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> |
| 49 | |
Paul E. McKenney | 9f77da9 | 2009-08-22 13:56:45 -0700 | [diff] [blame] | 50 | #include "rcutree.h" |
| 51 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 52 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| 53 | static struct lock_class_key rcu_lock_key; |
| 54 | struct lockdep_map rcu_lock_map = |
| 55 | STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key); |
| 56 | EXPORT_SYMBOL_GPL(rcu_lock_map); |
| 57 | #endif |
| 58 | |
| 59 | /* Data structures. */ |
| 60 | |
| 61 | #define RCU_STATE_INITIALIZER(name) { \ |
| 62 | .level = { &name.node[0] }, \ |
| 63 | .levelcnt = { \ |
| 64 | NUM_RCU_LVL_0, /* root of hierarchy. */ \ |
| 65 | NUM_RCU_LVL_1, \ |
| 66 | NUM_RCU_LVL_2, \ |
| 67 | NUM_RCU_LVL_3, /* == MAX_RCU_LVLS */ \ |
| 68 | }, \ |
| 69 | .signaled = RCU_SIGNAL_INIT, \ |
| 70 | .gpnum = -300, \ |
| 71 | .completed = -300, \ |
| 72 | .onofflock = __SPIN_LOCK_UNLOCKED(&name.onofflock), \ |
| 73 | .fqslock = __SPIN_LOCK_UNLOCKED(&name.fqslock), \ |
| 74 | .n_force_qs = 0, \ |
| 75 | .n_force_qs_ngp = 0, \ |
| 76 | } |
| 77 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 78 | struct rcu_state rcu_sched_state = RCU_STATE_INITIALIZER(rcu_sched_state); |
| 79 | DEFINE_PER_CPU(struct rcu_data, rcu_sched_data); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 80 | |
Ingo Molnar | 6258c4f | 2009-03-25 16:42:24 +0100 | [diff] [blame] | 81 | struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state); |
| 82 | DEFINE_PER_CPU(struct rcu_data, rcu_bh_data); |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 83 | |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 84 | extern long rcu_batches_completed_sched(void); |
Paul E. McKenney | dd5d19b | 2009-08-27 14:58:16 -0700 | [diff] [blame] | 85 | static struct rcu_node *rcu_get_root(struct rcu_state *rsp); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 86 | static void cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, |
| 87 | struct rcu_node *rnp, unsigned long flags); |
| 88 | static void cpu_quiet_msk_finish(struct rcu_state *rsp, unsigned long flags); |
Paul E. McKenney | c935a33 | 2009-08-25 08:40:25 -0700 | [diff] [blame] | 89 | #ifdef CONFIG_HOTPLUG_CPU |
Paul E. McKenney | 33f7614 | 2009-08-24 09:42:01 -0700 | [diff] [blame] | 90 | static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp); |
Paul E. McKenney | c935a33 | 2009-08-25 08:40:25 -0700 | [diff] [blame] | 91 | #endif /* #ifdef CONFIG_HOTPLUG_CPU */ |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 92 | static void __rcu_process_callbacks(struct rcu_state *rsp, |
| 93 | struct rcu_data *rdp); |
| 94 | static void __call_rcu(struct rcu_head *head, |
| 95 | void (*func)(struct rcu_head *rcu), |
| 96 | struct rcu_state *rsp); |
| 97 | static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp); |
| 98 | static void __cpuinit rcu_init_percpu_data(int cpu, struct rcu_state *rsp, |
| 99 | int preemptable); |
| 100 | |
| 101 | #include "rcutree_plugin.h" |
| 102 | |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 103 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 104 | * Note a quiescent state. Because we do not need to know |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 105 | * how many quiescent states passed, just if there was at least |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 106 | * 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] | 107 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 108 | void rcu_sched_qs(int cpu) |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 109 | { |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 110 | struct rcu_data *rdp; |
| 111 | |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 112 | rdp = &per_cpu(rcu_sched_data, cpu); |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 113 | rdp->passed_quiesc_completed = rdp->completed; |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 114 | barrier(); |
| 115 | rdp->passed_quiesc = 1; |
| 116 | rcu_preempt_note_context_switch(cpu); |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 117 | } |
| 118 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 119 | void rcu_bh_qs(int cpu) |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 120 | { |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 121 | struct rcu_data *rdp; |
| 122 | |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 123 | rdp = &per_cpu(rcu_bh_data, cpu); |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 124 | rdp->passed_quiesc_completed = rdp->completed; |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 125 | barrier(); |
| 126 | rdp->passed_quiesc = 1; |
Ingo Molnar | b1f77b0 | 2009-03-13 03:20:49 +0100 | [diff] [blame] | 127 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 128 | |
| 129 | #ifdef CONFIG_NO_HZ |
Paul E. McKenney | 90a4d2c | 2009-01-04 11:41:11 -0800 | [diff] [blame] | 130 | DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { |
| 131 | .dynticks_nesting = 1, |
| 132 | .dynticks = 1, |
| 133 | }; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 134 | #endif /* #ifdef CONFIG_NO_HZ */ |
| 135 | |
| 136 | static int blimit = 10; /* Maximum callbacks per softirq. */ |
| 137 | static int qhimark = 10000; /* If this many pending, ignore blimit. */ |
| 138 | static int qlowmark = 100; /* Once only this many pending, use blimit. */ |
| 139 | |
| 140 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed); |
Paul E. McKenney | a157229 | 2009-08-22 13:56:51 -0700 | [diff] [blame] | 141 | static int rcu_pending(int cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 142 | |
| 143 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 144 | * 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] | 145 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 146 | long rcu_batches_completed_sched(void) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 147 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 148 | return rcu_sched_state.completed; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 149 | } |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 150 | EXPORT_SYMBOL_GPL(rcu_batches_completed_sched); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 151 | |
| 152 | /* |
| 153 | * Return the number of RCU BH batches processed thus far for debug & stats. |
| 154 | */ |
| 155 | long rcu_batches_completed_bh(void) |
| 156 | { |
| 157 | return rcu_bh_state.completed; |
| 158 | } |
| 159 | EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); |
| 160 | |
| 161 | /* |
| 162 | * Does the CPU have callbacks ready to be invoked? |
| 163 | */ |
| 164 | static int |
| 165 | cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp) |
| 166 | { |
| 167 | return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]; |
| 168 | } |
| 169 | |
| 170 | /* |
| 171 | * Does the current CPU require a yet-as-unscheduled grace period? |
| 172 | */ |
| 173 | static int |
| 174 | cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp) |
| 175 | { |
| 176 | /* ACCESS_ONCE() because we are accessing outside of lock. */ |
| 177 | return *rdp->nxttail[RCU_DONE_TAIL] && |
| 178 | ACCESS_ONCE(rsp->completed) == ACCESS_ONCE(rsp->gpnum); |
| 179 | } |
| 180 | |
| 181 | /* |
| 182 | * Return the root node of the specified rcu_state structure. |
| 183 | */ |
| 184 | static struct rcu_node *rcu_get_root(struct rcu_state *rsp) |
| 185 | { |
| 186 | return &rsp->node[0]; |
| 187 | } |
| 188 | |
| 189 | #ifdef CONFIG_SMP |
| 190 | |
| 191 | /* |
| 192 | * If the specified CPU is offline, tell the caller that it is in |
| 193 | * a quiescent state. Otherwise, whack it with a reschedule IPI. |
| 194 | * Grace periods can end up waiting on an offline CPU when that |
| 195 | * CPU is in the process of coming online -- it will be added to the |
| 196 | * rcu_node bitmasks before it actually makes it online. The same thing |
| 197 | * can happen while a CPU is in the process of coming online. Because this |
| 198 | * race is quite rare, we check for it after detecting that the grace |
| 199 | * period has been delayed rather than checking each and every CPU |
| 200 | * each and every time we start a new grace period. |
| 201 | */ |
| 202 | static int rcu_implicit_offline_qs(struct rcu_data *rdp) |
| 203 | { |
| 204 | /* |
| 205 | * If the CPU is offline, it is in a quiescent state. We can |
| 206 | * trust its state not to change because interrupts are disabled. |
| 207 | */ |
| 208 | if (cpu_is_offline(rdp->cpu)) { |
| 209 | rdp->offline_fqs++; |
| 210 | return 1; |
| 211 | } |
| 212 | |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 213 | /* If preemptable RCU, no point in sending reschedule IPI. */ |
| 214 | if (rdp->preemptable) |
| 215 | return 0; |
