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64db4cff PM |
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 - | |
a71fca58 | 28 | * Documentation/RCU |
64db4cff PM |
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> | |
c1dc0b9c | 38 | #include <linux/nmi.h> |
64db4cff PM |
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> | |
bbad9379 | 49 | #include <linux/kernel_stat.h> |
64db4cff | 50 | |
9f77da9f PM |
51 | #include "rcutree.h" |
52 | ||
64db4cff PM |
53 | /* Data structures. */ |
54 | ||
b668c9cf | 55 | static struct lock_class_key rcu_node_class[NUM_RCU_LVLS]; |
88b91c7c | 56 | |
4300aa64 PM |
57 | #define RCU_STATE_INITIALIZER(structname) { \ |
58 | .level = { &structname.node[0] }, \ | |
64db4cff PM |
59 | .levelcnt = { \ |
60 | NUM_RCU_LVL_0, /* root of hierarchy. */ \ | |
61 | NUM_RCU_LVL_1, \ | |
62 | NUM_RCU_LVL_2, \ | |
cf244dc0 PM |
63 | NUM_RCU_LVL_3, \ |
64 | NUM_RCU_LVL_4, /* == MAX_RCU_LVLS */ \ | |
64db4cff | 65 | }, \ |
83f5b01f | 66 | .signaled = RCU_GP_IDLE, \ |
64db4cff PM |
67 | .gpnum = -300, \ |
68 | .completed = -300, \ | |
4300aa64 | 69 | .onofflock = __RAW_SPIN_LOCK_UNLOCKED(&structname.onofflock), \ |
e74f4c45 | 70 | .orphan_cbs_list = NULL, \ |
4300aa64 | 71 | .orphan_cbs_tail = &structname.orphan_cbs_list, \ |
e74f4c45 | 72 | .orphan_qlen = 0, \ |
4300aa64 | 73 | .fqslock = __RAW_SPIN_LOCK_UNLOCKED(&structname.fqslock), \ |
64db4cff PM |
74 | .n_force_qs = 0, \ |
75 | .n_force_qs_ngp = 0, \ | |
4300aa64 | 76 | .name = #structname, \ |
64db4cff PM |
77 | } |
78 | ||
d6714c22 PM |
79 | struct rcu_state rcu_sched_state = RCU_STATE_INITIALIZER(rcu_sched_state); |
80 | DEFINE_PER_CPU(struct rcu_data, rcu_sched_data); | |
64db4cff | 81 | |
6258c4fb IM |
82 | struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state); |
83 | DEFINE_PER_CPU(struct rcu_data, rcu_bh_data); | |
b1f77b05 | 84 | |
bbad9379 PM |
85 | int rcu_scheduler_active __read_mostly; |
86 | EXPORT_SYMBOL_GPL(rcu_scheduler_active); | |
87 | ||
fc2219d4 PM |
88 | /* |
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 | ||
b1f77b05 | 98 | /* |
d6714c22 | 99 | * Note a quiescent state. Because we do not need to know |
b1f77b05 | 100 | * how many quiescent states passed, just if there was at least |
d6714c22 | 101 | * one since the start of the grace period, this just sets a flag. |
b1f77b05 | 102 | */ |
d6714c22 | 103 | void rcu_sched_qs(int cpu) |
b1f77b05 | 104 | { |
25502a6c | 105 | struct rcu_data *rdp = &per_cpu(rcu_sched_data, cpu); |
f41d911f | 106 | |
c64ac3ce | 107 | rdp->passed_quiesc_completed = rdp->gpnum - 1; |
c3422bea PM |
108 | barrier(); |
109 | rdp->passed_quiesc = 1; | |
b1f77b05 IM |
110 | } |
111 | ||
d6714c22 | 112 | void rcu_bh_qs(int cpu) |
b1f77b05 | 113 | { |
25502a6c | 114 | struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu); |
f41d911f | 115 | |
c64ac3ce | 116 | rdp->passed_quiesc_completed = rdp->gpnum - 1; |
c3422bea PM |
117 | barrier(); |
118 | rdp->passed_quiesc = 1; | |
b1f77b05 | 119 | } |
64db4cff | 120 | |
25502a6c PM |
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 | ||
64db4cff | 131 | #ifdef CONFIG_NO_HZ |
90a4d2c0 PM |
132 | DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { |
133 | .dynticks_nesting = 1, | |
134 | .dynticks = 1, | |
135 | }; | |
64db4cff PM |
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 | ||
3d76c082 PM |
142 | module_param(blimit, int, 0); |
143 | module_param(qhimark, int, 0); | |
144 | module_param(qlowmark, int, 0); | |
145 | ||
742734ee PM |
146 | #ifdef CONFIG_RCU_CPU_STALL_DETECTOR |
147 | int rcu_cpu_stall_suppress __read_mostly; | |
f2e0dd70 | 148 | module_param(rcu_cpu_stall_suppress, int, 0644); |
742734ee PM |
149 | #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ |
150 | ||
64db4cff | 151 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed); |
a157229c | 152 | static int rcu_pending(int cpu); |
64db4cff PM |
153 | |
154 | /* | |
d6714c22 | 155 | * Return the number of RCU-sched batches processed thus far for debug & stats. |
64db4cff | 156 | */ |
d6714c22 | 157 | long rcu_batches_completed_sched(void) |
64db4cff | 158 | { |
d6714c22 | 159 | return rcu_sched_state.completed; |
64db4cff | 160 | } |
d6714c22 | 161 | EXPORT_SYMBOL_GPL(rcu_batches_completed_sched); |
64db4cff PM |
162 | |
163 | /* | |
164 | * Return the number of RCU BH batches processed thus far for debug & stats. | |
165 | */ | |
166 | long rcu_batches_completed_bh(void) | |
167 | { | |
168 | return rcu_bh_state.completed; | |
169 | } | |
170 | EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); | |
171 | ||
bf66f18e PM |
172 | /* |
173 | * Force a quiescent state for RCU BH. | |
174 | */ | |
175 | void rcu_bh_force_quiescent_state(void) | |
176 | { | |
177 | force_quiescent_state(&rcu_bh_state, 0); | |
178 | } | |
179 | EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state); | |
180 | ||
181 | /* | |
182 | * Force a quiescent state for RCU-sched. | |
183 | */ | |
184 | void rcu_sched_force_quiescent_state(void) | |
185 | { | |
186 | force_quiescent_state(&rcu_sched_state, 0); | |
187 | } | |
188 | EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state); | |
189 | ||
64db4cff PM |
190 | /* |
191 | * Does the CPU have callbacks ready to be invoked? | |
192 | */ | |
193 | static int | |
194 | cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp) | |
195 | { | |
196 | return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]; | |
197 | } | |
198 | ||
199 | /* | |
200 | * Does the current CPU require a yet-as-unscheduled grace period? | |
201 | */ | |
202 | static int | |
203 | cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp) | |
204 | { | |
fc2219d4 | 205 | return *rdp->nxttail[RCU_DONE_TAIL] && !rcu_gp_in_progress(rsp); |
64db4cff PM |
206 | } |
207 | ||
208 | /* | |
209 | * Return the root node of the specified rcu_state structure. | |
210 | */ | |
211 | static struct rcu_node *rcu_get_root(struct rcu_state *rsp) | |
212 | { | |
213 | return &rsp->node[0]; | |
214 | } | |
215 | ||
216 | #ifdef CONFIG_SMP | |
217 | ||
218 | /* | |
219 | * If the specified CPU is offline, tell the caller that it is in | |
220 | * a quiescent state. Otherwise, whack it with a reschedule IPI. | |
221 | * Grace periods can end up waiting on an offline CPU when that | |
222 | * CPU is in the process of coming online -- it will be added to the | |
223 | * rcu_node bitmasks before it actually makes it online. The same thing | |
224 | * can happen while a CPU is in the process of coming online. Because this | |
225 | * race is quite rare, we check for it after detecting that the grace | |
226 | * period has been delayed rather than checking each and every CPU | |
227 | * each and every time we start a new grace period. | |
228 | */ | |
229 | static int rcu_implicit_offline_qs(struct rcu_data *rdp) | |
230 | { | |
231 | /* | |
232 | * If the CPU is offline, it is in a quiescent state. We can | |
233 | * trust its state not to change because interrupts are disabled. | |
234 | */ | |
235 | if (cpu_is_offline(rdp->cpu)) { | |
236 | rdp->offline_fqs++; | |
237 | return 1; | |
238 | } | |
239 | ||
f41d911f PM |
240 | /* If preemptable RCU, no point in sending reschedule IPI. */ |
241 | if (rdp->preemptable) | |
242 | return 0; | |
243 | ||
64db4cff PM |
244 | /* The CPU is online, so send it a reschedule IPI. */ |
245 | if (rdp->cpu != smp_processor_id()) | |
246 | smp_send_reschedule(rdp->cpu); | |
247 | else | |
248 | set_need_resched(); | |
249 | rdp->resched_ipi++; | |
250 | return 0; | |
251 | } | |
252 | ||
253 | #endif /* #ifdef CONFIG_SMP */ | |
254 | ||
255 | #ifdef CONFIG_NO_HZ | |
64db4cff PM |
256 | |
257 | /** | |
258 | * rcu_enter_nohz - inform RCU that current CPU is entering nohz | |
259 | * | |
260 | * Enter nohz mode, in other words, -leave- the mode in which RCU | |
261 | * read-side critical sections can occur. (Though RCU read-side | |
262 | * critical sections can occur in irq handlers in nohz mode, a possibility | |
263 | * handled by rcu_irq_enter() and rcu_irq_exit()). | |
264 | */ | |
265 | void rcu_enter_nohz(void) | |
266 | { | |
267 | unsigned long flags; | |
268 | struct rcu_dynticks *rdtp; | |
269 | ||
270 | smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ | |
271 | local_irq_save(flags); | |
272 | rdtp = &__get_cpu_var(rcu_dynticks); | |
273 | rdtp->dynticks++; | |
274 | rdtp->dynticks_nesting--; | |
86848966 | 275 | WARN_ON_ONCE(rdtp->dynticks & 0x1); |
64db4cff PM |
276 | local_irq_restore(flags); |
277 | } | |
278 | ||
279 | /* | |
280 | * rcu_exit_nohz - inform RCU that current CPU is leaving nohz | |
281 | * | |
282 | * Exit nohz mode, in other words, -enter- the mode in which RCU | |
283 | * read-side critical sections normally occur. | |
284 | */ | |
285 | void rcu_exit_nohz(void) | |
286 | { | |
287 | unsigned long flags; | |
288 | struct rcu_dynticks *rdtp; | |
289 | ||
290 | local_irq_save(flags); | |
291 | rdtp = &__get_cpu_var(rcu_dynticks); | |
292 | rdtp->dynticks++; | |
293 | rdtp->dynticks_nesting++; | |
86848966 | 294 | WARN_ON_ONCE(!(rdtp->dynticks & 0x1)); |
64db4cff PM |
295 | local_irq_restore(flags); |
296 | smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ | |
297 | } | |
298 | ||
299 | /** | |
300 | * rcu_nmi_enter - inform RCU of entry to NMI context | |
301 | * | |
302 | * If the CPU was idle with dynamic ticks active, and there is no | |
303 | * irq handler running, this updates rdtp->dynticks_nmi to let the | |
304 | * RCU grace-period handling know that the CPU is active. | |
305 | */ | |
306 | void rcu_nmi_enter(void) | |
307 | { | |
308 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); | |
309 | ||
310 | if (rdtp->dynticks & 0x1) | |
311 | return; | |
312 | rdtp->dynticks_nmi++; | |
86848966 | 313 | WARN_ON_ONCE(!(rdtp->dynticks_nmi & 0x1)); |
64db4cff PM |
314 | smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ |
315 | } | |
