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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> | |
49 | ||
9f77da9f PM |
50 | #include "rcutree.h" |
51 | ||
64db4cff PM |
52 | /* Data structures. */ |
53 | ||
b668c9cf | 54 | static struct lock_class_key rcu_node_class[NUM_RCU_LVLS]; |
88b91c7c | 55 | |
64db4cff PM |
56 | #define RCU_STATE_INITIALIZER(name) { \ |
57 | .level = { &name.node[0] }, \ | |
58 | .levelcnt = { \ | |
59 | NUM_RCU_LVL_0, /* root of hierarchy. */ \ | |
60 | NUM_RCU_LVL_1, \ | |
61 | NUM_RCU_LVL_2, \ | |
cf244dc0 PM |
62 | NUM_RCU_LVL_3, \ |
63 | NUM_RCU_LVL_4, /* == MAX_RCU_LVLS */ \ | |
64db4cff | 64 | }, \ |
83f5b01f | 65 | .signaled = RCU_GP_IDLE, \ |
64db4cff PM |
66 | .gpnum = -300, \ |
67 | .completed = -300, \ | |
1304afb2 | 68 | .onofflock = __RAW_SPIN_LOCK_UNLOCKED(&name.onofflock), \ |
e74f4c45 PM |
69 | .orphan_cbs_list = NULL, \ |
70 | .orphan_cbs_tail = &name.orphan_cbs_list, \ | |
71 | .orphan_qlen = 0, \ | |
1304afb2 | 72 | .fqslock = __RAW_SPIN_LOCK_UNLOCKED(&name.fqslock), \ |
64db4cff PM |
73 | .n_force_qs = 0, \ |
74 | .n_force_qs_ngp = 0, \ | |
75 | } | |
76 | ||
d6714c22 PM |
77 | struct rcu_state rcu_sched_state = RCU_STATE_INITIALIZER(rcu_sched_state); |
78 | DEFINE_PER_CPU(struct rcu_data, rcu_sched_data); | |
64db4cff | 79 | |
6258c4fb IM |
80 | struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state); |
81 | DEFINE_PER_CPU(struct rcu_data, rcu_bh_data); | |
b1f77b05 | 82 | |
fc2219d4 PM |
83 | /* |
84 | * Return true if an RCU grace period is in progress. The ACCESS_ONCE()s | |
85 | * permit this function to be invoked without holding the root rcu_node | |
86 | * structure's ->lock, but of course results can be subject to change. | |
87 | */ | |
88 | static int rcu_gp_in_progress(struct rcu_state *rsp) | |
89 | { | |
90 | return ACCESS_ONCE(rsp->completed) != ACCESS_ONCE(rsp->gpnum); | |
91 | } | |
92 | ||
b1f77b05 | 93 | /* |
d6714c22 | 94 | * Note a quiescent state. Because we do not need to know |
b1f77b05 | 95 | * how many quiescent states passed, just if there was at least |
d6714c22 | 96 | * one since the start of the grace period, this just sets a flag. |
b1f77b05 | 97 | */ |
d6714c22 | 98 | void rcu_sched_qs(int cpu) |
b1f77b05 | 99 | { |
f41d911f PM |
100 | struct rcu_data *rdp; |
101 | ||
f41d911f | 102 | rdp = &per_cpu(rcu_sched_data, cpu); |
c64ac3ce | 103 | rdp->passed_quiesc_completed = rdp->gpnum - 1; |
c3422bea PM |
104 | barrier(); |
105 | rdp->passed_quiesc = 1; | |
106 | rcu_preempt_note_context_switch(cpu); | |
b1f77b05 IM |
107 | } |
108 | ||
d6714c22 | 109 | void rcu_bh_qs(int cpu) |
b1f77b05 | 110 | { |
f41d911f PM |
111 | struct rcu_data *rdp; |
112 | ||
f41d911f | 113 | rdp = &per_cpu(rcu_bh_data, cpu); |
c64ac3ce | 114 | rdp->passed_quiesc_completed = rdp->gpnum - 1; |
c3422bea PM |
115 | barrier(); |
116 | rdp->passed_quiesc = 1; | |
b1f77b05 | 117 | } |
64db4cff PM |
118 | |
119 | #ifdef CONFIG_NO_HZ | |
90a4d2c0 PM |
120 | DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { |
121 | .dynticks_nesting = 1, | |
122 | .dynticks = 1, | |
123 | }; | |
64db4cff PM |
124 | #endif /* #ifdef CONFIG_NO_HZ */ |
125 | ||
126 | static int blimit = 10; /* Maximum callbacks per softirq. */ | |
127 | static int qhimark = 10000; /* If this many pending, ignore blimit. */ | |
128 | static int qlowmark = 100; /* Once only this many pending, use blimit. */ | |
129 | ||
3d76c082 PM |
130 | module_param(blimit, int, 0); |
131 | module_param(qhimark, int, 0); | |
132 | module_param(qlowmark, int, 0); | |
133 | ||
64db4cff | 134 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed); |
a157229c | 135 | static int rcu_pending(int cpu); |
64db4cff PM |
136 | |
137 | /* | |
d6714c22 | 138 | * Return the number of RCU-sched batches processed thus far for debug & stats. |
64db4cff | 139 | */ |
d6714c22 | 140 | long rcu_batches_completed_sched(void) |
64db4cff | 141 | { |
d6714c22 | 142 | return rcu_sched_state.completed; |
64db4cff | 143 | } |
d6714c22 | 144 | EXPORT_SYMBOL_GPL(rcu_batches_completed_sched); |
64db4cff PM |
145 | |
146 | /* | |
147 | * Return the number of RCU BH batches processed thus far for debug & stats. | |
148 | */ | |
149 | long rcu_batches_completed_bh(void) | |
150 | { | |
151 | return rcu_bh_state.completed; | |
152 | } | |
153 | EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); | |
154 | ||
bf66f18e PM |
155 | /* |
156 | * Force a quiescent state for RCU BH. | |
157 | */ | |
158 | void rcu_bh_force_quiescent_state(void) | |
159 | { | |
160 | force_quiescent_state(&rcu_bh_state, 0); | |
161 | } | |
162 | EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state); | |
163 | ||
164 | /* | |
165 | * Force a quiescent state for RCU-sched. | |
166 | */ | |
167 | void rcu_sched_force_quiescent_state(void) | |
168 | { | |
169 | force_quiescent_state(&rcu_sched_state, 0); | |
170 | } | |
171 | EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state); | |
172 | ||
64db4cff PM |
173 | /* |
174 | * Does the CPU have callbacks ready to be invoked? | |
175 | */ | |
176 | static int | |
177 | cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp) | |
178 | { | |
179 | return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]; | |
180 | } | |
181 | ||
182 | /* | |
183 | * Does the current CPU require a yet-as-unscheduled grace period? | |
184 | */ | |
185 | static int | |
186 | cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp) | |
187 | { | |
fc2219d4 | 188 | return *rdp->nxttail[RCU_DONE_TAIL] && !rcu_gp_in_progress(rsp); |
64db4cff PM |
189 | } |
190 | ||
191 | /* | |
192 | * Return the root node of the specified rcu_state structure. | |
193 | */ | |
194 | static struct rcu_node *rcu_get_root(struct rcu_state *rsp) | |
195 | { | |
196 | return &rsp->node[0]; | |
197 | } | |
198 | ||
199 | #ifdef CONFIG_SMP | |
200 | ||
201 | /* | |
202 | * If the specified CPU is offline, tell the caller that it is in | |
203 | * a quiescent state. Otherwise, whack it with a reschedule IPI. | |
204 | * Grace periods can end up waiting on an offline CPU when that | |
205 | * CPU is in the process of coming online -- it will be added to the | |
206 | * rcu_node bitmasks before it actually makes it online. The same thing | |
207 | * can happen while a CPU is in the process of coming online. Because this | |
208 | * race is quite rare, we check for it after detecting that the grace | |
209 | * period has been delayed rather than checking each and every CPU | |
210 | * each and every time we start a new grace period. | |
211 | */ | |
212 | static int rcu_implicit_offline_qs(struct rcu_data *rdp) | |
213 | { | |
214 | /* | |
215 | * If the CPU is offline, it is in a quiescent state. We can | |
216 | * trust its state not to change because interrupts are disabled. | |
217 | */ | |
218 | if (cpu_is_offline(rdp->cpu)) { | |
219 | rdp->offline_fqs++; | |
220 | return 1; | |
221 | } | |
222 | ||
f41d911f PM |
223 | /* If preemptable RCU, no point in sending reschedule IPI. */ |
224 | if (rdp->preemptable) | |
225 | return 0; | |
226 | ||
64db4cff PM |
227 | /* The CPU is online, so send it a reschedule IPI. */ |
228 | if (rdp->cpu != smp_processor_id()) | |
229 | smp_send_reschedule(rdp->cpu); | |
230 | else | |
231 | set_need_resched(); | |
232 | rdp->resched_ipi++; | |
233 | return 0; | |
234 | } | |
235 | ||
236 | #endif /* #ifdef CONFIG_SMP */ | |
237 | ||
238 | #ifdef CONFIG_NO_HZ | |
64db4cff PM |
239 | |
240 | /** | |
241 | * rcu_enter_nohz - inform RCU that current CPU is entering nohz | |
242 | * | |
243 | * Enter nohz mode, in other words, -leave- the mode in which RCU | |
244 | * read-side critical sections can occur. (Though RCU read-side | |
245 | * critical sections can occur in irq handlers in nohz mode, a possibility | |
246 | * handled by rcu_irq_enter() and rcu_irq_exit()). | |
247 | */ | |
248 | void rcu_enter_nohz(void) | |
249 | { | |
250 | unsigned long flags; | |
251 | struct rcu_dynticks *rdtp; | |
252 | ||
253 | smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ | |
254 | local_irq_save(flags); | |
255 | rdtp = &__get_cpu_var(rcu_dynticks); | |
256 | rdtp->dynticks++; | |
257 | rdtp->dynticks_nesting--; | |
86848966 | 258 | WARN_ON_ONCE(rdtp->dynticks & 0x1); |
64db4cff PM |
259 | local_irq_restore(flags); |
260 | } | |
261 | ||
262 | /* | |
263 | * rcu_exit_nohz - inform RCU that current CPU is leaving nohz | |
264 | * | |
265 | * Exit nohz mode, in other words, -enter- the mode in which RCU | |
266 | * read-side critical sections normally occur. | |
267 | */ | |
268 | void rcu_exit_nohz(void) | |
269 | { | |
270 | unsigned long flags; | |
271 | struct rcu_dynticks *rdtp; | |
272 | ||
273 | local_irq_save(flags); | |
274 | rdtp = &__get_cpu_var(rcu_dynticks); | |
275 | rdtp->dynticks++; | |
276 | rdtp->dynticks_nesting++; | |
86848966 | 277 | WARN_ON_ONCE(!(rdtp->dynticks & 0x1)); |
64db4cff PM |
278 | local_irq_restore(flags); |
279 | smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ | |
280 | } | |
281 | ||
282 | /** | |
283 | * rcu_nmi_enter - inform RCU of entry to NMI context | |
284 | * | |
285 | * If the CPU was idle with dynamic ticks active, and there is no | |
286 | * irq handler running, this updates rdtp->dynticks_nmi to let the | |
287 | * RCU grace-period handling know that the CPU is active. | |
288 | */ | |
289 | void rcu_nmi_enter(void) | |
290 | { | |
291 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); | |
292 | ||
293 | if (rdtp->dynticks & 0x1) | |
294 | return; | |
295 | rdtp->dynticks_nmi++; | |
86848966 | 296 | WARN_ON_ONCE(!(rdtp->dynticks_nmi & 0x1)); |
64db4cff PM |
