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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/kernel/softirq.c | |
3 | * | |
4 | * Copyright (C) 1992 Linus Torvalds | |
5 | * | |
b10db7f0 PM |
6 | * Distribute under GPLv2. |
7 | * | |
8 | * Rewritten. Old one was good in 2.2, but in 2.3 it was immoral. --ANK (990903) | |
1da177e4 LT |
9 | */ |
10 | ||
11 | #include <linux/module.h> | |
12 | #include <linux/kernel_stat.h> | |
13 | #include <linux/interrupt.h> | |
14 | #include <linux/init.h> | |
15 | #include <linux/mm.h> | |
16 | #include <linux/notifier.h> | |
17 | #include <linux/percpu.h> | |
18 | #include <linux/cpu.h> | |
83144186 | 19 | #include <linux/freezer.h> |
1da177e4 LT |
20 | #include <linux/kthread.h> |
21 | #include <linux/rcupdate.h> | |
78eef01b | 22 | #include <linux/smp.h> |
79bf2bb3 | 23 | #include <linux/tick.h> |
1da177e4 LT |
24 | |
25 | #include <asm/irq.h> | |
26 | /* | |
27 | - No shared variables, all the data are CPU local. | |
28 | - If a softirq needs serialization, let it serialize itself | |
29 | by its own spinlocks. | |
30 | - Even if softirq is serialized, only local cpu is marked for | |
31 | execution. Hence, we get something sort of weak cpu binding. | |
32 | Though it is still not clear, will it result in better locality | |
33 | or will not. | |
34 | ||
35 | Examples: | |
36 | - NET RX softirq. It is multithreaded and does not require | |
37 | any global serialization. | |
38 | - NET TX softirq. It kicks software netdevice queues, hence | |
39 | it is logically serialized per device, but this serialization | |
40 | is invisible to common code. | |
41 | - Tasklets: serialized wrt itself. | |
42 | */ | |
43 | ||
44 | #ifndef __ARCH_IRQ_STAT | |
45 | irq_cpustat_t irq_stat[NR_CPUS] ____cacheline_aligned; | |
46 | EXPORT_SYMBOL(irq_stat); | |
47 | #endif | |
48 | ||
49 | static struct softirq_action softirq_vec[32] __cacheline_aligned_in_smp; | |
50 | ||
51 | static DEFINE_PER_CPU(struct task_struct *, ksoftirqd); | |
52 | ||
53 | /* | |
54 | * we cannot loop indefinitely here to avoid userspace starvation, | |
55 | * but we also don't want to introduce a worst case 1/HZ latency | |
56 | * to the pending events, so lets the scheduler to balance | |
57 | * the softirq load for us. | |
58 | */ | |
59 | static inline void wakeup_softirqd(void) | |
60 | { | |
61 | /* Interrupts are disabled: no need to stop preemption */ | |
62 | struct task_struct *tsk = __get_cpu_var(ksoftirqd); | |
63 | ||
64 | if (tsk && tsk->state != TASK_RUNNING) | |
65 | wake_up_process(tsk); | |
66 | } | |
67 | ||
de30a2b3 IM |
68 | /* |
69 | * This one is for softirq.c-internal use, | |
70 | * where hardirqs are disabled legitimately: | |
71 | */ | |
3c829c36 | 72 | #ifdef CONFIG_TRACE_IRQFLAGS |
de30a2b3 IM |
73 | static void __local_bh_disable(unsigned long ip) |
74 | { | |
75 | unsigned long flags; | |
76 | ||
77 | WARN_ON_ONCE(in_irq()); | |
78 | ||
79 | raw_local_irq_save(flags); | |
80 | add_preempt_count(SOFTIRQ_OFFSET); | |
81 | /* | |
82 | * Were softirqs turned off above: | |
83 | */ | |
84 | if (softirq_count() == SOFTIRQ_OFFSET) | |
85 | trace_softirqs_off(ip); | |
86 | raw_local_irq_restore(flags); | |
