsp->completed; |
Paul E. McKenney | c12172c | 2009-01-04 20:30:06 -0800 | [diff] [blame] | 754 | rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state OK. */ |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 755 | rcu_start_gp_per_cpu(rsp, rnp, rdp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 756 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 757 | return; |
| 758 | } |
| 759 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 760 | raw_spin_unlock(&rnp->lock); /* leave irqs disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 761 | |
| 762 | |
| 763 | /* Exclude any concurrent CPU-hotplug operations. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 764 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 765 | |
| 766 | /* |
Paul E. McKenney | b835db1 | 2009-09-08 15:54:37 -0700 | [diff] [blame] | 767 | * Set the quiescent-state-needed bits in all the rcu_node |
| 768 | * structures for all currently online CPUs in breadth-first |
| 769 | * order, starting from the root rcu_node structure. This |
| 770 | * operation relies on the layout of the hierarchy within the |
| 771 | * rsp->node[] array. Note that other CPUs will access only |
| 772 | * the leaves of the hierarchy, which still indicate that no |
| 773 | * grace period is in progress, at least until the corresponding |
| 774 | * leaf node has been initialized. In addition, we have excluded |
| 775 | * CPU-hotplug operations. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 776 | * |
| 777 | * Note that the grace period cannot complete until we finish |
| 778 | * the initialization process, as there will be at least one |
| 779 | * 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] | 780 | * one corresponding to this CPU, due to the fact that we have |
| 781 | * irqs disabled. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 782 | */ |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 783 | rcu_for_each_node_breadth_first(rsp, rnp) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 784 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | b0e165c | 2009-09-13 09:15:09 -0700 | [diff] [blame] | 785 | rcu_preempt_check_blocked_tasks(rnp); |
Paul E. McKenney | 49e2912 | 2009-09-18 09:50:19 -0700 | [diff] [blame] | 786 | rnp->qsmask = rnp->qsmaskinit; |
Paul E. McKenney | de078d8 | 2009-09-08 15:54:36 -0700 | [diff] [blame] | 787 | rnp->gpnum = rsp->gpnum; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 788 | rnp->completed = rsp->completed; |
| 789 | if (rnp == rdp->mynode) |
| 790 | rcu_start_gp_per_cpu(rsp, rnp, rdp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 791 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 792 | } |
| 793 | |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 794 | rnp = rcu_get_root(rsp); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 795 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 796 | rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state now OK. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 797 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
| 798 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 799 | } |
| 800 | |
| 801 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 802 | * Report a full set of quiescent states to the specified rcu_state |
| 803 | * data structure. This involves cleaning up after the prior grace |
| 804 | * period and letting rcu_start_gp() start up the next grace period |
| 805 | * if one is needed. Note that the caller must hold rnp->lock, as |
| 806 | * required by rcu_start_gp(), which will release it. |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 807 | */ |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 808 | 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] | 809 | __releases(rcu_get_root(rsp)->lock) |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 810 | { |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 811 | WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 812 | rsp->completed = rsp->gpnum; |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 813 | rsp->signaled = RCU_GP_IDLE; |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 814 | rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */ |
| 815 | } |
| 816 | |
| 817 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 818 | * Similar to rcu_report_qs_rdp(), for which it is a helper function. |
| 819 | * Allows quiescent states for a group of CPUs to be reported at one go |
| 820 | * to the specified rcu_node structure, though all the CPUs in the group |
| 821 | * must be represented by the same rcu_node structure (which need not be |
| 822 | * a leaf rcu_node structure, though it often will be). That structure's |
| 823 | * 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] | 824 | */ |
| 825 | static void |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 826 | rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp, |
| 827 | struct rcu_node *rnp, unsigned long flags) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 828 | __releases(rnp->lock) |
| 829 | { |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 830 | struct rcu_node *rnp_c; |
| 831 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 832 | /* Walk up the rcu_node hierarchy. */ |
| 833 | for (;;) { |
| 834 | if (!(rnp->qsmask & mask)) { |
| 835 | |
| 836 | /* Our bit has already been cleared, so done. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 837 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 838 | return; |
| 839 | } |
| 840 | rnp->qsmask &= ~mask; |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 841 | if (rnp->qsmask != 0 || rcu_preempted_readers(rnp)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 842 | |
| 843 | /* Other bits still set at this level, so done. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 844 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 845 | return; |
| 846 | } |
| 847 | mask = rnp->grpmask; |
| 848 | if (rnp->parent == NULL) { |
| 849 | |
| 850 | /* No more levels. Exit loop holding root lock. */ |
| 851 | |
| 852 | break; |
| 853 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 854 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 855 | rnp_c = rnp; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 856 | rnp = rnp->parent; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 857 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 858 | WARN_ON_ONCE(rnp_c->qsmask); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 859 | } |
| 860 | |
| 861 | /* |
| 862 | * 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] | 863 | * state for this grace period. Invoke rcu_report_qs_rsp() |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 864 | * 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] | 865 | */ |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 866 | rcu_report_qs_rsp(rsp, flags); /* releases rnp->lock. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 867 | } |
| 868 | |
| 869 | /* |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 870 | * Record a quiescent state for the specified CPU to that CPU's rcu_data |
| 871 | * structure. This must be either called from the specified CPU, or |
| 872 | * called when the specified CPU is known to be offline (and when it is |
| 873 | * also known that no other CPU is concurrently trying to help the offline |
| 874 | * CPU). The lastcomp argument is used to make sure we are still in the |
| 875 | * grace period of interest. We don't want to end the current grace period |
| 876 | * based on quiescent states detected in an earlier grace period! |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 877 | */ |
| 878 | static void |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 879 | rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 880 | { |
| 881 | unsigned long flags; |
| 882 | unsigned long mask; |
| 883 | struct rcu_node *rnp; |
| 884 | |
| 885 | rnp = rdp->mynode; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 886 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 560d4bc | 2009-11-13 19:51:38 -0800 | [diff] [blame] | 887 | if (lastcomp != rnp->completed) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 888 | |