297 | smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ |
298 | } | |
299 | ||
300 | /** | |
301 | * rcu_nmi_exit - inform RCU of exit from NMI context | |
302 | * | |
303 | * If the CPU was idle with dynamic ticks active, and there is no | |
304 | * irq handler running, this updates rdtp->dynticks_nmi to let the | |
305 | * RCU grace-period handling know that the CPU is no longer active. | |
306 | */ | |
307 | void rcu_nmi_exit(void) | |
308 | { | |
309 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); | |
310 | ||
311 | if (rdtp->dynticks & 0x1) | |
312 | return; | |
313 | smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ | |
314 | rdtp->dynticks_nmi++; | |
86848966 | 315 | WARN_ON_ONCE(rdtp->dynticks_nmi & 0x1); |
64db4cff PM |
316 | } |
317 | ||
318 | /** | |
319 | * rcu_irq_enter - inform RCU of entry to hard irq context | |
320 | * | |
321 | * If the CPU was idle with dynamic ticks active, this updates the | |
322 | * rdtp->dynticks to let the RCU handling know that the CPU is active. | |
323 | */ | |
324 | void rcu_irq_enter(void) | |
325 | { | |
326 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); | |
327 | ||
328 | if (rdtp->dynticks_nesting++) | |
329 | return; | |
330 | rdtp->dynticks++; | |
86848966 | 331 | WARN_ON_ONCE(!(rdtp->dynticks & 0x1)); |
64db4cff PM |
332 | smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ |
333 | } | |
334 | ||
335 | /** | |
336 | * rcu_irq_exit - inform RCU of exit from hard irq context | |
337 | * | |
338 | * If the CPU was idle with dynamic ticks active, update the rdp->dynticks | |
339 | * to put let the RCU handling be aware that the CPU is going back to idle | |
340 | * with no ticks. | |
341 | */ | |
342 | void rcu_irq_exit(void) | |
343 | { | |
344 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); | |
345 | ||
346 | if (--rdtp->dynticks_nesting) | |
347 | return; | |
348 | smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ | |
349 | rdtp->dynticks++; | |
86848966 | 350 | WARN_ON_ONCE(rdtp->dynticks & 0x1); |
64db4cff PM |
351 | |
352 | /* If the interrupt queued a callback, get out of dyntick mode. */ | |
d6714c22 | 353 | if (__get_cpu_var(rcu_sched_data).nxtlist || |
64db4cff PM |
354 | __get_cpu_var(rcu_bh_data).nxtlist) |
355 | set_need_resched(); | |
356 | } | |
357 | ||
64db4cff PM |
358 | #ifdef CONFIG_SMP |
359 | ||
64db4cff PM |
360 | /* |
361 | * Snapshot the specified CPU's dynticks counter so that we can later | |
362 | * credit them with an implicit quiescent state. Return 1 if this CPU | |
1eba8f84 | 363 | * is in dynticks idle mode, which is an extended quiescent state. |
64db4cff PM |
364 | */ |
365 | static int dyntick_save_progress_counter(struct rcu_data *rdp) | |
366 | { | |
367 | int ret; | |
368 | int snap; | |
369 | int snap_nmi; | |
370 | ||
371 | snap = rdp->dynticks->dynticks; | |
372 | snap_nmi = rdp->dynticks->dynticks_nmi; | |
373 | smp_mb(); /* Order sampling of snap with end of grace period. */ | |
374 | rdp->dynticks_snap = snap; | |
375 | rdp->dynticks_nmi_snap = snap_nmi; | |
376 | ret = ((snap & 0x1) == 0) && ((snap_nmi & 0x1) == 0); | |
377 | if (ret) | |
378 | rdp->dynticks_fqs++; | |
379 | return ret; | |
380 | } | |
381 | ||
382 | /* | |
383 | * Return true if the specified CPU has passed through a quiescent | |
384 | * state by virtue of being in or having passed through an dynticks | |
385 | * idle state since the last call to dyntick_save_progress_counter() | |
386 | * for this same CPU. | |
387 | */ | |
388 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) | |
389 | { | |
390 | long curr; | |
391 | long curr_nmi; | |
392 | long snap; | |
393 | long snap_nmi; | |
394 | ||
395 | curr = rdp->dynticks->dynticks; | |
396 | snap = rdp->dynticks_snap; | |
397 | curr_nmi = rdp->dynticks->dynticks_nmi; | |
398 | snap_nmi = rdp->dynticks_nmi_snap; | |
399 | smp_mb(); /* force ordering with cpu entering/leaving dynticks. */ | |
400 | ||
401 | /* | |
402 | * If the CPU passed through or entered a dynticks idle phase with | |
403 | * no active irq/NMI handlers, then we can safely pretend that the CPU | |
404 | * already acknowledged the request to pass through a quiescent | |
405 | * state. Either way, that CPU cannot possibly be in an RCU | |
406 | * read-side critical section that started before the beginning | |
407 | * of the current RCU grace period. | |
408 | */ | |
409 | if ((curr != snap || (curr & 0x1) == 0) && | |
410 | (curr_nmi != snap_nmi || (curr_nmi & 0x1) == 0)) { | |
411 | rdp->dynticks_fqs++; | |
412 | return 1; | |
413 | } | |
414 | ||
415 | /* Go check for the CPU being offline. */ | |
416 | return rcu_implicit_offline_qs(rdp); | |
417 | } | |
418 | ||
419 | #endif /* #ifdef CONFIG_SMP */ | |
420 | ||
421 | #else /* #ifdef CONFIG_NO_HZ */ | |
422 | ||
64db4cff PM |
423 | #ifdef CONFIG_SMP |
424 | ||
64db4cff PM |
425 | static int dyntick_save_progress_counter(struct rcu_data *rdp) |
426 | { | |
427 | return 0; | |
428 | } | |
429 | ||
430 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) | |
431 | { | |
432 | return rcu_implicit_offline_qs(rdp); | |
433 | } | |
434 | ||
435 | #endif /* #ifdef CONFIG_SMP */ | |
436 | ||
437 | #endif /* #else #ifdef CONFIG_NO_HZ */ | |
438 | ||
439 | #ifdef CONFIG_RCU_CPU_STALL_DETECTOR | |
440 | ||
441 | static void record_gp_stall_check_time(struct rcu_state *rsp) | |
442 | { | |
443 | rsp->gp_start = jiffies; | |
444 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_CHECK; | |
445 | } | |
446 | ||
447 | static void print_other_cpu_stall(struct rcu_state *rsp) | |
448 | { | |
449 | int cpu; | |
450 | long delta; | |
451 | unsigned long flags; | |
452 | struct rcu_node *rnp = rcu_get_root(rsp); | |
64db4cff PM |
453 | |
454 | /* Only let one CPU complain about others per time interval. */ | |
455 | ||
1304afb2 | 456 | raw_spin_lock_irqsave(&rnp->lock, flags); |
64db4cff | 457 | delta = jiffies - rsp->jiffies_stall; |
fc2219d4 | 458 | if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) { |
1304afb2 | 459 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
460 | return; |
461 | } | |
462 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_RECHECK; | |
a0b6c9a7 PM |
463 | |
464 | /* | |
465 | * Now rat on any tasks that got kicked up to the root rcu_node | |
466 | * due to CPU offlining. | |
467 | */ | |
468 | rcu_print_task_stall(rnp); | |
1304afb2 | 469 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
470 | |
471 | /* OK, time to rat on our buddy... */ | |
472 | ||
473 | printk(KERN_ERR "INFO: RCU detected CPU stalls:"); | |
a0b6c9a7 | 474 | rcu_for_each_leaf_node(rsp, rnp) { |
3acd9eb3 | 475 | raw_spin_lock_irqsave(&rnp->lock, flags); |
f41d911f | 476 | rcu_print_task_stall(rnp); |
3acd9eb3 | 477 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
a0b6c9a7 | 478 | if (rnp->qsmask == 0) |
64db4cff | 479 | continue; |
a0b6c9a7 PM |
480 | for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++) |
481 | if (rnp->qsmask & (1UL << cpu)) | |
482 | printk(" %d", rnp->grplo + cpu); | |
64db4cff PM |
483 | } |
484 | printk(" (detected by %d, t=%ld jiffies)\n", | |
485 | smp_processor_id(), (long)(jiffies - rsp->gp_start)); | |
c1dc0b9c IM |
486 | trigger_all_cpu_backtrace(); |
487 | ||
1ed509a2 PM |
488 | /* If so configured, complain about tasks blocking the grace period. */ |
489 | ||
490 | rcu_print_detail_task_stall(rsp); | |
491 | ||
64db4cff PM |
492 | force_quiescent_state(rsp, 0); /* Kick them all. */ |
493 | } | |
494 | ||
495 | static void print_cpu_stall(struct rcu_state *rsp) | |
496 | { | |
497 | unsigned long flags; | |
498 | struct rcu_node *rnp = rcu_get_root(rsp); | |
499 | ||
500 | printk(KERN_ERR "INFO: RCU detected CPU %d stall (t=%lu jiffies)\n", | |
501 | smp_processor_id(), jiffies - rsp->gp_start); | |
c1dc0b9c IM |
502 | trigger_all_cpu_backtrace(); |
503 | ||
1304afb2 | 504 | raw_spin_lock_irqsave(&rnp->lock, flags); |
20133cfc | 505 | if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall)) |
64db4cff PM |
506 | rsp->jiffies_stall = |
507 | jiffies + RCU_SECONDS_TILL_STALL_RECHECK; | |
1304afb2 | 508 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
c1dc0b9c | 509 | |
64db4cff PM |
510 | set_need_resched(); /* kick ourselves to get things going. */ |
511 | } | |
512 | ||
513 | static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) | |
514 | { | |
515 | long delta; | |
516 | struct rcu_node *rnp; | |
517 | ||
518 | delta = jiffies - rsp->jiffies_stall; | |
519 | rnp = rdp->mynode; | |
520 | if ((rnp->qsmask & rdp->grpmask) && delta >= 0) { | |
521 | ||
522 | /* We haven't checked in, so go dump stack. */ | |
523 | print_cpu_stall(rsp); | |
524 | ||
fc2219d4 | 525 | } else if (rcu_gp_in_progress(rsp) && delta >= RCU_STALL_RAT_DELAY) { |
64db4cff PM |
526 | |
527 | /* They had two time units to dump stack, so complain. */ | |
528 | print_other_cpu_stall(rsp); | |
529 | } | |
530 | } | |
531 | ||
532 | #else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ | |
533 | ||
534 | static void record_gp_stall_check_time(struct rcu_state *rsp) | |
535 | { | |
536 | } | |
537 | ||
538 | static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) | |
539 | { | |
540 | } | |
541 | ||
542 | #endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ | |
543 | ||
544 | /* | |
545 | * Update CPU-local rcu_data state to record the newly noticed grace period. | |
546 | * This is used both when we started the grace period and when we notice | |
9160306e PM |
547 | * that someone else started the grace period. The caller must hold the |
548 | * ->lock of the leaf rcu_node structure corresponding to the current CPU, | |
549 | * and must have irqs disabled. | |
