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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 | { |
25502a6c | 100 | struct rcu_data *rdp = &per_cpu(rcu_sched_data, cpu); |
f41d911f | 101 | |
c64ac3ce | 102 | rdp->passed_quiesc_completed = rdp->gpnum - 1; |
c3422bea PM |
103 | barrier(); |
104 | rdp->passed_quiesc = 1; | |
b1f77b05 IM |
105 | } |
106 | ||
d6714c22 | 107 | void rcu_bh_qs(int cpu) |
b1f77b05 | 108 | { |
25502a6c | 109 | struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu); |
f41d911f | 110 | |
c64ac3ce | 111 | rdp->passed_quiesc_completed = rdp->gpnum - 1; |
c3422bea PM |
112 | barrier(); |
113 | rdp->passed_quiesc = 1; | |
b1f77b05 | 114 | } |
64db4cff | 115 | |
25502a6c PM |
116 | /* |
117 | * Note a context switch. This is a quiescent state for RCU-sched, | |
118 | * and requires special handling for preemptible RCU. | |
119 | */ | |
120 | void rcu_note_context_switch(int cpu) | |
121 | { | |
122 | rcu_sched_qs(cpu); | |
123 | rcu_preempt_note_context_switch(cpu); | |
124 | } | |
125 | ||
64db4cff | 126 | #ifdef CONFIG_NO_HZ |
90a4d2c0 PM |
127 | DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { |
128 | .dynticks_nesting = 1, | |
129 | .dynticks = 1, | |
130 | }; | |
64db4cff PM |
131 | #endif /* #ifdef CONFIG_NO_HZ */ |
132 | ||
133 | static int blimit = 10; /* Maximum callbacks per softirq. */ | |
134 | static int qhimark = 10000; /* If this many pending, ignore blimit. */ | |
135 | static int qlowmark = 100; /* Once only this many pending, use blimit. */ | |
136 | ||
3d76c082 PM |
137 | module_param(blimit, int, 0); |
138 | module_param(qhimark, int, 0); | |
139 | module_param(qlowmark, int, 0); | |
140 | ||
64db4cff | 141 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed); |
a157229c | 142 | static int rcu_pending(int cpu); |
64db4cff PM |
143 | |
144 | /* | |
d6714c22 | 145 | * Return the number of RCU-sched batches processed thus far for debug & stats. |
64db4cff | 146 | */ |
d6714c22 | 147 | long rcu_batches_completed_sched(void) |
64db4cff | 148 | { |
d6714c22 | 149 | return rcu_sched_state.completed; |
64db4cff | 150 | } |
d6714c22 | 151 | EXPORT_SYMBOL_GPL(rcu_batches_completed_sched); |
64db4cff PM |
152 | |
153 | /* | |
154 | * Return the number of RCU BH batches processed thus far for debug & stats. | |
155 | */ | |
156 | long rcu_batches_completed_bh(void) | |
157 | { | |
158 | return rcu_bh_state.completed; | |
159 | } | |
160 | EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); | |
161 | ||
bf66f18e PM |
162 | /* |
163 | * Force a quiescent state for RCU BH. | |
164 | */ | |
165 | void rcu_bh_force_quiescent_state(void) | |
166 | { | |
167 | force_quiescent_state(&rcu_bh_state, 0); | |
168 | } | |
169 | EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state); | |
170 | ||
171 | /* | |
172 | * Force a quiescent state for RCU-sched. | |
173 | */ | |
174 | void rcu_sched_force_quiescent_state(void) | |
175 | { | |
176 | force_quiescent_state(&rcu_sched_state, 0); | |
177 | } | |
178 | EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state); | |
179 | ||
64db4cff PM |
180 | /* |
181 | * Does the CPU have callbacks ready to be invoked? | |
182 | */ | |
183 | static int | |
184 | cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp) | |
185 | { | |
186 | return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]; | |
187 | } | |
188 | ||
189 | /* | |
190 | * Does the current CPU require a yet-as-unscheduled grace period? | |
191 | */ | |
192 | static int | |
193 | cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp) | |
194 | { | |
fc2219d4 | 195 | return *rdp->nxttail[RCU_DONE_TAIL] && !rcu_gp_in_progress(rsp); |
64db4cff PM |
196 | } |
197 | ||
198 | /* | |
199 | * Return the root node of the specified rcu_state structure. | |
200 | */ | |
201 | static struct rcu_node *rcu_get_root(struct rcu_state *rsp) | |
202 | { | |
203 | return &rsp->node[0]; | |
204 | } | |
205 | ||
206 | #ifdef CONFIG_SMP | |
207 | ||
208 | /* | |
209 | * If the specified CPU is offline, tell the caller that it is in | |
210 | * a quiescent state. Otherwise, whack it with a reschedule IPI. | |
211 | * Grace periods can end up waiting on an offline CPU when that | |
212 | * CPU is in the process of coming online -- it will be added to the | |
213 | * rcu_node bitmasks before it actually makes it online. The same thing | |
214 | * can happen while a CPU is in the process of coming online. Because this | |
215 | * race is quite rare, we check for it after detecting that the grace | |
216 | * period has been delayed rather than checking each and every CPU | |
217 | * each and every time we start a new grace period. | |
218 | */ | |
219 | static int rcu_implicit_offline_qs(struct rcu_data *rdp) | |
220 | { | |
221 | /* | |
222 | * If the CPU is offline, it is in a quiescent state. We can | |
223 | * trust its state not to change because interrupts are disabled. | |
224 | */ | |
225 | if (cpu_is_offline(rdp->cpu)) { | |
226 | rdp->offline_fqs++; | |
227 | return 1; | |
228 | } | |
229 | ||
f41d911f PM |
230 | /* If preemptable RCU, no point in sending reschedule IPI. */ |
231 | if (rdp->preemptable) | |
232 | return 0; | |
233 | ||
64db4cff PM |
234 | /* The CPU is online, so send it a reschedule IPI. */ |
235 | if (rdp->cpu != smp_processor_id()) | |
236 | smp_send_reschedule(rdp->cpu); | |
237 | else | |
238 | set_need_resched(); | |
239 | rdp->resched_ipi++; | |
240 | return 0; | |
241 | } | |
242 | ||
243 | #endif /* #ifdef CONFIG_SMP */ | |
244 | ||
245 | #ifdef CONFIG_NO_HZ | |
64db4cff PM |
246 | |
247 | /** | |
248 | * rcu_enter_nohz - inform RCU that current CPU is entering nohz | |
249 | * | |
250 | * Enter nohz mode, in other words, -leave- the mode in which RCU | |
251 | * read-side critical sections can occur. (Though RCU read-side | |
252 | * critical sections can occur in irq handlers in nohz mode, a possibility | |
253 | * handled by rcu_irq_enter() and rcu_irq_exit()). | |
254 | */ | |
255 | void rcu_enter_nohz(void) | |
256 | { | |
257 | unsigned long flags; | |
258 | struct rcu_dynticks *rdtp; | |
259 | ||
260 | smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ | |
261 | local_irq_save(flags); | |
262 | rdtp = &__get_cpu_var(rcu_dynticks); | |
263 | rdtp->dynticks++; | |
264 | rdtp->dynticks_nesting--; | |
86848966 | 265 | WARN_ON_ONCE(rdtp->dynticks & 0x1); |
64db4cff PM |
266 | local_irq_restore(flags); |
267 | } | |
268 | ||
269 | /* | |
270 | * rcu_exit_nohz - inform RCU that current CPU is leaving nohz | |
271 | * | |
272 | * Exit nohz mode, in other words, -enter- the mode in which RCU | |
273 | * read-side critical sections normally occur. | |
274 | */ | |
275 | void rcu_exit_nohz(void) | |
276 | { | |
277 | unsigned long flags; | |
278 | struct rcu_dynticks *rdtp; | |
279 | ||
280 | local_irq_save(flags); | |
281 | rdtp = &__get_cpu_var(rcu_dynticks); | |
282 | rdtp->dynticks++; | |
283 | rdtp->dynticks_nesting++; | |
86848966 | 284 | WARN_ON_ONCE(!(rdtp->dynticks & 0x1)); |
64db4cff PM |
285 | local_irq_restore(flags); |
286 | smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ | |
287 | } | |
288 | ||
289 | /** | |
290 | * rcu_nmi_enter - inform RCU of entry to NMI context | |
291 | * | |
292 | * If the CPU was idle with dynamic ticks active, and there is no | |
293 | * irq handler running, this updates rdtp->dynticks_nmi to let the | |
294 | * RCU grace-period handling know that the CPU is active. | |
295 | */ | |
296 | void rcu_nmi_enter(void) | |
297 | { | |
298 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); | |
299 | ||
300 | if (rdtp->dynticks & 0x1) | |
301 | return; | |
302 | rdtp->dynticks_nmi++; | |
86848966 | 303 | WARN_ON_ONCE(!(rdtp->dynticks_nmi & 0x1)); |
64db4cff PM |
304 | smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ |
305 | } | |
306 | ||
307 | /** | |
308 | * rcu_nmi_exit - inform RCU of exit from NMI context | |
309 | * | |
310 | * If the CPU was idle with dynamic ticks active, and there is no | |
311 | * irq handler running, this updates rdtp->dynticks_nmi to let the | |
312 | * RCU grace-period handling know that the CPU is no longer active. | |
313 | */ | |
314 | void rcu_nmi_exit(void) | |
315 | { | |
316 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); | |
317 | ||
318 | if (rdtp->dynticks & 0x1) | |
319 | return; | |
320 | smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ | |
321 | rdtp->dynticks_nmi++; | |
86848966 | 322 | WARN_ON_ONCE(rdtp->dynticks_nmi & 0x1); |
64db4cff PM |
323 | } |
324 | ||
325 | /** | |
326 | * rcu_irq_enter - inform RCU of entry to hard irq context | |
327 | * | |
328 | * If the CPU was idle with dynamic ticks active, this updates the | |
329 | * rdtp->dynticks to let the RCU handling know that the CPU is active. | |
330 | */ | |
331 | void rcu_irq_enter(void) | |
332 | { | |
333 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); | |
334 | ||
335 | if (rdtp->dynticks_nesting++) | |
336 | return; | |
337 | rdtp->dynticks++; | |
86848966 | 338 | WARN_ON_ONCE(!(rdtp->dynticks & 0x1)); |
64db4cff PM |
339 | smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ |
340 | } | |
341 | ||
342 | /** | |
343 | * rcu_irq_exit - inform RCU of exit from hard irq context | |
344 | * | |
345 | * If the CPU was idle with dynamic ticks active, update the rdp->dynticks | |
346 | * to put let the RCU handling be aware that the CPU is going back to idle | |
347 | * with no ticks. | |
348 | */ | |
