Commit | Line | Data |
---|---|---|
01c1c660 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, 2001 | |
19 | * | |
20 | * Authors: Dipankar Sarma <dipankar@in.ibm.com> | |
21 | * Manfred Spraul <manfred@colorfullife.com> | |
22 | * | |
23 | * Based on the original work by Paul McKenney <paulmck@us.ibm.com> | |
24 | * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. | |
25 | * Papers: | |
26 | * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf | |
27 | * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001) | |
28 | * | |
29 | * For detailed explanation of Read-Copy Update mechanism see - | |
30 | * Documentation/RCU | |
31 | * | |
32 | */ | |
33 | #include <linux/types.h> | |
34 | #include <linux/kernel.h> | |
35 | #include <linux/init.h> | |
36 | #include <linux/spinlock.h> | |
37 | #include <linux/smp.h> | |
38 | #include <linux/rcupdate.h> | |
39 | #include <linux/interrupt.h> | |
40 | #include <linux/sched.h> | |
41 | #include <asm/atomic.h> | |
42 | #include <linux/bitops.h> | |
43 | #include <linux/module.h> | |
44 | #include <linux/completion.h> | |
45 | #include <linux/moduleparam.h> | |
46 | #include <linux/percpu.h> | |
47 | #include <linux/notifier.h> | |
01c1c660 PM |
48 | #include <linux/cpu.h> |
49 | #include <linux/mutex.h> | |
50 | ||
51 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
52 | static struct lock_class_key rcu_lock_key; | |
53 | struct lockdep_map rcu_lock_map = | |
54 | STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key); | |
55 | EXPORT_SYMBOL_GPL(rcu_lock_map); | |
56 | #endif | |
57 | ||
58 | ||
59 | /* Definition for rcupdate control block. */ | |
60 | static struct rcu_ctrlblk rcu_ctrlblk = { | |
61 | .cur = -300, | |
62 | .completed = -300, | |
63 | .lock = __SPIN_LOCK_UNLOCKED(&rcu_ctrlblk.lock), | |
64 | .cpumask = CPU_MASK_NONE, | |
65 | }; | |
66 | static struct rcu_ctrlblk rcu_bh_ctrlblk = { | |
67 | .cur = -300, | |
68 | .completed = -300, | |
69 | .lock = __SPIN_LOCK_UNLOCKED(&rcu_bh_ctrlblk.lock), | |
70 | .cpumask = CPU_MASK_NONE, | |
71 | }; | |
72 | ||
73 | DEFINE_PER_CPU(struct rcu_data, rcu_data) = { 0L }; | |
74 | DEFINE_PER_CPU(struct rcu_data, rcu_bh_data) = { 0L }; | |
75 | ||
76 | static int blimit = 10; | |
77 | static int qhimark = 10000; | |
78 | static int qlowmark = 100; | |
79 | ||
80 | #ifdef CONFIG_SMP | |
81 | static void force_quiescent_state(struct rcu_data *rdp, | |
82 | struct rcu_ctrlblk *rcp) | |
83 | { | |
84 | int cpu; | |
85 | cpumask_t cpumask; | |
86 | set_need_resched(); | |
87 | if (unlikely(!rcp->signaled)) { | |
88 | rcp->signaled = 1; | |
89 | /* | |
90 | * Don't send IPI to itself. With irqs disabled, | |
91 | * rdp->cpu is the current cpu. | |
8558f8f8 GS |
92 | * |
93 | * cpu_online_map is updated by the _cpu_down() | |
9b1a4d38 RR |
94 | * using __stop_machine(). Since we're in irqs disabled |
95 | * section, __stop_machine() is not exectuting, hence | |
8558f8f8 GS |
96 | * the cpu_online_map is stable. |
97 | * | |
98 | * However, a cpu might have been offlined _just_ before | |
99 | * we disabled irqs while entering here. | |
100 | * And rcu subsystem might not yet have handled the CPU_DEAD | |