| 216 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 217 | /* The CPU is online, so send it a reschedule IPI. */ |
| 218 | if (rdp->cpu != smp_processor_id()) |
| 219 | smp_send_reschedule(rdp->cpu); |
| 220 | else |
| 221 | set_need_resched(); |
| 222 | rdp->resched_ipi++; |
| 223 | return 0; |
| 224 | } |
| 225 | |
| 226 | #endif /* #ifdef CONFIG_SMP */ |
| 227 | |
| 228 | #ifdef CONFIG_NO_HZ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 229 | |
| 230 | /** |
| 231 | * rcu_enter_nohz - inform RCU that current CPU is entering nohz |
| 232 | * |
| 233 | * Enter nohz mode, in other words, -leave- the mode in which RCU |
| 234 | * read-side critical sections can occur. (Though RCU read-side |
| 235 | * critical sections can occur in irq handlers in nohz mode, a possibility |
| 236 | * handled by rcu_irq_enter() and rcu_irq_exit()). |
| 237 | */ |
| 238 | void rcu_enter_nohz(void) |
| 239 | { |
| 240 | unsigned long flags; |
| 241 | struct rcu_dynticks *rdtp; |
| 242 | |
| 243 | smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ |
| 244 | local_irq_save(flags); |
| 245 | rdtp = &__get_cpu_var(rcu_dynticks); |
| 246 | rdtp->dynticks++; |
| 247 | rdtp->dynticks_nesting--; |
Paul E. McKenney | 8684896 | 2009-08-27 15:00:12 -0700 | [diff] [blame] | 248 | WARN_ON_ONCE(rdtp->dynticks & 0x1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 249 | local_irq_restore(flags); |
| 250 | } |
| 251 | |
| 252 | /* |
| 253 | * rcu_exit_nohz - inform RCU that current CPU is leaving nohz |
| 254 | * |
| 255 | * Exit nohz mode, in other words, -enter- the mode in which RCU |
| 256 | * read-side critical sections normally occur. |
| 257 | */ |
| 258 | void rcu_exit_nohz(void) |
| 259 | { |
| 260 | unsigned long flags; |
| 261 | struct rcu_dynticks *rdtp; |
| 262 | |
| 263 | local_irq_save(flags); |
| 264 | rdtp = &__get_cpu_var(rcu_dynticks); |
| 265 | rdtp->dynticks++; |
| 266 | rdtp->dynticks_nesting++; |
Paul E. McKenney | 8684896 | 2009-08-27 15:00:12 -0700 | [diff] [blame] | 267 | WARN_ON_ONCE(!(rdtp->dynticks & 0x1)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 268 | local_irq_restore(flags); |
| 269 | smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ |
| 270 | } |
| 271 | |
| 272 | /** |
| 273 | * rcu_nmi_enter - inform RCU of entry to NMI context |
| 274 | * |
| 275 | * If the CPU was idle with dynamic ticks active, and there is no |
| 276 | * irq handler running, this updates rdtp->dynticks_nmi to let the |
| 277 | * RCU grace-period handling know that the CPU is active. |
| 278 | */ |
| 279 | void rcu_nmi_enter(void) |
| 280 | { |
| 281 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 282 | |
| 283 | if (rdtp->dynticks & 0x1) |
| 284 | return; |
| 285 | rdtp->dynticks_nmi++; |
Paul E. McKenney | 8684896 | 2009-08-27 15:00:12 -0700 | [diff] [blame] | 286 | WARN_ON_ONCE(!(rdtp->dynticks_nmi & 0x1)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 287 | smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ |
| 288 | } |
| 289 | |
| 290 | /** |
| 291 | * rcu_nmi_exit - inform RCU of exit from NMI context |
| 292 | * |
| 293 | * If the CPU was idle with dynamic ticks active, and there is no |
| 294 | * irq handler running, this updates rdtp->dynticks_nmi to let the |
| 295 | * RCU grace-period handling know that the CPU is no longer active. |
| 296 | */ |
| 297 | void rcu_nmi_exit(void) |
| 298 | { |
| 299 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 300 | |
| 301 | if (rdtp->dynticks & 0x1) |
| 302 | return; |
| 303 | smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ |
| 304 | rdtp->dynticks_nmi++; |
Paul E. McKenney | 8684896 | 2009-08-27 15:00:12 -0700 | [diff] [blame] | 305 | WARN_ON_ONCE(rdtp->dynticks_nmi & 0x1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 306 | } |
| 307 | |
| 308 | /** |
| 309 | * rcu_irq_enter - inform RCU of entry to hard irq context |
| 310 | * |
| 311 | * If the CPU was idle with dynamic ticks active, this updates the |
| 312 | * rdtp->dynticks to let the RCU handling know that the CPU is active. |
| 313 | */ |
| 314 | void rcu_irq_enter(void) |
| 315 | { |
| 316 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 317 | |
| 318 | if (rdtp->dynticks_nesting++) |
| 319 | return; |
| 320 | rdtp->dynticks++; |
Paul E. McKenney | 8684896 | 2009-08-27 15:00:12 -0700 | [diff] [blame] | 321 | WARN_ON_ONCE(!(rdtp->dynticks & 0x1)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 322 | smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ |
| 323 | } |
| 324 | |
| 325 | /** |
| 326 | * rcu_irq_exit - inform RCU of exit from hard irq context |
| 327 | * |
| 328 | * If the CPU was idle with dynamic ticks active, update the rdp->dynticks |
| 329 | * to put let the RCU handling be aware that the CPU is going back to idle |
| 330 | * with no ticks. |
| 331 | */ |
| 332 | void rcu_irq_exit(void) |
| 333 | { |
| 334 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); |
| 335 | |
| 336 | if (--rdtp->dynticks_nesting) |
| 337 | return; |
| 338 | smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ |
| 339 | rdtp->dynticks++; |
Paul E. McKenney | 8684896 | 2009-08-27 15:00:12 -0700 | [diff] [blame] | 340 | WARN_ON_ONCE(rdtp->dynticks & 0x1); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 341 | |
| 342 | /* If the interrupt queued a callback, get out of dyntick mode. */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 343 | if (__get_cpu_var(rcu_sched_data).nxtlist || |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 344 | __get_cpu_var(rcu_bh_data).nxtlist) |
| 345 | set_need_resched(); |
| 346 | } |
| 347 | |
| 348 | /* |
| 349 | * Record the specified "completed" value, which is later used to validate |
| 350 | * dynticks counter manipulations. Specify "rsp->completed - 1" to |
| 351 | * unconditionally invalidate any future dynticks manipulations (which is |
| 352 | * useful at the beginning of a grace period). |
| 353 | */ |
| 354 | static void dyntick_record_completed(struct rcu_state *rsp, long comp) |
| 355 | { |
| 356 | rsp->dynticks_completed = comp; |
| 357 | } |
| 358 | |
| 359 | #ifdef CONFIG_SMP |
| 360 | |
| 361 | /* |
| 362 | * Recall the previously recorded value of the completion for dynticks. |
| 363 | */ |
| 364 | static long dyntick_recall_completed(struct rcu_state *rsp) |
| 365 | { |
| 366 | return rsp->dynticks_completed; |
| 367 | } |
| 368 | |
| 369 | /* |
| 370 | * Snapshot the specified CPU's dynticks counter so that we can later |
| 371 | * credit them with an implicit quiescent state. Return 1 if this CPU |
| 372 | * is already in a quiescent state courtesy of dynticks idle mode. |
| 373 | */ |
| 374 | static int dyntick_save_progress_counter(struct rcu_data *rdp) |
| 375 | { |
| 376 | int ret; |
| 377 | int snap; |
| 378 | int snap_nmi; |
| 379 | |
| 380 | snap = rdp->dynticks->dynticks; |
| 381 | snap_nmi = rdp->dynticks->dynticks_nmi; |
| 382 | smp_mb(); /* Order sampling of snap with end of grace period. */ |
| 383 | rdp->dynticks_snap = snap; |
| 384 | rdp->dynticks_nmi_snap = snap_nmi; |
| 385 | ret = ((snap & 0x1) == 0) && ((snap_nmi & 0x1) == 0); |
| 386 | if (ret) |
| 387 | rdp->dynticks_fqs++; |
| 388 | return ret; |
| 389 | } |
| 390 | |
| 391 | /* |
| 392 | * Return true if the specified CPU has passed through a quiescent |
| 393 | * state by virtue of being in or having passed through an dynticks |
| 394 | * idle state since the last call to dyntick_save_progress_counter() |
| 395 | * for this same CPU. |
| 396 | */ |
| 397 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) |
| 398 | { |
| 399 | long curr; |
| 400 | long curr_nmi; |
| 401 | long snap; |
| 402 | long snap_nmi; |
| 403 | |
| 404 | curr = rdp->dynticks->dynticks; |
| 405 | snap = rdp->dynticks_snap; |
| 406 | curr_nmi = rdp->dynticks->dynticks_nmi; |
| 407 | snap_nmi = rdp->dynticks_nmi_snap; |
| 408 | smp_mb(); /* force ordering with cpu entering/leaving dynticks. */ |
| 409 | |
| 410 | /* |
| 411 | * If the CPU passed through or entered a dynticks idle phase with |
| 412 | * no active irq/NMI handlers, then we can safely pretend that the CPU |
| 413 | * already acknowledged the request to pass through a quiescent |
| 414 | * state. Either way, that CPU cannot possibly be in an RCU |
| 415 | * read-side critical section that started before the beginning |
| 416 | * of the current RCU grace period. |
| 417 | */ |
| 418 | if ((curr != snap || (curr & 0x1) == 0) && |
| 419 | (curr_nmi != snap_nmi || (curr_nmi & 0x1) == 0)) { |
| 420 | rdp->dynticks_fqs++; |
| 421 | return 1; |
| 422 | } |
| 423 | |
| 424 | /* Go check for the CPU being offline. */ |
| 425 | return rcu_implicit_offline_qs(rdp); |
| 426 | } |
| 427 | |
| 428 | #endif /* #ifdef CONFIG_SMP */ |
| 429 | |
| 430 | #else /* #ifdef CONFIG_NO_HZ */ |