87 | } | |
3c829c36 TC |
88 | #else /* !CONFIG_TRACE_IRQFLAGS */ |
89 | static inline void __local_bh_disable(unsigned long ip) | |
90 | { | |
91 | add_preempt_count(SOFTIRQ_OFFSET); | |
92 | barrier(); | |
93 | } | |
94 | #endif /* CONFIG_TRACE_IRQFLAGS */ | |
de30a2b3 IM |
95 | |
96 | void local_bh_disable(void) | |
97 | { | |
98 | __local_bh_disable((unsigned long)__builtin_return_address(0)); | |
99 | } | |
100 | ||
101 | EXPORT_SYMBOL(local_bh_disable); | |
102 | ||
103 | void __local_bh_enable(void) | |
104 | { | |
105 | WARN_ON_ONCE(in_irq()); | |
106 | ||
107 | /* | |
108 | * softirqs should never be enabled by __local_bh_enable(), | |
109 | * it always nests inside local_bh_enable() sections: | |
110 | */ | |
111 | WARN_ON_ONCE(softirq_count() == SOFTIRQ_OFFSET); | |
112 | ||
113 | sub_preempt_count(SOFTIRQ_OFFSET); | |
114 | } | |
115 | EXPORT_SYMBOL_GPL(__local_bh_enable); | |
116 | ||
117 | /* | |
118 | * Special-case - softirqs can safely be enabled in | |
119 | * cond_resched_softirq(), or by __do_softirq(), | |
120 | * without processing still-pending softirqs: | |
121 | */ | |
122 | void _local_bh_enable(void) | |
123 | { | |
124 | WARN_ON_ONCE(in_irq()); | |
125 | WARN_ON_ONCE(!irqs_disabled()); | |
126 | ||
127 | if (softirq_count() == SOFTIRQ_OFFSET) | |
128 | trace_softirqs_on((unsigned long)__builtin_return_address(0)); | |
129 | sub_preempt_count(SOFTIRQ_OFFSET); | |
130 | } | |
131 | ||
132 | EXPORT_SYMBOL(_local_bh_enable); | |
133 | ||
0f476b6d | 134 | static inline void _local_bh_enable_ip(unsigned long ip) |
de30a2b3 | 135 | { |
0f476b6d | 136 | WARN_ON_ONCE(in_irq() || irqs_disabled()); |
3c829c36 | 137 | #ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d | 138 | local_irq_disable(); |
3c829c36 | 139 | #endif |
de30a2b3 IM |
140 | /* |
141 | * Are softirqs going to be turned on now: | |
142 | */ | |
143 | if (softirq_count() == SOFTIRQ_OFFSET) | |
0f476b6d | 144 | trace_softirqs_on(ip); |
de30a2b3 IM |
145 | /* |
146 | * Keep preemption disabled until we are done with | |
147 | * softirq processing: | |
148 | */ | |
149 | sub_preempt_count(SOFTIRQ_OFFSET - 1); | |
150 | ||
151 | if (unlikely(!in_interrupt() && local_softirq_pending())) | |
152 | do_softirq(); | |
153 | ||
154 | dec_preempt_count(); | |
3c829c36 | 155 | #ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d | 156 | local_irq_enable(); |
3c829c36 | 157 | #endif |
de30a2b3 IM |
158 | preempt_check_resched(); |
159 | } | |
0f476b6d JB |
160 | |
161 | void local_bh_enable(void) | |
162 | { | |
163 | _local_bh_enable_ip((unsigned long)__builtin_return_address(0)); | |
164 | } | |
de30a2b3 IM |
165 | EXPORT_SYMBOL(local_bh_enable); |
166 | ||
167 | void local_bh_enable_ip(unsigned long ip) | |
168 | { | |
0f476b6d | 169 | _local_bh_enable_ip(ip); |
de30a2b3 IM |
170 | } |
171 | EXPORT_SYMBOL(local_bh_enable_ip); | |
172 | ||
1da177e4 LT |
173 | /* |
174 | * We restart softirq processing MAX_SOFTIRQ_RESTART times, | |
175 | * and we fall back to softirqd after that. | |
176 | * | |
177 | * This number has been established via experimentation. | |
178 | * The two things to balance is latency against fairness - | |