64db4cff | 550 | */ |
9160306e PM |
551 | static void __note_new_gpnum(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
552 | { | |
553 | if (rdp->gpnum != rnp->gpnum) { | |
554 | rdp->qs_pending = 1; | |
555 | rdp->passed_quiesc = 0; | |
556 | rdp->gpnum = rnp->gpnum; | |
557 | } | |
558 | } | |
559 | ||
64db4cff PM |
560 | static void note_new_gpnum(struct rcu_state *rsp, struct rcu_data *rdp) |
561 | { | |
9160306e PM |
562 | unsigned long flags; |
563 | struct rcu_node *rnp; | |
564 | ||
565 | local_irq_save(flags); | |
566 | rnp = rdp->mynode; | |
567 | if (rdp->gpnum == ACCESS_ONCE(rnp->gpnum) || /* outside lock. */ | |
1304afb2 | 568 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
9160306e PM |
569 | local_irq_restore(flags); |
570 | return; | |
571 | } | |
572 | __note_new_gpnum(rsp, rnp, rdp); | |
1304afb2 | 573 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
574 | } |
575 | ||
576 | /* | |
577 | * Did someone else start a new RCU grace period start since we last | |
578 | * checked? Update local state appropriately if so. Must be called | |
579 | * on the CPU corresponding to rdp. | |
580 | */ | |
581 | static int | |
582 | check_for_new_grace_period(struct rcu_state *rsp, struct rcu_data *rdp) | |
583 | { | |
584 | unsigned long flags; | |
585 | int ret = 0; | |
586 | ||
587 | local_irq_save(flags); | |
588 | if (rdp->gpnum != rsp->gpnum) { | |
589 | note_new_gpnum(rsp, rdp); | |
590 | ret = 1; | |
591 | } | |
592 | local_irq_restore(flags); | |
593 | return ret; | |
594 | } | |
595 | ||
d09b62df PM |
596 | /* |
597 | * Advance this CPU's callbacks, but only if the current grace period | |
598 | * has ended. This may be called only from the CPU to whom the rdp | |
599 | * belongs. In addition, the corresponding leaf rcu_node structure's | |
600 | * ->lock must be held by the caller, with irqs disabled. | |
601 | */ | |
602 | static void | |
603 | __rcu_process_gp_end(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) | |
604 | { | |
605 | /* Did another grace period end? */ | |
606 | if (rdp->completed != rnp->completed) { | |
607 | ||
608 | /* Advance callbacks. No harm if list empty. */ | |
609 | rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL]; | |
610 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL]; | |
611 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; | |
612 | ||
613 | /* Remember that we saw this grace-period completion. */ | |
614 | rdp->completed = rnp->completed; | |
615 | } | |
616 | } | |
617 | ||
618 | /* | |
619 | * Advance this CPU's callbacks, but only if the current grace period | |
620 | * has ended. This may be called only from the CPU to whom the rdp | |
621 | * belongs. | |
622 | */ | |
623 | static void | |
624 | rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp) | |
625 | { | |
626 | unsigned long flags; | |
627 | struct rcu_node *rnp; | |
628 | ||
629 | local_irq_save(flags); | |
630 | rnp = rdp->mynode; | |
631 | if (rdp->completed == ACCESS_ONCE(rnp->completed) || /* outside lock. */ | |
1304afb2 | 632 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
d09b62df PM |
633 | local_irq_restore(flags); |
634 | return; | |
635 | } | |
636 | __rcu_process_gp_end(rsp, rnp, rdp); | |
1304afb2 | 637 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
d09b62df PM |
638 | } |
639 | ||
640 | /* | |
641 | * Do per-CPU grace-period initialization for running CPU. The caller | |
642 | * must hold the lock of the leaf rcu_node structure corresponding to | |
643 | * this CPU. | |
644 | */ | |
645 | static void | |
646 | rcu_start_gp_per_cpu(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) | |
647 | { | |
648 | /* Prior grace period ended, so advance callbacks for current CPU. */ | |
649 | __rcu_process_gp_end(rsp, rnp, rdp); | |
650 | ||
651 | /* | |
652 | * Because this CPU just now started the new grace period, we know | |
653 | * that all of its callbacks will be covered by this upcoming grace | |
654 | * period, even the ones that were registered arbitrarily recently. | |
655 | * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL. | |
656 | * | |
657 | * Other CPUs cannot be sure exactly when the grace period started. | |
658 | * Therefore, their recently registered callbacks must pass through | |
659 | * an additional RCU_NEXT_READY stage, so that they will be handled | |
660 | * by the next RCU grace period. | |
661 | */ | |
662 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; | |
663 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; | |
9160306e PM |
664 | |
665 | /* Set state so that this CPU will detect the next quiescent state. */ | |
666 | __note_new_gpnum(rsp, rnp, rdp); | |
d09b62df PM |
667 | } |
668 | ||
64db4cff PM |
669 | /* |
670 | * Start a new RCU grace period if warranted, re-initializing the hierarchy | |
671 | * in preparation for detecting the next grace period. The caller must hold | |
672 | * the root node's ->lock, which is released before return. Hard irqs must | |
673 | * be disabled. | |
674 | */ | |
675 | static void | |
676 | rcu_start_gp(struct rcu_state *rsp, unsigned long flags) | |
677 | __releases(rcu_get_root(rsp)->lock) | |
678 | { | |
679 | struct rcu_data *rdp = rsp->rda[smp_processor_id()]; | |
680 | struct rcu_node *rnp = rcu_get_root(rsp); | |
64db4cff | 681 | |
07079d53 | 682 | if (!cpu_needs_another_gp(rsp, rdp) || rsp->fqs_active) { |
46a1e34e PM |
683 | if (cpu_needs_another_gp(rsp, rdp)) |
684 | rsp->fqs_need_gp = 1; | |
b32e9eb6 | 685 | if (rnp->completed == rsp->completed) { |
1304afb2 | 686 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
b32e9eb6 PM |
687 | return; |
688 | } | |
1304afb2 | 689 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
b32e9eb6 PM |
690 | |
691 | /* | |
692 | * Propagate new ->completed value to rcu_node structures | |
693 | * so that other CPUs don't have to wait until the start | |
694 | * of the next grace period to process their callbacks. | |
695 | */ | |
696 | rcu_for_each_node_breadth_first(rsp, rnp) { | |
1304afb2 | 697 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
b32e9eb6 | 698 | rnp->completed = rsp->completed; |
1304afb2 | 699 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
b32e9eb6 PM |
700 | } |
701 | local_irq_restore(flags); | |
64db4cff PM |
702 | return; |
703 | } | |
704 | ||
705 | /* Advance to a new grace period and initialize state. */ | |
706 | rsp->gpnum++; | |
c3422bea | 707 | WARN_ON_ONCE(rsp->signaled == RCU_GP_INIT); |
64db4cff PM |
708 | rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */ |
709 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; | |
64db4cff | 710 | record_gp_stall_check_time(rsp); |
64db4cff | 711 | |
64db4cff PM |
712 | /* Special-case the common single-level case. */ |
713 | if (NUM_RCU_NODES == 1) { | |
b0e165c0 | 714 | rcu_preempt_check_blocked_tasks(rnp); |
28ecd580 | 715 | rnp->qsmask = rnp->qsmaskinit; |
de078d87 | 716 | rnp->gpnum = rsp->gpnum; |
d09b62df | 717 | rnp->completed = rsp->completed; |
c12172c0 | 718 | rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state OK. */ |
d09b62df | 719 | rcu_start_gp_per_cpu(rsp, rnp, rdp); |
1304afb2 | 720 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
721 | return; |
722 | } | |
723 | ||
1304afb2 | 724 | raw_spin_unlock(&rnp->lock); /* leave irqs disabled. */ |
64db4cff PM |
725 | |
726 | ||
727 | /* Exclude any concurrent CPU-hotplug operations. */ | |
1304afb2 | 728 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
64db4cff PM |
729 | |
730 | /* | |
b835db1f PM |
731 | * Set the quiescent-state-needed bits in all the rcu_node |
732 | * structures for all currently online CPUs in breadth-first | |
733 | * order, starting from the root rcu_node structure. This | |
734 | * operation relies on the layout of the hierarchy within the | |
735 | * rsp->node[] array. Note that other CPUs will access only | |
736 | * the leaves of the hierarchy, which still indicate that no | |
737 | * grace period is in progress, at least until the corresponding | |
738 | * leaf node has been initialized. In addition, we have excluded | |
739 | * CPU-hotplug operations. | |
64db4cff PM |
740 | * |
741 | * Note that the grace period cannot complete until we finish | |
742 | * the initialization process, as there will be at least one | |
743 | * qsmask bit set in the root node until that time, namely the | |
b835db1f PM |
744 | * one corresponding to this CPU, due to the fact that we have |
745 | * irqs disabled. | |
64db4cff | 746 | */ |
a0b6c9a7 | 747 | rcu_for_each_node_breadth_first(rsp, rnp) { |
1304afb2 | 748 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
b0e165c0 | 749 | rcu_preempt_check_blocked_tasks(rnp); |
49e29126 | 750 | rnp->qsmask = rnp->qsmaskinit; |
de078d87 | 751 | rnp->gpnum = rsp->gpnum; |
d09b62df PM |
752 | rnp->completed = rsp->completed; |
753 | if (rnp == rdp->mynode) | |
754 | rcu_start_gp_per_cpu(rsp, rnp, rdp); | |
1304afb2 | 755 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
64db4cff PM |
756 | } |
757 | ||
83f5b01f | 758 | rnp = rcu_get_root(rsp); |
1304afb2 | 759 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
64db4cff | 760 | rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state now OK. */ |
1304afb2 PM |
761 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
762 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); | |
64db4cff PM |
763 | } |
764 | ||
f41d911f | 765 | /* |
d3f6bad3 PM |
766 | * Report a full set of quiescent states to the specified rcu_state |
767 | * data structure. This involves cleaning up after the prior grace | |
768 | * period and letting rcu_start_gp() start up the next grace period | |