| 431 | |
| 432 | static void dyntick_record_completed(struct rcu_state *rsp, long comp) |
| 433 | { |
| 434 | } |
| 435 | |
| 436 | #ifdef CONFIG_SMP |
| 437 | |
| 438 | /* |
| 439 | * If there are no dynticks, then the only way that a CPU can passively |
| 440 | * be in a quiescent state is to be offline. Unlike dynticks idle, which |
| 441 | * is a point in time during the prior (already finished) grace period, |
| 442 | * an offline CPU is always in a quiescent state, and thus can be |
| 443 | * unconditionally applied. So just return the current value of completed. |
| 444 | */ |
| 445 | static long dyntick_recall_completed(struct rcu_state *rsp) |
| 446 | { |
| 447 | return rsp->completed; |
| 448 | } |
| 449 | |
| 450 | static int dyntick_save_progress_counter(struct rcu_data *rdp) |
| 451 | { |
| 452 | return 0; |
| 453 | } |
| 454 | |
| 455 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) |
| 456 | { |
| 457 | return rcu_implicit_offline_qs(rdp); |
| 458 | } |
| 459 | |
| 460 | #endif /* #ifdef CONFIG_SMP */ |
| 461 | |
| 462 | #endif /* #else #ifdef CONFIG_NO_HZ */ |
| 463 | |
| 464 | #ifdef CONFIG_RCU_CPU_STALL_DETECTOR |
| 465 | |
| 466 | static void record_gp_stall_check_time(struct rcu_state *rsp) |
| 467 | { |
| 468 | rsp->gp_start = jiffies; |
| 469 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_CHECK; |
| 470 | } |
| 471 | |
| 472 | static void print_other_cpu_stall(struct rcu_state *rsp) |
| 473 | { |
| 474 | int cpu; |
| 475 | long delta; |
| 476 | unsigned long flags; |
| 477 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 478 | struct rcu_node *rnp_cur = rsp->level[NUM_RCU_LVLS - 1]; |
| 479 | struct rcu_node *rnp_end = &rsp->node[NUM_RCU_NODES]; |
| 480 | |
| 481 | /* Only let one CPU complain about others per time interval. */ |
| 482 | |
| 483 | spin_lock_irqsave(&rnp->lock, flags); |
| 484 | delta = jiffies - rsp->jiffies_stall; |
| 485 | if (delta < RCU_STALL_RAT_DELAY || rsp->gpnum == rsp->completed) { |
| 486 | spin_unlock_irqrestore(&rnp->lock, flags); |
| 487 | return; |
| 488 | } |
| 489 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_RECHECK; |
| 490 | spin_unlock_irqrestore(&rnp->lock, flags); |
| 491 | |
| 492 | /* OK, time to rat on our buddy... */ |
| 493 | |
| 494 | printk(KERN_ERR "INFO: RCU detected CPU stalls:"); |
| 495 | for (; rnp_cur < rnp_end; rnp_cur++) { |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 496 | rcu_print_task_stall(rnp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 497 | if (rnp_cur->qsmask == 0) |
| 498 | continue; |
| 499 | for (cpu = 0; cpu <= rnp_cur->grphi - rnp_cur->grplo; cpu++) |
| 500 | if (rnp_cur->qsmask & (1UL << cpu)) |
| 501 | printk(" %d", rnp_cur->grplo + cpu); |
| 502 | } |
| 503 | printk(" (detected by %d, t=%ld jiffies)\n", |
| 504 | smp_processor_id(), (long)(jiffies - rsp->gp_start)); |
Ingo Molnar | c1dc0b9 | 2009-08-02 11:28:21 +0200 | [diff] [blame] | 505 | trigger_all_cpu_backtrace(); |
| 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 | |
| 515 | printk(KERN_ERR "INFO: RCU detected CPU %d stall (t=%lu jiffies)\n", |
| 516 | 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 | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 519 | spin_lock_irqsave(&rnp->lock, flags); |
| 520 | if ((long)(jiffies - rsp->jiffies_stall) >= 0) |
| 521 | rsp->jiffies_stall = |
| 522 | jiffies + RCU_SECONDS_TILL_STALL_RECHECK; |
| 523 | 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 | |
| 533 | delta = jiffies - rsp->jiffies_stall; |
| 534 | rnp = rdp->mynode; |
| 535 | if ((rnp->qsmask & rdp->grpmask) && delta >= 0) { |
| 536 | |
| 537 | /* We haven't checked in, so go dump stack. */ |
| 538 | print_cpu_stall(rsp); |
| 539 | |
| 540 | } else if (rsp->gpnum != rsp->completed && |
| 541 | delta >= RCU_STALL_RAT_DELAY) { |
| 542 | |
| 543 | /* They had two time units to dump stack, so complain. */ |
| 544 | print_other_cpu_stall(rsp); |
| 545 | } |
| 546 | } |
| 547 | |
| 548 | #else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ |
| 549 | |
| 550 | static void record_gp_stall_check_time(struct rcu_state *rsp) |
| 551 | { |
| 552 | } |
| 553 | |
| 554 | static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) |
| 555 | { |
| 556 | } |
| 557 | |
| 558 | #endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ |
| 559 | |
| 560 | /* |
| 561 | * Update CPU-local rcu_data state to record the newly noticed grace period. |
| 562 | * This is used both when we started the grace period and when we notice |
| 563 | * that someone else started the grace period. |
| 564 | */ |
| 565 | static void note_new_gpnum(struct rcu_state *rsp, struct rcu_data *rdp) |
| 566 | { |
| 567 | rdp->qs_pending = 1; |
| 568 | rdp->passed_quiesc = 0; |
| 569 | rdp->gpnum = rsp->gpnum; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 570 | } |
| 571 | |
| 572 | /* |
| 573 | * Did someone else start a new RCU grace period start since we last |
| 574 | * checked? Update local state appropriately if so. Must be called |
| 575 | * on the CPU corresponding to rdp. |
| 576 | */ |
| 577 | static int |
| 578 | check_for_new_grace_period(struct rcu_state *rsp, struct rcu_data *rdp) |
| 579 | { |
| 580 | unsigned long flags; |
| 581 | int ret = 0; |
| 582 | |
| 583 | local_irq_save(flags); |
| 584 | if (rdp->gpnum != rsp->gpnum) { |
| 585 | note_new_gpnum(rsp, rdp); |
| 586 | ret = 1; |
| 587 | } |
| 588 | local_irq_restore(flags); |
| 589 | return ret; |
| 590 | } |
| 591 | |
| 592 | /* |
| 593 | * Start a new RCU grace period if warranted, re-initializing the hierarchy |
| 594 | * in preparation for detecting the next grace period. The caller must hold |
| 595 | * the root node's ->lock, which is released before return. Hard irqs must |
| 596 | * be disabled. |
| 597 | */ |
| 598 | static void |
| 599 | rcu_start_gp(struct rcu_state *rsp, unsigned long flags) |
| 600 | __releases(rcu_get_root(rsp)->lock) |
| 601 | { |
| 602 | struct rcu_data *rdp = rsp->rda[smp_processor_id()]; |
| 603 | struct rcu_node *rnp = rcu_get_root(rsp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 604 | |
| 605 | if (!cpu_needs_another_gp(rsp, rdp)) { |
| 606 | spin_unlock_irqrestore(&rnp->lock, flags); |
| 607 | return; |
| 608 | } |
| 609 | |
| 610 | /* Advance to a new grace period and initialize state. */ |
| 611 | rsp->gpnum++; |
Paul E. McKenney | c3422be | 2009-09-13 09:15:10 -0700 | [diff] [blame] | 612 | WARN_ON_ONCE(rsp->signaled == RCU_GP_INIT); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 613 | rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */ |
| 614 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 615 | record_gp_stall_check_time(rsp); |
| 616 | dyntick_record_completed(rsp, rsp->completed - 1); |
| 617 | note_new_gpnum(rsp, rdp); |
| 618 | |
| 619 | /* |
| 620 | * Because we are first, we know that all our callbacks will |
| 621 | * be covered by this upcoming grace period, even the ones |
| 622 | * that were registered arbitrarily recently. |
| 623 | */ |
| 624 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 625 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 626 | |
| 627 | /* Special-case the common single-level case. */ |
| 628 | if (NUM_RCU_NODES == 1) { |
Paul E. McKenney | b0e165c | 2009-09-13 09:15:09 -0700 | [diff] [blame] | 629 | rcu_preempt_check_blocked_tasks(rnp); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 630 | rnp->qsmask = rnp->qsmaskinit; |
Paul E. McKenney | de078d8 | 2009-09-08 15:54:36 -0700 | [diff] [blame] | 631 | rnp->gpnum = rsp->gpnum; |
Paul E. McKenney | c12172c | 2009-01-04 20:30:06 -0800 | [diff] [blame] | 632 | rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state OK. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 633 | spin_unlock_irqrestore(&rnp->lock, flags); |
| 634 | return; |
| 635 | } |
| 636 | |
| 637 | spin_unlock(&rnp->lock); /* leave irqs disabled. */ |
| 638 | |
| 639 | |
| 640 | /* Exclude any concurrent CPU-hotplug operations. */ |
| 641 | spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
| 642 | |
| 643 | /* |
Paul E. McKenney | b835db1 | 2009-09-08 15:54:37 -0700 | [diff] [blame] | 644 | * Set the quiescent-state-needed bits in all the rcu_node |
| 645 | * structures for all currently online CPUs in breadth-first |
| 646 | * order, starting from the root rcu_node structure. This |
| 647 | * operation relies on the layout of the hierarchy within the |
| 648 | * rsp->node[] array. Note that other CPUs will access only |
| 649 | * the leaves of the hierarchy, which still indicate that no |
| 650 | * grace period is in progress, at least until the corresponding |
| 651 | * leaf node has been initialized. In addition, we have excluded |
| 652 | * CPU-hotplug operations. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 653 | * |