179 | * we want to handle softirqs as soon as possible, but they | |
180 | * should not be able to lock up the box. | |
181 | */ | |
182 | #define MAX_SOFTIRQ_RESTART 10 | |
183 | ||
184 | asmlinkage void __do_softirq(void) | |
185 | { | |
186 | struct softirq_action *h; | |
187 | __u32 pending; | |
188 | int max_restart = MAX_SOFTIRQ_RESTART; | |
189 | int cpu; | |
190 | ||
191 | pending = local_softirq_pending(); | |
829035fd PM |
192 | account_system_vtime(current); |
193 | ||
de30a2b3 IM |
194 | __local_bh_disable((unsigned long)__builtin_return_address(0)); |
195 | trace_softirq_enter(); | |
1da177e4 | 196 | |
1da177e4 LT |
197 | cpu = smp_processor_id(); |
198 | restart: | |
199 | /* Reset the pending bitmask before enabling irqs */ | |
3f74478b | 200 | set_softirq_pending(0); |
1da177e4 | 201 | |
c70f5d66 | 202 | local_irq_enable(); |
1da177e4 LT |
203 | |
204 | h = softirq_vec; | |
205 | ||
206 | do { | |
207 | if (pending & 1) { | |
208 | h->action(h); | |
209 | rcu_bh_qsctr_inc(cpu); | |
210 | } | |
211 | h++; | |
212 | pending >>= 1; | |
213 | } while (pending); | |
214 | ||
c70f5d66 | 215 | local_irq_disable(); |
1da177e4 LT |
216 | |
217 | pending = local_softirq_pending(); | |
218 | if (pending && --max_restart) | |
219 | goto restart; | |
220 | ||
221 | if (pending) | |
222 | wakeup_softirqd(); | |
223 | ||
de30a2b3 | 224 | trace_softirq_exit(); |
829035fd PM |
225 | |
226 | account_system_vtime(current); | |
de30a2b3 | 227 | _local_bh_enable(); |
1da177e4 LT |
228 | } |
229 | ||
230 | #ifndef __ARCH_HAS_DO_SOFTIRQ | |
231 | ||
232 | asmlinkage void do_softirq(void) | |
233 | { | |
234 | __u32 pending; | |
235 | unsigned long flags; | |
236 | ||
237 | if (in_interrupt()) | |
238 | return; | |
239 | ||
240 | local_irq_save(flags); | |
241 | ||
242 | pending = local_softirq_pending(); | |
243 | ||
244 | if (pending) | |
245 | __do_softirq(); | |
246 | ||
247 | local_irq_restore(flags); | |
248 | } | |
249 | ||
1da177e4 LT |
250 | #endif |
251 | ||
dde4b2b5 IM |
252 | /* |
253 | * Enter an interrupt context. | |
254 | */ | |
255 | void irq_enter(void) | |
256 | { | |
6378ddb5 VP |
257 | #ifdef CONFIG_NO_HZ |
258 | int cpu = smp_processor_id(); | |
259 | if (idle_cpu(cpu) && !in_interrupt()) | |
260 | tick_nohz_stop_idle(cpu); | |
261 | #endif | |
79bf2bb3 TG |
262 | __irq_enter(); |
263 | #ifdef CONFIG_NO_HZ | |
6378ddb5 | 264 | if (idle_cpu(cpu)) |
79bf2bb3 TG |
265 | tick_nohz_update_jiffies(); |
266 | #endif | |
dde4b2b5 IM |
267 | } |
268 | ||
1da177e4 LT |
269 | #ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED |
270 | # define invoke_softirq() __do_softirq() | |
271 | #else | |
272 | # define invoke_softirq() do_softirq() | |
273 | #endif | |
274 | ||
275 | /* | |
276 | * Exit an interrupt context. Process softirqs if needed and possible: | |
277 | */ | |
278 | void irq_exit(void) | |
279 | { | |
280 | account_system_vtime(current); | |
de30a2b3 | 281 | trace_hardirq_exit(); |
1da177e4 LT |
282 | sub_preempt_count(IRQ_EXIT_OFFSET); |
283 | if (!in_interrupt() && local_softirq_pending()) | |
284 | invoke_softirq(); | |
79bf2bb3 TG |
285 | |
286 | #ifdef CONFIG_NO_HZ | |
287 | /* Make sure that timer wheel updates are propagated */ | |