769 | * if one is needed. Note that the caller must hold rnp->lock, as | |
770 | * required by rcu_start_gp(), which will release it. | |
f41d911f | 771 | */ |
d3f6bad3 | 772 | static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags) |
fc2219d4 | 773 | __releases(rcu_get_root(rsp)->lock) |
f41d911f | 774 | { |
fc2219d4 | 775 | WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); |
f41d911f | 776 | rsp->completed = rsp->gpnum; |
83f5b01f | 777 | rsp->signaled = RCU_GP_IDLE; |
f41d911f PM |
778 | rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */ |
779 | } | |
780 | ||
64db4cff | 781 | /* |
d3f6bad3 PM |
782 | * Similar to rcu_report_qs_rdp(), for which it is a helper function. |
783 | * Allows quiescent states for a group of CPUs to be reported at one go | |
784 | * to the specified rcu_node structure, though all the CPUs in the group | |
785 | * must be represented by the same rcu_node structure (which need not be | |
786 | * a leaf rcu_node structure, though it often will be). That structure's | |
787 | * lock must be held upon entry, and it is released before return. | |
64db4cff PM |
788 | */ |
789 | static void | |
d3f6bad3 PM |
790 | rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp, |
791 | struct rcu_node *rnp, unsigned long flags) | |
64db4cff PM |
792 | __releases(rnp->lock) |
793 | { | |
28ecd580 PM |
794 | struct rcu_node *rnp_c; |
795 | ||
64db4cff PM |
796 | /* Walk up the rcu_node hierarchy. */ |
797 | for (;;) { | |
798 | if (!(rnp->qsmask & mask)) { | |
799 | ||
800 | /* Our bit has already been cleared, so done. */ | |
1304afb2 | 801 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
802 | return; |
803 | } | |
804 | rnp->qsmask &= ~mask; | |
f41d911f | 805 | if (rnp->qsmask != 0 || rcu_preempted_readers(rnp)) { |
64db4cff PM |
806 | |
807 | /* Other bits still set at this level, so done. */ | |
1304afb2 | 808 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
809 | return; |
810 | } | |
811 | mask = rnp->grpmask; | |
812 | if (rnp->parent == NULL) { | |
813 | ||
814 | /* No more levels. Exit loop holding root lock. */ | |
815 | ||
816 | break; | |
817 | } | |
1304afb2 | 818 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
28ecd580 | 819 | rnp_c = rnp; |
64db4cff | 820 | rnp = rnp->parent; |
1304afb2 | 821 | raw_spin_lock_irqsave(&rnp->lock, flags); |
28ecd580 | 822 | WARN_ON_ONCE(rnp_c->qsmask); |
64db4cff PM |
823 | } |
824 | ||
825 | /* | |
826 | * Get here if we are the last CPU to pass through a quiescent | |
d3f6bad3 | 827 | * state for this grace period. Invoke rcu_report_qs_rsp() |
f41d911f | 828 | * to clean up and start the next grace period if one is needed. |
64db4cff | 829 | */ |
d3f6bad3 | 830 | rcu_report_qs_rsp(rsp, flags); /* releases rnp->lock. */ |
64db4cff PM |
831 | } |
832 | ||
833 | /* | |
d3f6bad3 PM |
834 | * Record a quiescent state for the specified CPU to that CPU's rcu_data |
835 | * structure. This must be either called from the specified CPU, or | |
836 | * called when the specified CPU is known to be offline (and when it is | |
837 | * also known that no other CPU is concurrently trying to help the offline | |
838 | * CPU). The lastcomp argument is used to make sure we are still in the | |
839 | * grace period of interest. We don't want to end the current grace period | |
840 | * based on quiescent states detected in an earlier grace period! | |
64db4cff PM |
841 | */ |
842 | static void | |
d3f6bad3 | 843 | rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp) |
64db4cff PM |
844 | { |
845 | unsigned long flags; | |
846 | unsigned long mask; | |
847 | struct rcu_node *rnp; | |
848 | ||
849 | rnp = rdp->mynode; | |
1304afb2 | 850 | raw_spin_lock_irqsave(&rnp->lock, flags); |
560d4bc0 | 851 | if (lastcomp != rnp->completed) { |
64db4cff PM |
852 | |
853 | /* | |
854 | * Someone beat us to it for this grace period, so leave. | |
855 | * The race with GP start is resolved by the fact that we | |
856 | * hold the leaf rcu_node lock, so that the per-CPU bits | |
857 | * cannot yet be initialized -- so we would simply find our | |
d3f6bad3 PM |
858 | * CPU's bit already cleared in rcu_report_qs_rnp() if this |
859 | * race occurred. | |
64db4cff PM |
860 | */ |
861 | rdp->passed_quiesc = 0; /* try again later! */ | |
1304afb2 | 862 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
863 | return; |
864 | } | |
865 | mask = rdp->grpmask; | |
866 | if ((rnp->qsmask & mask) == 0) { | |
1304afb2 | 867 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
868 | } else { |
869 | rdp->qs_pending = 0; | |
870 | ||
871 | /* | |
872 | * This GP can't end until cpu checks in, so all of our | |
873 | * callbacks can be processed during the next GP. | |
874 | */ | |
64db4cff PM |
875 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
876 | ||
d3f6bad3 | 877 | rcu_report_qs_rnp(mask, rsp, rnp, flags); /* rlses rnp->lock */ |
64db4cff PM |
878 | } |
879 | } | |
880 | ||
881 | /* | |
882 | * Check to see if there is a new grace period of which this CPU | |
883 | * is not yet aware, and if so, set up local rcu_data state for it. | |
884 | * Otherwise, see if this CPU has just passed through its first | |
885 | * quiescent state for this grace period, and record that fact if so. | |
886 | */ | |
887 | static void | |
888 | rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp) | |
889 | { | |
890 | /* If there is now a new grace period, record and return. */ | |
891 | if (check_for_new_grace_period(rsp, rdp)) | |
892 | return; | |
893 | ||
894 | /* | |
895 | * Does this CPU still need to do its part for current grace period? | |
896 | * If no, return and let the other CPUs do their part as well. | |
897 | */ | |
898 | if (!rdp->qs_pending) | |
899 | return; | |
900 | ||
901 | /* | |
902 | * Was there a quiescent state since the beginning of the grace | |
903 | * period? If no, then exit and wait for the next call. | |
904 | */ | |
905 | if (!rdp->passed_quiesc) | |
906 | return; | |
907 | ||
d3f6bad3 PM |
908 | /* |
909 | * Tell RCU we are done (but rcu_report_qs_rdp() will be the | |
910 | * judge of that). | |
911 | */ | |
912 | rcu_report_qs_rdp(rdp->cpu, rsp, rdp, rdp->passed_quiesc_completed); | |
64db4cff PM |
913 | } |
914 | ||
915 | #ifdef CONFIG_HOTPLUG_CPU | |
916 | ||
e74f4c45 PM |
917 | /* |
918 | * Move a dying CPU's RCU callbacks to the ->orphan_cbs_list for the | |
919 | * specified flavor of RCU. The callbacks will be adopted by the next | |
920 | * _rcu_barrier() invocation or by the CPU_DEAD notifier, whichever | |
921 | * comes first. Because this is invoked from the CPU_DYING notifier, | |
922 | * irqs are already disabled. | |
923 | */ | |
924 | static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp) | |
925 | { | |
926 | int i; | |
927 | struct rcu_data *rdp = rsp->rda[smp_processor_id()]; | |
928 | ||
929 | if (rdp->nxtlist == NULL) | |
930 | return; /* irqs disabled, so comparison is stable. */ | |
1304afb2 | 931 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
e74f4c45 PM |
932 | *rsp->orphan_cbs_tail = rdp->nxtlist; |
933 | rsp->orphan_cbs_tail = rdp->nxttail[RCU_NEXT_TAIL]; | |
934 | rdp->nxtlist = NULL; | |
935 | for (i = 0; i < RCU_NEXT_SIZE; i++) | |
936 | rdp->nxttail[i] = &rdp->nxtlist; | |
937 | rsp->orphan_qlen += rdp->qlen; | |
938 | rdp->qlen = 0; | |
1304afb2 | 939 | raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ |
e74f4c45 PM |
940 | } |
941 | ||
942 | /* | |
943 | * Adopt previously orphaned RCU callbacks. | |
944 | */ | |
945 | static void rcu_adopt_orphan_cbs(struct rcu_state *rsp) | |
946 | { | |
947 | unsigned long flags; | |
948 | struct rcu_data *rdp; | |
949 | ||
1304afb2 | 950 | raw_spin_lock_irqsave(&rsp->onofflock, flags); |
e74f4c45 PM |
951 | rdp = rsp->rda[smp_processor_id()]; |
952 | if (rsp->orphan_cbs_list == NULL) { | |
1304afb2 | 953 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
e74f4c45 PM |
954 | return; |
955 | } | |
956 | *rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_cbs_list; | |
957 | rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_cbs_tail; | |
958 | rdp->qlen += rsp->orphan_qlen; | |
959 | rsp->orphan_cbs_list = NULL; | |
960 | rsp->orphan_cbs_tail = &rsp->orphan_cbs_list; | |
961 | rsp->orphan_qlen = 0; | |
1304afb2 | 962 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
e74f4c45 PM |
963 | } |
964 | ||
64db4cff PM |
965 | /* |
966 | * Remove the outgoing CPU from the bitmasks in the rcu_node hierarchy | |
967 | * and move all callbacks from the outgoing CPU to the current one. | |
968 | */ | |
969 | static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) | |
970 | { | |
64db4cff | 971 | unsigned long flags; |
64db4cff | 972 | unsigned long mask; |
d9a3da06 | 973 | int need_report = 0; |
64db4cff | 974 | struct rcu_data *rdp = rsp->rda[cpu]; |
64db4cff PM |
975 | struct rcu_node *rnp; |
976 | ||
977 | /* Exclude any attempts to start a new grace period. */ | |
1304afb2 | 978 | raw_spin_lock_irqsave(&rsp->onofflock, flags); |
64db4cff PM |
979 | |
980 | /* Remove the outgoing CPU from the masks in the rcu_node hierarchy. */ | |
28ecd580 | 981 | rnp = rdp->mynode; /* this is the outgoing CPU's rnp. */ |
64db4cff PM |
982 | mask = rdp->grpmask; /* rnp->grplo is constant. */ |
983 | do { | |
1304afb2 | 984 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
64db4cff PM |
985 | rnp->qsmaskinit &= ~mask; |
986 | if (rnp->qsmaskinit != 0) { | |
b668c9cf | 987 | if (rnp != rdp->mynode) |
1304afb2 | 988 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
64db4cff PM |
989 | break; |
990 | } | |
b668c9cf | 991 | if (rnp == rdp->mynode) |