| 889 | /* |
| 890 | * Someone beat us to it for this grace period, so leave. |
| 891 | * The race with GP start is resolved by the fact that we |
| 892 | * hold the leaf rcu_node lock, so that the per-CPU bits |
| 893 | * cannot yet be initialized -- so we would simply find our |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 894 | * CPU's bit already cleared in rcu_report_qs_rnp() if this |
| 895 | * race occurred. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 896 | */ |
| 897 | rdp->passed_quiesc = 0; /* try again later! */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 898 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 899 | return; |
| 900 | } |
| 901 | mask = rdp->grpmask; |
| 902 | if ((rnp->qsmask & mask) == 0) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 903 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 904 | } else { |
| 905 | rdp->qs_pending = 0; |
| 906 | |
| 907 | /* |
| 908 | * This GP can't end until cpu checks in, so all of our |
| 909 | * callbacks can be processed during the next GP. |
| 910 | */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 911 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 912 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 913 | rcu_report_qs_rnp(mask, rsp, rnp, flags); /* rlses rnp->lock */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 914 | } |
| 915 | } |
| 916 | |
| 917 | /* |
| 918 | * Check to see if there is a new grace period of which this CPU |
| 919 | * is not yet aware, and if so, set up local rcu_data state for it. |
| 920 | * Otherwise, see if this CPU has just passed through its first |
| 921 | * quiescent state for this grace period, and record that fact if so. |
| 922 | */ |
| 923 | static void |
| 924 | rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp) |
| 925 | { |
| 926 | /* If there is now a new grace period, record and return. */ |
| 927 | if (check_for_new_grace_period(rsp, rdp)) |
| 928 | return; |
| 929 | |
| 930 | /* |
| 931 | * Does this CPU still need to do its part for current grace period? |
| 932 | * If no, return and let the other CPUs do their part as well. |
| 933 | */ |
| 934 | if (!rdp->qs_pending) |
| 935 | return; |
| 936 | |
| 937 | /* |
| 938 | * Was there a quiescent state since the beginning of the grace |
| 939 | * period? If no, then exit and wait for the next call. |
| 940 | */ |
| 941 | if (!rdp->passed_quiesc) |
| 942 | return; |
| 943 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 944 | /* |
| 945 | * Tell RCU we are done (but rcu_report_qs_rdp() will be the |
| 946 | * judge of that). |
| 947 | */ |
| 948 | rcu_report_qs_rdp(rdp->cpu, rsp, rdp, rdp->passed_quiesc_completed); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 949 | } |
| 950 | |
| 951 | #ifdef CONFIG_HOTPLUG_CPU |
| 952 | |
| 953 | /* |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 954 | * Move a dying CPU's RCU callbacks to the ->orphan_cbs_list for the |
| 955 | * specified flavor of RCU. The callbacks will be adopted by the next |
| 956 | * _rcu_barrier() invocation or by the CPU_DEAD notifier, whichever |
| 957 | * comes first. Because this is invoked from the CPU_DYING notifier, |
| 958 | * irqs are already disabled. |
| 959 | */ |
| 960 | static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp) |
| 961 | { |
| 962 | int i; |
| 963 | struct rcu_data *rdp = rsp->rda[smp_processor_id()]; |
| 964 | |
| 965 | if (rdp->nxtlist == NULL) |
| 966 | return; /* irqs disabled, so comparison is stable. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 967 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 968 | *rsp->orphan_cbs_tail = rdp->nxtlist; |
| 969 | rsp->orphan_cbs_tail = rdp->nxttail[RCU_NEXT_TAIL]; |
| 970 | rdp->nxtlist = NULL; |
| 971 | for (i = 0; i < RCU_NEXT_SIZE; i++) |
| 972 | rdp->nxttail[i] = &rdp->nxtlist; |
| 973 | rsp->orphan_qlen += rdp->qlen; |
| 974 | rdp->qlen = 0; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 975 | raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 976 | } |
| 977 | |
| 978 | /* |
| 979 | * Adopt previously orphaned RCU callbacks. |
| 980 | */ |
| 981 | static void rcu_adopt_orphan_cbs(struct rcu_state *rsp) |
| 982 | { |
| 983 | unsigned long flags; |
| 984 | struct rcu_data *rdp; |
| 985 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 986 | raw_spin_lock_irqsave(&rsp->onofflock, flags); |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 987 | rdp = rsp->rda[smp_processor_id()]; |
| 988 | if (rsp->orphan_cbs_list == NULL) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 989 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 990 | return; |
| 991 | } |
| 992 | *rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_cbs_list; |
| 993 | rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_cbs_tail; |
| 994 | rdp->qlen += rsp->orphan_qlen; |
| 995 | rsp->orphan_cbs_list = NULL; |
| 996 | rsp->orphan_cbs_tail = &rsp->orphan_cbs_list; |
| 997 | rsp->orphan_qlen = 0; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 998 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 999 | } |
| 1000 | |
| 1001 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1002 | * Remove the outgoing CPU from the bitmasks in the rcu_node hierarchy |
| 1003 | * and move all callbacks from the outgoing CPU to the current one. |
| 1004 | */ |
| 1005 | static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) |
| 1006 | { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1007 | unsigned long flags; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1008 | unsigned long mask; |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1009 | int need_report = 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1010 | struct rcu_data *rdp = rsp->rda[cpu]; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1011 | struct rcu_node *rnp; |
| 1012 | |
| 1013 | /* Exclude any attempts to start a new grace period. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1014 | raw_spin_lock_irqsave(&rsp->onofflock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1015 | |
| 1016 | /* 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] | 1017 | rnp = rdp->mynode; /* this is the outgoing CPU's rnp. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1018 | mask = rdp->grpmask; /* rnp->grplo is constant. */ |
| 1019 | do { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1020 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1021 | rnp->qsmaskinit &= ~mask; |
| 1022 | if (rnp->qsmaskinit != 0) { |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1023 | if (rnp != rdp->mynode) |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1024 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1025 | break; |
| 1026 | } |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1027 | if (rnp == rdp->mynode) |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1028 | need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp); |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1029 | else |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1030 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1031 | mask = rnp->grpmask; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1032 | rnp = rnp->parent; |
| 1033 | } while (rnp != NULL); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1034 | |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1035 | /* |
| 1036 | * We still hold the leaf rcu_node structure lock here, and |
| 1037 | * irqs are still disabled. The reason for this subterfuge is |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1038 | * because invoking rcu_report_unblock_qs_rnp() with ->onofflock |
| 1039 | * held leads to deadlock. |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1040 | */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1041 | raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1042 | rnp = rdp->mynode; |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1043 | if (need_report & RCU_OFL_TASKS_NORM_GP) |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1044 | rcu_report_unblock_qs_rnp(rnp, flags); |