288 | if (!in_interrupt() && idle_cpu(smp_processor_id()) && !need_resched()) | |
289 | tick_nohz_stop_sched_tick(); | |
2232c2d8 | 290 | rcu_irq_exit(); |
79bf2bb3 | 291 | #endif |
1da177e4 LT |
292 | preempt_enable_no_resched(); |
293 | } | |
294 | ||
295 | /* | |
296 | * This function must run with irqs disabled! | |
297 | */ | |
7ad5b3a5 | 298 | inline void raise_softirq_irqoff(unsigned int nr) |
1da177e4 LT |
299 | { |
300 | __raise_softirq_irqoff(nr); | |
301 | ||
302 | /* | |
303 | * If we're in an interrupt or softirq, we're done | |
304 | * (this also catches softirq-disabled code). We will | |
305 | * actually run the softirq once we return from | |
306 | * the irq or softirq. | |
307 | * | |
308 | * Otherwise we wake up ksoftirqd to make sure we | |
309 | * schedule the softirq soon. | |
310 | */ | |
311 | if (!in_interrupt()) | |
312 | wakeup_softirqd(); | |
313 | } | |
314 | ||
7ad5b3a5 | 315 | void raise_softirq(unsigned int nr) |
1da177e4 LT |
316 | { |
317 | unsigned long flags; | |
318 | ||
319 | local_irq_save(flags); | |
320 | raise_softirq_irqoff(nr); | |
321 | local_irq_restore(flags); | |
322 | } | |
323 | ||
962cf36c | 324 | void open_softirq(int nr, void (*action)(struct softirq_action *)) |
1da177e4 | 325 | { |
1da177e4 LT |
326 | softirq_vec[nr].action = action; |
327 | } | |
328 | ||
1da177e4 LT |
329 | /* Tasklets */ |
330 | struct tasklet_head | |
331 | { | |
48f20a9a OJ |
332 | struct tasklet_struct *head; |
333 | struct tasklet_struct **tail; | |
1da177e4 LT |
334 | }; |
335 | ||
4620b49f VN |
336 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec); |
337 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec); | |
1da177e4 | 338 | |
7ad5b3a5 | 339 | void __tasklet_schedule(struct tasklet_struct *t) |
1da177e4 LT |
340 | { |
341 | unsigned long flags; | |
342 | ||
343 | local_irq_save(flags); | |
48f20a9a OJ |
344 | t->next = NULL; |
345 | *__get_cpu_var(tasklet_vec).tail = t; | |
346 | __get_cpu_var(tasklet_vec).tail = &(t->next); | |
1da177e4 LT |
347 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
348 | local_irq_restore(flags); | |
349 | } | |
350 | ||
351 | EXPORT_SYMBOL(__tasklet_schedule); | |
352 | ||
7ad5b3a5 | 353 | void __tasklet_hi_schedule(struct tasklet_struct *t) |
1da177e4 LT |
354 | { |
355 | unsigned long flags; | |
356 | ||
357 | local_irq_save(flags); | |
48f20a9a OJ |
358 | t->next = NULL; |
359 | *__get_cpu_var(tasklet_hi_vec).tail = t; | |
360 | __get_cpu_var(tasklet_hi_vec).tail = &(t->next); | |
1da177e4 LT |
361 | raise_softirq_irqoff(HI_SOFTIRQ); |
362 | local_irq_restore(flags); | |
363 | } | |
364 | ||
365 | EXPORT_SYMBOL(__tasklet_hi_schedule); | |
366 | ||
367 | static void tasklet_action(struct softirq_action *a) | |
368 | { | |
369 | struct tasklet_struct *list; | |
370 | ||
371 | local_irq_disable(); | |
48f20a9a OJ |
372 | list = __get_cpu_var(tasklet_vec).head; |
373 | __get_cpu_var(tasklet_vec).head = NULL; | |
374 | __get_cpu_var(tasklet_vec).tail = &__get_cpu_var(tasklet_vec).head; | |
1da177e4 LT |
375 | local_irq_enable(); |
376 | ||
377 | while (list) { | |
378 | struct tasklet_struct *t = list; | |
379 | ||