d9a3da06 | 992 | need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp); |
b668c9cf | 993 | else |
1304afb2 | 994 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
64db4cff | 995 | mask = rnp->grpmask; |
64db4cff PM |
996 | rnp = rnp->parent; |
997 | } while (rnp != NULL); | |
64db4cff | 998 | |
b668c9cf PM |
999 | /* |
1000 | * We still hold the leaf rcu_node structure lock here, and | |
1001 | * irqs are still disabled. The reason for this subterfuge is | |
d3f6bad3 PM |
1002 | * because invoking rcu_report_unblock_qs_rnp() with ->onofflock |
1003 | * held leads to deadlock. | |
b668c9cf | 1004 | */ |
1304afb2 | 1005 | raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ |
b668c9cf | 1006 | rnp = rdp->mynode; |
d9a3da06 | 1007 | if (need_report & RCU_OFL_TASKS_NORM_GP) |
d3f6bad3 | 1008 | rcu_report_unblock_qs_rnp(rnp, flags); |
b668c9cf | 1009 | else |
1304afb2 | 1010 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
d9a3da06 PM |
1011 | if (need_report & RCU_OFL_TASKS_EXP_GP) |
1012 | rcu_report_exp_rnp(rsp, rnp); | |
64db4cff | 1013 | |
e74f4c45 | 1014 | rcu_adopt_orphan_cbs(rsp); |
64db4cff PM |
1015 | } |
1016 | ||
1017 | /* | |
1018 | * Remove the specified CPU from the RCU hierarchy and move any pending | |
1019 | * callbacks that it might have to the current CPU. This code assumes | |
1020 | * that at least one CPU in the system will remain running at all times. | |
1021 | * Any attempt to offline -all- CPUs is likely to strand RCU callbacks. | |
1022 | */ | |
1023 | static void rcu_offline_cpu(int cpu) | |
1024 | { | |
d6714c22 | 1025 | __rcu_offline_cpu(cpu, &rcu_sched_state); |
64db4cff | 1026 | __rcu_offline_cpu(cpu, &rcu_bh_state); |
33f76148 | 1027 | rcu_preempt_offline_cpu(cpu); |
64db4cff PM |
1028 | } |
1029 | ||
1030 | #else /* #ifdef CONFIG_HOTPLUG_CPU */ | |
1031 | ||
e74f4c45 PM |
1032 | static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp) |
1033 | { | |
1034 | } | |
1035 | ||
1036 | static void rcu_adopt_orphan_cbs(struct rcu_state *rsp) | |
1037 | { | |
1038 | } | |
1039 | ||
64db4cff PM |
1040 | static void rcu_offline_cpu(int cpu) |
1041 | { | |
1042 | } | |
1043 | ||
1044 | #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */ | |
1045 | ||
1046 | /* | |
1047 | * Invoke any RCU callbacks that have made it to the end of their grace | |
1048 | * period. Thottle as specified by rdp->blimit. | |
1049 | */ | |
37c72e56 | 1050 | static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp) |
64db4cff PM |
1051 | { |
1052 | unsigned long flags; | |
1053 | struct rcu_head *next, *list, **tail; | |
1054 | int count; | |
1055 | ||
1056 | /* If no callbacks are ready, just return.*/ | |
1057 | if (!cpu_has_callbacks_ready_to_invoke(rdp)) | |
1058 | return; | |
1059 | ||
1060 | /* | |
1061 | * Extract the list of ready callbacks, disabling to prevent | |
1062 | * races with call_rcu() from interrupt handlers. | |
1063 | */ | |
1064 | local_irq_save(flags); | |
1065 | list = rdp->nxtlist; | |
1066 | rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL]; | |
1067 | *rdp->nxttail[RCU_DONE_TAIL] = NULL; | |
1068 | tail = rdp->nxttail[RCU_DONE_TAIL]; | |
1069 | for (count = RCU_NEXT_SIZE - 1; count >= 0; count--) | |
1070 | if (rdp->nxttail[count] == rdp->nxttail[RCU_DONE_TAIL]) | |
1071 | rdp->nxttail[count] = &rdp->nxtlist; | |
1072 | local_irq_restore(flags); | |
1073 | ||
1074 | /* Invoke callbacks. */ | |
1075 | count = 0; | |
1076 | while (list) { | |
1077 | next = list->next; | |
1078 | prefetch(next); | |
1079 | list->func(list); | |
1080 | list = next; | |
1081 | if (++count >= rdp->blimit) | |
1082 | break; | |
1083 | } | |
1084 | ||
1085 | local_irq_save(flags); | |
1086 | ||
1087 | /* Update count, and requeue any remaining callbacks. */ | |
1088 | rdp->qlen -= count; | |
1089 | if (list != NULL) { | |
1090 | *tail = rdp->nxtlist; | |
1091 | rdp->nxtlist = list; | |
1092 | for (count = 0; count < RCU_NEXT_SIZE; count++) | |
1093 | if (&rdp->nxtlist == rdp->nxttail[count]) | |
1094 | rdp->nxttail[count] = tail; | |
1095 | else | |
1096 | break; | |
1097 | } | |
1098 | ||
1099 | /* Reinstate batch limit if we have worked down the excess. */ | |
1100 | if (rdp->blimit == LONG_MAX && rdp->qlen <= qlowmark) | |
1101 | rdp->blimit = blimit; | |
1102 | ||
37c72e56 PM |
1103 | /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */ |
1104 | if (rdp->qlen == 0 && rdp->qlen_last_fqs_check != 0) { | |
1105 | rdp->qlen_last_fqs_check = 0; | |
1106 | rdp->n_force_qs_snap = rsp->n_force_qs; | |
1107 | } else if (rdp->qlen < rdp->qlen_last_fqs_check - qhimark) | |
1108 | rdp->qlen_last_fqs_check = rdp->qlen; | |
1109 | ||
64db4cff PM |
1110 | local_irq_restore(flags); |
1111 | ||
1112 | /* Re-raise the RCU softirq if there are callbacks remaining. */ | |
1113 | if (cpu_has_callbacks_ready_to_invoke(rdp)) | |
1114 | raise_softirq(RCU_SOFTIRQ); | |
1115 | } | |
1116 | ||
1117 | /* | |
1118 | * Check to see if this CPU is in a non-context-switch quiescent state | |
1119 | * (user mode or idle loop for rcu, non-softirq execution for rcu_bh). | |
1120 | * Also schedule the RCU softirq handler. | |
1121 | * | |
1122 | * This function must be called with hardirqs disabled. It is normally | |
1123 | * invoked from the scheduling-clock interrupt. If rcu_pending returns | |
1124 | * false, there is no point in invoking rcu_check_callbacks(). | |
1125 | */ | |
1126 | void rcu_check_callbacks(int cpu, int user) | |
1127 | { | |
a157229c PM |
1128 | if (!rcu_pending(cpu)) |
1129 | return; /* if nothing for RCU to do. */ | |
64db4cff | 1130 | if (user || |
a6826048 PM |
1131 | (idle_cpu(cpu) && rcu_scheduler_active && |
1132 | !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) { | |
64db4cff PM |
1133 | |
1134 | /* | |
1135 | * Get here if this CPU took its interrupt from user | |
1136 | * mode or from the idle loop, and if this is not a | |
1137 | * nested interrupt. In this case, the CPU is in | |
d6714c22 | 1138 | * a quiescent state, so note it. |
64db4cff PM |
1139 | * |
1140 | * No memory barrier is required here because both | |
d6714c22 PM |
1141 | * rcu_sched_qs() and rcu_bh_qs() reference only CPU-local |
1142 | * variables that other CPUs neither access nor modify, | |
1143 | * at least not while the corresponding CPU is online. | |
64db4cff PM |
1144 | */ |
1145 | ||
d6714c22 PM |
1146 | rcu_sched_qs(cpu); |
1147 | rcu_bh_qs(cpu); | |
64db4cff PM |
1148 | |
1149 | } else if (!in_softirq()) { | |
1150 | ||
1151 | /* | |
1152 | * Get here if this CPU did not take its interrupt from | |
1153 | * softirq, in other words, if it is not interrupting | |
1154 | * a rcu_bh read-side critical section. This is an _bh | |
d6714c22 | 1155 | * critical section, so note it. |
64db4cff PM |
1156 | */ |
1157 | ||
d6714c22 | 1158 | rcu_bh_qs(cpu); |
64db4cff | 1159 | } |
f41d911f | 1160 | rcu_preempt_check_callbacks(cpu); |
64db4cff PM |
1161 | raise_softirq(RCU_SOFTIRQ); |
1162 | } | |
1163 | ||
1164 | #ifdef CONFIG_SMP | |
1165 | ||
1166 | /* | |
1167 | * Scan the leaf rcu_node structures, processing dyntick state for any that | |
1168 | * have not yet encountered a quiescent state, using the function specified. | |
ee47eb9f | 1169 | * The caller must have suppressed start of new grace periods. |
64db4cff | 1170 | */ |
45f014c5 | 1171 | static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *)) |
64db4cff PM |
1172 | { |
1173 | unsigned long bit; | |
1174 | int cpu; | |
1175 | unsigned long flags; | |
1176 | unsigned long mask; | |
a0b6c9a7 | 1177 | struct rcu_node *rnp; |
64db4cff | 1178 | |
a0b6c9a7 | 1179 | rcu_for_each_leaf_node(rsp, rnp) { |
64db4cff | 1180 | mask = 0; |
1304afb2 | 1181 | raw_spin_lock_irqsave(&rnp->lock, flags); |
ee47eb9f | 1182 | if (!rcu_gp_in_progress(rsp)) { |
1304afb2 | 1183 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
0f10dc82 | 1184 | return; |
64db4cff | 1185 | } |
a0b6c9a7 | 1186 | if (rnp->qsmask == 0) { |
1304afb2 | 1187 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
1188 | continue; |
1189 | } | |
a0b6c9a7 | 1190 | cpu = rnp->grplo; |
64db4cff | 1191 | bit = 1; |
a0b6c9a7 PM |
1192 | for (; cpu <= rnp->grphi; cpu++, bit <<= 1) { |
1193 | if ((rnp->qsmask & bit) != 0 && f(rsp->rda[cpu])) | |
64db4cff PM |
1194 | mask |= bit; |
1195 | } | |
45f014c5 | 1196 | if (mask != 0) { |
64db4cff | 1197 | |
d3f6bad3 PM |
1198 | /* rcu_report_qs_rnp() releases rnp->lock. */ |
1199 | rcu_report_qs_rnp(mask, rsp, rnp, flags); | |
64db4cff PM |
1200 | continue; |
1201 | } | |
1304afb2 | 1202 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff | 1203 | } |
64db4cff PM |
1204 | } |
1205 | ||
1206 | /* | |
1207 | * Force quiescent states on reluctant CPUs, and also detect which | |
1208 | * CPUs are in dyntick-idle mode. | |
1209 | */ | |
1210 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) | |
1211 | { | |
1212 | unsigned long flags; | |
64db4cff | 1213 | struct rcu_node *rnp = rcu_get_root(rsp); |
64db4cff | 1214 | |
fc2219d4 | 1215 | if (!rcu_gp_in_progress(rsp)) |
64db4cff | 1216 | return; /* No grace period in progress, nothing to force. */ |
1304afb2 | 1217 | if (!raw_spin_trylock_irqsave(&rsp->fqslock, flags)) { |
64db4cff PM |
1218 | rsp->n_force_qs_lh++; /* Inexact, can lose counts. Tough! */ |
1219 | return; /* Someone else is already on the job. */ | |
1220 | } | |
20133cfc | 1221 | if (relaxed && ULONG_CMP_GE(rsp->jiffies_force_qs, jiffies)) |
f96e9232 | 1222 | goto unlock_fqs_ret; /* no emergency and done recently. */ |
64db4cff | 1223 | rsp->n_force_qs++; |
1304afb2 | 1224 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