101 | * notification, leading to the offlined cpu's bit | |
102 | * being set in the rcp->cpumask. | |
103 | * | |
104 | * Hence cpumask = (rcp->cpumask & cpu_online_map) to prevent | |
105 | * sending smp_reschedule() to an offlined CPU. | |
01c1c660 | 106 | */ |
8558f8f8 | 107 | cpus_and(cpumask, rcp->cpumask, cpu_online_map); |
01c1c660 | 108 | cpu_clear(rdp->cpu, cpumask); |
363ab6f1 | 109 | for_each_cpu_mask_nr(cpu, cpumask) |
01c1c660 PM |
110 | smp_send_reschedule(cpu); |
111 | } | |
112 | } | |
113 | #else | |
114 | static inline void force_quiescent_state(struct rcu_data *rdp, | |
115 | struct rcu_ctrlblk *rcp) | |
116 | { | |
117 | set_need_resched(); | |
118 | } | |
119 | #endif | |
120 | ||
121 | /** | |
122 | * call_rcu - Queue an RCU callback for invocation after a grace period. | |
123 | * @head: structure to be used for queueing the RCU updates. | |
124 | * @func: actual update function to be invoked after the grace period | |
125 | * | |
126 | * The update function will be invoked some time after a full grace | |
127 | * period elapses, in other words after all currently executing RCU | |
128 | * read-side critical sections have completed. RCU read-side critical | |
129 | * sections are delimited by rcu_read_lock() and rcu_read_unlock(), | |
130 | * and may be nested. | |
131 | */ | |
132 | void call_rcu(struct rcu_head *head, | |
133 | void (*func)(struct rcu_head *rcu)) | |
134 | { | |
135 | unsigned long flags; | |
136 | struct rcu_data *rdp; | |
137 | ||
138 | head->func = func; | |
139 | head->next = NULL; | |
140 | local_irq_save(flags); | |
141 | rdp = &__get_cpu_var(rcu_data); | |
142 | *rdp->nxttail = head; | |
143 | rdp->nxttail = &head->next; | |
144 | if (unlikely(++rdp->qlen > qhimark)) { | |
145 | rdp->blimit = INT_MAX; | |
146 | force_quiescent_state(rdp, &rcu_ctrlblk); | |
147 | } | |
148 | local_irq_restore(flags); | |
149 | } | |
150 | EXPORT_SYMBOL_GPL(call_rcu); | |
151 | ||
152 | /** | |
153 | * call_rcu_bh - Queue an RCU for invocation after a quicker grace period. | |
154 | * @head: structure to be used for queueing the RCU updates. | |
155 | * @func: actual update function to be invoked after the grace period | |
156 | * | |
157 | * The update function will be invoked some time after a full grace | |
158 | * period elapses, in other words after all currently executing RCU | |
159 | * read-side critical sections have completed. call_rcu_bh() assumes | |
160 | * that the read-side critical sections end on completion of a softirq | |
161 | * handler. This means that read-side critical sections in process | |
162 | * context must not be interrupted by softirqs. This interface is to be | |
163 | * used when most of the read-side critical sections are in softirq context. | |
164 | * RCU read-side critical sections are delimited by rcu_read_lock() and | |
165 | * rcu_read_unlock(), * if in interrupt context or rcu_read_lock_bh() | |
166 | * and rcu_read_unlock_bh(), if in process context. These may be nested. | |
167 | */ | |
168 | void call_rcu_bh(struct rcu_head *head, | |
169 | void (*func)(struct rcu_head *rcu)) | |
170 | { | |
171 | unsigned long flags; | |
172 | struct rcu_data *rdp; | |