380 | list = list->next; | |
381 | ||
382 | if (tasklet_trylock(t)) { | |
383 | if (!atomic_read(&t->count)) { | |
384 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
385 | BUG(); | |
386 | t->func(t->data); | |
387 | tasklet_unlock(t); | |
388 | continue; | |
389 | } | |
390 | tasklet_unlock(t); | |
391 | } | |
392 | ||
393 | local_irq_disable(); | |
48f20a9a OJ |
394 | t->next = NULL; |
395 | *__get_cpu_var(tasklet_vec).tail = t; | |
396 | __get_cpu_var(tasklet_vec).tail = &(t->next); | |
1da177e4 LT |
397 | __raise_softirq_irqoff(TASKLET_SOFTIRQ); |
398 | local_irq_enable(); | |
399 | } | |
400 | } | |
401 | ||
402 | static void tasklet_hi_action(struct softirq_action *a) | |
403 | { | |
404 | struct tasklet_struct *list; | |
405 | ||
406 | local_irq_disable(); | |
48f20a9a OJ |
407 | list = __get_cpu_var(tasklet_hi_vec).head; |
408 | __get_cpu_var(tasklet_hi_vec).head = NULL; | |
409 | __get_cpu_var(tasklet_hi_vec).tail = &__get_cpu_var(tasklet_hi_vec).head; | |
1da177e4 LT |
410 | local_irq_enable(); |
411 | ||
412 | while (list) { | |
413 | struct tasklet_struct *t = list; | |
414 | ||
415 | list = list->next; | |
416 | ||
417 | if (tasklet_trylock(t)) { | |
418 | if (!atomic_read(&t->count)) { | |
419 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
420 | BUG(); | |
421 | t->func(t->data); | |
422 | tasklet_unlock(t); | |
423 | continue; | |
424 | } | |
425 | tasklet_unlock(t); | |
426 | } | |
427 | ||
428 | local_irq_disable(); | |
48f20a9a OJ |
429 | t->next = NULL; |
430 | *__get_cpu_var(tasklet_hi_vec).tail = t; | |
431 | __get_cpu_var(tasklet_hi_vec).tail = &(t->next); | |
1da177e4 LT |
432 | __raise_softirq_irqoff(HI_SOFTIRQ); |
433 | local_irq_enable(); | |
434 | } | |
435 | } | |
436 | ||
437 | ||
438 | void tasklet_init(struct tasklet_struct *t, | |
439 | void (*func)(unsigned long), unsigned long data) | |
440 | { | |
441 | t->next = NULL; | |
442 | t->state = 0; | |
443 | atomic_set(&t->count, 0); | |
444 | t->func = func; | |
445 | t->data = data; | |
446 | } | |
447 | ||
448 | EXPORT_SYMBOL(tasklet_init); | |
449 | ||
450 | void tasklet_kill(struct tasklet_struct *t) | |
451 | { | |
452 | if (in_interrupt()) | |
453 | printk("Attempt to kill tasklet from interrupt\n"); | |
454 | ||
455 | while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { | |
456 | do | |
457 | yield(); | |
458 | while (test_bit(TASKLET_STATE_SCHED, &t->state)); | |
459 | } | |
460 | tasklet_unlock_wait(t); | |
461 | clear_bit(TASKLET_STATE_SCHED, &t->state); | |
462 | } | |
463 | ||
464 | EXPORT_SYMBOL(tasklet_kill); | |
465 | ||
466 | void __init softirq_init(void) | |
467 | { | |
48f20a9a OJ |
468 | int cpu; |
469 | ||
470 | for_each_possible_cpu(cpu) { | |
471 | per_cpu(tasklet_vec, cpu).tail = | |
472 | &per_cpu(tasklet_vec, cpu).head; | |
473 | per_cpu(tasklet_hi_vec, cpu).tail = | |
474 | &per_cpu(tasklet_hi_vec, cpu).head; | |
475 | } | |
476 | ||
962cf36c CM |
477 | open_softirq(TASKLET_SOFTIRQ, tasklet_action); |
478 | open_softirq(HI_SOFTIRQ, tasklet_hi_action); | |
1da177e4 LT |
479 | } |
480 | ||
481 | static int ksoftirqd(void * __bind_cpu) | |
482 | { | |
1da177e4 LT |
483 | set_current_state(TASK_INTERRUPTIBLE); |
484 | ||