349 | void rcu_irq_exit(void) | |
350 | { | |
351 | struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); | |
352 | ||
353 | if (--rdtp->dynticks_nesting) | |
354 | return; | |
355 | smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ | |
356 | rdtp->dynticks++; | |
86848966 | 357 | WARN_ON_ONCE(rdtp->dynticks & 0x1); |
64db4cff PM |
358 | |
359 | /* If the interrupt queued a callback, get out of dyntick mode. */ | |
d6714c22 | 360 | if (__get_cpu_var(rcu_sched_data).nxtlist || |
64db4cff PM |
361 | __get_cpu_var(rcu_bh_data).nxtlist) |
362 | set_need_resched(); | |
363 | } | |
364 | ||
64db4cff PM |
365 | #ifdef CONFIG_SMP |
366 | ||
64db4cff PM |
367 | /* |
368 | * Snapshot the specified CPU's dynticks counter so that we can later | |
369 | * credit them with an implicit quiescent state. Return 1 if this CPU | |
1eba8f84 | 370 | * is in dynticks idle mode, which is an extended quiescent state. |
64db4cff PM |
371 | */ |
372 | static int dyntick_save_progress_counter(struct rcu_data *rdp) | |
373 | { | |
374 | int ret; | |
375 | int snap; | |
376 | int snap_nmi; | |
377 | ||
378 | snap = rdp->dynticks->dynticks; | |
379 | snap_nmi = rdp->dynticks->dynticks_nmi; | |
380 | smp_mb(); /* Order sampling of snap with end of grace period. */ | |
381 | rdp->dynticks_snap = snap; | |
382 | rdp->dynticks_nmi_snap = snap_nmi; | |
383 | ret = ((snap & 0x1) == 0) && ((snap_nmi & 0x1) == 0); | |
384 | if (ret) | |
385 | rdp->dynticks_fqs++; | |
386 | return ret; | |
387 | } | |
388 | ||
389 | /* | |
390 | * Return true if the specified CPU has passed through a quiescent | |
391 | * state by virtue of being in or having passed through an dynticks | |
392 | * idle state since the last call to dyntick_save_progress_counter() | |
393 | * for this same CPU. | |
394 | */ | |
395 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) | |
396 | { | |
397 | long curr; | |
398 | long curr_nmi; | |
399 | long snap; | |
400 | long snap_nmi; | |
401 | ||
402 | curr = rdp->dynticks->dynticks; | |
403 | snap = rdp->dynticks_snap; | |
404 | curr_nmi = rdp->dynticks->dynticks_nmi; | |
405 | snap_nmi = rdp->dynticks_nmi_snap; | |
406 | smp_mb(); /* force ordering with cpu entering/leaving dynticks. */ | |
407 | ||
408 | /* | |
409 | * If the CPU passed through or entered a dynticks idle phase with | |
410 | * no active irq/NMI handlers, then we can safely pretend that the CPU | |
411 | * already acknowledged the request to pass through a quiescent | |
412 | * state. Either way, that CPU cannot possibly be in an RCU | |
413 | * read-side critical section that started before the beginning | |
414 | * of the current RCU grace period. | |
415 | */ | |
416 | if ((curr != snap || (curr & 0x1) == 0) && | |
417 | (curr_nmi != snap_nmi || (curr_nmi & 0x1) == 0)) { | |
418 | rdp->dynticks_fqs++; | |
419 | return 1; | |
420 | } | |
421 | ||
422 | /* Go check for the CPU being offline. */ | |
423 | return rcu_implicit_offline_qs(rdp); | |
424 | } | |
425 | ||
426 | #endif /* #ifdef CONFIG_SMP */ | |
427 | ||
428 | #else /* #ifdef CONFIG_NO_HZ */ | |
429 | ||
64db4cff PM |
430 | #ifdef CONFIG_SMP |
431 | ||
64db4cff PM |
432 | static int dyntick_save_progress_counter(struct rcu_data *rdp) |
433 | { | |
434 | return 0; | |
435 | } | |
436 | ||
437 | static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) | |
438 | { | |
439 | return rcu_implicit_offline_qs(rdp); | |
440 | } | |
441 | ||
442 | #endif /* #ifdef CONFIG_SMP */ | |
443 | ||
444 | #endif /* #else #ifdef CONFIG_NO_HZ */ | |
445 | ||
446 | #ifdef CONFIG_RCU_CPU_STALL_DETECTOR | |
447 | ||
448 | static void record_gp_stall_check_time(struct rcu_state *rsp) | |
449 | { | |
450 | rsp->gp_start = jiffies; | |
451 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_CHECK; | |
452 | } | |
453 | ||
454 | static void print_other_cpu_stall(struct rcu_state *rsp) | |
455 | { | |
456 | int cpu; | |
457 | long delta; | |
458 | unsigned long flags; | |
459 | struct rcu_node *rnp = rcu_get_root(rsp); | |
64db4cff PM |
460 | |
461 | /* Only let one CPU complain about others per time interval. */ | |
462 | ||
1304afb2 | 463 | raw_spin_lock_irqsave(&rnp->lock, flags); |
64db4cff | 464 | delta = jiffies - rsp->jiffies_stall; |
fc2219d4 | 465 | if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) { |
1304afb2 | 466 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
467 | return; |
468 | } | |
469 | rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_RECHECK; | |
a0b6c9a7 PM |
470 | |
471 | /* | |
472 | * Now rat on any tasks that got kicked up to the root rcu_node | |
473 | * due to CPU offlining. | |
474 | */ | |
475 | rcu_print_task_stall(rnp); | |
1304afb2 | 476 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
477 | |
478 | /* OK, time to rat on our buddy... */ | |
479 | ||
480 | printk(KERN_ERR "INFO: RCU detected CPU stalls:"); | |
a0b6c9a7 | 481 | rcu_for_each_leaf_node(rsp, rnp) { |
3acd9eb3 | 482 | raw_spin_lock_irqsave(&rnp->lock, flags); |
f41d911f | 483 | rcu_print_task_stall(rnp); |
3acd9eb3 | 484 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
a0b6c9a7 | 485 | if (rnp->qsmask == 0) |
64db4cff | 486 | continue; |
a0b6c9a7 PM |
487 | for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++) |
488 | if (rnp->qsmask & (1UL << cpu)) | |
489 | printk(" %d", rnp->grplo + cpu); | |
64db4cff PM |
490 | } |
491 | printk(" (detected by %d, t=%ld jiffies)\n", | |
492 | smp_processor_id(), (long)(jiffies - rsp->gp_start)); | |
c1dc0b9c IM |
493 | trigger_all_cpu_backtrace(); |
494 | ||
1ed509a2 PM |
495 | /* If so configured, complain about tasks blocking the grace period. */ |
496 | ||
497 | rcu_print_detail_task_stall(rsp); | |
498 | ||
64db4cff PM |
499 | force_quiescent_state(rsp, 0); /* Kick them all. */ |
500 | } | |
501 | ||
502 | static void print_cpu_stall(struct rcu_state *rsp) | |
503 | { | |
504 | unsigned long flags; | |
505 | struct rcu_node *rnp = rcu_get_root(rsp); | |
506 | ||
507 | printk(KERN_ERR "INFO: RCU detected CPU %d stall (t=%lu jiffies)\n", | |
508 | smp_processor_id(), jiffies - rsp->gp_start); | |
c1dc0b9c IM |
509 | trigger_all_cpu_backtrace(); |
510 | ||
1304afb2 | 511 | raw_spin_lock_irqsave(&rnp->lock, flags); |
20133cfc | 512 | if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall)) |
64db4cff PM |
513 | rsp->jiffies_stall = |
514 | jiffies + RCU_SECONDS_TILL_STALL_RECHECK; | |
1304afb2 | 515 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
c1dc0b9c | 516 | |
64db4cff PM |
517 | set_need_resched(); /* kick ourselves to get things going. */ |
518 | } | |
519 | ||
520 | static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) | |
521 | { | |
522 | long delta; | |
523 | struct rcu_node *rnp; | |
524 | ||
525 | delta = jiffies - rsp->jiffies_stall; | |
526 | rnp = rdp->mynode; | |
527 | if ((rnp->qsmask & rdp->grpmask) && delta >= 0) { | |
528 | ||
529 | /* We haven't checked in, so go dump stack. */ | |
530 | print_cpu_stall(rsp); | |
531 | ||
fc2219d4 | 532 | } else if (rcu_gp_in_progress(rsp) && delta >= RCU_STALL_RAT_DELAY) { |
64db4cff PM |
533 | |
534 | /* They had two time units to dump stack, so complain. */ | |
535 | print_other_cpu_stall(rsp); | |
536 | } | |
537 | } | |
538 | ||
539 | #else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ | |
540 | ||
541 | static void record_gp_stall_check_time(struct rcu_state *rsp) | |
542 | { | |
543 | } | |
544 | ||
545 | static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) | |
546 | { | |
547 | } | |
548 | ||
549 | #endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ | |
550 | ||
551 | /* | |
552 | * Update CPU-local rcu_data state to record the newly noticed grace period. | |
553 | * This is used both when we started the grace period and when we notice | |
9160306e PM |
554 | * that someone else started the grace period. The caller must hold the |
555 | * ->lock of the leaf rcu_node structure corresponding to the current CPU, | |
556 | * and must have irqs disabled. | |
64db4cff | 557 | */ |
9160306e PM |
558 | static void __note_new_gpnum(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) |
559 | { | |
560 | if (rdp->gpnum != rnp->gpnum) { | |
561 | rdp->qs_pending = 1; | |
562 | rdp->passed_quiesc = 0; | |
563 | rdp->gpnum = rnp->gpnum; | |
564 | } | |
565 | } | |
566 | ||
64db4cff PM |
567 | static void note_new_gpnum(struct rcu_state *rsp, struct rcu_data *rdp) |
568 | { | |
9160306e PM |
569 | unsigned long flags; |
570 | struct rcu_node *rnp; | |
571 | ||
572 | local_irq_save(flags); | |
573 | rnp = rdp->mynode; | |
574 | if (rdp->gpnum == ACCESS_ONCE(rnp->gpnum) || /* outside lock. */ | |
1304afb2 | 575 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
9160306e PM |
576 | local_irq_restore(flags); |
577 | return; | |
578 | } | |
579 | __note_new_gpnum(rsp, rnp, rdp); | |
1304afb2 | 580 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
581 | } |
582 | ||
583 | /* | |
584 | * Did someone else start a new RCU grace period start since we last | |
585 | * checked? Update local state appropriately if so. Must be called | |
586 | * on the CPU corresponding to rdp. | |
587 | */ | |
588 | static int | |
589 | check_for_new_grace_period(struct rcu_state *rsp, struct rcu_data *rdp) | |
590 | { | |
591 | unsigned long flags; | |
592 | int ret = 0; | |
593 | ||
594 | local_irq_save(flags); | |
595 | if (rdp->gpnum != rsp->gpnum) { | |
596 | note_new_gpnum(rsp, rdp); | |
597 | ret = 1; | |
598 | } | |
599 | local_irq_restore(flags); | |