Paul E. McKenney | b668c9c | 2009-11-22 08:53:48 -0800 | [diff] [blame] | 1045 | else |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1046 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1047 | if (need_report & RCU_OFL_TASKS_EXP_GP) |
| 1048 | rcu_report_exp_rnp(rsp, rnp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1049 | |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1050 | rcu_adopt_orphan_cbs(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1051 | } |
| 1052 | |
| 1053 | /* |
| 1054 | * Remove the specified CPU from the RCU hierarchy and move any pending |
| 1055 | * callbacks that it might have to the current CPU. This code assumes |
| 1056 | * that at least one CPU in the system will remain running at all times. |
| 1057 | * Any attempt to offline -all- CPUs is likely to strand RCU callbacks. |
| 1058 | */ |
| 1059 | static void rcu_offline_cpu(int cpu) |
| 1060 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1061 | __rcu_offline_cpu(cpu, &rcu_sched_state); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1062 | __rcu_offline_cpu(cpu, &rcu_bh_state); |
Paul E. McKenney | 33f7614 | 2009-08-24 09:42:01 -0700 | [diff] [blame] | 1063 | rcu_preempt_offline_cpu(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1064 | } |
| 1065 | |
| 1066 | #else /* #ifdef CONFIG_HOTPLUG_CPU */ |
| 1067 | |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1068 | static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp) |
| 1069 | { |
| 1070 | } |
| 1071 | |
| 1072 | static void rcu_adopt_orphan_cbs(struct rcu_state *rsp) |
| 1073 | { |
| 1074 | } |
| 1075 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1076 | static void rcu_offline_cpu(int cpu) |
| 1077 | { |
| 1078 | } |
| 1079 | |
| 1080 | #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */ |
| 1081 | |
| 1082 | /* |
| 1083 | * Invoke any RCU callbacks that have made it to the end of their grace |
| 1084 | * period. Thottle as specified by rdp->blimit. |
| 1085 | */ |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1086 | 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] | 1087 | { |
| 1088 | unsigned long flags; |
| 1089 | struct rcu_head *next, *list, **tail; |
| 1090 | int count; |
| 1091 | |
| 1092 | /* If no callbacks are ready, just return.*/ |
| 1093 | if (!cpu_has_callbacks_ready_to_invoke(rdp)) |
| 1094 | return; |
| 1095 | |
| 1096 | /* |
| 1097 | * Extract the list of ready callbacks, disabling to prevent |
| 1098 | * races with call_rcu() from interrupt handlers. |
| 1099 | */ |
| 1100 | local_irq_save(flags); |
| 1101 | list = rdp->nxtlist; |
| 1102 | rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL]; |
| 1103 | *rdp->nxttail[RCU_DONE_TAIL] = NULL; |
| 1104 | tail = rdp->nxttail[RCU_DONE_TAIL]; |
| 1105 | for (count = RCU_NEXT_SIZE - 1; count >= 0; count--) |
| 1106 | if (rdp->nxttail[count] == rdp->nxttail[RCU_DONE_TAIL]) |
| 1107 | rdp->nxttail[count] = &rdp->nxtlist; |
| 1108 | local_irq_restore(flags); |
| 1109 | |
| 1110 | /* Invoke callbacks. */ |
| 1111 | count = 0; |
| 1112 | while (list) { |
| 1113 | next = list->next; |
| 1114 | prefetch(next); |
| 1115 | list->func(list); |
| 1116 | list = next; |
| 1117 | if (++count >= rdp->blimit) |
| 1118 | break; |
| 1119 | } |
| 1120 | |
| 1121 | local_irq_save(flags); |
| 1122 | |
| 1123 | /* Update count, and requeue any remaining callbacks. */ |
| 1124 | rdp->qlen -= count; |
| 1125 | if (list != NULL) { |
| 1126 | *tail = rdp->nxtlist; |
| 1127 | rdp->nxtlist = list; |
| 1128 | for (count = 0; count < RCU_NEXT_SIZE; count++) |
| 1129 | if (&rdp->nxtlist == rdp->nxttail[count]) |
| 1130 | rdp->nxttail[count] = tail; |
| 1131 | else |
| 1132 | break; |
| 1133 | } |
| 1134 | |
| 1135 | /* Reinstate batch limit if we have worked down the excess. */ |
| 1136 | if (rdp->blimit == LONG_MAX && rdp->qlen <= qlowmark) |
| 1137 | rdp->blimit = blimit; |
| 1138 | |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1139 | /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */ |
| 1140 | if (rdp->qlen == 0 && rdp->qlen_last_fqs_check != 0) { |
| 1141 | rdp->qlen_last_fqs_check = 0; |
| 1142 | rdp->n_force_qs_snap = rsp->n_force_qs; |
| 1143 | } else if (rdp->qlen < rdp->qlen_last_fqs_check - qhimark) |
| 1144 | rdp->qlen_last_fqs_check = rdp->qlen; |
| 1145 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1146 | local_irq_restore(flags); |
| 1147 | |
| 1148 | /* Re-raise the RCU softirq if there are callbacks remaining. */ |
| 1149 | if (cpu_has_callbacks_ready_to_invoke(rdp)) |
| 1150 | raise_softirq(RCU_SOFTIRQ); |
| 1151 | } |
| 1152 | |
| 1153 | /* |
| 1154 | * Check to see if this CPU is in a non-context-switch quiescent state |
| 1155 | * (user mode or idle loop for rcu, non-softirq execution for rcu_bh). |
| 1156 | * Also schedule the RCU softirq handler. |
| 1157 | * |
| 1158 | * This function must be called with hardirqs disabled. It is normally |
| 1159 | * invoked from the scheduling-clock interrupt. If rcu_pending returns |
| 1160 | * false, there is no point in invoking rcu_check_callbacks(). |
| 1161 | */ |
| 1162 | void rcu_check_callbacks(int cpu, int user) |
| 1163 | { |
| 1164 | if (user || |
Paul E. McKenney | a682604 | 2009-02-25 18:03:42 -0800 | [diff] [blame] | 1165 | (idle_cpu(cpu) && rcu_scheduler_active && |
| 1166 | !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1167 | |
| 1168 | /* |
| 1169 | * Get here if this CPU took its interrupt from user |
| 1170 | * mode or from the idle loop, and if this is not a |
| 1171 | * nested interrupt. In this case, the CPU is in |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1172 | * a quiescent state, so note it. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1173 | * |
| 1174 | * No memory barrier is required here because both |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1175 | * rcu_sched_qs() and rcu_bh_qs() reference only CPU-local |
| 1176 | * variables that other CPUs neither access nor modify, |
| 1177 | * at least not while the corresponding CPU is online. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1178 | */ |
| 1179 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1180 | rcu_sched_qs(cpu); |
| 1181 | rcu_bh_qs(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1182 | |
| 1183 | } else if (!in_softirq()) { |
| 1184 | |
| 1185 | /* |
| 1186 | * Get here if this CPU did not take its interrupt from |
| 1187 | * softirq, in other words, if it is not interrupting |
| 1188 | * a rcu_bh read-side critical section. This is an _bh |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1189 | * critical section, so note it. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1190 | */ |
| 1191 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1192 | rcu_bh_qs(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1193 | } |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1194 | rcu_preempt_check_callbacks(cpu); |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 1195 | if (rcu_pending(cpu)) |
| 1196 | raise_softirq(RCU_SOFTIRQ); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1197 | } |
| 1198 | |
| 1199 | #ifdef CONFIG_SMP |
| 1200 | |
| 1201 | /* |
| 1202 | * Scan the leaf rcu_node structures, processing dyntick state for any that |
| 1203 | * have not yet encountered a quiescent state, using the function specified. |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1204 | * The caller must have suppressed start of new grace periods. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1205 | */ |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1206 | 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] | 1207 | { |
| 1208 | unsigned long bit; |
| 1209 | int cpu; |
| 1210 | unsigned long flags; |
| 1211 | unsigned long mask; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1212 | struct rcu_node *rnp; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1213 | |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1214 | rcu_for_each_leaf_node(rsp, rnp) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1215 | mask = 0; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1216 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1217 | if (!rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1218 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 0f10dc82 | 2010-01-04 15:09:06 -0800 | [diff] [blame] | 1219 | return; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1220 | } |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1221 | if (rnp->qsmask == 0) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1222 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1223 | continue; |