485 | while (!kthread_should_stop()) { | |
486 | preempt_disable(); | |
487 | if (!local_softirq_pending()) { | |
488 | preempt_enable_no_resched(); | |
489 | schedule(); | |
490 | preempt_disable(); | |
491 | } | |
492 | ||
493 | __set_current_state(TASK_RUNNING); | |
494 | ||
495 | while (local_softirq_pending()) { | |
496 | /* Preempt disable stops cpu going offline. | |
497 | If already offline, we'll be on wrong CPU: | |
498 | don't process */ | |
499 | if (cpu_is_offline((long)__bind_cpu)) | |
500 | goto wait_to_die; | |
501 | do_softirq(); | |
502 | preempt_enable_no_resched(); | |
503 | cond_resched(); | |
504 | preempt_disable(); | |
505 | } | |
506 | preempt_enable(); | |
507 | set_current_state(TASK_INTERRUPTIBLE); | |
508 | } | |
509 | __set_current_state(TASK_RUNNING); | |
510 | return 0; | |
511 | ||
512 | wait_to_die: | |
513 | preempt_enable(); | |
514 | /* Wait for kthread_stop */ | |
515 | set_current_state(TASK_INTERRUPTIBLE); | |
516 | while (!kthread_should_stop()) { | |
517 | schedule(); | |
518 | set_current_state(TASK_INTERRUPTIBLE); | |
519 | } | |
520 | __set_current_state(TASK_RUNNING); | |
521 | return 0; | |
522 | } | |
523 | ||
524 | #ifdef CONFIG_HOTPLUG_CPU | |
525 | /* | |
526 | * tasklet_kill_immediate is called to remove a tasklet which can already be | |
527 | * scheduled for execution on @cpu. | |
528 | * | |
529 | * Unlike tasklet_kill, this function removes the tasklet | |
530 | * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state. | |
531 | * | |
532 | * When this function is called, @cpu must be in the CPU_DEAD state. | |
533 | */ | |
534 | void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu) | |
535 | { | |
536 | struct tasklet_struct **i; | |
537 | ||
538 | BUG_ON(cpu_online(cpu)); | |
539 | BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state)); | |
540 | ||
541 | if (!test_bit(TASKLET_STATE_SCHED, &t->state)) | |
542 | return; | |
543 | ||
544 | /* CPU is dead, so no lock needed. */ | |
48f20a9a | 545 | for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) { |
1da177e4 LT |
546 | if (*i == t) { |
547 | *i = t->next; | |
48f20a9a OJ |
548 | /* If this was the tail element, move the tail ptr */ |
549 | if (*i == NULL) | |
550 | per_cpu(tasklet_vec, cpu).tail = i; | |
1da177e4 LT |
551 | return; |
552 | } | |
553 | } | |
554 | BUG(); | |
555 | } | |
556 | ||
557 | static void takeover_tasklets(unsigned int cpu) | |
558 | { | |
1da177e4 LT |
559 | /* CPU is dead, so no lock needed. */ |
560 | local_irq_disable(); | |
561 | ||
562 | /* Find end, append list for that CPU. */ | |
e5e41723 CB |
563 | if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) { |
564 | *(__get_cpu_var(tasklet_vec).tail) = per_cpu(tasklet_vec, cpu).head; | |
565 | __get_cpu_var(tasklet_vec).tail = per_cpu(tasklet_vec, cpu).tail; | |
566 | per_cpu(tasklet_vec, cpu).head = NULL; | |
567 | per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; | |
568 | } | |
1da177e4 LT |
569 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
570 | ||
e5e41723 CB |
571 | if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) { |
572 | *__get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).head; | |