173 | ||
174 | head->func = func; | |
175 | head->next = NULL; | |
176 | local_irq_save(flags); | |
177 | rdp = &__get_cpu_var(rcu_bh_data); | |
178 | *rdp->nxttail = head; | |
179 | rdp->nxttail = &head->next; | |
180 | ||
181 | if (unlikely(++rdp->qlen > qhimark)) { | |
182 | rdp->blimit = INT_MAX; | |
183 | force_quiescent_state(rdp, &rcu_bh_ctrlblk); | |
184 | } | |
185 | ||
186 | local_irq_restore(flags); | |
187 | } | |
188 | EXPORT_SYMBOL_GPL(call_rcu_bh); | |
189 | ||
190 | /* | |
191 | * Return the number of RCU batches processed thus far. Useful | |
192 | * for debug and statistics. | |
193 | */ | |
194 | long rcu_batches_completed(void) | |
195 | { | |
196 | return rcu_ctrlblk.completed; | |
197 | } | |
198 | EXPORT_SYMBOL_GPL(rcu_batches_completed); | |
199 | ||
200 | /* | |
201 | * Return the number of RCU batches processed thus far. Useful | |
202 | * for debug and statistics. | |
203 | */ | |
204 | long rcu_batches_completed_bh(void) | |
205 | { | |
206 | return rcu_bh_ctrlblk.completed; | |
207 | } | |
208 | EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); | |
209 | ||
210 | /* Raises the softirq for processing rcu_callbacks. */ | |
211 | static inline void raise_rcu_softirq(void) | |
212 | { | |
213 | raise_softirq(RCU_SOFTIRQ); | |
214 | /* | |
215 | * The smp_mb() here is required to ensure that this cpu's | |
216 | * __rcu_process_callbacks() reads the most recently updated | |
217 | * value of rcu->cur. | |
218 | */ | |
219 | smp_mb(); | |
220 | } | |
221 | ||
222 | /* | |
223 | * Invoke the completed RCU callbacks. They are expected to be in | |
224 | * a per-cpu list. | |
225 | */ | |
226 | static void rcu_do_batch(struct rcu_data *rdp) | |
227 | { | |
228 | struct rcu_head *next, *list; | |
229 | int count = 0; | |
230 | ||
231 | list = rdp->donelist; | |
232 | while (list) { | |
233 | next = list->next; | |
234 | prefetch(next); | |
235 | list->func(list); | |
236 | list = next; | |
237 | if (++count >= rdp->blimit) | |
238 | break; | |
239 | } | |
240 | rdp->donelist = list; | |
241 | ||
242 | local_irq_disable(); | |
243 | rdp->qlen -= count; | |
244 | local_irq_enable(); | |
245 | if (rdp->blimit == INT_MAX && rdp->qlen <= qlowmark) | |
246 | rdp->blimit = blimit; | |
247 | ||
248 | if (!rdp->donelist) | |
249 | rdp->donetail = &rdp->donelist; | |
250 | else | |
251 | raise_rcu_softirq(); | |
252 | } | |
253 | ||
254 | /* | |
255 | * Grace period handling: | |
256 | * The grace period handling consists out of two steps: | |
257 | * - A new grace period is started. | |
258 | * This is done by rcu_start_batch. The start is not broadcasted to | |
259 | * all cpus, they must pick this up by comparing rcp->cur with | |
260 | * rdp->quiescbatch. All cpus are recorded in the | |
261 | * rcu_ctrlblk.cpumask bitmap. | |
262 | * - All cpus must go through a quiescent state. | |
263 | * Since the start of the grace period is not broadcasted, at least two | |
264 | * calls to rcu_check_quiescent_state are required: | |
265 | * The first call just notices that a new grace period is running. The | |
266 | * following calls check if there was a quiescent state since the beginning | |