600 | return ret; | |
601 | } | |
602 | ||
d09b62df PM |
603 | /* |
604 | * Advance this CPU's callbacks, but only if the current grace period | |
605 | * has ended. This may be called only from the CPU to whom the rdp | |
606 | * belongs. In addition, the corresponding leaf rcu_node structure's | |
607 | * ->lock must be held by the caller, with irqs disabled. | |
608 | */ | |
609 | static void | |
610 | __rcu_process_gp_end(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) | |
611 | { | |
612 | /* Did another grace period end? */ | |
613 | if (rdp->completed != rnp->completed) { | |
614 | ||
615 | /* Advance callbacks. No harm if list empty. */ | |
616 | rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL]; | |
617 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL]; | |
618 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; | |
619 | ||
620 | /* Remember that we saw this grace-period completion. */ | |
621 | rdp->completed = rnp->completed; | |
622 | } | |
623 | } | |
624 | ||
625 | /* | |
626 | * Advance this CPU's callbacks, but only if the current grace period | |
627 | * has ended. This may be called only from the CPU to whom the rdp | |
628 | * belongs. | |
629 | */ | |
630 | static void | |
631 | rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp) | |
632 | { | |
633 | unsigned long flags; | |
634 | struct rcu_node *rnp; | |
635 | ||
636 | local_irq_save(flags); | |
637 | rnp = rdp->mynode; | |
638 | if (rdp->completed == ACCESS_ONCE(rnp->completed) || /* outside lock. */ | |
1304afb2 | 639 | !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */ |
d09b62df PM |
640 | local_irq_restore(flags); |
641 | return; | |
642 | } | |
643 | __rcu_process_gp_end(rsp, rnp, rdp); | |
1304afb2 | 644 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
d09b62df PM |
645 | } |
646 | ||
647 | /* | |
648 | * Do per-CPU grace-period initialization for running CPU. The caller | |
649 | * must hold the lock of the leaf rcu_node structure corresponding to | |
650 | * this CPU. | |
651 | */ | |
652 | static void | |
653 | rcu_start_gp_per_cpu(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) | |
654 | { | |
655 | /* Prior grace period ended, so advance callbacks for current CPU. */ | |
656 | __rcu_process_gp_end(rsp, rnp, rdp); | |
657 | ||
658 | /* | |
659 | * Because this CPU just now started the new grace period, we know | |
660 | * that all of its callbacks will be covered by this upcoming grace | |
661 | * period, even the ones that were registered arbitrarily recently. | |
662 | * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL. | |
663 | * | |
664 | * Other CPUs cannot be sure exactly when the grace period started. | |
665 | * Therefore, their recently registered callbacks must pass through | |
666 | * an additional RCU_NEXT_READY stage, so that they will be handled | |
667 | * by the next RCU grace period. | |
668 | */ | |
669 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; | |
670 | rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; | |
9160306e PM |
671 | |
672 | /* Set state so that this CPU will detect the next quiescent state. */ | |
673 | __note_new_gpnum(rsp, rnp, rdp); | |
d09b62df PM |
674 | } |
675 | ||
64db4cff PM |
676 | /* |
677 | * Start a new RCU grace period if warranted, re-initializing the hierarchy | |
678 | * in preparation for detecting the next grace period. The caller must hold | |
679 | * the root node's ->lock, which is released before return. Hard irqs must | |
680 | * be disabled. | |
681 | */ | |
682 | static void | |
683 | rcu_start_gp(struct rcu_state *rsp, unsigned long flags) | |
684 | __releases(rcu_get_root(rsp)->lock) | |
685 | { | |
686 | struct rcu_data *rdp = rsp->rda[smp_processor_id()]; | |
687 | struct rcu_node *rnp = rcu_get_root(rsp); | |
64db4cff | 688 | |
07079d53 | 689 | if (!cpu_needs_another_gp(rsp, rdp) || rsp->fqs_active) { |
46a1e34e PM |
690 | if (cpu_needs_another_gp(rsp, rdp)) |
691 | rsp->fqs_need_gp = 1; | |
b32e9eb6 | 692 | if (rnp->completed == rsp->completed) { |
1304afb2 | 693 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
b32e9eb6 PM |
694 | return; |
695 | } | |
1304afb2 | 696 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
b32e9eb6 PM |
697 | |
698 | /* | |
699 | * Propagate new ->completed value to rcu_node structures | |
700 | * so that other CPUs don't have to wait until the start | |
701 | * of the next grace period to process their callbacks. | |
702 | */ | |
703 | rcu_for_each_node_breadth_first(rsp, rnp) { | |
1304afb2 | 704 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
b32e9eb6 | 705 | rnp->completed = rsp->completed; |
1304afb2 | 706 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
b32e9eb6 PM |
707 | } |
708 | local_irq_restore(flags); | |
64db4cff PM |
709 | return; |
710 | } | |
711 | ||
712 | /* Advance to a new grace period and initialize state. */ | |
713 | rsp->gpnum++; | |
c3422bea | 714 | WARN_ON_ONCE(rsp->signaled == RCU_GP_INIT); |
64db4cff PM |
715 | rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */ |
716 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; | |
64db4cff | 717 | record_gp_stall_check_time(rsp); |
64db4cff | 718 | |
64db4cff PM |
719 | /* Special-case the common single-level case. */ |
720 | if (NUM_RCU_NODES == 1) { | |
b0e165c0 | 721 | rcu_preempt_check_blocked_tasks(rnp); |
28ecd580 | 722 | rnp->qsmask = rnp->qsmaskinit; |
de078d87 | 723 | rnp->gpnum = rsp->gpnum; |
d09b62df | 724 | rnp->completed = rsp->completed; |
c12172c0 | 725 | rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state OK. */ |
d09b62df | 726 | rcu_start_gp_per_cpu(rsp, rnp, rdp); |
1304afb2 | 727 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
728 | return; |
729 | } | |
730 | ||
1304afb2 | 731 | raw_spin_unlock(&rnp->lock); /* leave irqs disabled. */ |
64db4cff PM |
732 | |
733 | ||
734 | /* Exclude any concurrent CPU-hotplug operations. */ | |
1304afb2 | 735 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
64db4cff PM |
736 | |
737 | /* | |
b835db1f PM |
738 | * Set the quiescent-state-needed bits in all the rcu_node |
739 | * structures for all currently online CPUs in breadth-first | |
740 | * order, starting from the root rcu_node structure. This | |
741 | * operation relies on the layout of the hierarchy within the | |
742 | * rsp->node[] array. Note that other CPUs will access only | |
743 | * the leaves of the hierarchy, which still indicate that no | |
744 | * grace period is in progress, at least until the corresponding | |
745 | * leaf node has been initialized. In addition, we have excluded | |
746 | * CPU-hotplug operations. | |
64db4cff PM |
747 | * |
748 | * Note that the grace period cannot complete until we finish | |
749 | * the initialization process, as there will be at least one | |
750 | * qsmask bit set in the root node until that time, namely the | |
b835db1f PM |
751 | * one corresponding to this CPU, due to the fact that we have |
752 | * irqs disabled. | |
64db4cff | 753 | */ |
a0b6c9a7 | 754 | rcu_for_each_node_breadth_first(rsp, rnp) { |
1304afb2 | 755 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
b0e165c0 | 756 | rcu_preempt_check_blocked_tasks(rnp); |
49e29126 | 757 | rnp->qsmask = rnp->qsmaskinit; |
de078d87 | 758 | rnp->gpnum = rsp->gpnum; |
d09b62df PM |
759 | rnp->completed = rsp->completed; |
760 | if (rnp == rdp->mynode) | |
761 | rcu_start_gp_per_cpu(rsp, rnp, rdp); | |
1304afb2 | 762 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
64db4cff PM |
763 | } |
764 | ||
83f5b01f | 765 | rnp = rcu_get_root(rsp); |
1304afb2 | 766 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
64db4cff | 767 | rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state now OK. */ |
1304afb2 PM |
768 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
769 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); | |
64db4cff PM |
770 | } |
771 | ||
f41d911f | 772 | /* |
d3f6bad3 PM |
773 | * Report a full set of quiescent states to the specified rcu_state |
774 | * data structure. This involves cleaning up after the prior grace | |
775 | * period and letting rcu_start_gp() start up the next grace period | |
776 | * if one is needed. Note that the caller must hold rnp->lock, as | |
777 | * required by rcu_start_gp(), which will release it. | |
f41d911f | 778 | */ |
d3f6bad3 | 779 | static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags) |
fc2219d4 | 780 | __releases(rcu_get_root(rsp)->lock) |
f41d911f | 781 | { |
fc2219d4 | 782 | WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); |
f41d911f | 783 | rsp->completed = rsp->gpnum; |
83f5b01f | 784 | rsp->signaled = RCU_GP_IDLE; |
f41d911f PM |
785 | rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */ |
786 | } | |
787 | ||
64db4cff | 788 | /* |
d3f6bad3 PM |
789 | * Similar to rcu_report_qs_rdp(), for which it is a helper function. |
790 | * Allows quiescent states for a group of CPUs to be reported at one go | |
791 | * to the specified rcu_node structure, though all the CPUs in the group | |
792 | * must be represented by the same rcu_node structure (which need not be | |
793 | * a leaf rcu_node structure, though it often will be). That structure's | |
794 | * lock must be held upon entry, and it is released before return. | |
64db4cff PM |
795 | */ |
796 | static void | |
d3f6bad3 PM |
797 | rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp, |
798 | struct rcu_node *rnp, unsigned long flags) | |
64db4cff PM |