64db4cff | 1225 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
560d4bc0 | 1226 | if(!rcu_gp_in_progress(rsp)) { |
64db4cff | 1227 | rsp->n_force_qs_ngp++; |
1304afb2 | 1228 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
f96e9232 | 1229 | goto unlock_fqs_ret; /* no GP in progress, time updated. */ |
64db4cff | 1230 | } |
07079d53 | 1231 | rsp->fqs_active = 1; |
f3a8b5c6 | 1232 | switch (rsp->signaled) { |
83f5b01f | 1233 | case RCU_GP_IDLE: |
64db4cff PM |
1234 | case RCU_GP_INIT: |
1235 | ||
83f5b01f | 1236 | break; /* grace period idle or initializing, ignore. */ |
64db4cff PM |
1237 | |
1238 | case RCU_SAVE_DYNTICK: | |
1239 | ||
1304afb2 | 1240 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
64db4cff PM |
1241 | if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK) |
1242 | break; /* So gcc recognizes the dead code. */ | |
1243 | ||
1244 | /* Record dyntick-idle state. */ | |
45f014c5 | 1245 | force_qs_rnp(rsp, dyntick_save_progress_counter); |
1304afb2 | 1246 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
ee47eb9f | 1247 | if (rcu_gp_in_progress(rsp)) |
64db4cff | 1248 | rsp->signaled = RCU_FORCE_QS; |
ee47eb9f | 1249 | break; |
64db4cff PM |
1250 | |
1251 | case RCU_FORCE_QS: | |
1252 | ||
1253 | /* Check dyntick-idle state, send IPI to laggarts. */ | |
1304afb2 | 1254 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
45f014c5 | 1255 | force_qs_rnp(rsp, rcu_implicit_dynticks_qs); |
64db4cff PM |
1256 | |
1257 | /* Leave state in case more forcing is required. */ | |
1258 | ||
1304afb2 | 1259 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
f96e9232 | 1260 | break; |
64db4cff | 1261 | } |
07079d53 | 1262 | rsp->fqs_active = 0; |
46a1e34e | 1263 | if (rsp->fqs_need_gp) { |
1304afb2 | 1264 | raw_spin_unlock(&rsp->fqslock); /* irqs remain disabled */ |
46a1e34e PM |
1265 | rsp->fqs_need_gp = 0; |
1266 | rcu_start_gp(rsp, flags); /* releases rnp->lock */ | |
1267 | return; | |
1268 | } | |
1304afb2 | 1269 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
f96e9232 | 1270 | unlock_fqs_ret: |
1304afb2 | 1271 | raw_spin_unlock_irqrestore(&rsp->fqslock, flags); |
64db4cff PM |
1272 | } |
1273 | ||
1274 | #else /* #ifdef CONFIG_SMP */ | |
1275 | ||
1276 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) | |
1277 | { | |
1278 | set_need_resched(); | |
1279 | } | |
1280 | ||
1281 | #endif /* #else #ifdef CONFIG_SMP */ | |
1282 | ||
1283 | /* | |
1284 | * This does the RCU processing work from softirq context for the | |
1285 | * specified rcu_state and rcu_data structures. This may be called | |
1286 | * only from the CPU to whom the rdp belongs. | |
1287 | */ | |
1288 | static void | |
1289 | __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) | |
1290 | { | |
1291 | unsigned long flags; | |
1292 | ||
2e597558 PM |
1293 | WARN_ON_ONCE(rdp->beenonline == 0); |
1294 | ||
64db4cff PM |
1295 | /* |
1296 | * If an RCU GP has gone long enough, go check for dyntick | |
1297 | * idle CPUs and, if needed, send resched IPIs. | |
1298 | */ | |
20133cfc | 1299 | if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) |
64db4cff PM |
1300 | force_quiescent_state(rsp, 1); |
1301 | ||
1302 | /* | |
1303 | * Advance callbacks in response to end of earlier grace | |
1304 | * period that some other CPU ended. | |
1305 | */ | |
1306 | rcu_process_gp_end(rsp, rdp); | |
1307 | ||
1308 | /* Update RCU state based on any recent quiescent states. */ | |
1309 | rcu_check_quiescent_state(rsp, rdp); | |
1310 | ||
1311 | /* Does this CPU require a not-yet-started grace period? */ | |
1312 | if (cpu_needs_another_gp(rsp, rdp)) { | |
1304afb2 | 1313 | raw_spin_lock_irqsave(&rcu_get_root(rsp)->lock, flags); |
64db4cff PM |
1314 | rcu_start_gp(rsp, flags); /* releases above lock */ |
1315 | } | |
1316 | ||
1317 | /* If there are callbacks ready, invoke them. */ | |
37c72e56 | 1318 | rcu_do_batch(rsp, rdp); |
64db4cff PM |
1319 | } |
1320 | ||
1321 | /* | |
1322 | * Do softirq processing for the current CPU. | |
1323 | */ | |
1324 | static void rcu_process_callbacks(struct softirq_action *unused) | |
1325 | { | |
1326 | /* | |
1327 | * Memory references from any prior RCU read-side critical sections | |
1328 | * executed by the interrupted code must be seen before any RCU | |
1329 | * grace-period manipulations below. | |
1330 | */ | |
1331 | smp_mb(); /* See above block comment. */ | |
1332 | ||
d6714c22 PM |
1333 | __rcu_process_callbacks(&rcu_sched_state, |
1334 | &__get_cpu_var(rcu_sched_data)); | |
64db4cff | 1335 | __rcu_process_callbacks(&rcu_bh_state, &__get_cpu_var(rcu_bh_data)); |
f41d911f | 1336 | rcu_preempt_process_callbacks(); |
64db4cff PM |
1337 | |
1338 | /* | |
1339 | * Memory references from any later RCU read-side critical sections | |
1340 | * executed by the interrupted code must be seen after any RCU | |
1341 | * grace-period manipulations above. | |
1342 | */ | |
1343 | smp_mb(); /* See above block comment. */ | |
a47cd880 PM |
1344 | |
1345 | /* If we are last CPU on way to dyntick-idle mode, accelerate it. */ | |
1346 | rcu_needs_cpu_flush(); | |
64db4cff PM |
1347 | } |
1348 | ||
1349 | static void | |
1350 | __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), | |
1351 | struct rcu_state *rsp) | |
1352 | { | |
1353 | unsigned long flags; | |
1354 | struct rcu_data *rdp; | |
1355 | ||
1356 | head->func = func; | |
1357 | head->next = NULL; | |
1358 | ||
1359 | smp_mb(); /* Ensure RCU update seen before callback registry. */ | |
1360 | ||
1361 | /* | |
1362 | * Opportunistically note grace-period endings and beginnings. | |
1363 | * Note that we might see a beginning right after we see an | |
1364 | * end, but never vice versa, since this CPU has to pass through | |
1365 | * a quiescent state betweentimes. | |
1366 | */ | |
1367 | local_irq_save(flags); | |
1368 | rdp = rsp->rda[smp_processor_id()]; | |
1369 | rcu_process_gp_end(rsp, rdp); | |
1370 | check_for_new_grace_period(rsp, rdp); | |
1371 | ||
1372 | /* Add the callback to our list. */ | |
1373 | *rdp->nxttail[RCU_NEXT_TAIL] = head; | |
1374 | rdp->nxttail[RCU_NEXT_TAIL] = &head->next; | |
1375 | ||
1376 | /* Start a new grace period if one not already started. */ | |
fc2219d4 | 1377 | if (!rcu_gp_in_progress(rsp)) { |
64db4cff PM |
1378 | unsigned long nestflag; |
1379 | struct rcu_node *rnp_root = rcu_get_root(rsp); | |
1380 | ||
1304afb2 | 1381 | raw_spin_lock_irqsave(&rnp_root->lock, nestflag); |
64db4cff PM |
1382 | rcu_start_gp(rsp, nestflag); /* releases rnp_root->lock. */ |
1383 | } | |
1384 | ||
37c72e56 PM |
1385 | /* |
1386 | * Force the grace period if too many callbacks or too long waiting. | |
1387 | * Enforce hysteresis, and don't invoke force_quiescent_state() | |
1388 | * if some other CPU has recently done so. Also, don't bother | |
1389 | * invoking force_quiescent_state() if the newly enqueued callback | |
1390 | * is the only one waiting for a grace period to complete. | |
1391 | */ | |
1392 | if (unlikely(++rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) { | |
64db4cff | 1393 | rdp->blimit = LONG_MAX; |
37c72e56 PM |
1394 | if (rsp->n_force_qs == rdp->n_force_qs_snap && |
1395 | *rdp->nxttail[RCU_DONE_TAIL] != head) | |
1396 | force_quiescent_state(rsp, 0); | |
1397 | rdp->n_force_qs_snap = rsp->n_force_qs; | |
1398 | rdp->qlen_last_fqs_check = rdp->qlen; | |
20133cfc | 1399 | } else if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) |
64db4cff PM |
1400 | force_quiescent_state(rsp, 1); |
1401 | local_irq_restore(flags); | |
1402 | } | |
1403 | ||
1404 | /* | |
d6714c22 | 1405 | * Queue an RCU-sched callback for invocation after a grace period. |
64db4cff | 1406 | */ |
d6714c22 | 1407 | void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) |
64db4cff | 1408 | { |
d6714c22 | 1409 | __call_rcu(head, func, &rcu_sched_state); |
64db4cff | 1410 | } |
d6714c22 | 1411 | EXPORT_SYMBOL_GPL(call_rcu_sched); |
64db4cff PM |
1412 | |
1413 | /* | |
1414 | * Queue an RCU for invocation after a quicker grace period. | |
1415 | */ | |
1416 | void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) | |
1417 | { | |
1418 | __call_rcu(head, func, &rcu_bh_state); | |
1419 | } | |
1420 | EXPORT_SYMBOL_GPL(call_rcu_bh); | |
1421 | ||
6ebb237b PM |
1422 | /** |
1423 | * synchronize_sched - wait until an rcu-sched grace period has elapsed. | |
1424 | * | |
1425 | * Control will return to the caller some time after a full rcu-sched | |
1426 | * grace period has elapsed, in other words after all currently executing | |
1427 | * rcu-sched read-side critical sections have completed. These read-side | |
1428 | * critical sections are delimited by rcu_read_lock_sched() and | |
1429 | * rcu_read_unlock_sched(), and may be nested. Note that preempt_disable(), | |
1430 | * local_irq_disable(), and so on may be used in place of | |
1431 | * rcu_read_lock_sched(). | |
1432 | * | |
1433 | * This means that all preempt_disable code sequences, including NMI and | |
1434 | * hardware-interrupt handlers, in progress on entry will have completed | |
1435 | * before this primitive returns. However, this does not guarantee that | |
1436 | * softirq handlers will have completed, since in some kernels, these | |
1437 | * handlers can run in process context, and can block. | |
1438 | * | |
1439 | * This primitive provides the guarantees made by the (now removed) | |
1440 | * synchronize_kernel() API. In contrast, synchronize_rcu() only | |
1441 | * guarantees that rcu_read_lock() sections will have completed. | |
1442 | * In "classic RCU", these two guarantees happen to be one and | |
1443 | * the same, but can differ in realtime RCU implementations. | |
1444 | */ | |