| 1224 | } |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1225 | cpu = rnp->grplo; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1226 | bit = 1; |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1227 | for (; cpu <= rnp->grphi; cpu++, bit <<= 1) { |
| 1228 | if ((rnp->qsmask & bit) != 0 && f(rsp->rda[cpu])) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1229 | mask |= bit; |
| 1230 | } |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1231 | if (mask != 0) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1232 | |
Paul E. McKenney | d3f6bad | 2009-12-02 12:10:13 -0800 | [diff] [blame] | 1233 | /* rcu_report_qs_rnp() releases rnp->lock. */ |
| 1234 | rcu_report_qs_rnp(mask, rsp, rnp, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1235 | continue; |
| 1236 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1237 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1238 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1239 | } |
| 1240 | |
| 1241 | /* |
| 1242 | * Force quiescent states on reluctant CPUs, and also detect which |
| 1243 | * CPUs are in dyntick-idle mode. |
| 1244 | */ |
| 1245 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) |
| 1246 | { |
| 1247 | unsigned long flags; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1248 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1249 | |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 1250 | if (!rcu_gp_in_progress(rsp)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1251 | return; /* No grace period in progress, nothing to force. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1252 | if (!raw_spin_trylock_irqsave(&rsp->fqslock, flags)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1253 | rsp->n_force_qs_lh++; /* Inexact, can lose counts. Tough! */ |
| 1254 | return; /* Someone else is already on the job. */ |
| 1255 | } |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1256 | if (relaxed && ULONG_CMP_GE(rsp->jiffies_force_qs, jiffies)) |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1257 | goto unlock_fqs_ret; /* no emergency and done recently. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1258 | rsp->n_force_qs++; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1259 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1260 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
Paul E. McKenney | 560d4bc | 2009-11-13 19:51:38 -0800 | [diff] [blame] | 1261 | if(!rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1262 | rsp->n_force_qs_ngp++; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1263 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1264 | goto unlock_fqs_ret; /* no GP in progress, time updated. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1265 | } |
Paul E. McKenney | 07079d5 | 2010-01-04 15:09:02 -0800 | [diff] [blame] | 1266 | rsp->fqs_active = 1; |
Paul E. McKenney | f3a8b5c | 2010-01-04 15:09:03 -0800 | [diff] [blame] | 1267 | switch (rsp->signaled) { |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 1268 | case RCU_GP_IDLE: |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1269 | case RCU_GP_INIT: |
| 1270 | |
Paul E. McKenney | 83f5b01 | 2009-10-28 08:14:49 -0700 | [diff] [blame] | 1271 | break; /* grace period idle or initializing, ignore. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1272 | |
| 1273 | case RCU_SAVE_DYNTICK: |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1274 | if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK) |
| 1275 | break; /* So gcc recognizes the dead code. */ |
| 1276 | |
Lai Jiangshan | f261414 | 2010-03-28 11:15:20 +0800 | [diff] [blame] | 1277 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
| 1278 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1279 | /* Record dyntick-idle state. */ |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1280 | force_qs_rnp(rsp, dyntick_save_progress_counter); |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1281 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1282 | if (rcu_gp_in_progress(rsp)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1283 | rsp->signaled = RCU_FORCE_QS; |
Paul E. McKenney | ee47eb9 | 2010-01-04 15:09:07 -0800 | [diff] [blame] | 1284 | break; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1285 | |
| 1286 | case RCU_FORCE_QS: |
| 1287 | |
| 1288 | /* Check dyntick-idle state, send IPI to laggarts. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1289 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
Paul E. McKenney | 45f014c52e | 2010-01-04 15:09:08 -0800 | [diff] [blame] | 1290 | force_qs_rnp(rsp, rcu_implicit_dynticks_qs); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1291 | |
| 1292 | /* Leave state in case more forcing is required. */ |
| 1293 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1294 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1295 | break; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1296 | } |
Paul E. McKenney | 07079d5 | 2010-01-04 15:09:02 -0800 | [diff] [blame] | 1297 | rsp->fqs_active = 0; |
Paul E. McKenney | 46a1e34 | 2010-01-04 15:09:09 -0800 | [diff] [blame] | 1298 | if (rsp->fqs_need_gp) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1299 | raw_spin_unlock(&rsp->fqslock); /* irqs remain disabled */ |
Paul E. McKenney | 46a1e34 | 2010-01-04 15:09:09 -0800 | [diff] [blame] | 1300 | rsp->fqs_need_gp = 0; |
| 1301 | rcu_start_gp(rsp, flags); /* releases rnp->lock */ |
| 1302 | return; |
| 1303 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1304 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
Paul E. McKenney | f96e923 | 2010-01-04 15:09:00 -0800 | [diff] [blame] | 1305 | unlock_fqs_ret: |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1306 | raw_spin_unlock_irqrestore(&rsp->fqslock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1307 | } |
| 1308 | |
| 1309 | #else /* #ifdef CONFIG_SMP */ |
| 1310 | |
| 1311 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) |
| 1312 | { |
| 1313 | set_need_resched(); |
| 1314 | } |
| 1315 | |
| 1316 | #endif /* #else #ifdef CONFIG_SMP */ |
| 1317 | |
| 1318 | /* |
| 1319 | * This does the RCU processing work from softirq context for the |
| 1320 | * specified rcu_state and rcu_data structures. This may be called |
| 1321 | * only from the CPU to whom the rdp belongs. |
| 1322 | */ |
| 1323 | static void |
| 1324 | __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) |
| 1325 | { |
| 1326 | unsigned long flags; |
| 1327 | |
Paul E. McKenney | 2e59755 | 2009-08-15 09:53:48 -0700 | [diff] [blame] | 1328 | WARN_ON_ONCE(rdp->beenonline == 0); |
| 1329 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1330 | /* |
| 1331 | * If an RCU GP has gone long enough, go check for dyntick |
| 1332 | * idle CPUs and, if needed, send resched IPIs. |
| 1333 | */ |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1334 | if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1335 | force_quiescent_state(rsp, 1); |
| 1336 | |
| 1337 | /* |
| 1338 | * Advance callbacks in response to end of earlier grace |
| 1339 | * period that some other CPU ended. |
| 1340 | */ |
| 1341 | rcu_process_gp_end(rsp, rdp); |
| 1342 | |
| 1343 | /* Update RCU state based on any recent quiescent states. */ |
| 1344 | rcu_check_quiescent_state(rsp, rdp); |
| 1345 | |
| 1346 | /* Does this CPU require a not-yet-started grace period? */ |
| 1347 | if (cpu_needs_another_gp(rsp, rdp)) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1348 | raw_spin_lock_irqsave(&rcu_get_root(rsp)->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1349 | rcu_start_gp(rsp, flags); /* releases above lock */ |
| 1350 | } |
| 1351 | |
| 1352 | /* If there are callbacks ready, invoke them. */ |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1353 | rcu_do_batch(rsp, rdp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1354 | } |