267 | * of the grace period. If so, it updates rcu_ctrlblk.cpumask. If | |
268 | * the bitmap is empty, then the grace period is completed. | |
269 | * rcu_check_quiescent_state calls rcu_start_batch(0) to start the next grace | |
270 | * period (if necessary). | |
271 | */ | |
272 | /* | |
273 | * Register a new batch of callbacks, and start it up if there is currently no | |
274 | * active batch and the batch to be registered has not already occurred. | |
275 | * Caller must hold rcu_ctrlblk.lock. | |
276 | */ | |
277 | static void rcu_start_batch(struct rcu_ctrlblk *rcp) | |
278 | { | |
279 | if (rcp->next_pending && | |
280 | rcp->completed == rcp->cur) { | |
281 | rcp->next_pending = 0; | |
282 | /* | |
283 | * next_pending == 0 must be visible in | |
284 | * __rcu_process_callbacks() before it can see new value of cur. | |
285 | */ | |
286 | smp_wmb(); | |
287 | rcp->cur++; | |
288 | ||
289 | /* | |
290 | * Accessing nohz_cpu_mask before incrementing rcp->cur needs a | |
291 | * Barrier Otherwise it can cause tickless idle CPUs to be | |
292 | * included in rcp->cpumask, which will extend graceperiods | |
293 | * unnecessarily. | |
294 | */ | |
295 | smp_mb(); | |
296 | cpus_andnot(rcp->cpumask, cpu_online_map, nohz_cpu_mask); | |
297 | ||
298 | rcp->signaled = 0; | |
299 | } | |
300 | } | |
301 | ||
302 | /* | |
303 | * cpu went through a quiescent state since the beginning of the grace period. | |
304 | * Clear it from the cpu mask and complete the grace period if it was the last | |
305 | * cpu. Start another grace period if someone has further entries pending | |
306 | */ | |
307 | static void cpu_quiet(int cpu, struct rcu_ctrlblk *rcp) | |
308 | { | |
309 | cpu_clear(cpu, rcp->cpumask); | |
310 | if (cpus_empty(rcp->cpumask)) { | |
311 | /* batch completed ! */ | |
312 | rcp->completed = rcp->cur; | |
313 | rcu_start_batch(rcp); | |
314 | } | |
315 | } | |
316 | ||
317 | /* | |
318 | * Check if the cpu has gone through a quiescent state (say context | |
319 | * switch). If so and if it already hasn't done so in this RCU | |
320 | * quiescent cycle, then indicate that it has done so. | |
321 | */ | |
322 | static void rcu_check_quiescent_state(struct rcu_ctrlblk *rcp, | |
323 | struct rcu_data *rdp) | |
324 | { | |
325 | if (rdp->quiescbatch != rcp->cur) { | |
326 | /* start new grace period: */ | |
327 | rdp->qs_pending = 1; | |
328 | rdp->passed_quiesc = 0; | |
329 | rdp->quiescbatch = rcp->cur; | |
330 | return; | |
331 | } | |
332 | ||
333 | /* Grace period already completed for this cpu? | |
334 | * qs_pending is checked instead of the actual bitmap to avoid | |
335 | * cacheline trashing. | |
336 | */ | |
337 | if (!rdp->qs_pending) | |
338 | return; | |
339 | ||
340 | /* | |
341 | * Was there a quiescent state since the beginning of the grace | |
342 | * period? If no, then exit and wait for the next call. | |
343 | */ | |
344 | if (!rdp->passed_quiesc) | |
345 | return; | |
346 | rdp->qs_pending = 0; | |
347 | ||
348 | spin_lock(&rcp->lock); | |
349 | /* | |
350 | * rdp->quiescbatch/rcp->cur and the cpu bitmap can come out of sync | |
351 | * during cpu startup. Ignore the quiescent state. | |
352 | */ | |