573 | __get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).tail; | |
574 | per_cpu(tasklet_hi_vec, cpu).head = NULL; | |
575 | per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; | |
576 | } | |
1da177e4 LT |
577 | raise_softirq_irqoff(HI_SOFTIRQ); |
578 | ||
579 | local_irq_enable(); | |
580 | } | |
581 | #endif /* CONFIG_HOTPLUG_CPU */ | |
582 | ||
8c78f307 | 583 | static int __cpuinit cpu_callback(struct notifier_block *nfb, |
1da177e4 LT |
584 | unsigned long action, |
585 | void *hcpu) | |
586 | { | |
587 | int hotcpu = (unsigned long)hcpu; | |
588 | struct task_struct *p; | |
589 | ||
590 | switch (action) { | |
591 | case CPU_UP_PREPARE: | |
8bb78442 | 592 | case CPU_UP_PREPARE_FROZEN: |
1da177e4 LT |
593 | p = kthread_create(ksoftirqd, hcpu, "ksoftirqd/%d", hotcpu); |
594 | if (IS_ERR(p)) { | |
595 | printk("ksoftirqd for %i failed\n", hotcpu); | |
596 | return NOTIFY_BAD; | |
597 | } | |
598 | kthread_bind(p, hotcpu); | |
599 | per_cpu(ksoftirqd, hotcpu) = p; | |
600 | break; | |
601 | case CPU_ONLINE: | |
8bb78442 | 602 | case CPU_ONLINE_FROZEN: |
1da177e4 LT |
603 | wake_up_process(per_cpu(ksoftirqd, hotcpu)); |
604 | break; | |
605 | #ifdef CONFIG_HOTPLUG_CPU | |
606 | case CPU_UP_CANCELED: | |
8bb78442 | 607 | case CPU_UP_CANCELED_FROZEN: |
fc75cdfa HC |
608 | if (!per_cpu(ksoftirqd, hotcpu)) |
609 | break; | |
1da177e4 | 610 | /* Unbind so it can run. Fall thru. */ |
a4c4af7c HC |
611 | kthread_bind(per_cpu(ksoftirqd, hotcpu), |
612 | any_online_cpu(cpu_online_map)); | |
1da177e4 | 613 | case CPU_DEAD: |
1c6b4aa9 ST |
614 | case CPU_DEAD_FROZEN: { |
615 | struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; | |
616 | ||
1da177e4 LT |
617 | p = per_cpu(ksoftirqd, hotcpu); |
618 | per_cpu(ksoftirqd, hotcpu) = NULL; | |
961ccddd | 619 | sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m); |
1da177e4 LT |
620 | kthread_stop(p); |
621 | takeover_tasklets(hotcpu); | |
622 | break; | |
1c6b4aa9 | 623 | } |
1da177e4 LT |
624 | #endif /* CONFIG_HOTPLUG_CPU */ |
625 | } | |
626 | return NOTIFY_OK; | |
627 | } | |
628 | ||
8c78f307 | 629 | static struct notifier_block __cpuinitdata cpu_nfb = { |
1da177e4 LT |
630 | .notifier_call = cpu_callback |
631 | }; | |
632 | ||
633 | __init int spawn_ksoftirqd(void) | |
634 | { | |
635 | void *cpu = (void *)(long)smp_processor_id(); | |
07dccf33 AM |
636 | int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu); |
637 | ||
638 | BUG_ON(err == NOTIFY_BAD); | |
1da177e4 LT |
639 | cpu_callback(&cpu_nfb, CPU_ONLINE, cpu); |
640 | register_cpu_notifier(&cpu_nfb); | |
641 | return 0; | |
642 | } | |
78eef01b AM |
643 | |
644 | #ifdef CONFIG_SMP | |
645 | /* | |
646 | * Call a function on all processors | |
647 | */ | |
15c8b6c1 | 648 | int on_each_cpu(void (*func) (void *info), void *info, int wait) |
78eef01b AM |
649 | { |
650 | int ret = 0; | |
651 | ||
652 | preempt_disable(); | |
8691e5a8 | 653 | ret = smp_call_function(func, info, wait); |
78eef01b AM |
654 | local_irq_disable(); |
655 | func(info); | |
656 | local_irq_enable(); | |
657 | preempt_enable(); | |
658 | return ret; | |
659 | } | |
660 | EXPORT_SYMBOL(on_each_cpu); | |
661 | #endif |