| 654 | * Note that the grace period cannot complete until we finish |
| 655 | * the initialization process, as there will be at least one |
| 656 | * 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] | 657 | * one corresponding to this CPU, due to the fact that we have |
| 658 | * irqs disabled. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 659 | */ |
Paul E. McKenney | 49e2912 | 2009-09-18 09:50:19 -0700 | [diff] [blame] | 660 | for (rnp = &rsp->node[0]; rnp < &rsp->node[NUM_RCU_NODES]; rnp++) { |
| 661 | spin_lock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | b0e165c | 2009-09-13 09:15:09 -0700 | [diff] [blame] | 662 | rcu_preempt_check_blocked_tasks(rnp); |
Paul E. McKenney | 49e2912 | 2009-09-18 09:50:19 -0700 | [diff] [blame] | 663 | rnp->qsmask = rnp->qsmaskinit; |
Paul E. McKenney | de078d8 | 2009-09-08 15:54:36 -0700 | [diff] [blame] | 664 | rnp->gpnum = rsp->gpnum; |
Paul E. McKenney | 49e2912 | 2009-09-18 09:50:19 -0700 | [diff] [blame] | 665 | spin_unlock(&rnp->lock); /* irqs already disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 666 | } |
| 667 | |
| 668 | rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state now OK. */ |
| 669 | spin_unlock_irqrestore(&rsp->onofflock, flags); |
| 670 | } |
| 671 | |
| 672 | /* |
| 673 | * Advance this CPU's callbacks, but only if the current grace period |
| 674 | * has ended. This may be called only from the CPU to whom the rdp |
| 675 | * belongs. |
| 676 | */ |
| 677 | static void |
| 678 | rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp) |
| 679 | { |
| 680 | long completed_snap; |
| 681 | unsigned long flags; |
| 682 | |
| 683 | local_irq_save(flags); |
| 684 | completed_snap = ACCESS_ONCE(rsp->completed); /* outside of lock. */ |
| 685 | |
| 686 | /* Did another grace period end? */ |
| 687 | if (rdp->completed != completed_snap) { |
| 688 | |
| 689 | /* Advance callbacks. No harm if list empty. */ |
| 690 | rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL]; |
| 691 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL]; |
| 692 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 693 | |
| 694 | /* Remember that we saw this grace-period completion. */ |
| 695 | rdp->completed = completed_snap; |
| 696 | } |
| 697 | local_irq_restore(flags); |
| 698 | } |
| 699 | |
| 700 | /* |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 701 | * Clean up after the prior grace period and let rcu_start_gp() start up |
| 702 | * the next grace period if one is needed. Note that the caller must |
| 703 | * hold rnp->lock, as required by rcu_start_gp(), which will release it. |
| 704 | */ |
| 705 | static void cpu_quiet_msk_finish(struct rcu_state *rsp, unsigned long flags) |
| 706 | __releases(rnp->lock) |
| 707 | { |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 708 | WARN_ON_ONCE(rsp->completed == rsp->gpnum); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 709 | rsp->completed = rsp->gpnum; |
| 710 | rcu_process_gp_end(rsp, rsp->rda[smp_processor_id()]); |
| 711 | rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */ |
| 712 | } |
| 713 | |
| 714 | /* |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 715 | * Similar to cpu_quiet(), for which it is a helper function. Allows |
| 716 | * a group of CPUs to be quieted at one go, though all the CPUs in the |
| 717 | * group must be represented by the same leaf rcu_node structure. |
| 718 | * That structure's lock must be held upon entry, and it is released |
| 719 | * before return. |
| 720 | */ |
| 721 | static void |
| 722 | cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, struct rcu_node *rnp, |
| 723 | unsigned long flags) |
| 724 | __releases(rnp->lock) |
| 725 | { |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 726 | struct rcu_node *rnp_c; |
| 727 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 728 | /* Walk up the rcu_node hierarchy. */ |
| 729 | for (;;) { |
| 730 | if (!(rnp->qsmask & mask)) { |
| 731 | |
| 732 | /* Our bit has already been cleared, so done. */ |
| 733 | spin_unlock_irqrestore(&rnp->lock, flags); |
| 734 | return; |
| 735 | } |
| 736 | rnp->qsmask &= ~mask; |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 737 | if (rnp->qsmask != 0 || rcu_preempted_readers(rnp)) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 738 | |
| 739 | /* Other bits still set at this level, so done. */ |
| 740 | spin_unlock_irqrestore(&rnp->lock, flags); |
| 741 | return; |
| 742 | } |
| 743 | mask = rnp->grpmask; |
| 744 | if (rnp->parent == NULL) { |
| 745 | |
| 746 | /* No more levels. Exit loop holding root lock. */ |
| 747 | |
| 748 | break; |
| 749 | } |
| 750 | spin_unlock_irqrestore(&rnp->lock, flags); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 751 | rnp_c = rnp; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 752 | rnp = rnp->parent; |
| 753 | spin_lock_irqsave(&rnp->lock, flags); |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 754 | WARN_ON_ONCE(rnp_c->qsmask); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 755 | } |
| 756 | |
| 757 | /* |
| 758 | * Get here if we are the last CPU to pass through a quiescent |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 759 | * state for this grace period. Invoke cpu_quiet_msk_finish() |
| 760 | * 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] | 761 | */ |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 762 | cpu_quiet_msk_finish(rsp, flags); /* releases rnp->lock. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 763 | } |
| 764 | |
| 765 | /* |
| 766 | * Record a quiescent state for the specified CPU, which must either be |
Paul E. McKenney | e7d8842 | 2009-09-18 09:50:18 -0700 | [diff] [blame] | 767 | * the current CPU. The lastcomp argument is used to make sure we are |
| 768 | * still in the grace period of interest. We don't want to end the current |
| 769 | * grace period based on quiescent states detected in an earlier grace |
| 770 | * period! |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 771 | */ |
| 772 | static void |
| 773 | cpu_quiet(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp) |
| 774 | { |
| 775 | unsigned long flags; |
| 776 | unsigned long mask; |
| 777 | struct rcu_node *rnp; |
| 778 | |
| 779 | rnp = rdp->mynode; |
| 780 | spin_lock_irqsave(&rnp->lock, flags); |
| 781 | if (lastcomp != ACCESS_ONCE(rsp->completed)) { |
| 782 | |
| 783 | /* |
| 784 | * Someone beat us to it for this grace period, so leave. |
| 785 | * The race with GP start is resolved by the fact that we |
| 786 | * hold the leaf rcu_node lock, so that the per-CPU bits |
| 787 | * cannot yet be initialized -- so we would simply find our |
| 788 | * CPU's bit already cleared in cpu_quiet_msk() if this race |
| 789 | * occurred. |
| 790 | */ |
| 791 | rdp->passed_quiesc = 0; /* try again later! */ |
| 792 | spin_unlock_irqrestore(&rnp->lock, flags); |
| 793 | return; |
| 794 | } |
| 795 | mask = rdp->grpmask; |
| 796 | if ((rnp->qsmask & mask) == 0) { |
| 797 | spin_unlock_irqrestore(&rnp->lock, flags); |
| 798 | } else { |
| 799 | rdp->qs_pending = 0; |
| 800 | |
| 801 | /* |
| 802 | * This GP can't end until cpu checks in, so all of our |
| 803 | * callbacks can be processed during the next GP. |
| 804 | */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 805 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 806 | |
| 807 | cpu_quiet_msk(mask, rsp, rnp, flags); /* releases rnp->lock */ |
| 808 | } |
| 809 | } |
| 810 | |
| 811 | /* |
| 812 | * Check to see if there is a new grace period of which this CPU |
| 813 | * is not yet aware, and if so, set up local rcu_data state for it. |
| 814 | * Otherwise, see if this CPU has just passed through its first |
| 815 | * quiescent state for this grace period, and record that fact if so. |
| 816 | */ |
| 817 | static void |
| 818 | rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp) |
| 819 | { |
| 820 | /* If there is now a new grace period, record and return. */ |
| 821 | if (check_for_new_grace_period(rsp, rdp)) |
| 822 | return; |
| 823 | |
| 824 | /* |
| 825 | * Does this CPU still need to do its part for current grace period? |
| 826 | * If no, return and let the other CPUs do their part as well. |
| 827 | */ |
| 828 | if (!rdp->qs_pending) |
| 829 | return; |
| 830 | |
| 831 | /* |
| 832 | * Was there a quiescent state since the beginning of the grace |
| 833 | * period? If no, then exit and wait for the next call. |
| 834 | */ |
| 835 | if (!rdp->passed_quiesc) |
| 836 | return; |
| 837 | |
| 838 | /* Tell RCU we are done (but cpu_quiet() will be the judge of that). */ |
| 839 | cpu_quiet(rdp->cpu, rsp, rdp, rdp->passed_quiesc_completed); |
| 840 | } |
| 841 | |
| 842 | #ifdef CONFIG_HOTPLUG_CPU |
| 843 | |