353 | if (likely(rdp->quiescbatch == rcp->cur)) | |
354 | cpu_quiet(rdp->cpu, rcp); | |
355 | ||
356 | spin_unlock(&rcp->lock); | |
357 | } | |
358 | ||
359 | ||
360 | #ifdef CONFIG_HOTPLUG_CPU | |
361 | ||
362 | /* warning! helper for rcu_offline_cpu. do not use elsewhere without reviewing | |
363 | * locking requirements, the list it's pulling from has to belong to a cpu | |
364 | * which is dead and hence not processing interrupts. | |
365 | */ | |
366 | static void rcu_move_batch(struct rcu_data *this_rdp, struct rcu_head *list, | |
367 | struct rcu_head **tail) | |
368 | { | |
369 | local_irq_disable(); | |
370 | *this_rdp->nxttail = list; | |
371 | if (list) | |
372 | this_rdp->nxttail = tail; | |
373 | local_irq_enable(); | |
374 | } | |
375 | ||
376 | static void __rcu_offline_cpu(struct rcu_data *this_rdp, | |
377 | struct rcu_ctrlblk *rcp, struct rcu_data *rdp) | |
378 | { | |
379 | /* if the cpu going offline owns the grace period | |
380 | * we can block indefinitely waiting for it, so flush | |
381 | * it here | |
382 | */ | |
383 | spin_lock_bh(&rcp->lock); | |
384 | if (rcp->cur != rcp->completed) | |
385 | cpu_quiet(rdp->cpu, rcp); | |
386 | spin_unlock_bh(&rcp->lock); | |
e0ecfa79 | 387 | rcu_move_batch(this_rdp, rdp->donelist, rdp->donetail); |
01c1c660 PM |
388 | rcu_move_batch(this_rdp, rdp->curlist, rdp->curtail); |
389 | rcu_move_batch(this_rdp, rdp->nxtlist, rdp->nxttail); | |
199a9528 LJ |
390 | |
391 | local_irq_disable(); | |
392 | this_rdp->qlen += rdp->qlen; | |
393 | local_irq_enable(); | |
01c1c660 PM |
394 | } |
395 | ||
396 | static void rcu_offline_cpu(int cpu) | |
397 | { | |
398 | struct rcu_data *this_rdp = &get_cpu_var(rcu_data); | |
399 | struct rcu_data *this_bh_rdp = &get_cpu_var(rcu_bh_data); | |
400 | ||
401 | __rcu_offline_cpu(this_rdp, &rcu_ctrlblk, | |
402 | &per_cpu(rcu_data, cpu)); | |
403 | __rcu_offline_cpu(this_bh_rdp, &rcu_bh_ctrlblk, | |
404 | &per_cpu(rcu_bh_data, cpu)); | |
405 | put_cpu_var(rcu_data); | |
406 | put_cpu_var(rcu_bh_data); | |
407 | } | |
408 | ||
409 | #else | |
410 | ||
411 | static void rcu_offline_cpu(int cpu) | |
412 | { | |
413 | } | |
414 | ||
415 | #endif | |
416 | ||
417 | /* | |
418 | * This does the RCU processing work from softirq context. | |
419 | */ | |
420 | static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp, | |
421 | struct rcu_data *rdp) | |
422 | { | |
423 | if (rdp->curlist && !rcu_batch_before(rcp->completed, rdp->batch)) { | |
424 | *rdp->donetail = rdp->curlist; | |
425 | rdp->donetail = rdp->curtail; | |
426 | rdp->curlist = NULL; | |
427 | rdp->curtail = &rdp->curlist; | |
428 | } | |
429 | ||
430 | if (rdp->nxtlist && !rdp->curlist) { | |
431 | local_irq_disable(); | |
432 | rdp->curlist = rdp->nxtlist; | |
433 | rdp->curtail = rdp->nxttail; | |
434 | rdp->nxtlist = NULL; | |
435 | rdp->nxttail = &rdp->nxtlist; | |
436 | local_irq_enable(); | |
437 | ||
438 | /* | |
439 | * start the next batch of callbacks | |
440 | */ | |
441 | ||
442 | /* determine batch number */ | |
443 | rdp->batch = rcp->cur + 1; | |
444 | /* see the comment and corresponding wmb() in | |
445 | * the rcu_start_batch() | |
446 | */ | |
447 | smp_rmb(); | |