316 | ||
317 | /** | |
318 | * rcu_nmi_exit - inform RCU of exit from NMI context | |
319 | * | |
320 | * If the CPU was idle with dynamic ticks active, and there is no | |
321 | * irq handler running, this updates rdtp->dynticks_nmi to let the | |
322 | * RCU grace-period handling know that the CPU is no longer active. | |
323 | */ | |
324 | void rcu_nmi_exit(void) | |
325 | { | |
326 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); | |
327 | ||
328 | if (rdtp->dynticks & 0x1) | |
329 | return; | |
330 | smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ | |
331 | rdtp->dynticks_nmi++; | |
86848966 | 332 | WARN_ON_ONCE(rdtp->dynticks_nmi & 0x1); |
64db4cff PM |
333 | } |
334 | ||
335 | /** | |
336 | * rcu_irq_enter - inform RCU of entry to hard irq context | |
337 | * | |
338 | * If the CPU was idle with dynamic ticks active, this updates the | |
339 | * rdtp->dynticks to let the RCU handling know that the CPU is active. | |
340 | */ | |
341 | void rcu_irq_enter(void) | |
342 | { | |
343 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); | |
344 | ||
345 | if (rdtp->dynticks_nesting++) | |
346 | return; | |
347 | rdtp->dynticks++; | |
86848966 | 348 | WARN_ON_ONCE(!(rdtp->dynticks & 0x1)); |
64db4cff PM |
349 | smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ |
350 | } | |
351 | ||
352 | /** | |
353 | * rcu_irq_exit - inform RCU of exit from hard irq context | |
354 | * | |
355 | * If the CPU was idle with dynamic ticks active, update the rdp->dynticks | |
356 | * to put let the RCU handling be aware that the CPU is going back to idle | |
357 | * with no ticks. | |
358 | */ | |
359 | void rcu_irq_exit(void) | |
360 | { | |
361 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); | |
362 | ||
363 | if (--rdtp->dynticks_nesting) | |
364 | return; | |
365 | smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ | |
366 | rdtp->dynticks++; | |
86848966 | 367 | WARN_ON_ONCE(rdtp->dynticks & 0x1); |
64db4cff PM |
368 | |
369 | /* If the interrupt queued a callback, get out of dyntick mode. */ | |
d6714c22 | 370 | if (__get_cpu_var(rcu_sched_data).nxtlist || |
64db4cff PM |
371 | __get_cpu_var(rcu_bh_data).nxtlist) |
372 | set_need_resched(); | |
373 | } | |
374 | ||
64db4cff PM |
375 | #ifdef CONFIG_SMP |
376 | ||
64db4cff PM |
377 | /* |
378 | * Snapshot the specified CPU's dynticks counter so that we can later | |
379 | * credit them with an implicit quiescent state. Return 1 if this CPU | |
1eba8f84 | 380 | * is in dynticks idle mode, which is an extended quiescent state. |
64db4cff PM |
381 | */ |
382 | static int dyntick_save_progress_counter(struct rcu_data *rdp) | |
383 | { | |
384 | int ret; | |
385 | int snap; | |
386 | int snap_nmi; | |
387 | ||
388 | snap = rdp->dynticks->dynticks; | |
389 | snap_nmi = rdp->dynticks->dynticks_nmi; | |
390 | smp_mb(); /* Order sampling of snap with end of grace period. */ | |
391 | rdp->dynticks_snap = snap; | |
392 | rdp->dynticks_nmi_snap = snap_nmi; | |
393 | ret = ((snap & 0x1) == 0) && ((snap_nmi & 0x1) == 0); | |
394 | if (ret) | |
395 | rdp->dynticks_fqs++; | |
396 | return ret; | |
397 | } | |
398 | ||
399 | /* | |
400 | * Return true if the specified CPU has passed through a quiescent | |
401 | * state by virtue of being in or having passed through an dynticks | |
402 | * idle state since the last call to dyntick_save_progress_counter() | |
403 | * for this same CPU. | |
404 | */ | |
405 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) | |
406 | { | |
407 | long curr; | |
408 | long curr_nmi; | |
409 | long snap; | |
410 | long snap_nmi; | |
411 | ||
412 | curr = rdp->dynticks->dynticks; | |
413 | snap = rdp->dynticks_snap; | |
414 | curr_nmi = rdp->dynticks->dynticks_nmi; | |
415 | snap_nmi = rdp->dynticks_nmi_snap; | |
416 | smp_mb(); /* force ordering with cpu entering/leaving dynticks. */ | |
417 | ||
418 | /* | |
419 | * If the CPU passed through or entered a dynticks idle phase with | |
420 | * no active irq/NMI handlers, then we can safely pretend that the CPU | |
421 | * already acknowledged the request to pass through a quiescent | |
422 | * state. Either way, that CPU cannot possibly be in an RCU | |
423 | * read-side critical section that started before the beginning | |
424 | * of the current RCU grace period. | |
425 | */ | |
426 | if ((curr != snap || (curr & 0x1) == 0) && | |
427 | (curr_nmi != snap_nmi || (curr_nmi & 0x1) == 0)) { | |
428 | rdp->dynticks_fqs++; | |
429 | return 1; | |
430 | } | |
431 | ||
432 | /* Go check for the CPU being offline. */ | |
433 | return rcu_implicit_offline_qs(rdp); | |
434 | } | |
435 | ||
436 | #endif /* #ifdef CONFIG_SMP */ | |
437 | ||
438 | #else /* #ifdef CONFIG_NO_HZ */ | |
439 | ||
64db4cff PM |
440 | #ifdef CONFIG_SMP |
441 | ||
64db4cff PM |
442 | static int dyntick_save_progress_counter(struct rcu_data *rdp) |
443 | { | |
444 | return 0; | |
445 | } | |
446 | ||
447 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) | |
448 | { | |
449 | return rcu_implicit_offline_qs(rdp); | |
450 | } | |
451 | ||
452 | #endif /* #ifdef CONFIG_SMP */ | |
453 | ||
454 | #endif /* #else #ifdef CONFIG_NO_HZ */ | |
455 | ||
456 | #ifdef CONFIG_RCU_CPU_STALL_DETECTOR | |
457 | ||
742734ee | 458 | int rcu_cpu_stall_suppress __read_mostly; |
c68de209 | 459 | |
64db4cff PM |
460 | static void record_gp_stall_check_time(struct rcu_state *rsp) |
461 | { | |
462 | rsp->gp_start = jiffies; | |
463 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_CHECK; | |
464 | } | |
465 | ||
466 | static void print_other_cpu_stall(struct rcu_state *rsp) | |
467 | { | |
468 | int cpu; | |
469 | long delta; | |
470 | unsigned long flags; | |
471 | struct rcu_node *rnp = rcu_get_root(rsp); | |
64db4cff PM |
472 | |
473 | /* Only let one CPU complain about others per time interval. */ | |
474 | ||
1304afb2 | 475 | raw_spin_lock_irqsave(&rnp->lock, flags); |
64db4cff | 476 | delta = jiffies - rsp->jiffies_stall; |
fc2219d4 | 477 | if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) { |
1304afb2 | 478 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
479 | return; |
480 | } | |
481 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_RECHECK; | |
a0b6c9a7 PM |
482 | |
483 | /* | |
484 | * Now rat on any tasks that got kicked up to the root rcu_node | |
485 | * due to CPU offlining. | |
486 | */ | |
487 | rcu_print_task_stall(rnp); | |
1304afb2 | 488 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
489 | |
490 | /* OK, time to rat on our buddy... */ | |
491 | ||
4300aa64 PM |
492 | printk(KERN_ERR "INFO: %s detected stalls on CPUs/tasks: {", |
493 | rsp->name); | |
a0b6c9a7 | 494 | rcu_for_each_leaf_node(rsp, rnp) { |
3acd9eb3 | 495 | raw_spin_lock_irqsave(&rnp->lock, flags); |
f41d911f | 496 | rcu_print_task_stall(rnp); |
3acd9eb3 | 497 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
a0b6c9a7 | 498 | if (rnp->qsmask == 0) |
64db4cff | 499 | continue; |
a0b6c9a7 PM |
500 | for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++) |
501 | if (rnp->qsmask & (1UL << cpu)) | |
502 | printk(" %d", rnp->grplo + cpu); | |
64db4cff | 503 | } |
4300aa64 | 504 | printk("} (detected by %d, t=%ld jiffies)\n", |
64db4cff | 505 | smp_processor_id(), (long)(jiffies - rsp->gp_start)); |
c1dc0b9c IM |
506 | trigger_all_cpu_backtrace(); |
507 | ||
1ed509a2 PM |
508 | /* If so configured, complain about tasks blocking the grace period. */ |
509 | ||
510 | rcu_print_detail_task_stall(rsp); | |
511 | ||
64db4cff PM |
512 | force_quiescent_state(rsp, 0); /* Kick them all. */ |
513 | } | |
514 | ||
515 | static void print_cpu_stall(struct rcu_state *rsp) | |
516 | { | |
517 | unsigned long flags; | |
518 | struct rcu_node *rnp = rcu_get_root(rsp); | |
519 | ||
4300aa64 PM |
520 | printk(KERN_ERR "INFO: %s detected stall on CPU %d (t=%lu jiffies)\n", |
521 | rsp->name, smp_processor_id(), jiffies - rsp->gp_start); | |
c1dc0b9c IM |
522 | trigger_all_cpu_backtrace(); |
523 | ||
1304afb2 | 524 | raw_spin_lock_irqsave(&rnp->lock, flags); |
20133cfc | 525 | if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall)) |
64db4cff PM |
526 | rsp->jiffies_stall = |
527 | jiffies + RCU_SECONDS_TILL_STALL_RECHECK; | |
1304afb2 | 528 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
c1dc0b9c | 529 | |
64db4cff PM |
530 | set_need_resched(); /* kick ourselves to get things going. */ |
531 | } | |
532 | ||
533 | static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) | |
534 | { | |
535 | long delta; | |
536 | struct rcu_node *rnp; | |
537 | ||
742734ee | 538 | if (rcu_cpu_stall_suppress) |
c68de209 | 539 | return; |
64db4cff PM |
540 | delta = jiffies - rsp->jiffies_stall; |
541 | rnp = rdp->mynode; | |
542 | if ((rnp->qsmask & rdp->grpmask) && delta >= 0) { | |
543 | ||
544 | /* We haven't checked in, so go dump stack. */ | |
545 | print_cpu_stall(rsp); | |
546 | ||
fc2219d4 | 547 | } else if (rcu_gp_in_progress(rsp) && delta >= RCU_STALL_RAT_DELAY) { |
64db4cff PM |
548 | |
549 | /* They had two time units to dump stack, so complain. */ | |
550 | print_other_cpu_stall(rsp); | |
551 | } | |
552 | } | |
553 | ||
c68de209 PM |
554 | static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr) |
555 | { | |
742734ee | 556 | rcu_cpu_stall_suppress = 1; |
c68de209 PM |
557 | return NOTIFY_DONE; |
558 | } | |
559 | ||
560 | static struct notifier_block rcu_panic_block = { | |
561 | .notifier_call = rcu_panic, | |
562 | }; | |
563 | ||
564 | static void __init check_cpu_stall_init(void) | |
565 | { | |
566 | atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block); | |
567 | } | |
568 | ||
64db4cff PM |
569 | #else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ |
570 | ||
571 | static void record_gp_stall_check_time(struct rcu_state *rsp) | |
572 | { | |
573 | } | |
574 | ||
575 | static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) | |
576 | { | |
577 | } | |
578 | ||
c68de209 PM |