| 844 | /* |
| 845 | * Remove the outgoing CPU from the bitmasks in the rcu_node hierarchy |
| 846 | * and move all callbacks from the outgoing CPU to the current one. |
| 847 | */ |
| 848 | static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) |
| 849 | { |
| 850 | int i; |
| 851 | unsigned long flags; |
| 852 | long lastcomp; |
| 853 | unsigned long mask; |
| 854 | struct rcu_data *rdp = rsp->rda[cpu]; |
| 855 | struct rcu_data *rdp_me; |
| 856 | struct rcu_node *rnp; |
| 857 | |
| 858 | /* Exclude any attempts to start a new grace period. */ |
| 859 | spin_lock_irqsave(&rsp->onofflock, flags); |
| 860 | |
| 861 | /* 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] | 862 | rnp = rdp->mynode; /* this is the outgoing CPU's rnp. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 863 | mask = rdp->grpmask; /* rnp->grplo is constant. */ |
| 864 | do { |
| 865 | spin_lock(&rnp->lock); /* irqs already disabled. */ |
| 866 | rnp->qsmaskinit &= ~mask; |
| 867 | if (rnp->qsmaskinit != 0) { |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 868 | spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 869 | break; |
| 870 | } |
Paul E. McKenney | 28ecd58 | 2009-09-18 09:50:17 -0700 | [diff] [blame] | 871 | rcu_preempt_offline_tasks(rsp, rnp, rdp); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 872 | mask = rnp->grpmask; |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 873 | spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 874 | rnp = rnp->parent; |
| 875 | } while (rnp != NULL); |
| 876 | lastcomp = rsp->completed; |
| 877 | |
| 878 | spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ |
| 879 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 880 | /* |
| 881 | * Move callbacks from the outgoing CPU to the running CPU. |
| 882 | * Note that the outgoing CPU is now quiscent, so it is now |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 883 | * (uncharacteristically) safe to access its rcu_data structure. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 884 | * Note also that we must carefully retain the order of the |
| 885 | * outgoing CPU's callbacks in order for rcu_barrier() to work |
| 886 | * correctly. Finally, note that we start all the callbacks |
| 887 | * afresh, even those that have passed through a grace period |
| 888 | * and are therefore ready to invoke. The theory is that hotplug |
| 889 | * events are rare, and that if they are frequent enough to |
| 890 | * indefinitely delay callbacks, you have far worse things to |
| 891 | * be worrying about. |
| 892 | */ |
| 893 | rdp_me = rsp->rda[smp_processor_id()]; |
| 894 | if (rdp->nxtlist != NULL) { |
| 895 | *rdp_me->nxttail[RCU_NEXT_TAIL] = rdp->nxtlist; |
| 896 | rdp_me->nxttail[RCU_NEXT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
| 897 | rdp->nxtlist = NULL; |
| 898 | for (i = 0; i < RCU_NEXT_SIZE; i++) |
| 899 | rdp->nxttail[i] = &rdp->nxtlist; |
| 900 | rdp_me->qlen += rdp->qlen; |
| 901 | rdp->qlen = 0; |
| 902 | } |
| 903 | local_irq_restore(flags); |
| 904 | } |
| 905 | |
| 906 | /* |
| 907 | * Remove the specified CPU from the RCU hierarchy and move any pending |
| 908 | * callbacks that it might have to the current CPU. This code assumes |
| 909 | * that at least one CPU in the system will remain running at all times. |
| 910 | * Any attempt to offline -all- CPUs is likely to strand RCU callbacks. |
| 911 | */ |
| 912 | static void rcu_offline_cpu(int cpu) |
| 913 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 914 | __rcu_offline_cpu(cpu, &rcu_sched_state); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 915 | __rcu_offline_cpu(cpu, &rcu_bh_state); |
Paul E. McKenney | 33f7614 | 2009-08-24 09:42:01 -0700 | [diff] [blame] | 916 | rcu_preempt_offline_cpu(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 917 | } |
| 918 | |
| 919 | #else /* #ifdef CONFIG_HOTPLUG_CPU */ |
| 920 | |
| 921 | static void rcu_offline_cpu(int cpu) |
| 922 | { |
| 923 | } |
| 924 | |
| 925 | #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */ |
| 926 | |
| 927 | /* |
| 928 | * Invoke any RCU callbacks that have made it to the end of their grace |
| 929 | * period. Thottle as specified by rdp->blimit. |
| 930 | */ |
| 931 | static void rcu_do_batch(struct rcu_data *rdp) |
| 932 | { |
| 933 | unsigned long flags; |
| 934 | struct rcu_head *next, *list, **tail; |
| 935 | int count; |
| 936 | |
| 937 | /* If no callbacks are ready, just return.*/ |
| 938 | if (!cpu_has_callbacks_ready_to_invoke(rdp)) |
| 939 | return; |
| 940 | |
| 941 | /* |
| 942 | * Extract the list of ready callbacks, disabling to prevent |
| 943 | * races with call_rcu() from interrupt handlers. |
| 944 | */ |
| 945 | local_irq_save(flags); |
| 946 | list = rdp->nxtlist; |
| 947 | rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL]; |
| 948 | *rdp->nxttail[RCU_DONE_TAIL] = NULL; |
| 949 | tail = rdp->nxttail[RCU_DONE_TAIL]; |
| 950 | for (count = RCU_NEXT_SIZE - 1; count >= 0; count--) |
| 951 | if (rdp->nxttail[count] == rdp->nxttail[RCU_DONE_TAIL]) |
| 952 | rdp->nxttail[count] = &rdp->nxtlist; |
| 953 | local_irq_restore(flags); |
| 954 | |
| 955 | /* Invoke callbacks. */ |
| 956 | count = 0; |
| 957 | while (list) { |
| 958 | next = list->next; |
| 959 | prefetch(next); |
| 960 | list->func(list); |
| 961 | list = next; |
| 962 | if (++count >= rdp->blimit) |
| 963 | break; |
| 964 | } |
| 965 | |
| 966 | local_irq_save(flags); |
| 967 | |
| 968 | /* Update count, and requeue any remaining callbacks. */ |
| 969 | rdp->qlen -= count; |
| 970 | if (list != NULL) { |
| 971 | *tail = rdp->nxtlist; |
| 972 | rdp->nxtlist = list; |
| 973 | for (count = 0; count < RCU_NEXT_SIZE; count++) |
| 974 | if (&rdp->nxtlist == rdp->nxttail[count]) |
| 975 | rdp->nxttail[count] = tail; |
| 976 | else |
| 977 | break; |
| 978 | } |
| 979 | |
| 980 | /* Reinstate batch limit if we have worked down the excess. */ |
| 981 | if (rdp->blimit == LONG_MAX && rdp->qlen <= qlowmark) |
| 982 | rdp->blimit = blimit; |
| 983 | |
| 984 | local_irq_restore(flags); |
| 985 | |
| 986 | /* Re-raise the RCU softirq if there are callbacks remaining. */ |
| 987 | if (cpu_has_callbacks_ready_to_invoke(rdp)) |
| 988 | raise_softirq(RCU_SOFTIRQ); |
| 989 | } |
| 990 | |
| 991 | /* |
| 992 | * Check to see if this CPU is in a non-context-switch quiescent state |
| 993 | * (user mode or idle loop for rcu, non-softirq execution for rcu_bh). |
| 994 | * Also schedule the RCU softirq handler. |
| 995 | * |
| 996 | * This function must be called with hardirqs disabled. It is normally |
| 997 | * invoked from the scheduling-clock interrupt. If rcu_pending returns |
| 998 | * false, there is no point in invoking rcu_check_callbacks(). |
| 999 | */ |
| 1000 | void rcu_check_callbacks(int cpu, int user) |
| 1001 | { |
Paul E. McKenney | a157229 | 2009-08-22 13:56:51 -0700 | [diff] [blame] | 1002 | if (!rcu_pending(cpu)) |
| 1003 | return; /* if nothing for RCU to do. */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1004 | if (user || |
Paul E. McKenney | a682604 | 2009-02-25 18:03:42 -0800 | [diff] [blame] | 1005 | (idle_cpu(cpu) && rcu_scheduler_active && |
| 1006 | !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) { |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1007 | |
| 1008 | /* |
| 1009 | * Get here if this CPU took its interrupt from user |
| 1010 | * mode or from the idle loop, and if this is not a |
| 1011 | * nested interrupt. In this case, the CPU is in |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1012 | * a quiescent state, so note it. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1013 | * |
| 1014 | * No memory barrier is required here because both |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1015 | * rcu_sched_qs() and rcu_bh_qs() reference only CPU-local |
| 1016 | * variables that other CPUs neither access nor modify, |
| 1017 | * at least not while the corresponding CPU is online. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1018 | */ |
| 1019 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1020 | rcu_sched_qs(cpu); |
| 1021 | rcu_bh_qs(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1022 | |
| 1023 | } else if (!in_softirq()) { |
| 1024 | |
| 1025 | /* |
| 1026 | * Get here if this CPU did not take its interrupt from |
| 1027 | * softirq, in other words, if it is not interrupting |
| 1028 | * a rcu_bh read-side critical section. This is an _bh |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1029 | * critical section, so note it. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1030 | */ |
| 1031 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1032 | rcu_bh_qs(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1033 | } |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1034 | rcu_preempt_check_callbacks(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1035 | raise_softirq(RCU_SOFTIRQ); |