799 | __releases(rnp->lock) |
800 | { | |
28ecd580 PM |
801 | struct rcu_node *rnp_c; |
802 | ||
64db4cff PM |
803 | /* Walk up the rcu_node hierarchy. */ |
804 | for (;;) { | |
805 | if (!(rnp->qsmask & mask)) { | |
806 | ||
807 | /* Our bit has already been cleared, so done. */ | |
1304afb2 | 808 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
809 | return; |
810 | } | |
811 | rnp->qsmask &= ~mask; | |
f41d911f | 812 | if (rnp->qsmask != 0 || rcu_preempted_readers(rnp)) { |
64db4cff PM |
813 | |
814 | /* Other bits still set at this level, so done. */ | |
1304afb2 | 815 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
816 | return; |
817 | } | |
818 | mask = rnp->grpmask; | |
819 | if (rnp->parent == NULL) { | |
820 | ||
821 | /* No more levels. Exit loop holding root lock. */ | |
822 | ||
823 | break; | |
824 | } | |
1304afb2 | 825 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
28ecd580 | 826 | rnp_c = rnp; |
64db4cff | 827 | rnp = rnp->parent; |
1304afb2 | 828 | raw_spin_lock_irqsave(&rnp->lock, flags); |
28ecd580 | 829 | WARN_ON_ONCE(rnp_c->qsmask); |
64db4cff PM |
830 | } |
831 | ||
832 | /* | |
833 | * Get here if we are the last CPU to pass through a quiescent | |
d3f6bad3 | 834 | * state for this grace period. Invoke rcu_report_qs_rsp() |
f41d911f | 835 | * to clean up and start the next grace period if one is needed. |
64db4cff | 836 | */ |
d3f6bad3 | 837 | rcu_report_qs_rsp(rsp, flags); /* releases rnp->lock. */ |
64db4cff PM |
838 | } |
839 | ||
840 | /* | |
d3f6bad3 PM |
841 | * Record a quiescent state for the specified CPU to that CPU's rcu_data |
842 | * structure. This must be either called from the specified CPU, or | |
843 | * called when the specified CPU is known to be offline (and when it is | |
844 | * also known that no other CPU is concurrently trying to help the offline | |
845 | * CPU). The lastcomp argument is used to make sure we are still in the | |
846 | * grace period of interest. We don't want to end the current grace period | |
847 | * based on quiescent states detected in an earlier grace period! | |
64db4cff PM |
848 | */ |
849 | static void | |
d3f6bad3 | 850 | rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp) |
64db4cff PM |
851 | { |
852 | unsigned long flags; | |
853 | unsigned long mask; | |
854 | struct rcu_node *rnp; | |
855 | ||
856 | rnp = rdp->mynode; | |
1304afb2 | 857 | raw_spin_lock_irqsave(&rnp->lock, flags); |
560d4bc0 | 858 | if (lastcomp != rnp->completed) { |
64db4cff PM |
859 | |
860 | /* | |
861 | * Someone beat us to it for this grace period, so leave. | |
862 | * The race with GP start is resolved by the fact that we | |
863 | * hold the leaf rcu_node lock, so that the per-CPU bits | |
864 | * cannot yet be initialized -- so we would simply find our | |
d3f6bad3 PM |
865 | * CPU's bit already cleared in rcu_report_qs_rnp() if this |
866 | * race occurred. | |
64db4cff PM |
867 | */ |
868 | rdp->passed_quiesc = 0; /* try again later! */ | |
1304afb2 | 869 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
870 | return; |
871 | } | |
872 | mask = rdp->grpmask; | |
873 | if ((rnp->qsmask & mask) == 0) { | |
1304afb2 | 874 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
875 | } else { |
876 | rdp->qs_pending = 0; | |
877 | ||
878 | /* | |
879 | * This GP can't end until cpu checks in, so all of our | |
880 | * callbacks can be processed during the next GP. | |
881 | */ | |
64db4cff PM |
882 | rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; |
883 | ||
d3f6bad3 | 884 | rcu_report_qs_rnp(mask, rsp, rnp, flags); /* rlses rnp->lock */ |
64db4cff PM |
885 | } |
886 | } | |
887 | ||
888 | /* | |
889 | * Check to see if there is a new grace period of which this CPU | |
890 | * is not yet aware, and if so, set up local rcu_data state for it. | |
891 | * Otherwise, see if this CPU has just passed through its first | |
892 | * quiescent state for this grace period, and record that fact if so. | |
893 | */ | |
894 | static void | |
895 | rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp) | |
896 | { | |
897 | /* If there is now a new grace period, record and return. */ | |
898 | if (check_for_new_grace_period(rsp, rdp)) | |
899 | return; | |
900 | ||
901 | /* | |
902 | * Does this CPU still need to do its part for current grace period? | |
903 | * If no, return and let the other CPUs do their part as well. | |
904 | */ | |
905 | if (!rdp->qs_pending) | |
906 | return; | |
907 | ||
908 | /* | |
909 | * Was there a quiescent state since the beginning of the grace | |
910 | * period? If no, then exit and wait for the next call. | |
911 | */ | |
912 | if (!rdp->passed_quiesc) | |
913 | return; | |
914 | ||
d3f6bad3 PM |
915 | /* |
916 | * Tell RCU we are done (but rcu_report_qs_rdp() will be the | |
917 | * judge of that). | |
918 | */ | |
919 | rcu_report_qs_rdp(rdp->cpu, rsp, rdp, rdp->passed_quiesc_completed); | |
64db4cff PM |
920 | } |
921 | ||
922 | #ifdef CONFIG_HOTPLUG_CPU | |
923 | ||
e74f4c45 PM |
924 | /* |
925 | * Move a dying CPU's RCU callbacks to the ->orphan_cbs_list for the | |
926 | * specified flavor of RCU. The callbacks will be adopted by the next | |
927 | * _rcu_barrier() invocation or by the CPU_DEAD notifier, whichever | |
928 | * comes first. Because this is invoked from the CPU_DYING notifier, | |
929 | * irqs are already disabled. | |
930 | */ | |
931 | static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp) | |
932 | { | |
933 | int i; | |
934 | struct rcu_data *rdp = rsp->rda[smp_processor_id()]; | |
935 | ||
936 | if (rdp->nxtlist == NULL) | |
937 | return; /* irqs disabled, so comparison is stable. */ | |
1304afb2 | 938 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
e74f4c45 PM |
939 | *rsp->orphan_cbs_tail = rdp->nxtlist; |
940 | rsp->orphan_cbs_tail = rdp->nxttail[RCU_NEXT_TAIL]; | |
941 | rdp->nxtlist = NULL; | |
942 | for (i = 0; i < RCU_NEXT_SIZE; i++) | |
943 | rdp->nxttail[i] = &rdp->nxtlist; | |
944 | rsp->orphan_qlen += rdp->qlen; | |
945 | rdp->qlen = 0; | |
1304afb2 | 946 | raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ |
e74f4c45 PM |
947 | } |
948 | ||
949 | /* | |
950 | * Adopt previously orphaned RCU callbacks. | |
951 | */ | |
952 | static void rcu_adopt_orphan_cbs(struct rcu_state *rsp) | |
953 | { | |
954 | unsigned long flags; | |
955 | struct rcu_data *rdp; | |
956 | ||
1304afb2 | 957 | raw_spin_lock_irqsave(&rsp->onofflock, flags); |
e74f4c45 PM |
958 | rdp = rsp->rda[smp_processor_id()]; |
959 | if (rsp->orphan_cbs_list == NULL) { | |
1304afb2 | 960 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
e74f4c45 PM |
961 | return; |
962 | } | |
963 | *rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_cbs_list; | |
964 | rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_cbs_tail; | |
965 | rdp->qlen += rsp->orphan_qlen; | |
966 | rsp->orphan_cbs_list = NULL; | |
967 | rsp->orphan_cbs_tail = &rsp->orphan_cbs_list; | |
968 | rsp->orphan_qlen = 0; | |
1304afb2 | 969 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
e74f4c45 PM |
970 | } |
971 | ||
64db4cff PM |
972 | /* |
973 | * Remove the outgoing CPU from the bitmasks in the rcu_node hierarchy | |
974 | * and move all callbacks from the outgoing CPU to the current one. | |
975 | */ | |
976 | static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) | |
977 | { | |
64db4cff | 978 | unsigned long flags; |
64db4cff | 979 | unsigned long mask; |
d9a3da06 | 980 | int need_report = 0; |
64db4cff | 981 | struct rcu_data *rdp = rsp->rda[cpu]; |
64db4cff PM |
982 | struct rcu_node *rnp; |
983 | ||
984 | /* Exclude any attempts to start a new grace period. */ | |
1304afb2 | 985 | raw_spin_lock_irqsave(&rsp->onofflock, flags); |
64db4cff PM |
986 | |
987 | /* Remove the outgoing CPU from the masks in the rcu_node hierarchy. */ | |
28ecd580 | 988 | rnp = rdp->mynode; /* this is the outgoing CPU's rnp. */ |
64db4cff PM |
989 | mask = rdp->grpmask; /* rnp->grplo is constant. */ |
990 | do { | |
1304afb2 | 991 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
64db4cff PM |
992 | rnp->qsmaskinit &= ~mask; |
993 | if (rnp->qsmaskinit != 0) { | |
b668c9cf | 994 | if (rnp != rdp->mynode) |
1304afb2 | 995 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
64db4cff PM |
996 | break; |
997 | } | |
b668c9cf | 998 | if (rnp == rdp->mynode) |
d9a3da06 | 999 | need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp); |
b668c9cf | 1000 | else |
1304afb2 | 1001 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
64db4cff | 1002 | mask = rnp->grpmask; |
64db4cff PM |
1003 | rnp = rnp->parent; |
1004 | } while (rnp != NULL); | |
64db4cff | 1005 | |
b668c9cf PM |
1006 | /* |
1007 | * We still hold the leaf rcu_node structure lock here, and | |
1008 | * irqs are still disabled. The reason for this subterfuge is | |
d3f6bad3 PM |
1009 | * because invoking rcu_report_unblock_qs_rnp() with ->onofflock |
1010 | * held leads to deadlock. | |
b668c9cf | 1011 | */ |
1304afb2 | 1012 | raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ |
b668c9cf | 1013 | rnp = rdp->mynode; |
d9a3da06 | 1014 | if (need_report & RCU_OFL_TASKS_NORM_GP) |
d3f6bad3 | 1015 | rcu_report_unblock_qs_rnp(rnp, flags); |
b668c9cf | 1016 | else |
1304afb2 | 1017 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
d9a3da06 PM |
1018 | if (need_report & RCU_OFL_TASKS_EXP_GP) |
1019 | rcu_report_exp_rnp(rsp, rnp); | |
64db4cff | 1020 | |
e74f4c45 | 1021 | rcu_adopt_orphan_cbs(rsp); |
64db4cff PM |