448 | ||
449 | if (!rcp->next_pending) { | |
450 | /* and start it/schedule start if it's a new batch */ | |
451 | spin_lock(&rcp->lock); | |
452 | rcp->next_pending = 1; | |
453 | rcu_start_batch(rcp); | |
454 | spin_unlock(&rcp->lock); | |
455 | } | |
456 | } | |
457 | ||
458 | rcu_check_quiescent_state(rcp, rdp); | |
459 | if (rdp->donelist) | |
460 | rcu_do_batch(rdp); | |
461 | } | |
462 | ||
463 | static void rcu_process_callbacks(struct softirq_action *unused) | |
464 | { | |
465 | __rcu_process_callbacks(&rcu_ctrlblk, &__get_cpu_var(rcu_data)); | |
466 | __rcu_process_callbacks(&rcu_bh_ctrlblk, &__get_cpu_var(rcu_bh_data)); | |
467 | } | |
468 | ||
469 | static int __rcu_pending(struct rcu_ctrlblk *rcp, struct rcu_data *rdp) | |
470 | { | |
471 | /* This cpu has pending rcu entries and the grace period | |
472 | * for them has completed. | |
473 | */ | |
474 | if (rdp->curlist && !rcu_batch_before(rcp->completed, rdp->batch)) | |
475 | return 1; | |
476 | ||
477 | /* This cpu has no pending entries, but there are new entries */ | |
478 | if (!rdp->curlist && rdp->nxtlist) | |
479 | return 1; | |
480 | ||
481 | /* This cpu has finished callbacks to invoke */ | |
482 | if (rdp->donelist) | |
483 | return 1; | |
484 | ||
485 | /* The rcu core waits for a quiescent state from the cpu */ | |
486 | if (rdp->quiescbatch != rcp->cur || rdp->qs_pending) | |
487 | return 1; | |
488 | ||
489 | /* nothing to do */ | |
490 | return 0; | |
491 | } | |
492 | ||
493 | /* | |
494 | * Check to see if there is any immediate RCU-related work to be done | |
495 | * by the current CPU, returning 1 if so. This function is part of the | |
496 | * RCU implementation; it is -not- an exported member of the RCU API. | |
497 | */ | |
498 | int rcu_pending(int cpu) | |
499 | { | |
500 | return __rcu_pending(&rcu_ctrlblk, &per_cpu(rcu_data, cpu)) || | |
501 | __rcu_pending(&rcu_bh_ctrlblk, &per_cpu(rcu_bh_data, cpu)); | |
502 | } | |
503 | ||
504 | /* | |
505 | * Check to see if any future RCU-related work will need to be done | |
506 | * by the current CPU, even if none need be done immediately, returning | |
507 | * 1 if so. This function is part of the RCU implementation; it is -not- | |
508 | * an exported member of the RCU API. | |
509 | */ | |
510 | int rcu_needs_cpu(int cpu) | |
511 | { | |
512 | struct rcu_data *rdp = &per_cpu(rcu_data, cpu); | |
513 | struct rcu_data *rdp_bh = &per_cpu(rcu_bh_data, cpu); | |
514 | ||
515 | return (!!rdp->curlist || !!rdp_bh->curlist || rcu_pending(cpu)); | |
516 | } | |
517 | ||
518 | void rcu_check_callbacks(int cpu, int user) | |
519 | { | |
520 | if (user || | |
521 | (idle_cpu(cpu) && !in_softirq() && | |
522 | hardirq_count() <= (1 << HARDIRQ_SHIFT))) { | |
8db559b8 PM |
523 | |
524 | /* | |
525 | * Get here if this CPU took its interrupt from user | |
526 | * mode or from the idle loop, and if this is not a | |
527 | * nested interrupt. In this case, the CPU is in | |
528 | * a quiescent state, so count it. | |
529 | * | |
530 | * Also do a memory barrier. This is needed to handle | |
531 | * the case where writes from a preempt-disable section | |
532 | * of code get reordered into schedule() by this CPU's | |