| 1355 | |
| 1356 | /* |
| 1357 | * Do softirq processing for the current CPU. |
| 1358 | */ |
| 1359 | static void rcu_process_callbacks(struct softirq_action *unused) |
| 1360 | { |
| 1361 | /* |
| 1362 | * Memory references from any prior RCU read-side critical sections |
| 1363 | * executed by the interrupted code must be seen before any RCU |
| 1364 | * grace-period manipulations below. |
| 1365 | */ |
| 1366 | smp_mb(); /* See above block comment. */ |
| 1367 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1368 | __rcu_process_callbacks(&rcu_sched_state, |
| 1369 | &__get_cpu_var(rcu_sched_data)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1370 | __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] | 1371 | rcu_preempt_process_callbacks(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1372 | |
| 1373 | /* |
| 1374 | * Memory references from any later RCU read-side critical sections |
| 1375 | * executed by the interrupted code must be seen after any RCU |
| 1376 | * grace-period manipulations above. |
| 1377 | */ |
| 1378 | smp_mb(); /* See above block comment. */ |
Paul E. McKenney | a47cd88 | 2010-02-26 16:38:56 -0800 | [diff] [blame] | 1379 | |
| 1380 | /* If we are last CPU on way to dyntick-idle mode, accelerate it. */ |
| 1381 | rcu_needs_cpu_flush(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1382 | } |
| 1383 | |
| 1384 | static void |
| 1385 | __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), |
| 1386 | struct rcu_state *rsp) |
| 1387 | { |
| 1388 | unsigned long flags; |
| 1389 | struct rcu_data *rdp; |
| 1390 | |
| 1391 | head->func = func; |
| 1392 | head->next = NULL; |
| 1393 | |
| 1394 | smp_mb(); /* Ensure RCU update seen before callback registry. */ |
| 1395 | |
| 1396 | /* |
| 1397 | * Opportunistically note grace-period endings and beginnings. |
| 1398 | * Note that we might see a beginning right after we see an |
| 1399 | * end, but never vice versa, since this CPU has to pass through |
| 1400 | * a quiescent state betweentimes. |
| 1401 | */ |
| 1402 | local_irq_save(flags); |
| 1403 | rdp = rsp->rda[smp_processor_id()]; |
| 1404 | rcu_process_gp_end(rsp, rdp); |
| 1405 | check_for_new_grace_period(rsp, rdp); |
| 1406 | |
| 1407 | /* Add the callback to our list. */ |
| 1408 | *rdp->nxttail[RCU_NEXT_TAIL] = head; |
| 1409 | rdp->nxttail[RCU_NEXT_TAIL] = &head->next; |
| 1410 | |
| 1411 | /* Start a new grace period if one not already started. */ |
Paul E. McKenney | fc2219d | 2009-09-23 09:50:41 -0700 | [diff] [blame] | 1412 | if (!rcu_gp_in_progress(rsp)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1413 | unsigned long nestflag; |
| 1414 | struct rcu_node *rnp_root = rcu_get_root(rsp); |
| 1415 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1416 | raw_spin_lock_irqsave(&rnp_root->lock, nestflag); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1417 | rcu_start_gp(rsp, nestflag); /* releases rnp_root->lock. */ |
| 1418 | } |
| 1419 | |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1420 | /* |
| 1421 | * Force the grace period if too many callbacks or too long waiting. |
| 1422 | * Enforce hysteresis, and don't invoke force_quiescent_state() |
| 1423 | * if some other CPU has recently done so. Also, don't bother |
| 1424 | * invoking force_quiescent_state() if the newly enqueued callback |
| 1425 | * is the only one waiting for a grace period to complete. |
| 1426 | */ |
| 1427 | if (unlikely(++rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1428 | rdp->blimit = LONG_MAX; |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1429 | if (rsp->n_force_qs == rdp->n_force_qs_snap && |
| 1430 | *rdp->nxttail[RCU_DONE_TAIL] != head) |
| 1431 | force_quiescent_state(rsp, 0); |
| 1432 | rdp->n_force_qs_snap = rsp->n_force_qs; |
| 1433 | rdp->qlen_last_fqs_check = rdp->qlen; |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1434 | } 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] | 1435 | force_quiescent_state(rsp, 1); |
| 1436 | local_irq_restore(flags); |
| 1437 | } |
| 1438 | |
| 1439 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1440 | * Queue an RCU-sched callback for invocation after a grace period. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1441 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1442 | 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] | 1443 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1444 | __call_rcu(head, func, &rcu_sched_state); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1445 | } |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1446 | EXPORT_SYMBOL_GPL(call_rcu_sched); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1447 | |
| 1448 | /* |
| 1449 | * Queue an RCU for invocation after a quicker grace period. |
| 1450 | */ |
| 1451 | void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) |
| 1452 | { |
| 1453 | __call_rcu(head, func, &rcu_bh_state); |
| 1454 | } |
| 1455 | EXPORT_SYMBOL_GPL(call_rcu_bh); |
| 1456 | |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1457 | /** |
| 1458 | * synchronize_sched - wait until an rcu-sched grace period has elapsed. |
| 1459 | * |
| 1460 | * Control will return to the caller some time after a full rcu-sched |
| 1461 | * grace period has elapsed, in other words after all currently executing |
| 1462 | * rcu-sched read-side critical sections have completed. These read-side |
| 1463 | * critical sections are delimited by rcu_read_lock_sched() and |
| 1464 | * rcu_read_unlock_sched(), and may be nested. Note that preempt_disable(), |
| 1465 | * local_irq_disable(), and so on may be used in place of |
| 1466 | * rcu_read_lock_sched(). |
| 1467 | * |
| 1468 | * This means that all preempt_disable code sequences, including NMI and |
| 1469 | * hardware-interrupt handlers, in progress on entry will have completed |
| 1470 | * before this primitive returns. However, this does not guarantee that |
| 1471 | * softirq handlers will have completed, since in some kernels, these |
| 1472 | * handlers can run in process context, and can block. |
| 1473 | * |
| 1474 | * This primitive provides the guarantees made by the (now removed) |
| 1475 | * synchronize_kernel() API. In contrast, synchronize_rcu() only |
| 1476 | * guarantees that rcu_read_lock() sections will have completed. |
| 1477 | * In "classic RCU", these two guarantees happen to be one and |
| 1478 | * the same, but can differ in realtime RCU implementations. |
| 1479 | */ |
| 1480 | void synchronize_sched(void) |
| 1481 | { |
| 1482 | struct rcu_synchronize rcu; |
| 1483 | |
| 1484 | if (rcu_blocking_is_gp()) |
| 1485 | return; |
| 1486 | |
Paul E. McKenney | 72d5a9f | 2010-05-10 17:12:17 -0700 | [diff] [blame] | 1487 | init_rcu_head_on_stack(&rcu.head); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1488 | init_completion(&rcu.completion); |
| 1489 | /* Will wake me after RCU finished. */ |
| 1490 | call_rcu_sched(&rcu.head, wakeme_after_rcu); |
| 1491 | /* Wait for it. */ |
| 1492 | wait_for_completion(&rcu.completion); |
Paul E. McKenney | 72d5a9f | 2010-05-10 17:12:17 -0700 | [diff] [blame] | 1493 | destroy_rcu_head_on_stack(&rcu.head); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1494 | } |
| 1495 | EXPORT_SYMBOL_GPL(synchronize_sched); |
| 1496 | |
| 1497 | /** |
| 1498 | * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed. |
| 1499 | * |
| 1500 | * Control will return to the caller some time after a full rcu_bh grace |
| 1501 | * period has elapsed, in other words after all currently executing rcu_bh |
| 1502 | * read-side critical sections have completed. RCU read-side critical |
| 1503 | * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(), |
| 1504 | * and may be nested. |
| 1505 | */ |
| 1506 | void synchronize_rcu_bh(void) |
| 1507 | { |
| 1508 | struct rcu_synchronize rcu; |
| 1509 | |
| 1510 | if (rcu_blocking_is_gp()) |
| 1511 | return; |
| 1512 | |
Paul E. McKenney | 72d5a9f | 2010-05-10 17:12:17 -0700 | [diff] [blame] | 1513 | init_rcu_head_on_stack(&rcu.head); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1514 | init_completion(&rcu.completion); |
| 1515 | /* Will wake me after RCU finished. */ |
| 1516 | call_rcu_bh(&rcu.head, wakeme_after_rcu); |
