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