| 1036 | } |
| 1037 | |
| 1038 | #ifdef CONFIG_SMP |
| 1039 | |
| 1040 | /* |
| 1041 | * Scan the leaf rcu_node structures, processing dyntick state for any that |
| 1042 | * have not yet encountered a quiescent state, using the function specified. |
| 1043 | * Returns 1 if the current grace period ends while scanning (possibly |
| 1044 | * because we made it end). |
| 1045 | */ |
| 1046 | static int rcu_process_dyntick(struct rcu_state *rsp, long lastcomp, |
| 1047 | int (*f)(struct rcu_data *)) |
| 1048 | { |
| 1049 | unsigned long bit; |
| 1050 | int cpu; |
| 1051 | unsigned long flags; |
| 1052 | unsigned long mask; |
| 1053 | struct rcu_node *rnp_cur = rsp->level[NUM_RCU_LVLS - 1]; |
| 1054 | struct rcu_node *rnp_end = &rsp->node[NUM_RCU_NODES]; |
| 1055 | |
| 1056 | for (; rnp_cur < rnp_end; rnp_cur++) { |
| 1057 | mask = 0; |
| 1058 | spin_lock_irqsave(&rnp_cur->lock, flags); |
| 1059 | if (rsp->completed != lastcomp) { |
| 1060 | spin_unlock_irqrestore(&rnp_cur->lock, flags); |
| 1061 | return 1; |
| 1062 | } |
| 1063 | if (rnp_cur->qsmask == 0) { |
| 1064 | spin_unlock_irqrestore(&rnp_cur->lock, flags); |
| 1065 | continue; |
| 1066 | } |
| 1067 | cpu = rnp_cur->grplo; |
| 1068 | bit = 1; |
| 1069 | for (; cpu <= rnp_cur->grphi; cpu++, bit <<= 1) { |
| 1070 | if ((rnp_cur->qsmask & bit) != 0 && f(rsp->rda[cpu])) |
| 1071 | mask |= bit; |
| 1072 | } |
| 1073 | if (mask != 0 && rsp->completed == lastcomp) { |
| 1074 | |
| 1075 | /* cpu_quiet_msk() releases rnp_cur->lock. */ |
| 1076 | cpu_quiet_msk(mask, rsp, rnp_cur, flags); |
| 1077 | continue; |
| 1078 | } |
| 1079 | spin_unlock_irqrestore(&rnp_cur->lock, flags); |
| 1080 | } |
| 1081 | return 0; |
| 1082 | } |
| 1083 | |
| 1084 | /* |
| 1085 | * Force quiescent states on reluctant CPUs, and also detect which |
| 1086 | * CPUs are in dyntick-idle mode. |
| 1087 | */ |
| 1088 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) |
| 1089 | { |
| 1090 | unsigned long flags; |
| 1091 | long lastcomp; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1092 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 1093 | u8 signaled; |
| 1094 | |
| 1095 | if (ACCESS_ONCE(rsp->completed) == ACCESS_ONCE(rsp->gpnum)) |
| 1096 | return; /* No grace period in progress, nothing to force. */ |
| 1097 | if (!spin_trylock_irqsave(&rsp->fqslock, flags)) { |
| 1098 | rsp->n_force_qs_lh++; /* Inexact, can lose counts. Tough! */ |
| 1099 | return; /* Someone else is already on the job. */ |
| 1100 | } |
| 1101 | if (relaxed && |
Paul E. McKenney | ef631b0 | 2009-04-13 21:31:16 -0700 | [diff] [blame] | 1102 | (long)(rsp->jiffies_force_qs - jiffies) >= 0) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1103 | goto unlock_ret; /* no emergency and done recently. */ |
| 1104 | rsp->n_force_qs++; |
| 1105 | spin_lock(&rnp->lock); |
| 1106 | lastcomp = rsp->completed; |
| 1107 | signaled = rsp->signaled; |
| 1108 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1109 | if (lastcomp == rsp->gpnum) { |
| 1110 | rsp->n_force_qs_ngp++; |
| 1111 | spin_unlock(&rnp->lock); |
| 1112 | goto unlock_ret; /* no GP in progress, time updated. */ |
| 1113 | } |
| 1114 | spin_unlock(&rnp->lock); |
| 1115 | switch (signaled) { |
| 1116 | case RCU_GP_INIT: |
| 1117 | |
| 1118 | break; /* grace period still initializing, ignore. */ |
| 1119 | |
| 1120 | case RCU_SAVE_DYNTICK: |
| 1121 | |
| 1122 | if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK) |
| 1123 | break; /* So gcc recognizes the dead code. */ |
| 1124 | |
| 1125 | /* Record dyntick-idle state. */ |
| 1126 | if (rcu_process_dyntick(rsp, lastcomp, |
| 1127 | dyntick_save_progress_counter)) |
| 1128 | goto unlock_ret; |
| 1129 | |
| 1130 | /* Update state, record completion counter. */ |
| 1131 | spin_lock(&rnp->lock); |
| 1132 | if (lastcomp == rsp->completed) { |
| 1133 | rsp->signaled = RCU_FORCE_QS; |
| 1134 | dyntick_record_completed(rsp, lastcomp); |
| 1135 | } |
| 1136 | spin_unlock(&rnp->lock); |
| 1137 | break; |
| 1138 | |
| 1139 | case RCU_FORCE_QS: |
| 1140 | |
| 1141 | /* Check dyntick-idle state, send IPI to laggarts. */ |
| 1142 | if (rcu_process_dyntick(rsp, dyntick_recall_completed(rsp), |
| 1143 | rcu_implicit_dynticks_qs)) |
| 1144 | goto unlock_ret; |
| 1145 | |
| 1146 | /* Leave state in case more forcing is required. */ |
| 1147 | |
| 1148 | break; |
| 1149 | } |
| 1150 | unlock_ret: |
| 1151 | spin_unlock_irqrestore(&rsp->fqslock, flags); |
| 1152 | } |
| 1153 | |
| 1154 | #else /* #ifdef CONFIG_SMP */ |
| 1155 | |
| 1156 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) |
| 1157 | { |
| 1158 | set_need_resched(); |
| 1159 | } |
| 1160 | |
| 1161 | #endif /* #else #ifdef CONFIG_SMP */ |
| 1162 | |
| 1163 | /* |
| 1164 | * This does the RCU processing work from softirq context for the |
| 1165 | * specified rcu_state and rcu_data structures. This may be called |
| 1166 | * only from the CPU to whom the rdp belongs. |
| 1167 | */ |
| 1168 | static void |
| 1169 | __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) |
| 1170 | { |
| 1171 | unsigned long flags; |
| 1172 | |
Paul E. McKenney | 2e59755 | 2009-08-15 09:53:48 -0700 | [diff] [blame] | 1173 | WARN_ON_ONCE(rdp->beenonline == 0); |
| 1174 | |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1175 | /* |
| 1176 | * If an RCU GP has gone long enough, go check for dyntick |
| 1177 | * idle CPUs and, if needed, send resched IPIs. |
| 1178 | */ |
Paul E. McKenney | ef631b0 | 2009-04-13 21:31:16 -0700 | [diff] [blame] | 1179 | if ((long)(ACCESS_ONCE(rsp->jiffies_force_qs) - jiffies) < 0) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1180 | force_quiescent_state(rsp, 1); |
| 1181 | |
| 1182 | /* |
| 1183 | * Advance callbacks in response to end of earlier grace |
| 1184 | * period that some other CPU ended. |
| 1185 | */ |
| 1186 | rcu_process_gp_end(rsp, rdp); |
| 1187 | |
| 1188 | /* Update RCU state based on any recent quiescent states. */ |
| 1189 | rcu_check_quiescent_state(rsp, rdp); |
| 1190 | |
| 1191 | /* Does this CPU require a not-yet-started grace period? */ |
| 1192 | if (cpu_needs_another_gp(rsp, rdp)) { |
| 1193 | spin_lock_irqsave(&rcu_get_root(rsp)->lock, flags); |
| 1194 | rcu_start_gp(rsp, flags); /* releases above lock */ |
| 1195 | } |
| 1196 | |
| 1197 | /* If there are callbacks ready, invoke them. */ |
| 1198 | rcu_do_batch(rdp); |
| 1199 | } |
| 1200 | |
| 1201 | /* |
| 1202 | * Do softirq processing for the current CPU. |
| 1203 | */ |
| 1204 | static void rcu_process_callbacks(struct softirq_action *unused) |
| 1205 | { |
| 1206 | /* |
| 1207 | * Memory references from any prior RCU read-side critical sections |
| 1208 | * executed by the interrupted code must be seen before any RCU |
| 1209 | * grace-period manipulations below. |
| 1210 | */ |
| 1211 | smp_mb(); /* See above block comment. */ |
| 1212 | |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1213 | __rcu_process_callbacks(&rcu_sched_state, |
| 1214 | &__get_cpu_var(rcu_sched_data)); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1215 | __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] | 1216 | rcu_preempt_process_callbacks(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1217 | |
| 1218 | /* |
| 1219 | * Memory references from any later RCU read-side critical sections |
| 1220 | * executed by the interrupted code must be seen after any RCU |
| 1221 | * grace-period manipulations above. |
| 1222 | */ |
| 1223 | smp_mb(); /* See above block comment. */ |
| 1224 | } |
| 1225 | |
| 1226 | static void |
| 1227 | __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), |
| 1228 | struct rcu_state *rsp) |
| 1229 | { |
| 1230 | unsigned long flags; |
| 1231 | struct rcu_data *rdp; |
| 1232 | |
| 1233 | head->func = func; |
| 1234 | head->next = NULL; |
| 1235 | |
| 1236 | smp_mb(); /* Ensure RCU update seen before callback registry. */ |
| 1237 | |
| 1238 | /* |
| 1239 | * Opportunistically note grace-period endings and beginnings. |
| 1240 | * Note that we might see a beginning right after we see an |
| 1241 | * end, but never vice versa, since this CPU has to pass through |
| 1242 | * a quiescent state betweentimes. |
| 1243 | */ |
| 1244 | local_irq_save(flags); |
| 1245 | rdp = rsp->rda[smp_processor_id()]; |
| 1246 | rcu_process_gp_end(rsp, rdp); |
| 1247 | check_for_new_grace_period(rsp, rdp); |
| 1248 | |
| 1249 | /* Add the callback to our list. */ |
| 1250 | *rdp->nxttail[RCU_NEXT_TAIL] = head; |
| 1251 | rdp->nxttail[RCU_NEXT_TAIL] = &head->next; |
| 1252 | |
| 1253 | /* Start a new grace period if one not already started. */ |
| 1254 | if (ACCESS_ONCE(rsp->completed) == ACCESS_ONCE(rsp->gpnum)) { |