| 1517 | /* Wait for it. */ |
| 1518 | wait_for_completion(&rcu.completion); |
Paul E. McKenney | 72d5a9f | 2010-05-10 17:12:17 -0700 | [diff] [blame] | 1519 | destroy_rcu_head_on_stack(&rcu.head); |
Paul E. McKenney | 6ebb237 | 2009-11-22 08:53:50 -0800 | [diff] [blame] | 1520 | } |
| 1521 | EXPORT_SYMBOL_GPL(synchronize_rcu_bh); |
| 1522 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1523 | /* |
| 1524 | * Check to see if there is any immediate RCU-related work to be done |
| 1525 | * by the current CPU, for the specified type of RCU, returning 1 if so. |
| 1526 | * The checks are in order of increasing expense: checks that can be |
| 1527 | * carried out against CPU-local state are performed first. However, |
| 1528 | * we must check for CPU stalls first, else we might not get a chance. |
| 1529 | */ |
| 1530 | static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) |
| 1531 | { |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 1532 | struct rcu_node *rnp = rdp->mynode; |
| 1533 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1534 | rdp->n_rcu_pending++; |
| 1535 | |
| 1536 | /* Check for CPU stalls, if enabled. */ |
| 1537 | check_cpu_stall(rsp, rdp); |
| 1538 | |
| 1539 | /* Is the RCU core waiting for a quiescent state from this CPU? */ |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 1540 | if (rdp->qs_pending && !rdp->passed_quiesc) { |
Paul E. McKenney | d25eb94 | 2010-03-18 21:36:51 -0700 | [diff] [blame] | 1541 | |
| 1542 | /* |
| 1543 | * If force_quiescent_state() coming soon and this CPU |
| 1544 | * needs a quiescent state, and this is either RCU-sched |
| 1545 | * or RCU-bh, force a local reschedule. |
| 1546 | */ |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 1547 | rdp->n_rp_qs_pending++; |
Paul E. McKenney | d25eb94 | 2010-03-18 21:36:51 -0700 | [diff] [blame] | 1548 | if (!rdp->preemptable && |
| 1549 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs) - 1, |
| 1550 | jiffies)) |
| 1551 | set_need_resched(); |
Paul E. McKenney | d21670a | 2010-04-14 17:39:26 -0700 | [diff] [blame] | 1552 | } else if (rdp->qs_pending && rdp->passed_quiesc) { |
| 1553 | rdp->n_rp_report_qs++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1554 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1555 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1556 | |
| 1557 | /* Does this CPU have callbacks ready to invoke? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1558 | if (cpu_has_callbacks_ready_to_invoke(rdp)) { |
| 1559 | rdp->n_rp_cb_ready++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1560 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1561 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1562 | |
| 1563 | /* Has RCU gone idle with this CPU needing another grace period? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1564 | if (cpu_needs_another_gp(rsp, rdp)) { |
| 1565 | rdp->n_rp_cpu_needs_gp++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1566 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1567 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1568 | |
| 1569 | /* Has another RCU grace period completed? */ |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 1570 | if (ACCESS_ONCE(rnp->completed) != rdp->completed) { /* outside lock */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1571 | rdp->n_rp_gp_completed++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1572 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1573 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1574 | |
| 1575 | /* Has a new RCU grace period started? */ |
Paul E. McKenney | 2f51f98 | 2009-11-13 19:51:39 -0800 | [diff] [blame] | 1576 | if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum) { /* outside lock */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1577 | rdp->n_rp_gp_started++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1578 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1579 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1580 | |
| 1581 | /* 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] | 1582 | if (rcu_gp_in_progress(rsp) && |
Paul E. McKenney | 20133cf | 2010-02-22 17:05:01 -0800 | [diff] [blame] | 1583 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) { |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1584 | rdp->n_rp_need_fqs++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1585 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1586 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1587 | |
| 1588 | /* nothing to do */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1589 | rdp->n_rp_need_nothing++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1590 | return 0; |
| 1591 | } |
| 1592 | |
| 1593 | /* |
| 1594 | * Check to see if there is any immediate RCU-related work to be done |
| 1595 | * by the current CPU, returning 1 if so. This function is part of the |
| 1596 | * RCU implementation; it is -not- an exported member of the RCU API. |
| 1597 | */ |
Paul E. McKenney | a157229 | 2009-08-22 13:56:51 -0700 | [diff] [blame] | 1598 | static int rcu_pending(int cpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1599 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1600 | 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] | 1601 | __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu)) || |
| 1602 | rcu_preempt_pending(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1603 | } |
| 1604 | |
| 1605 | /* |
| 1606 | * Check to see if any future RCU-related work will need to be done |
| 1607 | * 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] | 1608 | * 1 if so. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1609 | */ |
Paul E. McKenney | 8bd93a2 | 2010-02-22 17:04:59 -0800 | [diff] [blame] | 1610 | static int rcu_needs_cpu_quick_check(int cpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1611 | { |
| 1612 | /* RCU callbacks either ready or pending? */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1613 | return per_cpu(rcu_sched_data, cpu).nxtlist || |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1614 | per_cpu(rcu_bh_data, cpu).nxtlist || |
| 1615 | rcu_preempt_needs_cpu(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1616 | } |
| 1617 | |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1618 | static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL}; |
| 1619 | static atomic_t rcu_barrier_cpu_count; |
| 1620 | static DEFINE_MUTEX(rcu_barrier_mutex); |
| 1621 | static struct completion rcu_barrier_completion; |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1622 | |
| 1623 | static void rcu_barrier_callback(struct rcu_head *notused) |
| 1624 | { |
| 1625 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) |
| 1626 | complete(&rcu_barrier_completion); |
| 1627 | } |
| 1628 | |
| 1629 | /* |
| 1630 | * Called with preemption disabled, and from cross-cpu IRQ context. |
| 1631 | */ |
| 1632 | static void rcu_barrier_func(void *type) |
| 1633 | { |
| 1634 | int cpu = smp_processor_id(); |
| 1635 | struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu); |
| 1636 | void (*call_rcu_func)(struct rcu_head *head, |
| 1637 | void (*func)(struct rcu_head *head)); |
| 1638 | |
| 1639 | atomic_inc(&rcu_barrier_cpu_count); |
| 1640 | call_rcu_func = type; |
| 1641 | call_rcu_func(head, rcu_barrier_callback); |
| 1642 | } |
| 1643 | |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1644 | /* |
| 1645 | * Orchestrate the specified type of RCU barrier, waiting for all |
| 1646 | * RCU callbacks of the specified type to complete. |
| 1647 | */ |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1648 | static void _rcu_barrier(struct rcu_state *rsp, |
| 1649 | void (*call_rcu_func)(struct rcu_head *head, |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1650 | void (*func)(struct rcu_head *head))) |
| 1651 | { |
| 1652 | BUG_ON(in_interrupt()); |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1653 | /* Take mutex to serialize concurrent rcu_barrier() requests. */ |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1654 | mutex_lock(&rcu_barrier_mutex); |
| 1655 | init_completion(&rcu_barrier_completion); |