1022 | } |
1023 | ||
1024 | /* | |
1025 | * Remove the specified CPU from the RCU hierarchy and move any pending | |
1026 | * callbacks that it might have to the current CPU. This code assumes | |
1027 | * that at least one CPU in the system will remain running at all times. | |
1028 | * Any attempt to offline -all- CPUs is likely to strand RCU callbacks. | |
1029 | */ | |
1030 | static void rcu_offline_cpu(int cpu) | |
1031 | { | |
d6714c22 | 1032 | __rcu_offline_cpu(cpu, &rcu_sched_state); |
64db4cff | 1033 | __rcu_offline_cpu(cpu, &rcu_bh_state); |
33f76148 | 1034 | rcu_preempt_offline_cpu(cpu); |
64db4cff PM |
1035 | } |
1036 | ||
1037 | #else /* #ifdef CONFIG_HOTPLUG_CPU */ | |
1038 | ||
e74f4c45 PM |
1039 | static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp) |
1040 | { | |
1041 | } | |
1042 | ||
1043 | static void rcu_adopt_orphan_cbs(struct rcu_state *rsp) | |
1044 | { | |
1045 | } | |
1046 | ||
64db4cff PM |
1047 | static void rcu_offline_cpu(int cpu) |
1048 | { | |
1049 | } | |
1050 | ||
1051 | #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */ | |
1052 | ||
1053 | /* | |
1054 | * Invoke any RCU callbacks that have made it to the end of their grace | |
1055 | * period. Thottle as specified by rdp->blimit. | |
1056 | */ | |
37c72e56 | 1057 | static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp) |
64db4cff PM |
1058 | { |
1059 | unsigned long flags; | |
1060 | struct rcu_head *next, *list, **tail; | |
1061 | int count; | |
1062 | ||
1063 | /* If no callbacks are ready, just return.*/ | |
1064 | if (!cpu_has_callbacks_ready_to_invoke(rdp)) | |
1065 | return; | |
1066 | ||
1067 | /* | |
1068 | * Extract the list of ready callbacks, disabling to prevent | |
1069 | * races with call_rcu() from interrupt handlers. | |
1070 | */ | |
1071 | local_irq_save(flags); | |
1072 | list = rdp->nxtlist; | |
1073 | rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL]; | |
1074 | *rdp->nxttail[RCU_DONE_TAIL] = NULL; | |
1075 | tail = rdp->nxttail[RCU_DONE_TAIL]; | |
1076 | for (count = RCU_NEXT_SIZE - 1; count >= 0; count--) | |
1077 | if (rdp->nxttail[count] == rdp->nxttail[RCU_DONE_TAIL]) | |
1078 | rdp->nxttail[count] = &rdp->nxtlist; | |
1079 | local_irq_restore(flags); | |
1080 | ||
1081 | /* Invoke callbacks. */ | |
1082 | count = 0; | |
1083 | while (list) { | |
1084 | next = list->next; | |
1085 | prefetch(next); | |
1086 | list->func(list); | |
1087 | list = next; | |
1088 | if (++count >= rdp->blimit) | |
1089 | break; | |
1090 | } | |
1091 | ||
1092 | local_irq_save(flags); | |
1093 | ||
1094 | /* Update count, and requeue any remaining callbacks. */ | |
1095 | rdp->qlen -= count; | |
1096 | if (list != NULL) { | |
1097 | *tail = rdp->nxtlist; | |
1098 | rdp->nxtlist = list; | |
1099 | for (count = 0; count < RCU_NEXT_SIZE; count++) | |
1100 | if (&rdp->nxtlist == rdp->nxttail[count]) | |
1101 | rdp->nxttail[count] = tail; | |
1102 | else | |
1103 | break; | |
1104 | } | |
1105 | ||
1106 | /* Reinstate batch limit if we have worked down the excess. */ | |
1107 | if (rdp->blimit == LONG_MAX && rdp->qlen <= qlowmark) | |
1108 | rdp->blimit = blimit; | |
1109 | ||
37c72e56 PM |
1110 | /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */ |
1111 | if (rdp->qlen == 0 && rdp->qlen_last_fqs_check != 0) { | |
1112 | rdp->qlen_last_fqs_check = 0; | |
1113 | rdp->n_force_qs_snap = rsp->n_force_qs; | |
1114 | } else if (rdp->qlen < rdp->qlen_last_fqs_check - qhimark) | |
1115 | rdp->qlen_last_fqs_check = rdp->qlen; | |
1116 | ||
64db4cff PM |
1117 | local_irq_restore(flags); |
1118 | ||
1119 | /* Re-raise the RCU softirq if there are callbacks remaining. */ | |
1120 | if (cpu_has_callbacks_ready_to_invoke(rdp)) | |
1121 | raise_softirq(RCU_SOFTIRQ); | |
1122 | } | |
1123 | ||
1124 | /* | |
1125 | * Check to see if this CPU is in a non-context-switch quiescent state | |
1126 | * (user mode or idle loop for rcu, non-softirq execution for rcu_bh). | |
1127 | * Also schedule the RCU softirq handler. | |
1128 | * | |
1129 | * This function must be called with hardirqs disabled. It is normally | |
1130 | * invoked from the scheduling-clock interrupt. If rcu_pending returns | |
1131 | * false, there is no point in invoking rcu_check_callbacks(). | |
1132 | */ | |
1133 | void rcu_check_callbacks(int cpu, int user) | |
1134 | { | |
a157229c PM |
1135 | if (!rcu_pending(cpu)) |
1136 | return; /* if nothing for RCU to do. */ | |
64db4cff | 1137 | if (user || |
a6826048 PM |
1138 | (idle_cpu(cpu) && rcu_scheduler_active && |
1139 | !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) { | |
64db4cff PM |
1140 | |
1141 | /* | |
1142 | * Get here if this CPU took its interrupt from user | |
1143 | * mode or from the idle loop, and if this is not a | |
1144 | * nested interrupt. In this case, the CPU is in | |
d6714c22 | 1145 | * a quiescent state, so note it. |
64db4cff PM |
1146 | * |
1147 | * No memory barrier is required here because both | |
d6714c22 PM |
1148 | * rcu_sched_qs() and rcu_bh_qs() reference only CPU-local |
1149 | * variables that other CPUs neither access nor modify, | |
1150 | * at least not while the corresponding CPU is online. | |
64db4cff PM |
1151 | */ |
1152 | ||
d6714c22 PM |
1153 | rcu_sched_qs(cpu); |
1154 | rcu_bh_qs(cpu); | |
64db4cff PM |
1155 | |
1156 | } else if (!in_softirq()) { | |
1157 | ||
1158 | /* | |
1159 | * Get here if this CPU did not take its interrupt from | |
1160 | * softirq, in other words, if it is not interrupting | |
1161 | * a rcu_bh read-side critical section. This is an _bh | |
d6714c22 | 1162 | * critical section, so note it. |
64db4cff PM |
1163 | */ |
1164 | ||
d6714c22 | 1165 | rcu_bh_qs(cpu); |
64db4cff | 1166 | } |
f41d911f | 1167 | rcu_preempt_check_callbacks(cpu); |
64db4cff PM |
1168 | raise_softirq(RCU_SOFTIRQ); |
1169 | } | |
1170 | ||
1171 | #ifdef CONFIG_SMP | |
1172 | ||
1173 | /* | |
1174 | * Scan the leaf rcu_node structures, processing dyntick state for any that | |
1175 | * have not yet encountered a quiescent state, using the function specified. | |
ee47eb9f | 1176 | * The caller must have suppressed start of new grace periods. |
64db4cff | 1177 | */ |
45f014c5 | 1178 | static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *)) |
64db4cff PM |
1179 | { |
1180 | unsigned long bit; | |
1181 | int cpu; | |
1182 | unsigned long flags; | |
1183 | unsigned long mask; | |
a0b6c9a7 | 1184 | struct rcu_node *rnp; |
64db4cff | 1185 | |
a0b6c9a7 | 1186 | rcu_for_each_leaf_node(rsp, rnp) { |
64db4cff | 1187 | mask = 0; |
1304afb2 | 1188 | raw_spin_lock_irqsave(&rnp->lock, flags); |
ee47eb9f | 1189 | if (!rcu_gp_in_progress(rsp)) { |
1304afb2 | 1190 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
0f10dc82 | 1191 | return; |
64db4cff | 1192 | } |
a0b6c9a7 | 1193 | if (rnp->qsmask == 0) { |
1304afb2 | 1194 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff PM |
1195 | continue; |
1196 | } | |
a0b6c9a7 | 1197 | cpu = rnp->grplo; |
64db4cff | 1198 | bit = 1; |
a0b6c9a7 PM |
1199 | for (; cpu <= rnp->grphi; cpu++, bit <<= 1) { |
1200 | if ((rnp->qsmask & bit) != 0 && f(rsp->rda[cpu])) | |
64db4cff PM |
1201 | mask |= bit; |
1202 | } | |
45f014c5 | 1203 | if (mask != 0) { |
64db4cff | 1204 | |
d3f6bad3 PM |
1205 | /* rcu_report_qs_rnp() releases rnp->lock. */ |
1206 | rcu_report_qs_rnp(mask, rsp, rnp, flags); | |
64db4cff PM |
1207 | continue; |
1208 | } | |
1304afb2 | 1209 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
64db4cff | 1210 | } |
64db4cff PM |
1211 | } |
1212 | ||
1213 | /* | |
1214 | * Force quiescent states on reluctant CPUs, and also detect which | |
1215 | * CPUs are in dyntick-idle mode. | |
1216 | */ | |
1217 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) | |
1218 | { | |
1219 | unsigned long flags; | |
64db4cff | 1220 | struct rcu_node *rnp = rcu_get_root(rsp); |
64db4cff | 1221 | |
fc2219d4 | 1222 | if (!rcu_gp_in_progress(rsp)) |
64db4cff | 1223 | return; /* No grace period in progress, nothing to force. */ |
1304afb2 | 1224 | if (!raw_spin_trylock_irqsave(&rsp->fqslock, flags)) { |
64db4cff PM |
1225 | rsp->n_force_qs_lh++; /* Inexact, can lose counts. Tough! */ |
1226 | return; /* Someone else is already on the job. */ | |
1227 | } | |
20133cfc | 1228 | if (relaxed && ULONG_CMP_GE(rsp->jiffies_force_qs, jiffies)) |
f96e9232 | 1229 | goto unlock_fqs_ret; /* no emergency and done recently. */ |
64db4cff | 1230 | rsp->n_force_qs++; |
1304afb2 | 1231 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
64db4cff | 1232 | rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; |
560d4bc0 | 1233 | if(!rcu_gp_in_progress(rsp)) { |
64db4cff | 1234 | rsp->n_force_qs_ngp++; |
1304afb2 | 1235 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
f96e9232 | 1236 | goto unlock_fqs_ret; /* no GP in progress, time updated. */ |
64db4cff | 1237 | } |
07079d53 | 1238 | rsp->fqs_active = 1; |
f3a8b5c6 | 1239 | switch (rsp->signaled) { |
83f5b01f | 1240 | case RCU_GP_IDLE: |
64db4cff PM |
1241 | case RCU_GP_INIT: |
1242 | ||
83f5b01f | 1243 | break; /* grace period idle or initializing, ignore. */ |
64db4cff PM |
1244 | |
1245 | case RCU_SAVE_DYNTICK: | |
64db4cff PM |
1246 | if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK) |
1247 | break; /* So gcc recognizes the dead code. */ | |
1248 | ||
f261414f LJ |
1249 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
1250 | ||
64db4cff | 1251 | /* Record dyntick-idle state. */ |
45f014c5 | 1252 | force_qs_rnp(rsp, dyntick_save_progress_counter); |