579 | static void __init check_cpu_stall_init(void) |
580 | { | |
581 | } | |
582 | ||
64db4cff PM |
583 | #endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ |
584 | ||
585 | /* | |
586 | * Update CPU-local rcu_data state to record the newly noticed grace period. | |
587 | * This is used both when we started the grace period and when we notice | |
9160306e PM |
588 | * that someone else started the grace period. The caller must hold the |
589 | * ->lock of the leaf rcu_node structure corresponding to the current CPU, | |
590 | * and must have irqs disabled. | |
64db4cff | 591 | */ |
9160306e PM |
592 | static void __note_new_gpnum(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
593 | { | |
594 | if (rdp->gpnum != rnp->gpnum) { | |
595 | rdp->qs_pending = 1; | |
596 | rdp->passed_quiesc = 0; | |
597 | rdp->gpnum = rnp->gpnum; | |
598 | } | |
599 | } | |
600 | ||
64db4cff PM |
601 | static void note_new_gpnum(struct rcu_state *rsp, struct rcu_data *rdp) |
602 | { | |
9160306e PM |
603 | unsigned long flags; |
604 | struct rcu_node *rnp; | |
605 | ||
606 | local_irq_save(flags); | |
607 | rnp = rdp->mynode; | |
608 | if (rdp->gpnum == ACCESS_ONCE(rnp->gpnum) || /* outside lock. */ | |
1304afb2 | 609 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
9160306e PM |
610 | local_irq_restore(flags); |
611 | return; | |
612 | } | |
613 | __note_new_gpnum(rsp, rnp, rdp); | |
1304afb2 | 614 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
615 | } |
616 | ||
617 | /* | |
618 | * Did someone else start a new RCU grace period start since we last | |
619 | * checked? Update local state appropriately if so. Must be called | |
620 | * on the CPU corresponding to rdp. | |
621 | */ | |
622 | static int | |
623 | check_for_new_grace_period(struct rcu_state *rsp, struct rcu_data *rdp) | |
624 | { | |
625 | unsigned long flags; | |
626 | int ret = 0; | |
627 | ||
628 | local_irq_save(flags); | |
629 | if (rdp->gpnum != rsp->gpnum) { | |
630 | note_new_gpnum(rsp, rdp); | |
631 | ret = 1; | |
632 | } | |
633 | local_irq_restore(flags); | |
634 | return ret; | |
635 | } | |
636 | ||
d09b62df PM |
637 | /* |
638 | * Advance this CPU's callbacks, but only if the current grace period | |
639 | * has ended. This may be called only from the CPU to whom the rdp | |
640 | * belongs. In addition, the corresponding leaf rcu_node structure's | |
641 | * ->lock must be held by the caller, with irqs disabled. | |
642 | */ | |
643 | static void | |
644 | __rcu_process_gp_end(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) | |
645 | { | |
646 | /* Did another grace period end? */ | |
647 | if (rdp->completed != rnp->completed) { | |
648 | ||
649 | /* Advance callbacks. No harm if list empty. */ | |
650 | rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL]; | |
651 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL]; | |
652 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; | |
653 | ||
654 | /* Remember that we saw this grace-period completion. */ | |
655 | rdp->completed = rnp->completed; | |
656 | } | |
657 | } | |
658 | ||
659 | /* | |
660 | * Advance this CPU's callbacks, but only if the current grace period | |
661 | * has ended. This may be called only from the CPU to whom the rdp | |
662 | * belongs. | |
663 | */ | |
664 | static void | |
665 | rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp) | |
666 | { | |
667 | unsigned long flags; | |
668 | struct rcu_node *rnp; | |
669 | ||
670 | local_irq_save(flags); | |
671 | rnp = rdp->mynode; | |
672 | if (rdp->completed == ACCESS_ONCE(rnp->completed) || /* outside lock. */ | |
1304afb2 | 673 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
d09b62df PM |
674 | local_irq_restore(flags); |
675 | return; | |
676 | } | |
677 | __rcu_process_gp_end(rsp, rnp, rdp); | |
1304afb2 | 678 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
d09b62df PM |
679 | } |
680 | ||
681 | /* | |
682 | * Do per-CPU grace-period initialization for running CPU. The caller | |
683 | * must hold the lock of the leaf rcu_node structure corresponding to | |
684 | * this CPU. | |
685 | */ | |
686 | static void | |
687 | rcu_start_gp_per_cpu(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) | |
688 | { | |
689 | /* Prior grace period ended, so advance callbacks for current CPU. */ | |
690 | __rcu_process_gp_end(rsp, rnp, rdp); | |
691 | ||
692 | /* | |
693 | * Because this CPU just now started the new grace period, we know | |
694 | * that all of its callbacks will be covered by this upcoming grace | |
695 | * period, even the ones that were registered arbitrarily recently. | |
696 | * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL. | |
697 | * | |
698 | * Other CPUs cannot be sure exactly when the grace period started. | |
699 | * Therefore, their recently registered callbacks must pass through | |
700 | * an additional RCU_NEXT_READY stage, so that they will be handled | |
701 | * by the next RCU grace period. | |
702 | */ | |
703 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; | |
704 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; | |
9160306e PM |
705 | |
706 | /* Set state so that this CPU will detect the next quiescent state. */ | |
707 | __note_new_gpnum(rsp, rnp, rdp); | |
d09b62df PM |
708 | } |
709 | ||
64db4cff PM |
710 | /* |
711 | * Start a new RCU grace period if warranted, re-initializing the hierarchy | |
712 | * in preparation for detecting the next grace period. The caller must hold | |
713 | * the root node's ->lock, which is released before return. Hard irqs must | |
714 | * be disabled. | |
715 | */ | |
716 | static void | |
717 | rcu_start_gp(struct rcu_state *rsp, unsigned long flags) | |
718 | __releases(rcu_get_root(rsp)->lock) | |
719 | { | |
394f99a9 | 720 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); |
64db4cff | 721 | struct rcu_node *rnp = rcu_get_root(rsp); |
64db4cff | 722 | |
07079d53 | 723 | if (!cpu_needs_another_gp(rsp, rdp) || rsp->fqs_active) { |
46a1e34e PM |
724 | if (cpu_needs_another_gp(rsp, rdp)) |
725 | rsp->fqs_need_gp = 1; | |
b32e9eb6 | 726 | if (rnp->completed == rsp->completed) { |
1304afb2 | 727 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
b32e9eb6 PM |
728 | return; |
729 | } | |
1304afb2 | 730 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
b32e9eb6 PM |
731 | |
732 | /* | |
733 | * Propagate new ->completed value to rcu_node structures | |
734 | * so that other CPUs don't have to wait until the start | |
735 | * of the next grace period to process their callbacks. | |
736 | */ | |
737 | rcu_for_each_node_breadth_first(rsp, rnp) { | |
1304afb2 | 738 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
b32e9eb6 | 739 | rnp->completed = rsp->completed; |
1304afb2 | 740 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
b32e9eb6 PM |
741 | } |
742 | local_irq_restore(flags); | |
64db4cff PM |
743 | return; |
744 | } | |
745 | ||
746 | /* Advance to a new grace period and initialize state. */ | |
747 | rsp->gpnum++; | |
c3422bea | 748 | WARN_ON_ONCE(rsp->signaled == RCU_GP_INIT); |
64db4cff PM |
749 | rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */ |
750 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; | |
64db4cff | 751 | record_gp_stall_check_time(rsp); |
64db4cff | 752 | |
64db4cff PM |
753 | /* Special-case the common single-level case. */ |
754 | if (NUM_RCU_NODES == 1) { | |
b0e165c0 | 755 | rcu_preempt_check_blocked_tasks(rnp); |
28ecd580 | 756 | rnp->qsmask = rnp->qsmaskinit; |
de078d87 | 757 | rnp->gpnum = rsp->gpnum; |
d09b62df | 758 | rnp->completed = rsp->completed; |
c12172c0 | 759 | rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state OK. */ |
d09b62df | 760 | rcu_start_gp_per_cpu(rsp, rnp, rdp); |
1304afb2 | 761 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
762 | return; |
763 | } | |
764 | ||
1304afb2 | 765 | raw_spin_unlock(&rnp->lock); /* leave irqs disabled. */ |
64db4cff PM |
766 | |
767 | ||
768 | /* Exclude any concurrent CPU-hotplug operations. */ | |
1304afb2 | 769 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
64db4cff PM |
770 | |
771 | /* | |
b835db1f PM |
772 | * Set the quiescent-state-needed bits in all the rcu_node |
773 | * structures for all currently online CPUs in breadth-first | |
774 | * order, starting from the root rcu_node structure. This | |
775 | * operation relies on the layout of the hierarchy within the | |
776 | * rsp->node[] array. Note that other CPUs will access only | |
777 | * the leaves of the hierarchy, which still indicate that no | |
778 | * grace period is in progress, at least until the corresponding | |
779 | * leaf node has been initialized. In addition, we have excluded | |
780 | * CPU-hotplug operations. | |
64db4cff PM |
781 | * |
782 | * Note that the grace period cannot complete until we finish | |
783 | * the initialization process, as there will be at least one | |
784 | * qsmask bit set in the root node until that time, namely the | |
b835db1f PM |
785 | * one corresponding to this CPU, due to the fact that we have |
786 | * irqs disabled. | |
64db4cff | 787 | */ |
a0b6c9a7 | 788 | rcu_for_each_node_breadth_first(rsp, rnp) { |
1304afb2 | 789 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
b0e165c0 | 790 | rcu_preempt_check_blocked_tasks(rnp); |
49e29126 | 791 | rnp->qsmask = rnp->qsmaskinit; |
de078d87 | 792 | rnp->gpnum = rsp->gpnum; |
d09b62df PM |
793 | rnp->completed = rsp->completed; |
794 | if (rnp == rdp->mynode) | |
795 | rcu_start_gp_per_cpu(rsp, rnp, rdp); | |
1304afb2 | 796 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
64db4cff PM |
797 | } |
798 | ||
83f5b01f | 799 | rnp = rcu_get_root(rsp); |
1304afb2 | 800 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
64db4cff | 801 | rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state now OK. */ |
1304afb2 PM |
802 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