| 1656 | /* |
| 1657 | * Initialize rcu_barrier_cpu_count to 1, then invoke |
| 1658 | * rcu_barrier_func() on each CPU, so that each CPU also has |
| 1659 | * incremented rcu_barrier_cpu_count. Only then is it safe to |
| 1660 | * decrement rcu_barrier_cpu_count -- otherwise the first CPU |
| 1661 | * might complete its grace period before all of the other CPUs |
| 1662 | * did their increment, causing this function to return too |
| 1663 | * early. |
| 1664 | */ |
| 1665 | atomic_set(&rcu_barrier_cpu_count, 1); |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1666 | preempt_disable(); /* stop CPU_DYING from filling orphan_cbs_list */ |
| 1667 | rcu_adopt_orphan_cbs(rsp); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1668 | on_each_cpu(rcu_barrier_func, (void *)call_rcu_func, 1); |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1669 | preempt_enable(); /* CPU_DYING can again fill orphan_cbs_list */ |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1670 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) |
| 1671 | complete(&rcu_barrier_completion); |
| 1672 | wait_for_completion(&rcu_barrier_completion); |
| 1673 | mutex_unlock(&rcu_barrier_mutex); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1674 | } |
| 1675 | |
| 1676 | /** |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1677 | * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete. |
| 1678 | */ |
| 1679 | void rcu_barrier_bh(void) |
| 1680 | { |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1681 | _rcu_barrier(&rcu_bh_state, call_rcu_bh); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1682 | } |
| 1683 | EXPORT_SYMBOL_GPL(rcu_barrier_bh); |
| 1684 | |
| 1685 | /** |
| 1686 | * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks. |
| 1687 | */ |
| 1688 | void rcu_barrier_sched(void) |
| 1689 | { |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1690 | _rcu_barrier(&rcu_sched_state, call_rcu_sched); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1691 | } |
| 1692 | EXPORT_SYMBOL_GPL(rcu_barrier_sched); |
| 1693 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1694 | /* |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1695 | * 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] | 1696 | */ |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1697 | static void __init |
| 1698 | rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1699 | { |
| 1700 | unsigned long flags; |
| 1701 | int i; |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1702 | struct rcu_data *rdp = rsp->rda[cpu]; |
| 1703 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 1704 | |
| 1705 | /* Set up local state, ensuring consistent view of global state. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1706 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1707 | rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo); |
| 1708 | rdp->nxtlist = NULL; |
| 1709 | for (i = 0; i < RCU_NEXT_SIZE; i++) |
| 1710 | rdp->nxttail[i] = &rdp->nxtlist; |
| 1711 | rdp->qlen = 0; |
| 1712 | #ifdef CONFIG_NO_HZ |
| 1713 | rdp->dynticks = &per_cpu(rcu_dynticks, cpu); |
| 1714 | #endif /* #ifdef CONFIG_NO_HZ */ |
| 1715 | rdp->cpu = cpu; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1716 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1717 | } |
| 1718 | |
| 1719 | /* |
| 1720 | * Initialize a CPU's per-CPU RCU data. Note that only one online or |
| 1721 | * offline event can be happening at a given time. Note also that we |
| 1722 | * can accept some slop in the rsp->completed access due to the fact |
| 1723 | * 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] | 1724 | */ |
| 1725 | static void __cpuinit |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1726 | rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1727 | { |
| 1728 | unsigned long flags; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1729 | unsigned long mask; |
| 1730 | struct rcu_data *rdp = rsp->rda[cpu]; |
| 1731 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 1732 | |
| 1733 | /* Set up local state, ensuring consistent view of global state. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1734 | raw_spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1735 | rdp->passed_quiesc = 0; /* We could be racing with new GP, */ |
| 1736 | rdp->qs_pending = 1; /* so set up to respond to current GP. */ |
| 1737 | rdp->beenonline = 1; /* We have now been online. */ |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1738 | rdp->preemptable = preemptable; |
Paul E. McKenney | 37c72e5 | 2009-10-14 10:15:55 -0700 | [diff] [blame] | 1739 | rdp->qlen_last_fqs_check = 0; |
| 1740 | rdp->n_force_qs_snap = rsp->n_force_qs; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1741 | rdp->blimit = blimit; |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1742 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1743 | |
| 1744 | /* |
| 1745 | * A new grace period might start here. If so, we won't be part |
| 1746 | * of it, but that is OK, as we are currently in a quiescent state. |
| 1747 | */ |
| 1748 | |
| 1749 | /* Exclude any attempts to start a new GP on large systems. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1750 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1751 | |
| 1752 | /* Add CPU to rcu_node bitmasks. */ |
| 1753 | rnp = rdp->mynode; |
| 1754 | mask = rdp->grpmask; |
| 1755 | do { |
| 1756 | /* Exclude any attempts to start a new GP on small systems. */ |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1757 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1758 | rnp->qsmaskinit |= mask; |
| 1759 | mask = rnp->grpmask; |
Paul E. McKenney | d09b62d | 2009-11-02 13:52:28 -0800 | [diff] [blame] | 1760 | if (rnp == rdp->mynode) { |
| 1761 | rdp->gpnum = rnp->completed; /* if GP in progress... */ |
| 1762 | rdp->completed = rnp->completed; |
| 1763 | rdp->passed_quiesc_completed = rnp->completed - 1; |
| 1764 | } |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1765 | raw_spin_unlock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1766 | rnp = rnp->parent; |
| 1767 | } while (rnp != NULL && !(rnp->qsmaskinit & mask)); |
| 1768 | |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1769 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1770 | } |
| 1771 | |
| 1772 | static void __cpuinit rcu_online_cpu(int cpu) |
| 1773 | { |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1774 | rcu_init_percpu_data(cpu, &rcu_sched_state, 0); |
| 1775 | rcu_init_percpu_data(cpu, &rcu_bh_state, 0); |
| 1776 | rcu_preempt_init_percpu_data(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1777 | } |
| 1778 | |
| 1779 | /* |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1780 | * Handle CPU online/offline notification events. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1781 | */ |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 1782 | static int __cpuinit rcu_cpu_notify(struct notifier_block *self, |
| 1783 | unsigned long action, void *hcpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1784 | { |
| 1785 | long cpu = (long)hcpu; |
| 1786 | |
| 1787 | switch (action) { |
| 1788 | case CPU_UP_PREPARE: |
| 1789 | case CPU_UP_PREPARE_FROZEN: |
| 1790 | rcu_online_cpu(cpu); |
| 1791 | break; |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1792 | case CPU_DYING: |
| 1793 | case CPU_DYING_FROZEN: |
| 1794 | /* |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1795 | * preempt_disable() in _rcu_barrier() prevents stop_machine(), |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1796 | * so when "on_each_cpu(rcu_barrier_func, (void *)type, 1);" |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1797 | * returns, all online cpus have queued rcu_barrier_func(). |
| 1798 | * The dying CPU clears its cpu_online_mask bit and |
| 1799 | * moves all of its RCU callbacks to ->orphan_cbs_list |
| 1800 | * in the context of stop_machine(), so subsequent calls |
| 1801 | * to _rcu_barrier() will adopt these callbacks and only |
| 1802 | * then queue rcu_barrier_func() on all remaining CPUs. |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1803 | */ |