1304afb2 | 1253 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
ee47eb9f | 1254 | if (rcu_gp_in_progress(rsp)) |
64db4cff | 1255 | rsp->signaled = RCU_FORCE_QS; |
ee47eb9f | 1256 | break; |
64db4cff PM |
1257 | |
1258 | case RCU_FORCE_QS: | |
1259 | ||
1260 | /* Check dyntick-idle state, send IPI to laggarts. */ | |
1304afb2 | 1261 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
45f014c5 | 1262 | force_qs_rnp(rsp, rcu_implicit_dynticks_qs); |
64db4cff PM |
1263 | |
1264 | /* Leave state in case more forcing is required. */ | |
1265 | ||
1304afb2 | 1266 | raw_spin_lock(&rnp->lock); /* irqs already disabled */ |
f96e9232 | 1267 | break; |
64db4cff | 1268 | } |
07079d53 | 1269 | rsp->fqs_active = 0; |
46a1e34e | 1270 | if (rsp->fqs_need_gp) { |
1304afb2 | 1271 | raw_spin_unlock(&rsp->fqslock); /* irqs remain disabled */ |
46a1e34e PM |
1272 | rsp->fqs_need_gp = 0; |
1273 | rcu_start_gp(rsp, flags); /* releases rnp->lock */ | |
1274 | return; | |
1275 | } | |
1304afb2 | 1276 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ |
f96e9232 | 1277 | unlock_fqs_ret: |
1304afb2 | 1278 | raw_spin_unlock_irqrestore(&rsp->fqslock, flags); |
64db4cff PM |
1279 | } |
1280 | ||
1281 | #else /* #ifdef CONFIG_SMP */ | |
1282 | ||
1283 | static void force_quiescent_state(struct rcu_state *rsp, int relaxed) | |
1284 | { | |
1285 | set_need_resched(); | |
1286 | } | |
1287 | ||
1288 | #endif /* #else #ifdef CONFIG_SMP */ | |
1289 | ||
1290 | /* | |
1291 | * This does the RCU processing work from softirq context for the | |
1292 | * specified rcu_state and rcu_data structures. This may be called | |
1293 | * only from the CPU to whom the rdp belongs. | |
1294 | */ | |
1295 | static void | |
1296 | __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) | |
1297 | { | |
1298 | unsigned long flags; | |
1299 | ||
2e597558 PM |
1300 | WARN_ON_ONCE(rdp->beenonline == 0); |
1301 | ||
64db4cff PM |
1302 | /* |
1303 | * If an RCU GP has gone long enough, go check for dyntick | |
1304 | * idle CPUs and, if needed, send resched IPIs. | |
1305 | */ | |
20133cfc | 1306 | if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) |
64db4cff PM |
1307 | force_quiescent_state(rsp, 1); |
1308 | ||
1309 | /* | |
1310 | * Advance callbacks in response to end of earlier grace | |
1311 | * period that some other CPU ended. | |
1312 | */ | |
1313 | rcu_process_gp_end(rsp, rdp); | |
1314 | ||
1315 | /* Update RCU state based on any recent quiescent states. */ | |
1316 | rcu_check_quiescent_state(rsp, rdp); | |
1317 | ||
1318 | /* Does this CPU require a not-yet-started grace period? */ | |
1319 | if (cpu_needs_another_gp(rsp, rdp)) { | |
1304afb2 | 1320 | raw_spin_lock_irqsave(&rcu_get_root(rsp)->lock, flags); |
64db4cff PM |
1321 | rcu_start_gp(rsp, flags); /* releases above lock */ |
1322 | } | |
1323 | ||
1324 | /* If there are callbacks ready, invoke them. */ | |
37c72e56 | 1325 | rcu_do_batch(rsp, rdp); |
64db4cff PM |
1326 | } |
1327 | ||
1328 | /* | |
1329 | * Do softirq processing for the current CPU. | |
1330 | */ | |
1331 | static void rcu_process_callbacks(struct softirq_action *unused) | |
1332 | { | |
1333 | /* | |
1334 | * Memory references from any prior RCU read-side critical sections | |
1335 | * executed by the interrupted code must be seen before any RCU | |
1336 | * grace-period manipulations below. | |
1337 | */ | |
1338 | smp_mb(); /* See above block comment. */ | |
1339 | ||
d6714c22 PM |
1340 | __rcu_process_callbacks(&rcu_sched_state, |
1341 | &__get_cpu_var(rcu_sched_data)); | |
64db4cff | 1342 | __rcu_process_callbacks(&rcu_bh_state, &__get_cpu_var(rcu_bh_data)); |
f41d911f | 1343 | rcu_preempt_process_callbacks(); |
64db4cff PM |
1344 | |
1345 | /* | |
1346 | * Memory references from any later RCU read-side critical sections | |
1347 | * executed by the interrupted code must be seen after any RCU | |
1348 | * grace-period manipulations above. | |
1349 | */ | |
1350 | smp_mb(); /* See above block comment. */ | |
a47cd880 PM |
1351 | |
1352 | /* If we are last CPU on way to dyntick-idle mode, accelerate it. */ | |
1353 | rcu_needs_cpu_flush(); | |
64db4cff PM |
1354 | } |
1355 | ||
1356 | static void | |
1357 | __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), | |
1358 | struct rcu_state *rsp) | |
1359 | { | |
1360 | unsigned long flags; | |
1361 | struct rcu_data *rdp; | |
1362 | ||
1363 | head->func = func; | |
1364 | head->next = NULL; | |
1365 | ||
1366 | smp_mb(); /* Ensure RCU update seen before callback registry. */ | |
1367 | ||
1368 | /* | |
1369 | * Opportunistically note grace-period endings and beginnings. | |
1370 | * Note that we might see a beginning right after we see an | |
1371 | * end, but never vice versa, since this CPU has to pass through | |
1372 | * a quiescent state betweentimes. | |
1373 | */ | |
1374 | local_irq_save(flags); | |
1375 | rdp = rsp->rda[smp_processor_id()]; | |
1376 | rcu_process_gp_end(rsp, rdp); | |
1377 | check_for_new_grace_period(rsp, rdp); | |
1378 | ||
1379 | /* Add the callback to our list. */ | |
1380 | *rdp->nxttail[RCU_NEXT_TAIL] = head; | |
1381 | rdp->nxttail[RCU_NEXT_TAIL] = &head->next; | |
1382 | ||
1383 | /* Start a new grace period if one not already started. */ | |
fc2219d4 | 1384 | if (!rcu_gp_in_progress(rsp)) { |
64db4cff PM |
1385 | unsigned long nestflag; |
1386 | struct rcu_node *rnp_root = rcu_get_root(rsp); | |
1387 | ||
1304afb2 | 1388 | raw_spin_lock_irqsave(&rnp_root->lock, nestflag); |
64db4cff PM |
1389 | rcu_start_gp(rsp, nestflag); /* releases rnp_root->lock. */ |
1390 | } | |
1391 | ||
37c72e56 PM |
1392 | /* |
1393 | * Force the grace period if too many callbacks or too long waiting. | |
1394 | * Enforce hysteresis, and don't invoke force_quiescent_state() | |
1395 | * if some other CPU has recently done so. Also, don't bother | |
1396 | * invoking force_quiescent_state() if the newly enqueued callback | |
1397 | * is the only one waiting for a grace period to complete. | |
1398 | */ | |
1399 | if (unlikely(++rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) { | |
64db4cff | 1400 | rdp->blimit = LONG_MAX; |
37c72e56 PM |
1401 | if (rsp->n_force_qs == rdp->n_force_qs_snap && |
1402 | *rdp->nxttail[RCU_DONE_TAIL] != head) | |
1403 | force_quiescent_state(rsp, 0); | |
1404 | rdp->n_force_qs_snap = rsp->n_force_qs; | |
1405 | rdp->qlen_last_fqs_check = rdp->qlen; | |
20133cfc | 1406 | } else if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) |
64db4cff PM |
1407 | force_quiescent_state(rsp, 1); |
1408 | local_irq_restore(flags); | |
1409 | } | |
1410 | ||
1411 | /* | |
d6714c22 | 1412 | * Queue an RCU-sched callback for invocation after a grace period. |
64db4cff | 1413 | */ |
d6714c22 | 1414 | void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) |
64db4cff | 1415 | { |
d6714c22 | 1416 | __call_rcu(head, func, &rcu_sched_state); |
64db4cff | 1417 | } |
d6714c22 | 1418 | EXPORT_SYMBOL_GPL(call_rcu_sched); |
64db4cff PM |
1419 | |
1420 | /* | |
1421 | * Queue an RCU for invocation after a quicker grace period. | |
1422 | */ | |
1423 | void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) | |
1424 | { | |
1425 | __call_rcu(head, func, &rcu_bh_state); | |
1426 | } | |
1427 | EXPORT_SYMBOL_GPL(call_rcu_bh); | |
1428 | ||
6ebb237b PM |
1429 | /** |
1430 | * synchronize_sched - wait until an rcu-sched grace period has elapsed. | |
1431 | * | |
1432 | * Control will return to the caller some time after a full rcu-sched | |
1433 | * grace period has elapsed, in other words after all currently executing | |
1434 | * rcu-sched read-side critical sections have completed. These read-side | |
1435 | * critical sections are delimited by rcu_read_lock_sched() and | |
1436 | * rcu_read_unlock_sched(), and may be nested. Note that preempt_disable(), | |
1437 | * local_irq_disable(), and so on may be used in place of | |
1438 | * rcu_read_lock_sched(). | |
1439 | * | |
1440 | * This means that all preempt_disable code sequences, including NMI and | |
1441 | * hardware-interrupt handlers, in progress on entry will have completed | |
1442 | * before this primitive returns. However, this does not guarantee that | |
1443 | * softirq handlers will have completed, since in some kernels, these | |
1444 | * handlers can run in process context, and can block. | |
1445 | * | |
1446 | * This primitive provides the guarantees made by the (now removed) | |
1447 | * synchronize_kernel() API. In contrast, synchronize_rcu() only | |
1448 | * guarantees that rcu_read_lock() sections will have completed. | |
1449 | * In "classic RCU", these two guarantees happen to be one and | |
1450 | * the same, but can differ in realtime RCU implementations. | |
1451 | */ | |
1452 | void synchronize_sched(void) | |
1453 | { | |
1454 | struct rcu_synchronize rcu; | |
1455 | ||
1456 | if (rcu_blocking_is_gp()) | |
1457 | return; | |
1458 | ||
1459 | init_completion(&rcu.completion); | |
1460 | /* Will wake me after RCU finished. */ | |
1461 | call_rcu_sched(&rcu.head, wakeme_after_rcu); | |
1462 | /* Wait for it. */ | |
1463 | wait_for_completion(&rcu.completion); | |
1464 | } | |
1465 | EXPORT_SYMBOL_GPL(synchronize_sched); | |
1466 | ||
1467 | /** | |
1468 | * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed. | |
1469 | * | |
1470 | * Control will return to the caller some time after a full rcu_bh grace | |
1471 | * period has elapsed, in other words after all currently executing rcu_bh | |