| 1255 | unsigned long nestflag; |
| 1256 | struct rcu_node *rnp_root = rcu_get_root(rsp); |
| 1257 | |
| 1258 | spin_lock_irqsave(&rnp_root->lock, nestflag); |
| 1259 | rcu_start_gp(rsp, nestflag); /* releases rnp_root->lock. */ |
| 1260 | } |
| 1261 | |
| 1262 | /* Force the grace period if too many callbacks or too long waiting. */ |
| 1263 | if (unlikely(++rdp->qlen > qhimark)) { |
| 1264 | rdp->blimit = LONG_MAX; |
| 1265 | force_quiescent_state(rsp, 0); |
Paul E. McKenney | ef631b0 | 2009-04-13 21:31:16 -0700 | [diff] [blame] | 1266 | } else if ((long)(ACCESS_ONCE(rsp->jiffies_force_qs) - jiffies) < 0) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1267 | force_quiescent_state(rsp, 1); |
| 1268 | local_irq_restore(flags); |
| 1269 | } |
| 1270 | |
| 1271 | /* |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1272 | * Queue an RCU-sched callback for invocation after a grace period. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1273 | */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1274 | 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] | 1275 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1276 | __call_rcu(head, func, &rcu_sched_state); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1277 | } |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1278 | EXPORT_SYMBOL_GPL(call_rcu_sched); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1279 | |
| 1280 | /* |
| 1281 | * Queue an RCU for invocation after a quicker grace period. |
| 1282 | */ |
| 1283 | void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) |
| 1284 | { |
| 1285 | __call_rcu(head, func, &rcu_bh_state); |
| 1286 | } |
| 1287 | EXPORT_SYMBOL_GPL(call_rcu_bh); |
| 1288 | |
| 1289 | /* |
| 1290 | * Check to see if there is any immediate RCU-related work to be done |
| 1291 | * by the current CPU, for the specified type of RCU, returning 1 if so. |
| 1292 | * The checks are in order of increasing expense: checks that can be |
| 1293 | * carried out against CPU-local state are performed first. However, |
| 1294 | * we must check for CPU stalls first, else we might not get a chance. |
| 1295 | */ |
| 1296 | static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) |
| 1297 | { |
| 1298 | rdp->n_rcu_pending++; |
| 1299 | |
| 1300 | /* Check for CPU stalls, if enabled. */ |
| 1301 | check_cpu_stall(rsp, rdp); |
| 1302 | |
| 1303 | /* Is the RCU core waiting for a quiescent state from this CPU? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1304 | if (rdp->qs_pending) { |
| 1305 | rdp->n_rp_qs_pending++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1306 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1307 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1308 | |
| 1309 | /* Does this CPU have callbacks ready to invoke? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1310 | if (cpu_has_callbacks_ready_to_invoke(rdp)) { |
| 1311 | rdp->n_rp_cb_ready++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1312 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1313 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1314 | |
| 1315 | /* Has RCU gone idle with this CPU needing another grace period? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1316 | if (cpu_needs_another_gp(rsp, rdp)) { |
| 1317 | rdp->n_rp_cpu_needs_gp++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1318 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1319 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1320 | |
| 1321 | /* Has another RCU grace period completed? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1322 | if (ACCESS_ONCE(rsp->completed) != rdp->completed) { /* outside lock */ |
| 1323 | rdp->n_rp_gp_completed++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1324 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1325 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1326 | |
| 1327 | /* Has a new RCU grace period started? */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1328 | if (ACCESS_ONCE(rsp->gpnum) != rdp->gpnum) { /* outside lock */ |
| 1329 | rdp->n_rp_gp_started++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1330 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1331 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1332 | |
| 1333 | /* Has an RCU GP gone long enough to send resched IPIs &c? */ |
| 1334 | if (ACCESS_ONCE(rsp->completed) != ACCESS_ONCE(rsp->gpnum) && |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1335 | ((long)(ACCESS_ONCE(rsp->jiffies_force_qs) - jiffies) < 0)) { |
| 1336 | rdp->n_rp_need_fqs++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1337 | return 1; |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1338 | } |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1339 | |
| 1340 | /* nothing to do */ |
Paul E. McKenney | 7ba5c84 | 2009-04-13 21:31:17 -0700 | [diff] [blame] | 1341 | rdp->n_rp_need_nothing++; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1342 | return 0; |
| 1343 | } |
| 1344 | |
| 1345 | /* |
| 1346 | * Check to see if there is any immediate RCU-related work to be done |
| 1347 | * by the current CPU, returning 1 if so. This function is part of the |
| 1348 | * RCU implementation; it is -not- an exported member of the RCU API. |
| 1349 | */ |
Paul E. McKenney | a157229 | 2009-08-22 13:56:51 -0700 | [diff] [blame] | 1350 | static int rcu_pending(int cpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1351 | { |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1352 | 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] | 1353 | __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu)) || |
| 1354 | rcu_preempt_pending(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1355 | } |
| 1356 | |
| 1357 | /* |
| 1358 | * Check to see if any future RCU-related work will need to be done |
| 1359 | * by the current CPU, even if none need be done immediately, returning |
| 1360 | * 1 if so. This function is part of the RCU implementation; it is -not- |
| 1361 | * an exported member of the RCU API. |
| 1362 | */ |
| 1363 | int rcu_needs_cpu(int cpu) |
| 1364 | { |
| 1365 | /* RCU callbacks either ready or pending? */ |
Paul E. McKenney | d6714c2 | 2009-08-22 13:56:46 -0700 | [diff] [blame] | 1366 | return per_cpu(rcu_sched_data, cpu).nxtlist || |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1367 | per_cpu(rcu_bh_data, cpu).nxtlist || |
| 1368 | rcu_preempt_needs_cpu(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1369 | } |
| 1370 | |
| 1371 | /* |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1372 | * 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] | 1373 | */ |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1374 | static void __init |
| 1375 | rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1376 | { |
| 1377 | unsigned long flags; |
| 1378 | int i; |
Paul E. McKenney | 2756962 | 2009-08-15 09:53:46 -0700 | [diff] [blame] | 1379 | struct rcu_data *rdp = rsp->rda[cpu]; |
| 1380 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 1381 | |
| 1382 | /* Set up local state, ensuring consistent view of global state. */ |
| 1383 | spin_lock_irqsave(&rnp->lock, flags); |
| 1384 | rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo); |
| 1385 | rdp->nxtlist = NULL; |
| 1386 | for (i = 0; i < RCU_NEXT_SIZE; i++) |
| 1387 | rdp->nxttail[i] = &rdp->nxtlist; |
| 1388 | rdp->qlen = 0; |
| 1389 | #ifdef CONFIG_NO_HZ |
| 1390 | rdp->dynticks = &per_cpu(rcu_dynticks, cpu); |
| 1391 | #endif /* #ifdef CONFIG_NO_HZ */ |
| 1392 | rdp->cpu = cpu; |
| 1393 | spin_unlock_irqrestore(&rnp->lock, flags); |
| 1394 | } |
| 1395 | |
| 1396 | /* |
| 1397 | * Initialize a CPU's per-CPU RCU data. Note that only one online or |
| 1398 | * offline event can be happening at a given time. Note also that we |
| 1399 | * can accept some slop in the rsp->completed access due to the fact |
| 1400 | * 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] | 1401 | */ |
| 1402 | static void __cpuinit |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1403 | 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] | 1404 | { |
| 1405 | unsigned long flags; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1406 | long lastcomp; |
| 1407 | unsigned long mask; |
| 1408 | struct rcu_data *rdp = rsp->rda[cpu]; |
| 1409 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 1410 | |
| 1411 | /* Set up local state, ensuring consistent view of global state. */ |
| 1412 | spin_lock_irqsave(&rnp->lock, flags); |
| 1413 | lastcomp = rsp->completed; |
| 1414 | rdp->completed = lastcomp; |
| 1415 | rdp->gpnum = lastcomp; |
| 1416 | rdp->passed_quiesc = 0; /* We could be racing with new GP, */ |
| 1417 | rdp->qs_pending = 1; /* so set up to respond to current GP. */ |