803 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); | |
64db4cff PM |
804 | } |
805 | ||
f41d911f | 806 | /* |
d3f6bad3 PM |
807 | * Report a full set of quiescent states to the specified rcu_state |
808 | * data structure. This involves cleaning up after the prior grace | |
809 | * period and letting rcu_start_gp() start up the next grace period | |
810 | * if one is needed. Note that the caller must hold rnp->lock, as | |
811 | * required by rcu_start_gp(), which will release it. | |
f41d911f | 812 | */ |
d3f6bad3 | 813 | static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags) |
fc2219d4 | 814 | __releases(rcu_get_root(rsp)->lock) |
f41d911f | 815 | { |
fc2219d4 | 816 | WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); |
f41d911f | 817 | rsp->completed = rsp->gpnum; |
83f5b01f | 818 | rsp->signaled = RCU_GP_IDLE; |
f41d911f PM |
819 | rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */ |
820 | } | |
821 | ||
64db4cff | 822 | /* |
d3f6bad3 PM |
823 | * Similar to rcu_report_qs_rdp(), for which it is a helper function. |
824 | * Allows quiescent states for a group of CPUs to be reported at one go | |
825 | * to the specified rcu_node structure, though all the CPUs in the group | |
826 | * must be represented by the same rcu_node structure (which need not be | |
827 | * a leaf rcu_node structure, though it often will be). That structure's | |
828 | * lock must be held upon entry, and it is released before return. | |
64db4cff PM |
829 | */ |
830 | static void | |
d3f6bad3 PM |
831 | rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp, |
832 | struct rcu_node *rnp, unsigned long flags) | |
64db4cff PM |
833 | __releases(rnp->lock) |
834 | { | |
28ecd580 PM |
835 | struct rcu_node *rnp_c; |
836 | ||
64db4cff PM |
837 | /* Walk up the rcu_node hierarchy. */ |
838 | for (;;) { | |
839 | if (!(rnp->qsmask & mask)) { | |
840 | ||
841 | /* Our bit has already been cleared, so done. */ | |
1304afb2 | 842 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
843 | return; |
844 | } | |
845 | rnp->qsmask &= ~mask; | |
f41d911f | 846 | if (rnp->qsmask != 0 || rcu_preempted_readers(rnp)) { |
64db4cff PM |
847 | |
848 | /* Other bits still set at this level, so done. */ | |
1304afb2 | 849 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
850 | return; |
851 | } | |
852 | mask = rnp->grpmask; | |
853 | if (rnp->parent == NULL) { | |
854 | ||
855 | /* No more levels. Exit loop holding root lock. */ | |
856 | ||
857 | break; | |
858 | } | |
1304afb2 | 859 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
28ecd580 | 860 | rnp_c = rnp; |
64db4cff | 861 | rnp = rnp->parent; |
1304afb2 | 862 | raw_spin_lock_irqsave(&rnp->lock, flags); |
28ecd580 | 863 | WARN_ON_ONCE(rnp_c->qsmask); |
64db4cff PM |
864 | } |
865 | ||
866 | /* | |
867 | * Get here if we are the last CPU to pass through a quiescent | |
d3f6bad3 | 868 | * state for this grace period. Invoke rcu_report_qs_rsp() |
f41d911f | 869 | * to clean up and start the next grace period if one is needed. |
64db4cff | 870 | */ |
d3f6bad3 | 871 | rcu_report_qs_rsp(rsp, flags); /* releases rnp->lock. */ |
64db4cff PM |
872 | } |
873 | ||
874 | /* | |
d3f6bad3 PM |
875 | * Record a quiescent state for the specified CPU to that CPU's rcu_data |
876 | * structure. This must be either called from the specified CPU, or | |
877 | * called when the specified CPU is known to be offline (and when it is | |
878 | * also known that no other CPU is concurrently trying to help the offline | |
879 | * CPU). The lastcomp argument is used to make sure we are still in the | |
880 | * grace period of interest. We don't want to end the current grace period | |
881 | * based on quiescent states detected in an earlier grace period! | |
64db4cff PM |
882 | */ |
883 | static void | |
d3f6bad3 | 884 | rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp) |
64db4cff PM |
885 | { |
886 | unsigned long flags; | |
887 | unsigned long mask; | |
888 | struct rcu_node *rnp; | |
889 | ||
890 | rnp = rdp->mynode; | |
1304afb2 | 891 | raw_spin_lock_irqsave(&rnp->lock, flags); |
560d4bc0 | 892 | if (lastcomp != rnp->completed) { |
64db4cff PM |
893 | |
894 | /* | |
895 | * Someone beat us to it for this grace period, so leave. | |
896 | * The race with GP start is resolved by the fact that we | |
897 | * hold the leaf rcu_node lock, so that the per-CPU bits | |
898 | * cannot yet be initialized -- so we would simply find our | |
d3f6bad3 PM |
899 | * CPU's bit already cleared in rcu_report_qs_rnp() if this |
900 | * race occurred. | |
64db4cff PM |
901 | */ |
902 | rdp->passed_quiesc = 0; /* try again later! */ | |
1304afb2 | 903 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
904 | return; |
905 | } | |
906 | mask = rdp->grpmask; | |
907 | if ((rnp->qsmask & mask) == 0) { | |
1304afb2 | 908 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
909 | } else { |
910 | rdp->qs_pending = 0; | |
911 | ||
912 | /* | |
913 | * This GP can't end until cpu checks in, so all of our | |
914 | * callbacks can be processed during the next GP. | |
915 | */ | |
64db4cff PM |
916 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
917 | ||
d3f6bad3 | 918 | rcu_report_qs_rnp(mask, rsp, rnp, flags); /* rlses rnp->lock */ |
64db4cff PM |
919 | } |
920 | } | |
921 | ||
922 | /* | |
923 | * Check to see if there is a new grace period of which this CPU | |
924 | * is not yet aware, and if so, set up local rcu_data state for it. | |
925 | * Otherwise, see if this CPU has just passed through its first | |
926 | * quiescent state for this grace period, and record that fact if so. | |
927 | */ | |
928 | static void | |
929 | rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp) | |
930 | { | |
931 | /* If there is now a new grace period, record and return. */ | |
932 | if (check_for_new_grace_period(rsp, rdp)) | |
933 | return; | |
934 | ||
935 | /* | |
936 | * Does this CPU still need to do its part for current grace period? | |
937 | * If no, return and let the other CPUs do their part as well. | |
938 | */ | |
939 | if (!rdp->qs_pending) | |
940 | return; | |
941 | ||
942 | /* | |
943 | * Was there a quiescent state since the beginning of the grace | |
944 | * period? If no, then exit and wait for the next call. | |
945 | */ | |
946 | if (!rdp->passed_quiesc) | |
947 | return; | |
948 | ||
d3f6bad3 PM |
949 | /* |
950 | * Tell RCU we are done (but rcu_report_qs_rdp() will be the | |
951 | * judge of that). | |
952 | */ | |
953 | rcu_report_qs_rdp(rdp->cpu, rsp, rdp, rdp->passed_quiesc_completed); | |
64db4cff PM |
954 | } |
955 | ||
956 | #ifdef CONFIG_HOTPLUG_CPU | |
957 | ||
e74f4c45 PM |
958 | /* |
959 | * Move a dying CPU's RCU callbacks to the ->orphan_cbs_list for the | |
960 | * specified flavor of RCU. The callbacks will be adopted by the next | |
961 | * _rcu_barrier() invocation or by the CPU_DEAD notifier, whichever | |
962 | * comes first. Because this is invoked from the CPU_DYING notifier, | |
963 | * irqs are already disabled. | |
964 | */ | |
965 | static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp) | |
966 | { | |
967 | int i; | |
394f99a9 | 968 | struct rcu_data *rdp = this_cpu_ptr(rsp->rda); |
e74f4c45 PM |
969 | |
970 | if (rdp->nxtlist == NULL) | |
971 | return; /* irqs disabled, so comparison is stable. */ | |
1304afb2 | 972 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
e74f4c45 PM |
973 | *rsp->orphan_cbs_tail = rdp->nxtlist; |
974 | rsp->orphan_cbs_tail = rdp->nxttail[RCU_NEXT_TAIL]; | |
975 | rdp->nxtlist = NULL; | |
976 | for (i = 0; i < RCU_NEXT_SIZE; i++) | |
977 | rdp->nxttail[i] = &rdp->nxtlist; | |
978 | rsp->orphan_qlen += rdp->qlen; | |
979 | rdp->qlen = 0; | |
1304afb2 | 980 | raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ |
e74f4c45 PM |
981 | } |
982 | ||
983 | /* | |
984 | * Adopt previously orphaned RCU callbacks. | |
985 | */ | |
986 | static void rcu_adopt_orphan_cbs(struct rcu_state *rsp) | |
987 | { | |
988 | unsigned long flags; | |
989 | struct rcu_data *rdp; | |
990 | ||
1304afb2 | 991 | raw_spin_lock_irqsave(&rsp->onofflock, flags); |
394f99a9 | 992 | rdp = this_cpu_ptr(rsp->rda); |
e74f4c45 | 993 | if (rsp->orphan_cbs_list == NULL) { |
1304afb2 | 994 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
e74f4c45 PM |
995 | return; |
996 | } | |
997 | *rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_cbs_list; | |
998 | rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_cbs_tail; | |
999 | rdp->qlen += rsp->orphan_qlen; | |
1000 | rsp->orphan_cbs_list = NULL; | |
1001 | rsp->orphan_cbs_tail = &rsp->orphan_cbs_list; | |
1002 | rsp->orphan_qlen = 0; | |
1304afb2 | 1003 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
e74f4c45 PM |
1004 | } |
1005 | ||
64db4cff PM |
1006 | /* |
1007 | * Remove the outgoing CPU from the bitmasks in the rcu_node hierarchy | |
1008 | * and move all callbacks from the outgoing CPU to the current one. | |
1009 | */ | |
1010 | static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) | |
1011 | { | |
64db4cff | 1012 | unsigned long flags; |
64db4cff | 1013 | unsigned long mask; |
d9a3da06 | 1014 | int need_report = 0; |
394f99a9 | 1015 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
64db4cff PM |
1016 | struct rcu_node *rnp; |
1017 | ||
1018 | /* Exclude any attempts to start a new grace period. */ | |
1304afb2 | 1019 | raw_spin_lock_irqsave(&rsp->onofflock, flags); |
64db4cff PM |
1020 | |
1021 | /* Remove the outgoing CPU from the masks in the rcu_node hierarchy. */ | |
28ecd580 | 1022 | rnp = rdp->mynode; /* this is the outgoing CPU's rnp. */ |
64db4cff PM |
1023 | mask = rdp->grpmask; /* rnp->grplo is constant. */ |
1024 | do { | |
1304afb2 | 1025 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
64db4cff PM |
1026 | rnp->qsmaskinit &= ~mask; |
1027 | if (rnp->qsmaskinit != 0) { | |
b668c9cf | 1028 | if (rnp != rdp->mynode) |
1304afb2 | 1029 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