533 | * write buffer. The memory barrier makes sure that | |
534 | * the rcu_qsctr_inc() and rcu_bh_qsctr_inc() are see | |
535 | * by other CPUs to happen after any such write. | |
536 | */ | |
537 | ||
538 | smp_mb(); /* See above block comment. */ | |
01c1c660 PM |
539 | rcu_qsctr_inc(cpu); |
540 | rcu_bh_qsctr_inc(cpu); | |
8db559b8 PM |
541 | |
542 | } else if (!in_softirq()) { | |
543 | ||
544 | /* | |
545 | * Get here if this CPU did not take its interrupt from | |
546 | * softirq, in other words, if it is not interrupting | |
547 | * a rcu_bh read-side critical section. This is an _bh | |
548 | * critical section, so count it. The memory barrier | |
549 | * is needed for the same reason as is the above one. | |
550 | */ | |
551 | ||
552 | smp_mb(); /* See above block comment. */ | |
01c1c660 | 553 | rcu_bh_qsctr_inc(cpu); |
8db559b8 | 554 | } |
01c1c660 PM |
555 | raise_rcu_softirq(); |
556 | } | |
557 | ||
558 | static void rcu_init_percpu_data(int cpu, struct rcu_ctrlblk *rcp, | |
559 | struct rcu_data *rdp) | |
560 | { | |
561 | memset(rdp, 0, sizeof(*rdp)); | |
562 | rdp->curtail = &rdp->curlist; | |
563 | rdp->nxttail = &rdp->nxtlist; | |
564 | rdp->donetail = &rdp->donelist; | |
565 | rdp->quiescbatch = rcp->completed; | |
566 | rdp->qs_pending = 0; | |
567 | rdp->cpu = cpu; | |
568 | rdp->blimit = blimit; | |
569 | } | |
570 | ||
571 | static void __cpuinit rcu_online_cpu(int cpu) | |
572 | { | |
573 | struct rcu_data *rdp = &per_cpu(rcu_data, cpu); | |
574 | struct rcu_data *bh_rdp = &per_cpu(rcu_bh_data, cpu); | |
575 | ||
576 | rcu_init_percpu_data(cpu, &rcu_ctrlblk, rdp); | |
577 | rcu_init_percpu_data(cpu, &rcu_bh_ctrlblk, bh_rdp); | |
962cf36c | 578 | open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); |
01c1c660 PM |
579 | } |
580 | ||
581 | static int __cpuinit rcu_cpu_notify(struct notifier_block *self, | |
582 | unsigned long action, void *hcpu) | |
583 | { | |
584 | long cpu = (long)hcpu; | |
585 | ||
586 | switch (action) { | |
587 | case CPU_UP_PREPARE: | |
588 | case CPU_UP_PREPARE_FROZEN: | |
589 | rcu_online_cpu(cpu); | |
590 | break; | |
591 | case CPU_DEAD: | |
592 | case CPU_DEAD_FROZEN: | |
593 | rcu_offline_cpu(cpu); | |
594 | break; | |
595 | default: | |
596 | break; | |
597 | } | |
598 | return NOTIFY_OK; | |
599 | } | |
600 | ||
601 | static struct notifier_block __cpuinitdata rcu_nb = { | |
602 | .notifier_call = rcu_cpu_notify, | |
603 | }; | |
604 | ||
605 | /* | |
606 | * Initializes rcu mechanism. Assumed to be called early. | |
607 | * That is before local timer(SMP) or jiffie timer (uniproc) is setup. | |
608 | * Note that rcu_qsctr and friends are implicitly | |
609 | * initialized due to the choice of ``0'' for RCU_CTR_INVALID. | |
610 | */ | |
611 | void __init __rcu_init(void) | |
612 | { | |
613 | rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE, | |
614 | (void *)(long)smp_processor_id()); | |
615 | /* Register notifier for non-boot CPUs */ | |
616 | register_cpu_notifier(&rcu_nb); | |
617 | } | |
618 | ||
619 | module_param(blimit, int, 0); | |
620 | module_param(qhimark, int, 0); | |
621 | module_param(qlowmark, int, 0); |