1472 | * read-side critical sections have completed. RCU read-side critical | |
1473 | * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(), | |
1474 | * and may be nested. | |
1475 | */ | |
1476 | void synchronize_rcu_bh(void) | |
1477 | { | |
1478 | struct rcu_synchronize rcu; | |
1479 | ||
1480 | if (rcu_blocking_is_gp()) | |
1481 | return; | |
1482 | ||
1483 | init_completion(&rcu.completion); | |
1484 | /* Will wake me after RCU finished. */ | |
1485 | call_rcu_bh(&rcu.head, wakeme_after_rcu); | |
1486 | /* Wait for it. */ | |
1487 | wait_for_completion(&rcu.completion); | |
1488 | } | |
1489 | EXPORT_SYMBOL_GPL(synchronize_rcu_bh); | |
1490 | ||
64db4cff PM |
1491 | /* |
1492 | * Check to see if there is any immediate RCU-related work to be done | |
1493 | * by the current CPU, for the specified type of RCU, returning 1 if so. | |
1494 | * The checks are in order of increasing expense: checks that can be | |
1495 | * carried out against CPU-local state are performed first. However, | |
1496 | * we must check for CPU stalls first, else we might not get a chance. | |
1497 | */ | |
1498 | static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) | |
1499 | { | |
2f51f988 PM |
1500 | struct rcu_node *rnp = rdp->mynode; |
1501 | ||
64db4cff PM |
1502 | rdp->n_rcu_pending++; |
1503 | ||
1504 | /* Check for CPU stalls, if enabled. */ | |
1505 | check_cpu_stall(rsp, rdp); | |
1506 | ||
1507 | /* Is the RCU core waiting for a quiescent state from this CPU? */ | |
7ba5c840 | 1508 | if (rdp->qs_pending) { |
d25eb944 PM |
1509 | |
1510 | /* | |
1511 | * If force_quiescent_state() coming soon and this CPU | |
1512 | * needs a quiescent state, and this is either RCU-sched | |
1513 | * or RCU-bh, force a local reschedule. | |
1514 | */ | |
1515 | if (!rdp->preemptable && | |
1516 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs) - 1, | |
1517 | jiffies)) | |
1518 | set_need_resched(); | |
7ba5c840 | 1519 | rdp->n_rp_qs_pending++; |
64db4cff | 1520 | return 1; |
7ba5c840 | 1521 | } |
64db4cff PM |
1522 | |
1523 | /* Does this CPU have callbacks ready to invoke? */ | |
7ba5c840 PM |
1524 | if (cpu_has_callbacks_ready_to_invoke(rdp)) { |
1525 | rdp->n_rp_cb_ready++; | |
64db4cff | 1526 | return 1; |
7ba5c840 | 1527 | } |
64db4cff PM |
1528 | |
1529 | /* Has RCU gone idle with this CPU needing another grace period? */ | |
7ba5c840 PM |
1530 | if (cpu_needs_another_gp(rsp, rdp)) { |
1531 | rdp->n_rp_cpu_needs_gp++; | |
64db4cff | 1532 | return 1; |
7ba5c840 | 1533 | } |
64db4cff PM |
1534 | |
1535 | /* Has another RCU grace period completed? */ | |
2f51f988 | 1536 | if (ACCESS_ONCE(rnp->completed) != rdp->completed) { /* outside lock */ |
7ba5c840 | 1537 | rdp->n_rp_gp_completed++; |
64db4cff | 1538 | return 1; |
7ba5c840 | 1539 | } |
64db4cff PM |
1540 | |
1541 | /* Has a new RCU grace period started? */ | |
2f51f988 | 1542 | if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum) { /* outside lock */ |
7ba5c840 | 1543 | rdp->n_rp_gp_started++; |
64db4cff | 1544 | return 1; |
7ba5c840 | 1545 | } |
64db4cff PM |
1546 | |
1547 | /* Has an RCU GP gone long enough to send resched IPIs &c? */ | |
fc2219d4 | 1548 | if (rcu_gp_in_progress(rsp) && |
20133cfc | 1549 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) { |
7ba5c840 | 1550 | rdp->n_rp_need_fqs++; |
64db4cff | 1551 | return 1; |
7ba5c840 | 1552 | } |
64db4cff PM |
1553 | |
1554 | /* nothing to do */ | |
7ba5c840 | 1555 | rdp->n_rp_need_nothing++; |
64db4cff PM |
1556 | return 0; |
1557 | } | |
1558 | ||
1559 | /* | |
1560 | * Check to see if there is any immediate RCU-related work to be done | |
1561 | * by the current CPU, returning 1 if so. This function is part of the | |
1562 | * RCU implementation; it is -not- an exported member of the RCU API. | |
1563 | */ | |
a157229c | 1564 | static int rcu_pending(int cpu) |
64db4cff | 1565 | { |
d6714c22 | 1566 | return __rcu_pending(&rcu_sched_state, &per_cpu(rcu_sched_data, cpu)) || |
f41d911f PM |
1567 | __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu)) || |
1568 | rcu_preempt_pending(cpu); | |
64db4cff PM |
1569 | } |
1570 | ||
1571 | /* | |
1572 | * Check to see if any future RCU-related work will need to be done | |
1573 | * by the current CPU, even if none need be done immediately, returning | |
8bd93a2c | 1574 | * 1 if so. |
64db4cff | 1575 | */ |
8bd93a2c | 1576 | static int rcu_needs_cpu_quick_check(int cpu) |
64db4cff PM |
1577 | { |
1578 | /* RCU callbacks either ready or pending? */ | |
d6714c22 | 1579 | return per_cpu(rcu_sched_data, cpu).nxtlist || |
f41d911f PM |
1580 | per_cpu(rcu_bh_data, cpu).nxtlist || |
1581 | rcu_preempt_needs_cpu(cpu); | |
64db4cff PM |
1582 | } |
1583 | ||
d0ec774c PM |
1584 | static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL}; |
1585 | static atomic_t rcu_barrier_cpu_count; | |
1586 | static DEFINE_MUTEX(rcu_barrier_mutex); | |
1587 | static struct completion rcu_barrier_completion; | |
d0ec774c PM |
1588 | |
1589 | static void rcu_barrier_callback(struct rcu_head *notused) | |
1590 | { | |
1591 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) | |
1592 | complete(&rcu_barrier_completion); | |
1593 | } | |
1594 | ||
1595 | /* | |
1596 | * Called with preemption disabled, and from cross-cpu IRQ context. | |
1597 | */ | |
1598 | static void rcu_barrier_func(void *type) | |
1599 | { | |
1600 | int cpu = smp_processor_id(); | |
1601 | struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu); | |
1602 | void (*call_rcu_func)(struct rcu_head *head, | |
1603 | void (*func)(struct rcu_head *head)); | |
1604 | ||
1605 | atomic_inc(&rcu_barrier_cpu_count); | |
1606 | call_rcu_func = type; | |
1607 | call_rcu_func(head, rcu_barrier_callback); | |
1608 | } | |
1609 | ||
d0ec774c PM |
1610 | /* |
1611 | * Orchestrate the specified type of RCU barrier, waiting for all | |
1612 | * RCU callbacks of the specified type to complete. | |
1613 | */ | |
e74f4c45 PM |
1614 | static void _rcu_barrier(struct rcu_state *rsp, |
1615 | void (*call_rcu_func)(struct rcu_head *head, | |
d0ec774c PM |
1616 | void (*func)(struct rcu_head *head))) |
1617 | { | |
1618 | BUG_ON(in_interrupt()); | |
e74f4c45 | 1619 | /* Take mutex to serialize concurrent rcu_barrier() requests. */ |
d0ec774c PM |
1620 | mutex_lock(&rcu_barrier_mutex); |
1621 | init_completion(&rcu_barrier_completion); | |
1622 | /* | |
1623 | * Initialize rcu_barrier_cpu_count to 1, then invoke | |
1624 | * rcu_barrier_func() on each CPU, so that each CPU also has | |
1625 | * incremented rcu_barrier_cpu_count. Only then is it safe to | |
1626 | * decrement rcu_barrier_cpu_count -- otherwise the first CPU | |
1627 | * might complete its grace period before all of the other CPUs | |
1628 | * did their increment, causing this function to return too | |
1629 | * early. | |
1630 | */ | |
1631 | atomic_set(&rcu_barrier_cpu_count, 1); | |
e74f4c45 PM |
1632 | preempt_disable(); /* stop CPU_DYING from filling orphan_cbs_list */ |
1633 | rcu_adopt_orphan_cbs(rsp); | |
d0ec774c | 1634 | on_each_cpu(rcu_barrier_func, (void *)call_rcu_func, 1); |
e74f4c45 | 1635 | preempt_enable(); /* CPU_DYING can again fill orphan_cbs_list */ |
d0ec774c PM |
1636 | if (atomic_dec_and_test(&rcu_barrier_cpu_count)) |
1637 | complete(&rcu_barrier_completion); | |
1638 | wait_for_completion(&rcu_barrier_completion); | |
1639 | mutex_unlock(&rcu_barrier_mutex); | |
d0ec774c | 1640 | } |
d0ec774c PM |
1641 | |
1642 | /** | |
1643 | * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete. | |
1644 | */ | |
1645 | void rcu_barrier_bh(void) | |
1646 | { | |
e74f4c45 | 1647 | _rcu_barrier(&rcu_bh_state, call_rcu_bh); |
d0ec774c PM |
1648 | } |
1649 | EXPORT_SYMBOL_GPL(rcu_barrier_bh); | |
1650 | ||
1651 | /** | |
1652 | * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks. | |
1653 | */ | |
1654 | void rcu_barrier_sched(void) | |
1655 | { | |
e74f4c45 | 1656 | _rcu_barrier(&rcu_sched_state, call_rcu_sched); |
d0ec774c PM |
1657 | } |
1658 | EXPORT_SYMBOL_GPL(rcu_barrier_sched); | |
1659 | ||
64db4cff | 1660 | /* |
27569620 | 1661 | * Do boot-time initialization of a CPU's per-CPU RCU data. |
64db4cff | 1662 | */ |
27569620 PM |
1663 | static void __init |
1664 | rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) | |
64db4cff PM |
1665 | { |
1666 | unsigned long flags; | |
1667 | int i; | |
27569620 PM |
1668 | struct rcu_data *rdp = rsp->rda[cpu]; |
1669 | struct rcu_node *rnp = rcu_get_root(rsp); | |
1670 | ||
1671 | /* Set up local state, ensuring consistent view of global state. */ | |
1304afb2 | 1672 | raw_spin_lock_irqsave(&rnp->lock, flags); |
27569620 PM |
1673 | rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo); |
1674 | rdp->nxtlist = NULL; | |
1675 | for (i = 0; i < RCU_NEXT_SIZE; i++) | |
1676 | rdp->nxttail[i] = &rdp->nxtlist; | |
1677 | rdp->qlen = 0; | |
1678 | #ifdef CONFIG_NO_HZ | |
1679 | rdp->dynticks = &per_cpu(rcu_dynticks, cpu); | |
1680 | #endif /* #ifdef CONFIG_NO_HZ */ | |
1681 | rdp->cpu = cpu; | |
1304afb2 | 1682 | raw_spin_unlock_irqrestore(&rnp->lock, flags); |
27569620 PM |
1683 | } |
1684 | ||
1685 | /* | |
1686 | * Initialize a CPU's per-CPU RCU data. Note that only one online or | |
1687 | * offline event can be happening at a given time. Note also that we | |
1688 | * can accept some slop in the rsp->completed access due to the fact | |
1689 | * that this CPU cannot possibly have any RCU callbacks in flight yet. | |
64db4cff | 1690 | */ |