64db4cff PM |
1030 | break; |
1031 | } | |
b668c9cf | 1032 | if (rnp == rdp->mynode) |
d9a3da06 | 1033 | need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp); |
b668c9cf | 1034 | else |
1304afb2 | 1035 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
64db4cff | 1036 | mask = rnp->grpmask; |
64db4cff PM |
1037 | rnp = rnp->parent; |
1038 | } while (rnp != NULL); | |
64db4cff | 1039 | |
b668c9cf PM |
1040 | /* |
1041 | * We still hold the leaf rcu_node structure lock here, and | |
1042 | * irqs are still disabled. The reason for this subterfuge is | |
d3f6bad3 PM |
1043 | * because invoking rcu_report_unblock_qs_rnp() with ->onofflock |
1044 | * held leads to deadlock. | |
b668c9cf | 1045 | */ |
1304afb2 | 1046 | raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ |
b668c9cf | 1047 | rnp = rdp->mynode; |
d9a3da06 | 1048 | if (need_report & RCU_OFL_TASKS_NORM_GP) |
d3f6bad3 | 1049 | rcu_report_unblock_qs_rnp(rnp, flags); |
b668c9cf | 1050 | else |
1304afb2 | 1051 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
d9a3da06 PM |
1052 | if (need_report & RCU_OFL_TASKS_EXP_GP) |
1053 | rcu_report_exp_rnp(rsp, rnp); | |
64db4cff | 1054 | |
e74f4c45 | 1055 | rcu_adopt_orphan_cbs(rsp); |
64db4cff PM |
1056 | } |
1057 | ||
1058 | /* | |
1059 | * Remove the specified CPU from the RCU hierarchy and move any pending | |
1060 | * callbacks that it might have to the current CPU. This code assumes | |
1061 | * that at least one CPU in the system will remain running at all times. | |
1062 | * Any attempt to offline -all- CPUs is likely to strand RCU callbacks. | |
1063 | */ | |
1064 | static void rcu_offline_cpu(int cpu) | |
1065 | { | |
d6714c22 | 1066 | __rcu_offline_cpu(cpu, &rcu_sched_state); |
64db4cff | 1067 | __rcu_offline_cpu(cpu, &rcu_bh_state); |
33f76148 | 1068 | rcu_preempt_offline_cpu(cpu); |
64db4cff PM |
1069 | } |
1070 | ||
1071 | #else /* #ifdef CONFIG_HOTPLUG_CPU */ | |
1072 | ||
e74f4c45 PM |
1073 | static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp) |
1074 | { | |
1075 | } | |
1076 | ||
1077 | static void rcu_adopt_orphan_cbs(struct rcu_state *rsp) | |
1078 | { | |
1079 | } | |
1080 | ||
64db4cff PM |
1081 | static void rcu_offline_cpu(int cpu) |
1082 | { | |
1083 | } | |
1084 | ||
1085 | #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */ | |
1086 | ||
1087 | /* | |
1088 | * Invoke any RCU callbacks that have made it to the end of their grace | |
1089 | * period. Thottle as specified by rdp->blimit. | |
1090 | */ | |
37c72e56 | 1091 | static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp) |
64db4cff PM |
1092 | { |
1093 | unsigned long flags; | |
1094 | struct rcu_head *next, *list, **tail; | |
1095 | int count; | |
1096 | ||
1097 | /* If no callbacks are ready, just return.*/ | |
1098 | if (!cpu_has_callbacks_ready_to_invoke(rdp)) | |
1099 | return; | |
1100 | ||
1101 | /* | |
1102 | * Extract the list of ready callbacks, disabling to prevent | |
1103 | * races with call_rcu() from interrupt handlers. | |
1104 | */ | |
1105 | local_irq_save(flags); | |
1106 | list = rdp->nxtlist; | |
1107 | rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL]; | |
1108 | *rdp->nxttail[RCU_DONE_TAIL] = NULL; | |
1109 | tail = rdp->nxttail[RCU_DONE_TAIL]; | |
1110 | for (count = RCU_NEXT_SIZE - 1; count >= 0; count--) | |
1111 | if (rdp->nxttail[count] == rdp->nxttail[RCU_DONE_TAIL]) | |
1112 | rdp->nxttail[count] = &rdp->nxtlist; | |
1113 | local_irq_restore(flags); | |
1114 | ||
1115 | /* Invoke callbacks. */ | |
1116 | count = 0; | |
1117 | while (list) { | |
1118 | next = list->next; | |
1119 | prefetch(next); | |
551d55a9 | 1120 | debug_rcu_head_unqueue(list); |
64db4cff PM |
1121 | list->func(list); |
1122 | list = next; | |
1123 | if (++count >= rdp->blimit) | |
1124 | break; | |
1125 | } | |
1126 | ||
1127 | local_irq_save(flags); | |
1128 | ||
1129 | /* Update count, and requeue any remaining callbacks. */ | |
1130 | rdp->qlen -= count; | |
1131 | if (list != NULL) { | |
1132 | *tail = rdp->nxtlist; | |
1133 | rdp->nxtlist = list; | |
1134 | for (count = 0; count < RCU_NEXT_SIZE; count++) | |
1135 | if (&rdp->nxtlist == rdp->nxttail[count]) | |
1136 | rdp->nxttail[count] = tail; | |
1137 | else | |
1138 | break; | |
1139 | } | |
1140 | ||
1141 | /* Reinstate batch limit if we have worked down the excess. */ | |
1142 | if (rdp->blimit == LONG_MAX && rdp->qlen <= qlowmark) | |
1143 | rdp->blimit = blimit; | |
1144 | ||
37c72e56 PM |
1145 | /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */ |
1146 | if (rdp->qlen == 0 && rdp->qlen_last_fqs_check != 0) { | |
1147 | rdp->qlen_last_fqs_check = 0; | |
1148 | rdp->n_force_qs_snap = rsp->n_force_qs; | |
1149 | } else if (rdp->qlen < rdp->qlen_last_fqs_check - qhimark) | |
1150 | rdp->qlen_last_fqs_check = rdp->qlen; | |
1151 | ||
64db4cff PM |
1152 | local_irq_restore(flags); |
1153 | ||
1154 | /* Re-raise the RCU softirq if there are callbacks remaining. */ | |
1155 | if (cpu_has_callbacks_ready_to_invoke(rdp)) | |
1156 | raise_softirq(RCU_SOFTIRQ); | |
1157 | } | |
1158 | ||
1159 | /* | |
1160 | * Check to see if this CPU is in a non-context-switch quiescent state | |
1161 | * (user mode or idle loop for rcu, non-softirq execution for rcu_bh). | |
1162 | * Also schedule the RCU softirq handler. | |
1163 | * | |
1164 | * This function must be called with hardirqs disabled. It is normally | |
1165 | * invoked from the scheduling-clock interrupt. If rcu_pending returns | |
1166 | * false, there is no point in invoking rcu_check_callbacks(). | |
1167 | */ | |
1168 | void rcu_check_callbacks(int cpu, int user) | |
1169 | { | |
1170 | if (user || | |
a6826048 PM |
1171 | (idle_cpu(cpu) && rcu_scheduler_active && |
1172 | !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) { | |
64db4cff PM |
1173 | |
1174 | /* | |
1175 | * Get here if this CPU took its interrupt from user | |
1176 | * mode or from the idle loop, and if this is not a | |
1177 | * nested interrupt. In this case, the CPU is in | |
d6714c22 | 1178 | * a quiescent state, so note it. |
64db4cff PM |
1179 | * |
1180 | * No memory barrier is required here because both | |
d6714c22 PM |
1181 | * rcu_sched_qs() and rcu_bh_qs() reference only CPU-local |
1182 | * variables that other CPUs neither access nor modify, | |
1183 | * at least not while the corresponding CPU is online. | |
64db4cff PM |
1184 | */ |
1185 | ||
d6714c22 PM |
1186 | rcu_sched_qs(cpu); |
1187 | rcu_bh_qs(cpu); | |
64db4cff PM |
1188 | |
1189 | } else if (!in_softirq()) { | |
1190 | ||
1191 | /* | |
1192 | * Get here if this CPU did not take its interrupt from | |
1193 | * softirq, in other words, if it is not interrupting | |
1194 | * a rcu_bh read-side critical section. This is an _bh | |
d6714c22 | 1195 | * critical section, so note it. |
64db4cff PM |
1196 | */ |
1197 | ||
d6714c22 | 1198 | rcu_bh_qs(cpu); |
64db4cff | 1199 | } |
f41d911f | 1200 | rcu_preempt_check_callbacks(cpu); |
d21670ac PM |
1201 | if (rcu_pending(cpu)) |
1202 | raise_softirq(RCU_SOFTIRQ); | |
64db4cff PM |
1203 | } |
1204 | ||
1205 | #ifdef CONFIG_SMP | |
1206 | ||
1207 | /* | |
1208 | * Scan the leaf rcu_node structures, processing dyntick state for any that | |
1209 | * have not yet encountered a quiescent state, using the function specified. | |
ee47eb9f | 1210 | * The caller must have suppressed start of new grace periods. |
64db4cff | 1211 | */ |
45f014c5 | 1212 | static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *)) |
64db4cff PM |
1213 | { |
1214 | unsigned long bit; | |
1215 | int cpu; | |
1216 | unsigned long flags; | |
1217 | unsigned long mask; | |
a0b6c9a7 | 1218 | struct rcu_node *rnp; |
64db4cff | 1219 | |
a0b6c9a7 | 1220 | rcu_for_each_leaf_node(rsp, rnp) { |
64db4cff | 1221 | mask = 0; |
1304afb2 | 1222 | raw_spin_lock_irqsave(&rnp->lock, flags); |
ee47eb9f | 1223 | if (!rcu_gp_in_progress(rsp)) { |
1304afb2 | 1224 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
0f10dc82 | 1225 | return; |
64db4cff | 1226 | } |
a0b6c9a7 | 1227 | if (rnp->qsmask == 0) { |
1304afb2 | 1228 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
1229 | continue; |
1230 | } | |
a0b6c9a7 | 1231 | cpu = rnp->grplo; |
64db4cff | 1232 | bit = 1; |
a0b6c9a7 | 1233 | for (; cpu <= rnp->grphi; cpu++, bit <<= 1) { |
394f99a9 LJ |
1234 | if ((rnp->qsmask & bit) != 0 && |
1235 | f(per_cpu_ptr(rsp->rda, cpu))) | |
64db4cff PM |
1236 | mask |= bit; |
1237 | } | |
45f014c5 | 1238 | if (mask != 0) { |
64db4cff | 1239 | |
d3f6bad3 PM |
1240 | /* rcu_report_qs_rnp() releases rnp->lock. */ |
1241 | rcu_report_qs_rnp(mask, rsp, rnp, flags); | |
64db4cff PM |
1242 | continue; |
1243 | } | |
1304afb2 | 1244 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff | 1245 | } |
64db4cff PM |
1246 | } |
1247 | ||
1248 | /* | |
1249 | * Force quiescent states on reluctant CPUs, and also detect which | |
1250 | * CPUs are in dyntick-idle mode. | |
1251 | */ | |
1252 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) | |
1253 | { | |
1254 | unsigned long flags; | |
64db4cff | 1255 | struct rcu_node *rnp = rcu_get_root(rsp); |
64db4cff | 1256 | |
fc2219d4 | 1257 | if (!rcu_gp_in_progress(rsp)) |
64db4cff | 1258 | return; /* No grace period in progress, nothing to force. */ |
1304afb2 | 1259 | if (!raw_spin_trylock_irqsave(&rsp->fqslock, flags)) { |
64db4cff PM |
1260 | rsp->n_force_qs_lh++; /* Inexact, can lose counts. Tough! */ |
1261 | return; /* Someone else is already on the job. */ | |
1262 | } | |
20133cfc | 1263 | if (relaxed && ULONG_CMP_GE(rsp->jiffies_force_qs, jiffies)) |
f96e9232 | 1264 | goto unlock_fqs_ret; /* no emergency and done recently. */ |
64db4cff | 1265 | rsp->n_force_qs++; |
1304afb2 | 1266 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
64db4cff | 1267 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
560d4bc0 | 1268 | if(!rcu_gp_in_progress(rsp)) { |