| 1418 | rdp->beenonline = 1; /* We have now been online. */ |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1419 | rdp->preemptable = preemptable; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1420 | rdp->passed_quiesc_completed = lastcomp - 1; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1421 | rdp->blimit = blimit; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1422 | spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
| 1423 | |
| 1424 | /* |
| 1425 | * A new grace period might start here. If so, we won't be part |
| 1426 | * of it, but that is OK, as we are currently in a quiescent state. |
| 1427 | */ |
| 1428 | |
| 1429 | /* Exclude any attempts to start a new GP on large systems. */ |
| 1430 | spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
| 1431 | |
| 1432 | /* Add CPU to rcu_node bitmasks. */ |
| 1433 | rnp = rdp->mynode; |
| 1434 | mask = rdp->grpmask; |
| 1435 | do { |
| 1436 | /* Exclude any attempts to start a new GP on small systems. */ |
| 1437 | spin_lock(&rnp->lock); /* irqs already disabled. */ |
| 1438 | rnp->qsmaskinit |= mask; |
| 1439 | mask = rnp->grpmask; |
| 1440 | spin_unlock(&rnp->lock); /* irqs already disabled. */ |
| 1441 | rnp = rnp->parent; |
| 1442 | } while (rnp != NULL && !(rnp->qsmaskinit & mask)); |
| 1443 | |
Paul E. McKenney | e7d8842 | 2009-09-18 09:50:18 -0700 | [diff] [blame] | 1444 | spin_unlock_irqrestore(&rsp->onofflock, flags); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1445 | } |
| 1446 | |
| 1447 | static void __cpuinit rcu_online_cpu(int cpu) |
| 1448 | { |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1449 | rcu_init_percpu_data(cpu, &rcu_sched_state, 0); |
| 1450 | rcu_init_percpu_data(cpu, &rcu_bh_state, 0); |
| 1451 | rcu_preempt_init_percpu_data(cpu); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1452 | } |
| 1453 | |
| 1454 | /* |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1455 | * Handle CPU online/offline notification events. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1456 | */ |
Paul E. McKenney | 2e59755 | 2009-08-15 09:53:48 -0700 | [diff] [blame] | 1457 | int __cpuinit rcu_cpu_notify(struct notifier_block *self, |
| 1458 | unsigned long action, void *hcpu) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1459 | { |
| 1460 | long cpu = (long)hcpu; |
| 1461 | |
| 1462 | switch (action) { |
| 1463 | case CPU_UP_PREPARE: |
| 1464 | case CPU_UP_PREPARE_FROZEN: |
| 1465 | rcu_online_cpu(cpu); |
| 1466 | break; |
| 1467 | case CPU_DEAD: |
| 1468 | case CPU_DEAD_FROZEN: |
| 1469 | case CPU_UP_CANCELED: |
| 1470 | case CPU_UP_CANCELED_FROZEN: |
| 1471 | rcu_offline_cpu(cpu); |
| 1472 | break; |
| 1473 | default: |
| 1474 | break; |
| 1475 | } |
| 1476 | return NOTIFY_OK; |
| 1477 | } |
| 1478 | |
| 1479 | /* |
| 1480 | * Compute the per-level fanout, either using the exact fanout specified |
| 1481 | * or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT. |
| 1482 | */ |
| 1483 | #ifdef CONFIG_RCU_FANOUT_EXACT |
| 1484 | static void __init rcu_init_levelspread(struct rcu_state *rsp) |
| 1485 | { |
| 1486 | int i; |
| 1487 | |
| 1488 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) |
| 1489 | rsp->levelspread[i] = CONFIG_RCU_FANOUT; |
| 1490 | } |
| 1491 | #else /* #ifdef CONFIG_RCU_FANOUT_EXACT */ |
| 1492 | static void __init rcu_init_levelspread(struct rcu_state *rsp) |
| 1493 | { |
| 1494 | int ccur; |
| 1495 | int cprv; |
| 1496 | int i; |
| 1497 | |
| 1498 | cprv = NR_CPUS; |
| 1499 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { |
| 1500 | ccur = rsp->levelcnt[i]; |
| 1501 | rsp->levelspread[i] = (cprv + ccur - 1) / ccur; |
| 1502 | cprv = ccur; |
| 1503 | } |
| 1504 | } |
| 1505 | #endif /* #else #ifdef CONFIG_RCU_FANOUT_EXACT */ |
| 1506 | |
| 1507 | /* |
| 1508 | * Helper function for rcu_init() that initializes one rcu_state structure. |
| 1509 | */ |
| 1510 | static void __init rcu_init_one(struct rcu_state *rsp) |
| 1511 | { |
| 1512 | int cpustride = 1; |
| 1513 | int i; |
| 1514 | int j; |
| 1515 | struct rcu_node *rnp; |
| 1516 | |
| 1517 | /* Initialize the level-tracking arrays. */ |
| 1518 | |
| 1519 | for (i = 1; i < NUM_RCU_LVLS; i++) |
| 1520 | rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1]; |
| 1521 | rcu_init_levelspread(rsp); |
| 1522 | |
| 1523 | /* Initialize the elements themselves, starting from the leaves. */ |
| 1524 | |
| 1525 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { |
| 1526 | cpustride *= rsp->levelspread[i]; |
| 1527 | rnp = rsp->level[i]; |
| 1528 | for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) { |
| 1529 | spin_lock_init(&rnp->lock); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1530 | rnp->gpnum = 0; |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1531 | rnp->qsmask = 0; |
| 1532 | rnp->qsmaskinit = 0; |
| 1533 | rnp->grplo = j * cpustride; |
| 1534 | rnp->grphi = (j + 1) * cpustride - 1; |
| 1535 | if (rnp->grphi >= NR_CPUS) |
| 1536 | rnp->grphi = NR_CPUS - 1; |
| 1537 | if (i == 0) { |
| 1538 | rnp->grpnum = 0; |
| 1539 | rnp->grpmask = 0; |
| 1540 | rnp->parent = NULL; |
| 1541 | } else { |
| 1542 | rnp->grpnum = j % rsp->levelspread[i - 1]; |
| 1543 | rnp->grpmask = 1UL << rnp->grpnum; |
| 1544 | rnp->parent = rsp->level[i - 1] + |
| 1545 | j / rsp->levelspread[i - 1]; |
| 1546 | } |
| 1547 | rnp->level = i; |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1548 | INIT_LIST_HEAD(&rnp->blocked_tasks[0]); |
| 1549 | INIT_LIST_HEAD(&rnp->blocked_tasks[1]); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1550 | } |
| 1551 | } |
| 1552 | } |
| 1553 | |
| 1554 | /* |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1555 | * Helper macro for __rcu_init() and __rcu_init_preempt(). To be used |
| 1556 | * nowhere else! Assigns leaf node pointers into each CPU's rcu_data |
| 1557 | * structure. |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1558 | */ |
Paul E. McKenney | 65cf8f8 | 2009-08-22 13:56:49 -0700 | [diff] [blame] | 1559 | #define RCU_INIT_FLAVOR(rsp, rcu_data) \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1560 | do { \ |
Paul E. McKenney | 65cf8f8 | 2009-08-22 13:56:49 -0700 | [diff] [blame] | 1561 | rcu_init_one(rsp); \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1562 | rnp = (rsp)->level[NUM_RCU_LVLS - 1]; \ |
| 1563 | j = 0; \ |
| 1564 | for_each_possible_cpu(i) { \ |
| 1565 | if (i > rnp[j].grphi) \ |
| 1566 | j++; \ |
| 1567 | per_cpu(rcu_data, i).mynode = &rnp[j]; \ |
| 1568 | (rsp)->rda[i] = &per_cpu(rcu_data, i); \ |
Paul E. McKenney | 65cf8f8 | 2009-08-22 13:56:49 -0700 | [diff] [blame] | 1569 | rcu_boot_init_percpu_data(i, rsp); \ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1570 | } \ |
| 1571 | } while (0) |
| 1572 | |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1573 | #ifdef CONFIG_TREE_PREEMPT_RCU |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1574 | |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1575 | void __init __rcu_init_preempt(void) |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1576 | { |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1577 | int i; /* All used by RCU_INIT_FLAVOR(). */ |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1578 | int j; |
| 1579 | struct rcu_node *rnp; |
| 1580 | |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1581 | RCU_INIT_FLAVOR(&rcu_preempt_state, rcu_preempt_data); |
| 1582 | } |
| 1583 | |
| 1584 | #else /* #ifdef CONFIG_TREE_PREEMPT_RCU */ |
| 1585 | |
| 1586 | void __init __rcu_init_preempt(void) |
| 1587 | { |
| 1588 | } |
| 1589 | |
| 1590 | #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */ |
| 1591 | |
| 1592 | void __init __rcu_init(void) |
| 1593 | { |
| 1594 | int i; /* All used by RCU_INIT_FLAVOR(). */ |
| 1595 | int j; |
| 1596 | struct rcu_node *rnp; |
| 1597 | |
| 1598 | rcu_bootup_announce(); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1599 | #ifdef CONFIG_RCU_CPU_STALL_DETECTOR |
| 1600 | printk(KERN_INFO "RCU-based detection of stalled CPUs is enabled.\n"); |
| 1601 | #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ |
Paul E. McKenney | 65cf8f8 | 2009-08-22 13:56:49 -0700 | [diff] [blame] | 1602 | RCU_INIT_FLAVOR(&rcu_sched_state, rcu_sched_data); |
| 1603 | RCU_INIT_FLAVOR(&rcu_bh_state, rcu_bh_data); |
Paul E. McKenney | f41d911 | 2009-08-22 13:56:52 -0700 | [diff] [blame] | 1604 | __rcu_init_preempt(); |
Paul E. McKenney | 2e59755 | 2009-08-15 09:53:48 -0700 | [diff] [blame] | 1605 | open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); |
Paul E. McKenney | 64db4cf | 2008-12-18 21:55:32 +0100 | [diff] [blame] | 1606 | } |
| 1607 | |
| 1608 | module_param(blimit, int, 0); |
| 1609 | module_param(qhimark, int, 0); |
| 1610 | module_param(qlowmark, int, 0); |