1445 | void synchronize_sched(void) | |
1446 | { | |
1447 | struct rcu_synchronize rcu; | |
1448 | ||
1449 | if (rcu_blocking_is_gp()) | |
1450 | return; | |
1451 | ||
1452 | init_completion(&rcu.completion); | |
1453 | /* Will wake me after RCU finished. */ | |
1454 | call_rcu_sched(&rcu.head, wakeme_after_rcu); | |
1455 | /* Wait for it. */ | |
1456 | wait_for_completion(&rcu.completion); | |
1457 | } | |
1458 | EXPORT_SYMBOL_GPL(synchronize_sched); | |
1459 | ||
1460 | /** | |
1461 | * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed. | |
1462 | * | |
1463 | * Control will return to the caller some time after a full rcu_bh grace | |
1464 | * period has elapsed, in other words after all currently executing rcu_bh | |
1465 | * read-side critical sections have completed. RCU read-side critical | |
1466 | * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(), | |
1467 | * and may be nested. | |
1468 | */ | |
1469 | void synchronize_rcu_bh(void) | |
1470 | { | |
1471 | struct rcu_synchronize rcu; | |
1472 | ||
1473 | if (rcu_blocking_is_gp()) | |
1474 | return; | |
1475 | ||
1476 | init_completion(&rcu.completion); | |
1477 | /* Will wake me after RCU finished. */ | |
1478 | call_rcu_bh(&rcu.head, wakeme_after_rcu); | |
1479 | /* Wait for it. */ | |
1480 | wait_for_completion(&rcu.completion); | |
1481 | } | |
1482 | EXPORT_SYMBOL_GPL(synchronize_rcu_bh); | |
1483 | ||
64db4cff PM |
1484 | /* |
1485 | * Check to see if there is any immediate RCU-related work to be done | |
1486 | * by the current CPU, for the specified type of RCU, returning 1 if so. | |
1487 | * The checks are in order of increasing expense: checks that can be | |
1488 | * carried out against CPU-local state are performed first. However, | |
1489 | * we must check for CPU stalls first, else we might not get a chance. | |
1490 | */ | |
1491 | static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) | |
1492 | { | |
2f51f988 PM |
1493 | struct rcu_node *rnp = rdp->mynode; |
1494 | ||
64db4cff PM |
1495 | rdp->n_rcu_pending++; |
1496 | ||
1497 | /* Check for CPU stalls, if enabled. */ | |
1498 | check_cpu_stall(rsp, rdp); | |
1499 | ||
1500 | /* Is the RCU core waiting for a quiescent state from this CPU? */ | |
7ba5c840 PM |
1501 | if (rdp->qs_pending) { |
1502 | rdp->n_rp_qs_pending++; | |
64db4cff | 1503 | return 1; |
7ba5c840 | 1504 | } |
64db4cff PM |
1505 | |
1506 | /* Does this CPU have callbacks ready to invoke? */ | |
7ba5c840 PM |
1507 | if (cpu_has_callbacks_ready_to_invoke(rdp)) { |
1508 | rdp->n_rp_cb_ready++; | |
64db4cff | 1509 | return 1; |
7ba5c840 | 1510 | } |
64db4cff PM |
1511 | |
1512 | /* Has RCU gone idle with this CPU needing another grace period? */ | |
7ba5c840 PM |
1513 | if (cpu_needs_another_gp(rsp, rdp)) { |
1514 | rdp->n_rp_cpu_needs_gp++; | |
64db4cff | 1515 | return 1; |
7ba5c840 | 1516 | } |
64db4cff PM |
1517 | |
1518 | /* Has another RCU grace period completed? */ | |
2f51f988 | 1519 | if (ACCESS_ONCE(rnp->completed) != rdp->completed) { /* outside lock */ |
7ba5c840 | 1520 | rdp->n_rp_gp_completed++; |
64db4cff | 1521 | return 1; |
7ba5c840 | 1522 | } |
64db4cff PM |
1523 | |
1524 | /* Has a new RCU grace period started? */ | |
2f51f988 | 1525 | if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum) { /* outside lock */ |
7ba5c840 | 1526 | rdp->n_rp_gp_started++; |
64db4cff | 1527 | return 1; |
7ba5c840 | 1528 | } |
64db4cff PM |
1529 | |
1530 | /* Has an RCU GP gone long enough to send resched IPIs &c? */ | |
fc2219d4 | 1531 | if (rcu_gp_in_progress(rsp) && |
20133cfc | 1532 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) { |
7ba5c840 | 1533 | rdp->n_rp_need_fqs++; |
64db4cff | 1534 | return 1; |
7ba5c840 | 1535 | } |
64db4cff PM |
1536 | |
1537 | /* nothing to do */ | |
7ba5c840 | 1538 | rdp->n_rp_need_nothing++; |
64db4cff PM |
1539 | return 0; |
1540 | } | |
1541 | ||
1542 | /* | |
1543 | * Check to see if there is any immediate RCU-related work to be done | |
1544 | * by the current CPU, returning 1 if so. This function is part of the | |
1545 | * RCU implementation; it is -not- an exported member of the RCU API. | |
1546 | */ | |
a157229c | 1547 | static int rcu_pending(int cpu) |
64db4cff | 1548 | { |
d6714c22 | 1549 | return __rcu_pending(&rcu_sched_state, &per_cpu(rcu_sched_data, cpu)) || |
f41d911f PM |
1550 | __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu)) || |
1551 | rcu_preempt_pending(cpu); | |
64db4cff PM |
1552 | } |
1553 | ||
1554 | /* | |
1555 | * Check to see if any future RCU-related work will need to be done | |
1556 | * by the current CPU, even if none need be done immediately, returning | |
8bd93a2c | 1557 | * 1 if so. |
64db4cff | 1558 | */ |
8bd93a2c | 1559 | static int rcu_needs_cpu_quick_check(int cpu) |
64db4cff PM |
1560 | { |
1561 | /* RCU callbacks either ready or pending? */ | |
d6714c22 | 1562 | return per_cpu(rcu_sched_data, cpu).nxtlist || |
f41d911f PM |
1563 | per_cpu(rcu_bh_data, cpu).nxtlist || |
1564 | rcu_preempt_needs_cpu(cpu); | |
64db4cff PM |
1565 | } |
1566 | ||
d0ec774c PM |
1567 | static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL}; |
1568 | static atomic_t rcu_barrier_cpu_count; | |
1569 | static DEFINE_MUTEX(rcu_barrier_mutex); | |
1570 | static struct completion rcu_barrier_completion; | |
d0ec774c PM |
1571 | |
1572 | static void rcu_barrier_callback(struct rcu_head *notused) | |
1573 | { | |
1574 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) | |
1575 | complete(&rcu_barrier_completion); | |
1576 | } | |
1577 | ||
1578 | /* | |
1579 | * Called with preemption disabled, and from cross-cpu IRQ context. | |
1580 | */ | |
1581 | static void rcu_barrier_func(void *type) | |
1582 | { | |
1583 | int cpu = smp_processor_id(); | |
1584 | struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu); | |
1585 | void (*call_rcu_func)(struct rcu_head *head, | |
1586 | void (*func)(struct rcu_head *head)); | |
1587 | ||
1588 | atomic_inc(&rcu_barrier_cpu_count); | |
1589 | call_rcu_func = type; | |
1590 | call_rcu_func(head, rcu_barrier_callback); | |
1591 | } | |
1592 | ||
d0ec774c PM |
1593 | /* |
1594 | * Orchestrate the specified type of RCU barrier, waiting for all | |
1595 | * RCU callbacks of the specified type to complete. | |
1596 | */ | |
e74f4c45 PM |
1597 | static void _rcu_barrier(struct rcu_state *rsp, |
1598 | void (*call_rcu_func)(struct rcu_head *head, | |
d0ec774c PM |
1599 | void (*func)(struct rcu_head *head))) |
1600 | { | |
1601 | BUG_ON(in_interrupt()); | |
e74f4c45 | 1602 | /* Take mutex to serialize concurrent rcu_barrier() requests. */ |
d0ec774c PM |
1603 | mutex_lock(&rcu_barrier_mutex); |
1604 | init_completion(&rcu_barrier_completion); | |
1605 | /* | |
1606 | * Initialize rcu_barrier_cpu_count to 1, then invoke | |
1607 | * rcu_barrier_func() on each CPU, so that each CPU also has | |
1608 | * incremented rcu_barrier_cpu_count. Only then is it safe to | |
1609 | * decrement rcu_barrier_cpu_count -- otherwise the first CPU | |
1610 | * might complete its grace period before all of the other CPUs | |
1611 | * did their increment, causing this function to return too | |
1612 | * early. | |
1613 | */ | |
1614 | atomic_set(&rcu_barrier_cpu_count, 1); | |
e74f4c45 PM |
1615 | preempt_disable(); /* stop CPU_DYING from filling orphan_cbs_list */ |
1616 | rcu_adopt_orphan_cbs(rsp); | |
d0ec774c | 1617 | on_each_cpu(rcu_barrier_func, (void *)call_rcu_func, 1); |
e74f4c45 | 1618 | preempt_enable(); /* CPU_DYING can again fill orphan_cbs_list */ |
d0ec774c PM |
1619 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) |
1620 | complete(&rcu_barrier_completion); | |
1621 | wait_for_completion(&rcu_barrier_completion); | |
1622 | mutex_unlock(&rcu_barrier_mutex); | |
d0ec774c | 1623 | } |
d0ec774c PM |
1624 | |
1625 | /** | |
1626 | * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete. | |
1627 | */ | |
1628 | void rcu_barrier_bh(void) | |
1629 | { | |
e74f4c45 | 1630 | _rcu_barrier(&rcu_bh_state, call_rcu_bh); |
d0ec774c PM |
1631 | } |
1632 | EXPORT_SYMBOL_GPL(rcu_barrier_bh); | |
1633 | ||
1634 | /** | |
1635 | * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks. | |
1636 | */ | |
1637 | void rcu_barrier_sched(void) | |
1638 | { | |
e74f4c45 | 1639 | _rcu_barrier(&rcu_sched_state, call_rcu_sched); |
d0ec774c PM |
1640 | } |
1641 | EXPORT_SYMBOL_GPL(rcu_barrier_sched); | |
1642 | ||
64db4cff | 1643 | /* |
27569620 | 1644 | * Do boot-time initialization of a CPU's per-CPU RCU data. |
64db4cff | 1645 | */ |
27569620 PM |
1646 | static void __init |
1647 | rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) | |
64db4cff PM |
1648 | { |
1649 | unsigned long flags; | |
1650 | int i; | |
27569620 PM |
1651 | struct rcu_data *rdp = rsp->rda[cpu]; |
1652 | struct rcu_node *rnp = rcu_get_root(rsp); | |
1653 | ||
1654 | /* Set up local state, ensuring consistent view of global state. */ | |
1304afb2 | 1655 | raw_spin_lock_irqsave(&rnp->lock, flags); |
27569620 PM |
1656 | rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo); |
1657 | rdp->nxtlist = NULL; | |
1658 | for (i = 0; i < RCU_NEXT_SIZE; i++) | |
1659 | rdp->nxttail[i] = &rdp->nxtlist; | |
1660 | rdp->qlen = 0; | |
1661 | #ifdef CONFIG_NO_HZ | |
1662 | rdp->dynticks = &per_cpu(rcu_dynticks, cpu); | |
1663 | #endif /* #ifdef CONFIG_NO_HZ */ | |
1664 | rdp->cpu = cpu; | |
1304afb2 | 1665 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
27569620 PM |
1666 | } |
1667 | ||
1668 | /* | |
1669 | * Initialize a CPU's per-CPU RCU data. Note that only one online or | |
1670 | * offline event can be happening at a given time. Note also that we | |