64db4cff | 1269 | rsp->n_force_qs_ngp++; |
1304afb2 | 1270 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
f96e9232 | 1271 | goto unlock_fqs_ret; /* no GP in progress, time updated. */ |
64db4cff | 1272 | } |
07079d53 | 1273 | rsp->fqs_active = 1; |
f3a8b5c6 | 1274 | switch (rsp->signaled) { |
83f5b01f | 1275 | case RCU_GP_IDLE: |
64db4cff PM |
1276 | case RCU_GP_INIT: |
1277 | ||
83f5b01f | 1278 | break; /* grace period idle or initializing, ignore. */ |
64db4cff PM |
1279 | |
1280 | case RCU_SAVE_DYNTICK: | |
64db4cff PM |
1281 | if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK) |
1282 | break; /* So gcc recognizes the dead code. */ | |
1283 | ||
f261414f LJ |
1284 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
1285 | ||
64db4cff | 1286 | /* Record dyntick-idle state. */ |
45f014c5 | 1287 | force_qs_rnp(rsp, dyntick_save_progress_counter); |
1304afb2 | 1288 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
ee47eb9f | 1289 | if (rcu_gp_in_progress(rsp)) |
64db4cff | 1290 | rsp->signaled = RCU_FORCE_QS; |
ee47eb9f | 1291 | break; |
64db4cff PM |
1292 | |
1293 | case RCU_FORCE_QS: | |
1294 | ||
1295 | /* Check dyntick-idle state, send IPI to laggarts. */ | |
1304afb2 | 1296 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
45f014c5 | 1297 | force_qs_rnp(rsp, rcu_implicit_dynticks_qs); |
64db4cff PM |
1298 | |
1299 | /* Leave state in case more forcing is required. */ | |
1300 | ||
1304afb2 | 1301 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
f96e9232 | 1302 | break; |
64db4cff | 1303 | } |
07079d53 | 1304 | rsp->fqs_active = 0; |
46a1e34e | 1305 | if (rsp->fqs_need_gp) { |
1304afb2 | 1306 | raw_spin_unlock(&rsp->fqslock); /* irqs remain disabled */ |
46a1e34e PM |
1307 | rsp->fqs_need_gp = 0; |
1308 | rcu_start_gp(rsp, flags); /* releases rnp->lock */ | |
1309 | return; | |
1310 | } | |
1304afb2 | 1311 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
f96e9232 | 1312 | unlock_fqs_ret: |
1304afb2 | 1313 | raw_spin_unlock_irqrestore(&rsp->fqslock, flags); |
64db4cff PM |
1314 | } |
1315 | ||
1316 | #else /* #ifdef CONFIG_SMP */ | |
1317 | ||
1318 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) | |
1319 | { | |
1320 | set_need_resched(); | |
1321 | } | |
1322 | ||
1323 | #endif /* #else #ifdef CONFIG_SMP */ | |
1324 | ||
1325 | /* | |
1326 | * This does the RCU processing work from softirq context for the | |
1327 | * specified rcu_state and rcu_data structures. This may be called | |
1328 | * only from the CPU to whom the rdp belongs. | |
1329 | */ | |
1330 | static void | |
1331 | __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) | |
1332 | { | |
1333 | unsigned long flags; | |
1334 | ||
2e597558 PM |
1335 | WARN_ON_ONCE(rdp->beenonline == 0); |
1336 | ||
64db4cff PM |
1337 | /* |
1338 | * If an RCU GP has gone long enough, go check for dyntick | |
1339 | * idle CPUs and, if needed, send resched IPIs. | |
1340 | */ | |
20133cfc | 1341 | if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) |
64db4cff PM |
1342 | force_quiescent_state(rsp, 1); |
1343 | ||
1344 | /* | |
1345 | * Advance callbacks in response to end of earlier grace | |
1346 | * period that some other CPU ended. | |
1347 | */ | |
1348 | rcu_process_gp_end(rsp, rdp); | |
1349 | ||
1350 | /* Update RCU state based on any recent quiescent states. */ | |
1351 | rcu_check_quiescent_state(rsp, rdp); | |
1352 | ||
1353 | /* Does this CPU require a not-yet-started grace period? */ | |
1354 | if (cpu_needs_another_gp(rsp, rdp)) { | |
1304afb2 | 1355 | raw_spin_lock_irqsave(&rcu_get_root(rsp)->lock, flags); |
64db4cff PM |
1356 | rcu_start_gp(rsp, flags); /* releases above lock */ |
1357 | } | |
1358 | ||
1359 | /* If there are callbacks ready, invoke them. */ | |
37c72e56 | 1360 | rcu_do_batch(rsp, rdp); |
64db4cff PM |
1361 | } |
1362 | ||
1363 | /* | |
1364 | * Do softirq processing for the current CPU. | |
1365 | */ | |
1366 | static void rcu_process_callbacks(struct softirq_action *unused) | |
1367 | { | |
1368 | /* | |
1369 | * Memory references from any prior RCU read-side critical sections | |
1370 | * executed by the interrupted code must be seen before any RCU | |
1371 | * grace-period manipulations below. | |
1372 | */ | |
1373 | smp_mb(); /* See above block comment. */ | |
1374 | ||
d6714c22 PM |
1375 | __rcu_process_callbacks(&rcu_sched_state, |
1376 | &__get_cpu_var(rcu_sched_data)); | |
64db4cff | 1377 | __rcu_process_callbacks(&rcu_bh_state, &__get_cpu_var(rcu_bh_data)); |
f41d911f | 1378 | rcu_preempt_process_callbacks(); |
64db4cff PM |
1379 | |
1380 | /* | |
1381 | * Memory references from any later RCU read-side critical sections | |
1382 | * executed by the interrupted code must be seen after any RCU | |
1383 | * grace-period manipulations above. | |
1384 | */ | |
1385 | smp_mb(); /* See above block comment. */ | |
a47cd880 PM |
1386 | |
1387 | /* If we are last CPU on way to dyntick-idle mode, accelerate it. */ | |
1388 | rcu_needs_cpu_flush(); | |
64db4cff PM |
1389 | } |
1390 | ||
1391 | static void | |
1392 | __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), | |
1393 | struct rcu_state *rsp) | |
1394 | { | |
1395 | unsigned long flags; | |
1396 | struct rcu_data *rdp; | |
1397 | ||
551d55a9 | 1398 | debug_rcu_head_queue(head); |
64db4cff PM |
1399 | head->func = func; |
1400 | head->next = NULL; | |
1401 | ||
1402 | smp_mb(); /* Ensure RCU update seen before callback registry. */ | |
1403 | ||
1404 | /* | |
1405 | * Opportunistically note grace-period endings and beginnings. | |
1406 | * Note that we might see a beginning right after we see an | |
1407 | * end, but never vice versa, since this CPU has to pass through | |
1408 | * a quiescent state betweentimes. | |
1409 | */ | |
1410 | local_irq_save(flags); | |
394f99a9 | 1411 | rdp = this_cpu_ptr(rsp->rda); |
64db4cff PM |
1412 | rcu_process_gp_end(rsp, rdp); |
1413 | check_for_new_grace_period(rsp, rdp); | |
1414 | ||
1415 | /* Add the callback to our list. */ | |
1416 | *rdp->nxttail[RCU_NEXT_TAIL] = head; | |
1417 | rdp->nxttail[RCU_NEXT_TAIL] = &head->next; | |
1418 | ||
1419 | /* Start a new grace period if one not already started. */ | |
fc2219d4 | 1420 | if (!rcu_gp_in_progress(rsp)) { |
64db4cff PM |
1421 | unsigned long nestflag; |
1422 | struct rcu_node *rnp_root = rcu_get_root(rsp); | |
1423 | ||
1304afb2 | 1424 | raw_spin_lock_irqsave(&rnp_root->lock, nestflag); |
64db4cff PM |
1425 | rcu_start_gp(rsp, nestflag); /* releases rnp_root->lock. */ |
1426 | } | |
1427 | ||
37c72e56 PM |
1428 | /* |
1429 | * Force the grace period if too many callbacks or too long waiting. | |
1430 | * Enforce hysteresis, and don't invoke force_quiescent_state() | |
1431 | * if some other CPU has recently done so. Also, don't bother | |
1432 | * invoking force_quiescent_state() if the newly enqueued callback | |
1433 | * is the only one waiting for a grace period to complete. | |
1434 | */ | |
1435 | if (unlikely(++rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) { | |
64db4cff | 1436 | rdp->blimit = LONG_MAX; |
37c72e56 PM |
1437 | if (rsp->n_force_qs == rdp->n_force_qs_snap && |
1438 | *rdp->nxttail[RCU_DONE_TAIL] != head) | |
1439 | force_quiescent_state(rsp, 0); | |
1440 | rdp->n_force_qs_snap = rsp->n_force_qs; | |
1441 | rdp->qlen_last_fqs_check = rdp->qlen; | |
20133cfc | 1442 | } else if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) |
64db4cff PM |
1443 | force_quiescent_state(rsp, 1); |
1444 | local_irq_restore(flags); | |
1445 | } | |
1446 | ||
1447 | /* | |
d6714c22 | 1448 | * Queue an RCU-sched callback for invocation after a grace period. |
64db4cff | 1449 | */ |
d6714c22 | 1450 | void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) |
64db4cff | 1451 | { |
d6714c22 | 1452 | __call_rcu(head, func, &rcu_sched_state); |
64db4cff | 1453 | } |
d6714c22 | 1454 | EXPORT_SYMBOL_GPL(call_rcu_sched); |
64db4cff PM |
1455 | |
1456 | /* | |
1457 | * Queue an RCU for invocation after a quicker grace period. | |
1458 | */ | |
1459 | void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) | |
1460 | { | |
1461 | __call_rcu(head, func, &rcu_bh_state); | |
1462 | } | |
1463 | EXPORT_SYMBOL_GPL(call_rcu_bh); | |
1464 | ||
6ebb237b PM |
1465 | /** |
1466 | * synchronize_sched - wait until an rcu-sched grace period has elapsed. | |
1467 | * | |
1468 | * Control will return to the caller some time after a full rcu-sched | |
1469 | * grace period has elapsed, in other words after all currently executing | |
1470 | * rcu-sched read-side critical sections have completed. These read-side | |
1471 | * critical sections are delimited by rcu_read_lock_sched() and | |
1472 | * rcu_read_unlock_sched(), and may be nested. Note that preempt_disable(), | |
1473 | * local_irq_disable(), and so on may be used in place of | |
1474 | * rcu_read_lock_sched(). | |
1475 | * | |
1476 | * This means that all preempt_disable code sequences, including NMI and | |
1477 | * hardware-interrupt handlers, in progress on entry will have completed | |
1478 | * before this primitive returns. However, this does not guarantee that | |
1479 | * softirq handlers will have completed, since in some kernels, these | |
1480 | * handlers can run in process context, and can block. | |
1481 | * | |
1482 | * This primitive provides the guarantees made by the (now removed) | |
1483 | * synchronize_kernel() API. In contrast, synchronize_rcu() only | |
1484 | * guarantees that rcu_read_lock() sections will have completed. | |
1485 | * In "classic RCU", these two guarantees happen to be one and | |
1486 | * the same, but can differ in realtime RCU implementations. | |
1487 | */ | |
1488 | void synchronize_sched(void) | |
1489 | { | |
1490 | struct rcu_synchronize rcu; | |
1491 | ||
1492 | if (rcu_blocking_is_gp()) | |
1493 | return; | |
1494 | ||
72d5a9f7 | 1495 | init_rcu_head_on_stack(&rcu.head); |
6ebb237b PM |
1496 | init_completion(&rcu.completion); |