e4fa4c97 | 1691 | static void __cpuinit |
f41d911f | 1692 | rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable) |
64db4cff PM |
1693 | { |
1694 | unsigned long flags; | |
64db4cff PM |
1695 | unsigned long mask; |
1696 | struct rcu_data *rdp = rsp->rda[cpu]; | |
1697 | struct rcu_node *rnp = rcu_get_root(rsp); | |
1698 | ||
1699 | /* Set up local state, ensuring consistent view of global state. */ | |
1304afb2 | 1700 | raw_spin_lock_irqsave(&rnp->lock, flags); |
64db4cff PM |
1701 | rdp->passed_quiesc = 0; /* We could be racing with new GP, */ |
1702 | rdp->qs_pending = 1; /* so set up to respond to current GP. */ | |
1703 | rdp->beenonline = 1; /* We have now been online. */ | |
f41d911f | 1704 | rdp->preemptable = preemptable; |
37c72e56 PM |
1705 | rdp->qlen_last_fqs_check = 0; |
1706 | rdp->n_force_qs_snap = rsp->n_force_qs; | |
64db4cff | 1707 | rdp->blimit = blimit; |
1304afb2 | 1708 | raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ |
64db4cff PM |
1709 | |
1710 | /* | |
1711 | * A new grace period might start here. If so, we won't be part | |
1712 | * of it, but that is OK, as we are currently in a quiescent state. | |
1713 | */ | |
1714 | ||
1715 | /* Exclude any attempts to start a new GP on large systems. */ | |
1304afb2 | 1716 | raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ |
64db4cff PM |
1717 | |
1718 | /* Add CPU to rcu_node bitmasks. */ | |
1719 | rnp = rdp->mynode; | |
1720 | mask = rdp->grpmask; | |
1721 | do { | |
1722 | /* Exclude any attempts to start a new GP on small systems. */ | |
1304afb2 | 1723 | raw_spin_lock(&rnp->lock); /* irqs already disabled. */ |
64db4cff PM |
1724 | rnp->qsmaskinit |= mask; |
1725 | mask = rnp->grpmask; | |
d09b62df PM |
1726 | if (rnp == rdp->mynode) { |
1727 | rdp->gpnum = rnp->completed; /* if GP in progress... */ | |
1728 | rdp->completed = rnp->completed; | |
1729 | rdp->passed_quiesc_completed = rnp->completed - 1; | |
1730 | } | |
1304afb2 | 1731 | raw_spin_unlock(&rnp->lock); /* irqs already disabled. */ |
64db4cff PM |
1732 | rnp = rnp->parent; |
1733 | } while (rnp != NULL && !(rnp->qsmaskinit & mask)); | |
1734 | ||
1304afb2 | 1735 | raw_spin_unlock_irqrestore(&rsp->onofflock, flags); |
64db4cff PM |
1736 | } |
1737 | ||
1738 | static void __cpuinit rcu_online_cpu(int cpu) | |
1739 | { | |
f41d911f PM |
1740 | rcu_init_percpu_data(cpu, &rcu_sched_state, 0); |
1741 | rcu_init_percpu_data(cpu, &rcu_bh_state, 0); | |
1742 | rcu_preempt_init_percpu_data(cpu); | |
64db4cff PM |
1743 | } |
1744 | ||
1745 | /* | |
f41d911f | 1746 | * Handle CPU online/offline notification events. |
64db4cff | 1747 | */ |
9f680ab4 PM |
1748 | static int __cpuinit rcu_cpu_notify(struct notifier_block *self, |
1749 | unsigned long action, void *hcpu) | |
64db4cff PM |
1750 | { |
1751 | long cpu = (long)hcpu; | |
1752 | ||
1753 | switch (action) { | |
1754 | case CPU_UP_PREPARE: | |
1755 | case CPU_UP_PREPARE_FROZEN: | |
1756 | rcu_online_cpu(cpu); | |
1757 | break; | |
d0ec774c PM |
1758 | case CPU_DYING: |
1759 | case CPU_DYING_FROZEN: | |
1760 | /* | |
e74f4c45 | 1761 | * preempt_disable() in _rcu_barrier() prevents stop_machine(), |
d0ec774c | 1762 | * so when "on_each_cpu(rcu_barrier_func, (void *)type, 1);" |
e74f4c45 PM |
1763 | * returns, all online cpus have queued rcu_barrier_func(). |
1764 | * The dying CPU clears its cpu_online_mask bit and | |
1765 | * moves all of its RCU callbacks to ->orphan_cbs_list | |
1766 | * in the context of stop_machine(), so subsequent calls | |
1767 | * to _rcu_barrier() will adopt these callbacks and only | |
1768 | * then queue rcu_barrier_func() on all remaining CPUs. | |
d0ec774c | 1769 | */ |
e74f4c45 PM |
1770 | rcu_send_cbs_to_orphanage(&rcu_bh_state); |
1771 | rcu_send_cbs_to_orphanage(&rcu_sched_state); | |
1772 | rcu_preempt_send_cbs_to_orphanage(); | |
d0ec774c | 1773 | break; |
64db4cff PM |
1774 | case CPU_DEAD: |
1775 | case CPU_DEAD_FROZEN: | |
1776 | case CPU_UP_CANCELED: | |
1777 | case CPU_UP_CANCELED_FROZEN: | |
1778 | rcu_offline_cpu(cpu); | |
1779 | break; | |
1780 | default: | |
1781 | break; | |
1782 | } | |
1783 | return NOTIFY_OK; | |
1784 | } | |
1785 | ||
1786 | /* | |
1787 | * Compute the per-level fanout, either using the exact fanout specified | |
1788 | * or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT. | |
1789 | */ | |
1790 | #ifdef CONFIG_RCU_FANOUT_EXACT | |
1791 | static void __init rcu_init_levelspread(struct rcu_state *rsp) | |
1792 | { | |
1793 | int i; | |
1794 | ||
1795 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) | |
1796 | rsp->levelspread[i] = CONFIG_RCU_FANOUT; | |
1797 | } | |
1798 | #else /* #ifdef CONFIG_RCU_FANOUT_EXACT */ | |
1799 | static void __init rcu_init_levelspread(struct rcu_state *rsp) | |
1800 | { | |
1801 | int ccur; | |
1802 | int cprv; | |
1803 | int i; | |
1804 | ||
1805 | cprv = NR_CPUS; | |
1806 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { | |
1807 | ccur = rsp->levelcnt[i]; | |
1808 | rsp->levelspread[i] = (cprv + ccur - 1) / ccur; | |
1809 | cprv = ccur; | |
1810 | } | |
1811 | } | |
1812 | #endif /* #else #ifdef CONFIG_RCU_FANOUT_EXACT */ | |
1813 | ||
1814 | /* | |
1815 | * Helper function for rcu_init() that initializes one rcu_state structure. | |
1816 | */ | |
1817 | static void __init rcu_init_one(struct rcu_state *rsp) | |
1818 | { | |
b6407e86 PM |
1819 | static char *buf[] = { "rcu_node_level_0", |
1820 | "rcu_node_level_1", | |
1821 | "rcu_node_level_2", | |
1822 | "rcu_node_level_3" }; /* Match MAX_RCU_LVLS */ | |
64db4cff PM |
1823 | int cpustride = 1; |
1824 | int i; | |
1825 | int j; | |
1826 | struct rcu_node *rnp; | |
1827 | ||
b6407e86 PM |
1828 | BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */ |
1829 | ||
64db4cff PM |
1830 | /* Initialize the level-tracking arrays. */ |
1831 | ||
1832 | for (i = 1; i < NUM_RCU_LVLS; i++) | |
1833 | rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1]; | |
1834 | rcu_init_levelspread(rsp); | |
1835 | ||
1836 | /* Initialize the elements themselves, starting from the leaves. */ | |
1837 | ||
1838 | for (i = NUM_RCU_LVLS - 1; i >= 0; i--) { | |
1839 | cpustride *= rsp->levelspread[i]; | |
1840 | rnp = rsp->level[i]; | |
1841 | for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) { | |
1304afb2 | 1842 | raw_spin_lock_init(&rnp->lock); |
b6407e86 PM |
1843 | lockdep_set_class_and_name(&rnp->lock, |
1844 | &rcu_node_class[i], buf[i]); | |
f41d911f | 1845 | rnp->gpnum = 0; |
64db4cff PM |
1846 | rnp->qsmask = 0; |
1847 | rnp->qsmaskinit = 0; | |
1848 | rnp->grplo = j * cpustride; | |
1849 | rnp->grphi = (j + 1) * cpustride - 1; | |
1850 | if (rnp->grphi >= NR_CPUS) | |
1851 | rnp->grphi = NR_CPUS - 1; | |
1852 | if (i == 0) { | |
1853 | rnp->grpnum = 0; | |
1854 | rnp->grpmask = 0; | |
1855 | rnp->parent = NULL; | |
1856 | } else { | |
1857 | rnp->grpnum = j % rsp->levelspread[i - 1]; | |
1858 | rnp->grpmask = 1UL << rnp->grpnum; | |
1859 | rnp->parent = rsp->level[i - 1] + | |
1860 | j / rsp->levelspread[i - 1]; | |
1861 | } | |
1862 | rnp->level = i; | |
f41d911f PM |
1863 | INIT_LIST_HEAD(&rnp->blocked_tasks[0]); |
1864 | INIT_LIST_HEAD(&rnp->blocked_tasks[1]); | |
d9a3da06 PM |
1865 | INIT_LIST_HEAD(&rnp->blocked_tasks[2]); |
1866 | INIT_LIST_HEAD(&rnp->blocked_tasks[3]); | |
64db4cff PM |
1867 | } |
1868 | } | |
0c34029a LJ |
1869 | |
1870 | rnp = rsp->level[NUM_RCU_LVLS - 1]; | |
1871 | for_each_possible_cpu(i) { | |
1872 | if (i > rnp->grphi) | |
1873 | rnp++; | |
1874 | rsp->rda[i]->mynode = rnp; | |
1875 | rcu_boot_init_percpu_data(i, rsp); | |
1876 | } | |
64db4cff PM |
1877 | } |
1878 | ||
1879 | /* | |
f41d911f PM |
1880 | * Helper macro for __rcu_init() and __rcu_init_preempt(). To be used |
1881 | * nowhere else! Assigns leaf node pointers into each CPU's rcu_data | |
1882 | * structure. | |
64db4cff | 1883 | */ |
65cf8f86 | 1884 | #define RCU_INIT_FLAVOR(rsp, rcu_data) \ |
64db4cff | 1885 | do { \ |
a0b6c9a7 | 1886 | int i; \ |
a0b6c9a7 | 1887 | \ |
64db4cff | 1888 | for_each_possible_cpu(i) { \ |
64db4cff PM |
1889 | (rsp)->rda[i] = &per_cpu(rcu_data, i); \ |
1890 | } \ | |
0c34029a | 1891 | rcu_init_one(rsp); \ |
64db4cff PM |
1892 | } while (0) |
1893 | ||
9f680ab4 | 1894 | void __init rcu_init(void) |
64db4cff | 1895 | { |
017c4261 | 1896 | int cpu; |
9f680ab4 | 1897 | |
f41d911f | 1898 | rcu_bootup_announce(); |
64db4cff PM |
1899 | #ifdef CONFIG_RCU_CPU_STALL_DETECTOR |
1900 | printk(KERN_INFO "RCU-based detection of stalled CPUs is enabled.\n"); | |
1901 | #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ | |
cf244dc0 PM |
1902 | #if NUM_RCU_LVL_4 != 0 |
1903 | printk(KERN_INFO "Experimental four-level hierarchy is enabled.\n"); | |
1904 | #endif /* #if NUM_RCU_LVL_4 != 0 */ | |
65cf8f86 PM |
1905 | RCU_INIT_FLAVOR(&rcu_sched_state, rcu_sched_data); |
1906 | RCU_INIT_FLAVOR(&rcu_bh_state, rcu_bh_data); | |
f41d911f | 1907 | __rcu_init_preempt(); |
2e597558 | 1908 | open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); |
9f680ab4 PM |
1909 | |
1910 | /* | |
1911 | * We don't need protection against CPU-hotplug here because | |
1912 | * this is called early in boot, before either interrupts | |
1913 | * or the scheduler are operational. | |
1914 | */ | |
1915 | cpu_notifier(rcu_cpu_notify, 0); | |
017c4261 PM |
1916 | for_each_online_cpu(cpu) |
1917 | rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu); | |
64db4cff PM |
1918 | } |
1919 | ||
1eba8f84 | 1920 | #include "rcutree_plugin.h" |