1671 | * can accept some slop in the rsp->completed access due to the fact | |
1672 | * that this CPU cannot possibly have any RCU callbacks in flight yet. | |
64db4cff | 1673 | */ |
e4fa4c97 | 1674 | static void __cpuinit |
f41d911f | 1675 | rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable) |
64db4cff PM |
1676 | { |
1677 | unsigned long flags; | |
64db4cff PM |
1678 | unsigned long mask; |
1679 | struct rcu_data *rdp = rsp->rda[cpu]; | |
1680 | struct rcu_node *rnp = rcu_get_root(rsp); | |
1681 | ||
1682 | /* Set up local state, ensuring consistent view of global state. */ | |
1304afb2 | 1683 | raw_spin_lock_irqsave(&rnp->lock, flags); |
64db4cff PM |
1684 | rdp->passed_quiesc = 0; /* We could be racing with new GP, */ |
1685 | rdp->qs_pending = 1; /* so set up to respond to current GP. */ | |
1686 | rdp->beenonline = 1; /* We have now been online. */ | |
f41d911f | 1687 | rdp->preemptable = preemptable; |
37c72e56 PM |
1688 | rdp->qlen_last_fqs_check = 0; |
1689 | rdp->n_force_qs_snap = rsp->n_force_qs; | |
64db4cff | 1690 | rdp->blimit = blimit; |
1304afb2 | 1691 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
64db4cff PM |
1692 | |
1693 | /* | |
1694 | * A new grace period might start here. If so, we won't be part | |
1695 | * of it, but that is OK, as we are currently in a quiescent state. | |
1696 | */ | |
1697 | ||
1698 | /* Exclude any attempts to start a new GP on large systems. */ | |
1304afb2 | 1699 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
64db4cff PM |
1700 | |
1701 | /* Add CPU to rcu_node bitmasks. */ | |
1702 | rnp = rdp->mynode; | |
1703 | mask = rdp->grpmask; | |
1704 | do { | |
1705 | /* Exclude any attempts to start a new GP on small systems. */ | |
1304afb2 | 1706 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
64db4cff PM |
1707 | rnp->qsmaskinit |= mask; |
1708 | mask = rnp->grpmask; | |
d09b62df PM |
1709 | if (rnp == rdp->mynode) { |
1710 | rdp->gpnum = rnp->completed; /* if GP in progress... */ | |
1711 | rdp->completed = rnp->completed; | |
1712 | rdp->passed_quiesc_completed = rnp->completed - 1; | |
1713 | } | |
1304afb2 | 1714 | raw_spin_unlock(&rnp->lock); /* irqs already disabled. */ |
64db4cff PM |
1715 | rnp = rnp->parent; |
1716 | } while (rnp != NULL && !(rnp->qsmaskinit & mask)); | |
1717 | ||
1304afb2 | 1718 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
64db4cff PM |
1719 | } |
1720 | ||
1721 | static void __cpuinit rcu_online_cpu(int cpu) | |
1722 | { | |
f41d911f PM |
1723 | rcu_init_percpu_data(cpu, &rcu_sched_state, 0); |
1724 | rcu_init_percpu_data(cpu, &rcu_bh_state, 0); | |
1725 | rcu_preempt_init_percpu_data(cpu); | |
64db4cff PM |
1726 | } |
1727 | ||
1728 | /* | |
f41d911f | 1729 | * Handle CPU online/offline notification events. |
64db4cff | 1730 | */ |
9f680ab4 PM |
1731 | static int __cpuinit rcu_cpu_notify(struct notifier_block *self, |
1732 | unsigned long action, void *hcpu) | |
64db4cff PM |
1733 | { |
1734 | long cpu = (long)hcpu; | |
1735 | ||
1736 | switch (action) { | |
1737 | case CPU_UP_PREPARE: | |
1738 | case CPU_UP_PREPARE_FROZEN: | |
1739 | rcu_online_cpu(cpu); | |
1740 | break; | |
d0ec774c PM |
1741 | case CPU_DYING: |
1742 | case CPU_DYING_FROZEN: | |
1743 | /* | |
e74f4c45 | 1744 | * preempt_disable() in _rcu_barrier() prevents stop_machine(), |
d0ec774c | 1745 | * so when "on_each_cpu(rcu_barrier_func, (void *)type, 1);" |
e74f4c45 PM |
1746 | * returns, all online cpus have queued rcu_barrier_func(). |
1747 | * The dying CPU clears its cpu_online_mask bit and | |
1748 | * moves all of its RCU callbacks to ->orphan_cbs_list | |
1749 | * in the context of stop_machine(), so subsequent calls | |
1750 | * to _rcu_barrier() will adopt these callbacks and only | |
1751 | * then queue rcu_barrier_func() on all remaining CPUs. | |
d0ec774c | 1752 | */ |
e74f4c45 PM |
1753 | rcu_send_cbs_to_orphanage(&rcu_bh_state); |
1754 | rcu_send_cbs_to_orphanage(&rcu_sched_state); | |
1755 | rcu_preempt_send_cbs_to_orphanage(); | |
d0ec774c | 1756 | break; |
64db4cff PM |
1757 | case CPU_DEAD: |
1758 | case CPU_DEAD_FROZEN: | |
1759 | case CPU_UP_CANCELED: | |
1760 | case CPU_UP_CANCELED_FROZEN: | |
1761 | rcu_offline_cpu(cpu); | |
1762 | break; | |
1763 | default: | |
1764 | break; | |
1765 | } | |
1766 | return NOTIFY_OK; | |
1767 | } | |
1768 | ||
1769 | /* | |
1770 | * Compute the per-level fanout, either using the exact fanout specified | |
1771 | * or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT. | |
1772 | */ | |
1773 | #ifdef CONFIG_RCU_FANOUT_EXACT | |
1774 | static void __init rcu_init_levelspread(struct rcu_state *rsp) | |
1775 | { | |
1776 | int i; | |
1777 | ||
1778 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) | |
1779 | rsp->levelspread[i] = CONFIG_RCU_FANOUT; | |
1780 | } | |
1781 | #else /* #ifdef CONFIG_RCU_FANOUT_EXACT */ | |
1782 | static void __init rcu_init_levelspread(struct rcu_state *rsp) | |
1783 | { | |
1784 | int ccur; | |
1785 | int cprv; | |
1786 | int i; | |
1787 | ||
1788 | cprv = NR_CPUS; | |
1789 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { | |
1790 | ccur = rsp->levelcnt[i]; | |
1791 | rsp->levelspread[i] = (cprv + ccur - 1) / ccur; | |
1792 | cprv = ccur; | |
1793 | } | |
1794 | } | |
1795 | #endif /* #else #ifdef CONFIG_RCU_FANOUT_EXACT */ | |
1796 | ||
1797 | /* | |
1798 | * Helper function for rcu_init() that initializes one rcu_state structure. | |
1799 | */ | |
1800 | static void __init rcu_init_one(struct rcu_state *rsp) | |
1801 | { | |
b6407e86 PM |
1802 | static char *buf[] = { "rcu_node_level_0", |
1803 | "rcu_node_level_1", | |
1804 | "rcu_node_level_2", | |
1805 | "rcu_node_level_3" }; /* Match MAX_RCU_LVLS */ | |
64db4cff PM |
1806 | int cpustride = 1; |
1807 | int i; | |
1808 | int j; | |
1809 | struct rcu_node *rnp; | |
1810 | ||
b6407e86 PM |
1811 | BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */ |
1812 | ||
64db4cff PM |
1813 | /* Initialize the level-tracking arrays. */ |
1814 | ||
1815 | for (i = 1; i < NUM_RCU_LVLS; i++) | |
1816 | rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1]; | |
1817 | rcu_init_levelspread(rsp); | |
1818 | ||
1819 | /* Initialize the elements themselves, starting from the leaves. */ | |
1820 | ||
1821 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { | |
1822 | cpustride *= rsp->levelspread[i]; | |
1823 | rnp = rsp->level[i]; | |
1824 | for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) { | |
1304afb2 | 1825 | raw_spin_lock_init(&rnp->lock); |
b6407e86 PM |
1826 | lockdep_set_class_and_name(&rnp->lock, |
1827 | &rcu_node_class[i], buf[i]); | |
f41d911f | 1828 | rnp->gpnum = 0; |
64db4cff PM |
1829 | rnp->qsmask = 0; |
1830 | rnp->qsmaskinit = 0; | |
1831 | rnp->grplo = j * cpustride; | |
1832 | rnp->grphi = (j + 1) * cpustride - 1; | |
1833 | if (rnp->grphi >= NR_CPUS) | |
1834 | rnp->grphi = NR_CPUS - 1; | |
1835 | if (i == 0) { | |
1836 | rnp->grpnum = 0; | |
1837 | rnp->grpmask = 0; | |
1838 | rnp->parent = NULL; | |
1839 | } else { | |
1840 | rnp->grpnum = j % rsp->levelspread[i - 1]; | |
1841 | rnp->grpmask = 1UL << rnp->grpnum; | |
1842 | rnp->parent = rsp->level[i - 1] + | |
1843 | j / rsp->levelspread[i - 1]; | |
1844 | } | |
1845 | rnp->level = i; | |
f41d911f PM |
1846 | INIT_LIST_HEAD(&rnp->blocked_tasks[0]); |
1847 | INIT_LIST_HEAD(&rnp->blocked_tasks[1]); | |
d9a3da06 PM |
1848 | INIT_LIST_HEAD(&rnp->blocked_tasks[2]); |
1849 | INIT_LIST_HEAD(&rnp->blocked_tasks[3]); | |
64db4cff PM |
1850 | } |
1851 | } | |
1852 | } | |
1853 | ||
1854 | /* | |
f41d911f PM |
1855 | * Helper macro for __rcu_init() and __rcu_init_preempt(). To be used |
1856 | * nowhere else! Assigns leaf node pointers into each CPU's rcu_data | |
1857 | * structure. | |
64db4cff | 1858 | */ |
65cf8f86 | 1859 | #define RCU_INIT_FLAVOR(rsp, rcu_data) \ |
64db4cff | 1860 | do { \ |
a0b6c9a7 PM |
1861 | int i; \ |
1862 | int j; \ | |
1863 | struct rcu_node *rnp; \ | |
1864 | \ | |
65cf8f86 | 1865 | rcu_init_one(rsp); \ |
64db4cff PM |
1866 | rnp = (rsp)->level[NUM_RCU_LVLS - 1]; \ |
1867 | j = 0; \ | |
1868 | for_each_possible_cpu(i) { \ | |
1869 | if (i > rnp[j].grphi) \ | |
1870 | j++; \ | |
1871 | per_cpu(rcu_data, i).mynode = &rnp[j]; \ | |
1872 | (rsp)->rda[i] = &per_cpu(rcu_data, i); \ | |
65cf8f86 | 1873 | rcu_boot_init_percpu_data(i, rsp); \ |
64db4cff PM |
1874 | } \ |
1875 | } while (0) | |
1876 | ||
9f680ab4 | 1877 | void __init rcu_init(void) |
64db4cff | 1878 | { |
017c4261 | 1879 | int cpu; |
9f680ab4 | 1880 | |
f41d911f | 1881 | rcu_bootup_announce(); |
64db4cff PM |
1882 | #ifdef CONFIG_RCU_CPU_STALL_DETECTOR |
1883 | printk(KERN_INFO "RCU-based detection of stalled CPUs is enabled.\n"); | |
1884 | #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ | |
cf244dc0 PM |
1885 | #if NUM_RCU_LVL_4 != 0 |
1886 | printk(KERN_INFO "Experimental four-level hierarchy is enabled.\n"); | |
1887 | #endif /* #if NUM_RCU_LVL_4 != 0 */ | |
65cf8f86 PM |
1888 | RCU_INIT_FLAVOR(&rcu_sched_state, rcu_sched_data); |
1889 | RCU_INIT_FLAVOR(&rcu_bh_state, rcu_bh_data); | |
f41d911f | 1890 | __rcu_init_preempt(); |
2e597558 | 1891 | open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); |
9f680ab4 PM |
1892 | |
1893 | /* | |
1894 | * We don't need protection against CPU-hotplug here because | |
1895 | * this is called early in boot, before either interrupts | |
1896 | * or the scheduler are operational. | |
1897 | */ | |
1898 | cpu_notifier(rcu_cpu_notify, 0); | |
017c4261 PM |
1899 | for_each_online_cpu(cpu) |
1900 | rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu); | |
64db4cff PM |
1901 | } |
1902 | ||
1eba8f84 | 1903 | #include "rcutree_plugin.h" |