1497 | /* Will wake me after RCU finished. */ | |
1498 | call_rcu_sched(&rcu.head, wakeme_after_rcu); | |
1499 | /* Wait for it. */ | |
1500 | wait_for_completion(&rcu.completion); | |
72d5a9f7 | 1501 | destroy_rcu_head_on_stack(&rcu.head); |
6ebb237b PM |
1502 | } |
1503 | EXPORT_SYMBOL_GPL(synchronize_sched); | |
1504 | ||
1505 | /** | |
1506 | * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed. | |
1507 | * | |
1508 | * Control will return to the caller some time after a full rcu_bh grace | |
1509 | * period has elapsed, in other words after all currently executing rcu_bh | |
1510 | * read-side critical sections have completed. RCU read-side critical | |
1511 | * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(), | |
1512 | * and may be nested. | |
1513 | */ | |
1514 | void synchronize_rcu_bh(void) | |
1515 | { | |
1516 | struct rcu_synchronize rcu; | |
1517 | ||
1518 | if (rcu_blocking_is_gp()) | |
1519 | return; | |
1520 | ||
72d5a9f7 | 1521 | init_rcu_head_on_stack(&rcu.head); |
6ebb237b PM |
1522 | init_completion(&rcu.completion); |
1523 | /* Will wake me after RCU finished. */ | |
1524 | call_rcu_bh(&rcu.head, wakeme_after_rcu); | |
1525 | /* Wait for it. */ | |
1526 | wait_for_completion(&rcu.completion); | |
72d5a9f7 | 1527 | destroy_rcu_head_on_stack(&rcu.head); |
6ebb237b PM |
1528 | } |
1529 | EXPORT_SYMBOL_GPL(synchronize_rcu_bh); | |
1530 | ||
64db4cff PM |
1531 | /* |
1532 | * Check to see if there is any immediate RCU-related work to be done | |
1533 | * by the current CPU, for the specified type of RCU, returning 1 if so. | |
1534 | * The checks are in order of increasing expense: checks that can be | |
1535 | * carried out against CPU-local state are performed first. However, | |
1536 | * we must check for CPU stalls first, else we might not get a chance. | |
1537 | */ | |
1538 | static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) | |
1539 | { | |
2f51f988 PM |
1540 | struct rcu_node *rnp = rdp->mynode; |
1541 | ||
64db4cff PM |
1542 | rdp->n_rcu_pending++; |
1543 | ||
1544 | /* Check for CPU stalls, if enabled. */ | |
1545 | check_cpu_stall(rsp, rdp); | |
1546 | ||
1547 | /* Is the RCU core waiting for a quiescent state from this CPU? */ | |
d21670ac | 1548 | if (rdp->qs_pending && !rdp->passed_quiesc) { |
d25eb944 PM |
1549 | |
1550 | /* | |
1551 | * If force_quiescent_state() coming soon and this CPU | |
1552 | * needs a quiescent state, and this is either RCU-sched | |
1553 | * or RCU-bh, force a local reschedule. | |
1554 | */ | |
d21670ac | 1555 | rdp->n_rp_qs_pending++; |
d25eb944 PM |
1556 | if (!rdp->preemptable && |
1557 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs) - 1, | |
1558 | jiffies)) | |
1559 | set_need_resched(); | |
d21670ac PM |
1560 | } else if (rdp->qs_pending && rdp->passed_quiesc) { |
1561 | rdp->n_rp_report_qs++; | |
64db4cff | 1562 | return 1; |
7ba5c840 | 1563 | } |
64db4cff PM |
1564 | |
1565 | /* Does this CPU have callbacks ready to invoke? */ | |
7ba5c840 PM |
1566 | if (cpu_has_callbacks_ready_to_invoke(rdp)) { |
1567 | rdp->n_rp_cb_ready++; | |
64db4cff | 1568 | return 1; |
7ba5c840 | 1569 | } |
64db4cff PM |
1570 | |
1571 | /* Has RCU gone idle with this CPU needing another grace period? */ | |
7ba5c840 PM |
1572 | if (cpu_needs_another_gp(rsp, rdp)) { |
1573 | rdp->n_rp_cpu_needs_gp++; | |
64db4cff | 1574 | return 1; |
7ba5c840 | 1575 | } |
64db4cff PM |
1576 | |
1577 | /* Has another RCU grace period completed? */ | |
2f51f988 | 1578 | if (ACCESS_ONCE(rnp->completed) != rdp->completed) { /* outside lock */ |
7ba5c840 | 1579 | rdp->n_rp_gp_completed++; |
64db4cff | 1580 | return 1; |
7ba5c840 | 1581 | } |
64db4cff PM |
1582 | |
1583 | /* Has a new RCU grace period started? */ | |
2f51f988 | 1584 | if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum) { /* outside lock */ |
7ba5c840 | 1585 | rdp->n_rp_gp_started++; |
64db4cff | 1586 | return 1; |
7ba5c840 | 1587 | } |
64db4cff PM |
1588 | |
1589 | /* Has an RCU GP gone long enough to send resched IPIs &c? */ | |
fc2219d4 | 1590 | if (rcu_gp_in_progress(rsp) && |
20133cfc | 1591 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) { |
7ba5c840 | 1592 | rdp->n_rp_need_fqs++; |
64db4cff | 1593 | return 1; |
7ba5c840 | 1594 | } |
64db4cff PM |
1595 | |
1596 | /* nothing to do */ | |
7ba5c840 | 1597 | rdp->n_rp_need_nothing++; |
64db4cff PM |
1598 | return 0; |
1599 | } | |
1600 | ||
1601 | /* | |
1602 | * Check to see if there is any immediate RCU-related work to be done | |
1603 | * by the current CPU, returning 1 if so. This function is part of the | |
1604 | * RCU implementation; it is -not- an exported member of the RCU API. | |
1605 | */ | |
a157229c | 1606 | static int rcu_pending(int cpu) |
64db4cff | 1607 | { |
d6714c22 | 1608 | return __rcu_pending(&rcu_sched_state, &per_cpu(rcu_sched_data, cpu)) || |
f41d911f PM |
1609 | __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu)) || |
1610 | rcu_preempt_pending(cpu); | |
64db4cff PM |
1611 | } |
1612 | ||
1613 | /* | |
1614 | * Check to see if any future RCU-related work will need to be done | |
1615 | * by the current CPU, even if none need be done immediately, returning | |
8bd93a2c | 1616 | * 1 if so. |
64db4cff | 1617 | */ |
8bd93a2c | 1618 | static int rcu_needs_cpu_quick_check(int cpu) |
64db4cff PM |
1619 | { |
1620 | /* RCU callbacks either ready or pending? */ | |
d6714c22 | 1621 | return per_cpu(rcu_sched_data, cpu).nxtlist || |
f41d911f PM |
1622 | per_cpu(rcu_bh_data, cpu).nxtlist || |
1623 | rcu_preempt_needs_cpu(cpu); | |
64db4cff PM |
1624 | } |
1625 | ||
d0ec774c PM |
1626 | static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL}; |
1627 | static atomic_t rcu_barrier_cpu_count; | |
1628 | static DEFINE_MUTEX(rcu_barrier_mutex); | |
1629 | static struct completion rcu_barrier_completion; | |
d0ec774c PM |
1630 | |
1631 | static void rcu_barrier_callback(struct rcu_head *notused) | |
1632 | { | |
1633 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) | |
1634 | complete(&rcu_barrier_completion); | |
1635 | } | |
1636 | ||
1637 | /* | |
1638 | * Called with preemption disabled, and from cross-cpu IRQ context. | |
1639 | */ | |
1640 | static void rcu_barrier_func(void *type) | |
1641 | { | |
1642 | int cpu = smp_processor_id(); | |
1643 | struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu); | |
1644 | void (*call_rcu_func)(struct rcu_head *head, | |
1645 | void (*func)(struct rcu_head *head)); | |
1646 | ||
1647 | atomic_inc(&rcu_barrier_cpu_count); | |
1648 | call_rcu_func = type; | |
1649 | call_rcu_func(head, rcu_barrier_callback); | |
1650 | } | |
1651 | ||
d0ec774c PM |
1652 | /* |
1653 | * Orchestrate the specified type of RCU barrier, waiting for all | |
1654 | * RCU callbacks of the specified type to complete. | |
1655 | */ | |
e74f4c45 PM |
1656 | static void _rcu_barrier(struct rcu_state *rsp, |
1657 | void (*call_rcu_func)(struct rcu_head *head, | |
d0ec774c PM |
1658 | void (*func)(struct rcu_head *head))) |
1659 | { | |
1660 | BUG_ON(in_interrupt()); | |
e74f4c45 | 1661 | /* Take mutex to serialize concurrent rcu_barrier() requests. */ |
d0ec774c PM |
1662 | mutex_lock(&rcu_barrier_mutex); |
1663 | init_completion(&rcu_barrier_completion); | |
1664 | /* | |
1665 | * Initialize rcu_barrier_cpu_count to 1, then invoke | |
1666 | * rcu_barrier_func() on each CPU, so that each CPU also has | |
1667 | * incremented rcu_barrier_cpu_count. Only then is it safe to | |
1668 | * decrement rcu_barrier_cpu_count -- otherwise the first CPU | |
1669 | * might complete its grace period before all of the other CPUs | |
1670 | * did their increment, causing this function to return too | |
1671 | * early. | |
1672 | */ | |
1673 | atomic_set(&rcu_barrier_cpu_count, 1); | |
e74f4c45 PM |
1674 | preempt_disable(); /* stop CPU_DYING from filling orphan_cbs_list */ |
1675 | rcu_adopt_orphan_cbs(rsp); | |
d0ec774c | 1676 | on_each_cpu(rcu_barrier_func, (void *)call_rcu_func, 1); |
e74f4c45 | 1677 | preempt_enable(); /* CPU_DYING can again fill orphan_cbs_list */ |
d0ec774c PM |
1678 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) |
1679 | complete(&rcu_barrier_completion); | |
1680 | wait_for_completion(&rcu_barrier_completion); | |
1681 | mutex_unlock(&rcu_barrier_mutex); | |
d0ec774c | 1682 | } |
d0ec774c PM |
1683 | |
1684 | /** | |
1685 | * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete. | |
1686 | */ | |
1687 | void rcu_barrier_bh(void) | |
1688 | { | |
e74f4c45 | 1689 | _rcu_barrier(&rcu_bh_state, call_rcu_bh); |
d0ec774c PM |
1690 | } |
1691 | EXPORT_SYMBOL_GPL(rcu_barrier_bh); | |
1692 | ||
1693 | /** | |
1694 | * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks. | |
1695 | */ | |
1696 | void rcu_barrier_sched(void) | |
1697 | { | |
e74f4c45 | 1698 | _rcu_barrier(&rcu_sched_state, call_rcu_sched); |
d0ec774c PM |
1699 | } |
1700 | EXPORT_SYMBOL_GPL(rcu_barrier_sched); | |
1701 | ||
64db4cff | 1702 | /* |
27569620 | 1703 | * Do boot-time initialization of a CPU's per-CPU RCU data. |
64db4cff | 1704 | */ |
27569620 PM |
1705 | static void __init |
1706 | rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) | |
64db4cff PM |
1707 | { |
1708 | unsigned long flags; | |
1709 | int i; | |
394f99a9 | 1710 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
27569620 PM |
1711 | struct rcu_node *rnp = rcu_get_root(rsp); |
1712 | ||
1713 | /* Set up local state, ensuring consistent view of global state. */ | |
1304afb2 | 1714 | raw_spin_lock_irqsave(&rnp->lock, flags); |
27569620 PM |
1715 | rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo); |
1716 | rdp->nxtlist = NULL; | |
1717 | for (i = 0; i < RCU_NEXT_SIZE; i++) | |
1718 | rdp->nxttail[i] = &rdp->nxtlist; | |
1719 | rdp->qlen = 0; | |
1720 | #ifdef CONFIG_NO_HZ | |
1721 | rdp->dynticks = &per_cpu(rcu_dynticks, cpu); | |
1722 | #endif /* #ifdef CONFIG_NO_HZ */ | |
1723 | rdp->cpu = cpu; | |