Paul E. McKenney | e74f4c4 | 2009-10-06 21:48:17 -0700 | [diff] [blame] | 1804 | rcu_send_cbs_to_orphanage(&rcu_bh_state); |
| 1805 | rcu_send_cbs_to_orphanage(&rcu_sched_state); |
| 1806 | rcu_preempt_send_cbs_to_orphanage(); |
Paul E. McKenney | d0ec774 | 2009-10-06 21:48:16 -0700 | [diff] [blame] | 1807 | break; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1808 | case CPU_DEAD: |
| 1809 | case CPU_DEAD_FROZEN: |
| 1810 | case CPU_UP_CANCELED: |
| 1811 | case CPU_UP_CANCELED_FROZEN: |
| 1812 | rcu_offline_cpu(cpu); |
| 1813 | break; |
| 1814 | default: |
| 1815 | break; |
| 1816 | } |
| 1817 | return NOTIFY_OK; |
| 1818 | } |
| 1819 | |
| 1820 | /* |
Paul E. McKenney | bbad937 | 2010-04-02 16:17:17 -0700 | [diff] [blame] | 1821 | * This function is invoked towards the end of the scheduler's initialization |
| 1822 | * process. Before this is called, the idle task might contain |
| 1823 | * RCU read-side critical sections (during which time, this idle |
| 1824 | * task is booting the system). After this function is called, the |
| 1825 | * idle tasks are prohibited from containing RCU read-side critical |
| 1826 | * sections. This function also enables RCU lockdep checking. |
| 1827 | */ |
| 1828 | void rcu_scheduler_starting(void) |
| 1829 | { |
| 1830 | WARN_ON(num_online_cpus() != 1); |
| 1831 | WARN_ON(nr_context_switches() > 0); |
| 1832 | rcu_scheduler_active = 1; |
| 1833 | } |
| 1834 | |
| 1835 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1836 | * Compute the per-level fanout, either using the exact fanout specified |
| 1837 | * or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT. |
| 1838 | */ |
| 1839 | #ifdef CONFIG_RCU_FANOUT_EXACT |
| 1840 | static void __init rcu_init_levelspread(struct rcu_state *rsp) |
| 1841 | { |
| 1842 | int i; |
| 1843 | |
| 1844 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) |
| 1845 | rsp->levelspread[i] = CONFIG_RCU_FANOUT; |
| 1846 | } |
| 1847 | #else /* #ifdef CONFIG_RCU_FANOUT_EXACT */ |
| 1848 | static void __init rcu_init_levelspread(struct rcu_state *rsp) |
| 1849 | { |
| 1850 | int ccur; |
| 1851 | int cprv; |
| 1852 | int i; |
| 1853 | |
| 1854 | cprv = NR_CPUS; |
| 1855 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { |
| 1856 | ccur = rsp->levelcnt[i]; |
| 1857 | rsp->levelspread[i] = (cprv + ccur - 1) / ccur; |
| 1858 | cprv = ccur; |
| 1859 | } |
| 1860 | } |
| 1861 | #endif /* #else #ifdef CONFIG_RCU_FANOUT_EXACT */ |
| 1862 | |
| 1863 | /* |
| 1864 | * Helper function for rcu_init() that initializes one rcu_state structure. |
| 1865 | */ |
| 1866 | static void __init rcu_init_one(struct rcu_state *rsp) |
| 1867 | { |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 1868 | static char *buf[] = { "rcu_node_level_0", |
| 1869 | "rcu_node_level_1", |
| 1870 | "rcu_node_level_2", |
| 1871 | "rcu_node_level_3" }; /* Match MAX_RCU_LVLS */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1872 | int cpustride = 1; |
| 1873 | int i; |
| 1874 | int j; |
| 1875 | struct rcu_node *rnp; |
| 1876 | |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 1877 | BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */ |
| 1878 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1879 | /* Initialize the level-tracking arrays. */ |
| 1880 | |
| 1881 | for (i = 1; i < NUM_RCU_LVLS; i++) |
| 1882 | rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1]; |
| 1883 | rcu_init_levelspread(rsp); |
| 1884 | |
| 1885 | /* Initialize the elements themselves, starting from the leaves. */ |
| 1886 | |
| 1887 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { |
| 1888 | cpustride *= rsp->levelspread[i]; |
| 1889 | rnp = rsp->level[i]; |
| 1890 | for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) { |
Paul E. McKenney | 1304afb | 2010-02-22 17:05:02 -0800 | [diff] [blame] | 1891 | raw_spin_lock_init(&rnp->lock); |
Paul E. McKenney | b6407e8 | 2010-01-04 16:04:02 -0800 | [diff] [blame] | 1892 | lockdep_set_class_and_name(&rnp->lock, |
| 1893 | &rcu_node_class[i], buf[i]); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1894 | rnp->gpnum = 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1895 | rnp->qsmask = 0; |
| 1896 | rnp->qsmaskinit = 0; |
| 1897 | rnp->grplo = j * cpustride; |
| 1898 | rnp->grphi = (j + 1) * cpustride - 1; |
| 1899 | if (rnp->grphi >= NR_CPUS) |
| 1900 | rnp->grphi = NR_CPUS - 1; |
| 1901 | if (i == 0) { |
| 1902 | rnp->grpnum = 0; |
| 1903 | rnp->grpmask = 0; |
| 1904 | rnp->parent = NULL; |
| 1905 | } else { |
| 1906 | rnp->grpnum = j % rsp->levelspread[i - 1]; |
| 1907 | rnp->grpmask = 1UL << rnp->grpnum; |
| 1908 | rnp->parent = rsp->level[i - 1] + |
| 1909 | j / rsp->levelspread[i - 1]; |
| 1910 | } |
| 1911 | rnp->level = i; |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1912 | INIT_LIST_HEAD(&rnp->blocked_tasks[0]); |
| 1913 | INIT_LIST_HEAD(&rnp->blocked_tasks[1]); |
Paul E. McKenney | d9a3da0 | 2009-12-02 12:10:15 -0800 | [diff] [blame] | 1914 | INIT_LIST_HEAD(&rnp->blocked_tasks[2]); |
| 1915 | INIT_LIST_HEAD(&rnp->blocked_tasks[3]); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1916 | } |
| 1917 | } |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 1918 | |
| 1919 | rnp = rsp->level[NUM_RCU_LVLS - 1]; |
| 1920 | for_each_possible_cpu(i) { |
Paul E. McKenney | 4a90a06 | 2010-04-14 16:48:11 -0700 | [diff] [blame] | 1921 | while (i > rnp->grphi) |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 1922 | rnp++; |
| 1923 | rsp->rda[i]->mynode = rnp; |
| 1924 | rcu_boot_init_percpu_data(i, rsp); |
| 1925 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1926 | } |
| 1927 | |
| 1928 | /* |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1929 | * Helper macro for __rcu_init() and __rcu_init_preempt(). To be used |
| 1930 | * nowhere else! Assigns leaf node pointers into each CPU's rcu_data |
| 1931 | * structure. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1932 | */ |
Paul E. McKenney | 65cf8f8 | 2009-08-22 13:56:49 -0700 | [diff] [blame] | 1933 | #define RCU_INIT_FLAVOR(rsp, rcu_data) \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1934 | do { \ |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1935 | int i; \ |
Paul E. McKenney | a0b6c9a | 2009-09-28 07:46:33 -0700 | [diff] [blame] | 1936 | \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1937 | for_each_possible_cpu(i) { \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1938 | (rsp)->rda[i] = &per_cpu(rcu_data, i); \ |
| 1939 | } \ |
Lai Jiangshan | 0c34029 | 2010-03-28 11:12:30 +0800 | [diff] [blame] | 1940 | rcu_init_one(rsp); \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1941 | } while (0) |
| 1942 | |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 1943 | void __init rcu_init(void) |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1944 | { |
Paul E. McKenney | 017c426 | 2010-01-14 16:10:58 -0800 | [diff] [blame] | 1945 | int cpu; |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 1946 | |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1947 | rcu_bootup_announce(); |
Paul E. McKenney | 65cf8f8 | 2009-08-22 13:56:49 -0700 | [diff] [blame] | 1948 | RCU_INIT_FLAVOR(&rcu_sched_state, rcu_sched_data); |
| 1949 | RCU_INIT_FLAVOR(&rcu_bh_state, rcu_bh_data); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1950 | __rcu_init_preempt(); |
Paul E. McKenney | 2e59755 | 2009-08-15 09:53:48 -0700 | [diff] [blame] | 1951 | open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); |
Paul E. McKenney | 9f680ab | 2009-11-22 08:53:49 -0800 | [diff] [blame] | 1952 | |
| 1953 | /* |
| 1954 | * We don't need protection against CPU-hotplug here because |
| 1955 | * this is called early in boot, before either interrupts |
| 1956 | * or the scheduler are operational. |
| 1957 | */ |
| 1958 | cpu_notifier(rcu_cpu_notify, 0); |
Paul E. McKenney | 017c426 | 2010-01-14 16:10:58 -0800 | [diff] [blame] | 1959 | for_each_online_cpu(cpu) |
| 1960 | rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu); |
Paul E. McKenney | c68de20 | 2010-04-15 10:12:40 -0700 | [diff] [blame] | 1961 | check_cpu_stall_init(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1962 | } |
| 1963 | |
Paul E. McKenney | 1eba8f8 | 2009-09-23 09:50:42 -0700 | [diff] [blame] | 1964 | #include "rcutree_plugin.h" |