1304afb2 | 1724 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
27569620 PM |
1725 | } |
1726 | ||
1727 | /* | |
1728 | * Initialize a CPU's per-CPU RCU data. Note that only one online or | |
1729 | * offline event can be happening at a given time. Note also that we | |
1730 | * can accept some slop in the rsp->completed access due to the fact | |
1731 | * that this CPU cannot possibly have any RCU callbacks in flight yet. | |
64db4cff | 1732 | */ |
e4fa4c97 | 1733 | static void __cpuinit |
f41d911f | 1734 | rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable) |
64db4cff PM |
1735 | { |
1736 | unsigned long flags; | |
64db4cff | 1737 | unsigned long mask; |
394f99a9 | 1738 | struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); |
64db4cff PM |
1739 | struct rcu_node *rnp = rcu_get_root(rsp); |
1740 | ||
1741 | /* Set up local state, ensuring consistent view of global state. */ | |
1304afb2 | 1742 | raw_spin_lock_irqsave(&rnp->lock, flags); |
64db4cff PM |
1743 | rdp->passed_quiesc = 0; /* We could be racing with new GP, */ |
1744 | rdp->qs_pending = 1; /* so set up to respond to current GP. */ | |
1745 | rdp->beenonline = 1; /* We have now been online. */ | |
f41d911f | 1746 | rdp->preemptable = preemptable; |
37c72e56 PM |
1747 | rdp->qlen_last_fqs_check = 0; |
1748 | rdp->n_force_qs_snap = rsp->n_force_qs; | |
64db4cff | 1749 | rdp->blimit = blimit; |
1304afb2 | 1750 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
64db4cff PM |
1751 | |
1752 | /* | |
1753 | * A new grace period might start here. If so, we won't be part | |
1754 | * of it, but that is OK, as we are currently in a quiescent state. | |
1755 | */ | |
1756 | ||
1757 | /* Exclude any attempts to start a new GP on large systems. */ | |
1304afb2 | 1758 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
64db4cff PM |
1759 | |
1760 | /* Add CPU to rcu_node bitmasks. */ | |
1761 | rnp = rdp->mynode; | |
1762 | mask = rdp->grpmask; | |
1763 | do { | |
1764 | /* Exclude any attempts to start a new GP on small systems. */ | |
1304afb2 | 1765 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
64db4cff PM |
1766 | rnp->qsmaskinit |= mask; |
1767 | mask = rnp->grpmask; | |
d09b62df PM |
1768 | if (rnp == rdp->mynode) { |
1769 | rdp->gpnum = rnp->completed; /* if GP in progress... */ | |
1770 | rdp->completed = rnp->completed; | |
1771 | rdp->passed_quiesc_completed = rnp->completed - 1; | |
1772 | } | |
1304afb2 | 1773 | raw_spin_unlock(&rnp->lock); /* irqs already disabled. */ |
64db4cff PM |
1774 | rnp = rnp->parent; |
1775 | } while (rnp != NULL && !(rnp->qsmaskinit & mask)); | |
1776 | ||
1304afb2 | 1777 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
64db4cff PM |
1778 | } |
1779 | ||
1780 | static void __cpuinit rcu_online_cpu(int cpu) | |
1781 | { | |
f41d911f PM |
1782 | rcu_init_percpu_data(cpu, &rcu_sched_state, 0); |
1783 | rcu_init_percpu_data(cpu, &rcu_bh_state, 0); | |
1784 | rcu_preempt_init_percpu_data(cpu); | |
64db4cff PM |
1785 | } |
1786 | ||
1787 | /* | |
f41d911f | 1788 | * Handle CPU online/offline notification events. |
64db4cff | 1789 | */ |
9f680ab4 PM |
1790 | static int __cpuinit rcu_cpu_notify(struct notifier_block *self, |
1791 | unsigned long action, void *hcpu) | |
64db4cff PM |
1792 | { |
1793 | long cpu = (long)hcpu; | |
1794 | ||
1795 | switch (action) { | |
1796 | case CPU_UP_PREPARE: | |
1797 | case CPU_UP_PREPARE_FROZEN: | |
1798 | rcu_online_cpu(cpu); | |
1799 | break; | |
d0ec774c PM |
1800 | case CPU_DYING: |
1801 | case CPU_DYING_FROZEN: | |
1802 | /* | |
e74f4c45 | 1803 | * preempt_disable() in _rcu_barrier() prevents stop_machine(), |
d0ec774c | 1804 | * so when "on_each_cpu(rcu_barrier_func, (void *)type, 1);" |
e74f4c45 PM |
1805 | * returns, all online cpus have queued rcu_barrier_func(). |
1806 | * The dying CPU clears its cpu_online_mask bit and | |
1807 | * moves all of its RCU callbacks to ->orphan_cbs_list | |
1808 | * in the context of stop_machine(), so subsequent calls | |
1809 | * to _rcu_barrier() will adopt these callbacks and only | |
1810 | * then queue rcu_barrier_func() on all remaining CPUs. | |
d0ec774c | 1811 | */ |
e74f4c45 PM |
1812 | rcu_send_cbs_to_orphanage(&rcu_bh_state); |
1813 | rcu_send_cbs_to_orphanage(&rcu_sched_state); | |
1814 | rcu_preempt_send_cbs_to_orphanage(); | |
d0ec774c | 1815 | break; |
64db4cff PM |
1816 | case CPU_DEAD: |
1817 | case CPU_DEAD_FROZEN: | |
1818 | case CPU_UP_CANCELED: | |
1819 | case CPU_UP_CANCELED_FROZEN: | |
1820 | rcu_offline_cpu(cpu); | |
1821 | break; | |
1822 | default: | |
1823 | break; | |
1824 | } | |
1825 | return NOTIFY_OK; | |
1826 | } | |
1827 | ||
bbad9379 PM |
1828 | /* |
1829 | * This function is invoked towards the end of the scheduler's initialization | |
1830 | * process. Before this is called, the idle task might contain | |
1831 | * RCU read-side critical sections (during which time, this idle | |
1832 | * task is booting the system). After this function is called, the | |
1833 | * idle tasks are prohibited from containing RCU read-side critical | |
1834 | * sections. This function also enables RCU lockdep checking. | |
1835 | */ | |
1836 | void rcu_scheduler_starting(void) | |
1837 | { | |
1838 | WARN_ON(num_online_cpus() != 1); | |
1839 | WARN_ON(nr_context_switches() > 0); | |
1840 | rcu_scheduler_active = 1; | |
1841 | } | |
1842 | ||
64db4cff PM |
1843 | /* |
1844 | * Compute the per-level fanout, either using the exact fanout specified | |
1845 | * or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT. | |
1846 | */ | |
1847 | #ifdef CONFIG_RCU_FANOUT_EXACT | |
1848 | static void __init rcu_init_levelspread(struct rcu_state *rsp) | |
1849 | { | |
1850 | int i; | |
1851 | ||
1852 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) | |
1853 | rsp->levelspread[i] = CONFIG_RCU_FANOUT; | |
1854 | } | |
1855 | #else /* #ifdef CONFIG_RCU_FANOUT_EXACT */ | |
1856 | static void __init rcu_init_levelspread(struct rcu_state *rsp) | |
1857 | { | |
1858 | int ccur; | |
1859 | int cprv; | |
1860 | int i; | |
1861 | ||
1862 | cprv = NR_CPUS; | |
1863 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { | |
1864 | ccur = rsp->levelcnt[i]; | |
1865 | rsp->levelspread[i] = (cprv + ccur - 1) / ccur; | |
1866 | cprv = ccur; | |
1867 | } | |
1868 | } | |
1869 | #endif /* #else #ifdef CONFIG_RCU_FANOUT_EXACT */ | |
1870 | ||
1871 | /* | |
1872 | * Helper function for rcu_init() that initializes one rcu_state structure. | |
1873 | */ | |
394f99a9 LJ |
1874 | static void __init rcu_init_one(struct rcu_state *rsp, |
1875 | struct rcu_data __percpu *rda) | |
64db4cff | 1876 | { |
b6407e86 PM |
1877 | static char *buf[] = { "rcu_node_level_0", |
1878 | "rcu_node_level_1", | |
1879 | "rcu_node_level_2", | |
1880 | "rcu_node_level_3" }; /* Match MAX_RCU_LVLS */ | |
64db4cff PM |
1881 | int cpustride = 1; |
1882 | int i; | |
1883 | int j; | |
1884 | struct rcu_node *rnp; | |
1885 | ||
b6407e86 PM |
1886 | BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */ |
1887 | ||
64db4cff PM |
1888 | /* Initialize the level-tracking arrays. */ |
1889 | ||
1890 | for (i = 1; i < NUM_RCU_LVLS; i++) | |
1891 | rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1]; | |
1892 | rcu_init_levelspread(rsp); | |
1893 | ||
1894 | /* Initialize the elements themselves, starting from the leaves. */ | |
1895 | ||
1896 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { | |
1897 | cpustride *= rsp->levelspread[i]; | |
1898 | rnp = rsp->level[i]; | |
1899 | for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) { | |
1304afb2 | 1900 | raw_spin_lock_init(&rnp->lock); |
b6407e86 PM |
1901 | lockdep_set_class_and_name(&rnp->lock, |
1902 | &rcu_node_class[i], buf[i]); | |
f41d911f | 1903 | rnp->gpnum = 0; |
64db4cff PM |
1904 | rnp->qsmask = 0; |
1905 | rnp->qsmaskinit = 0; | |
1906 | rnp->grplo = j * cpustride; | |
1907 | rnp->grphi = (j + 1) * cpustride - 1; | |
1908 | if (rnp->grphi >= NR_CPUS) | |
1909 | rnp->grphi = NR_CPUS - 1; | |
1910 | if (i == 0) { | |
1911 | rnp->grpnum = 0; | |
1912 | rnp->grpmask = 0; | |
1913 | rnp->parent = NULL; | |
1914 | } else { | |
1915 | rnp->grpnum = j % rsp->levelspread[i - 1]; | |
1916 | rnp->grpmask = 1UL << rnp->grpnum; | |
1917 | rnp->parent = rsp->level[i - 1] + | |
1918 | j / rsp->levelspread[i - 1]; | |
1919 | } | |
1920 | rnp->level = i; | |
f41d911f PM |
1921 | INIT_LIST_HEAD(&rnp->blocked_tasks[0]); |
1922 | INIT_LIST_HEAD(&rnp->blocked_tasks[1]); | |
d9a3da06 PM |
1923 | INIT_LIST_HEAD(&rnp->blocked_tasks[2]); |
1924 | INIT_LIST_HEAD(&rnp->blocked_tasks[3]); | |
64db4cff PM |
1925 | } |
1926 | } | |
0c34029a | 1927 | |
394f99a9 | 1928 | rsp->rda = rda; |
0c34029a LJ |
1929 | rnp = rsp->level[NUM_RCU_LVLS - 1]; |
1930 | for_each_possible_cpu(i) { | |
4a90a068 | 1931 | while (i > rnp->grphi) |
0c34029a | 1932 | rnp++; |
394f99a9 | 1933 | per_cpu_ptr(rsp->rda, i)->mynode = rnp; |
0c34029a LJ |
1934 | rcu_boot_init_percpu_data(i, rsp); |
1935 | } | |
64db4cff PM |
1936 | } |
1937 | ||
9f680ab4 | 1938 | void __init rcu_init(void) |
64db4cff | 1939 | { |
017c4261 | 1940 | int cpu; |
9f680ab4 | 1941 | |
f41d911f | 1942 | rcu_bootup_announce(); |
394f99a9 LJ |
1943 | rcu_init_one(&rcu_sched_state, &rcu_sched_data); |
1944 | rcu_init_one(&rcu_bh_state, &rcu_bh_data); | |
f41d911f | 1945 | __rcu_init_preempt(); |
2e597558 | 1946 | open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); |
9f680ab4 PM |
1947 | |
1948 | /* | |
1949 | * We don't need protection against CPU-hotplug here because | |
1950 | * this is called early in boot, before either interrupts | |
1951 | * or the scheduler are operational. | |
1952 | */ | |
1953 | cpu_notifier(rcu_cpu_notify, 0); | |
017c4261 PM |
1954 | for_each_online_cpu(cpu) |
1955 | rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu); | |
c68de209 | 1956 | check_cpu_stall_init(); |
64db4cff PM |
1957 | } |
1958 | ||
1eba8f84 | 1959 | #include "rcutree_plugin.h" |