Commit | Line | Data |
---|---|---|
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 | ||
978b0116 | 49 | static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp; |
1da177e4 LT |
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) { | |
8e85b4b5 TG |
208 | int prev_count = preempt_count(); |
209 | ||
1da177e4 | 210 | h->action(h); |
8e85b4b5 TG |
211 | |
212 | if (unlikely(prev_count != preempt_count())) { | |
1c95e1b6 | 213 | printk(KERN_ERR "huh, entered softirq %td %p" |
8e85b4b5 TG |
214 | "with preempt_count %08x," |
215 | " exited with %08x?\n", h - softirq_vec, | |
216 | h->action, prev_count, preempt_count()); | |
217 | preempt_count() = prev_count; | |
218 | } | |
219 | ||
1da177e4 LT |
220 | rcu_bh_qsctr_inc(cpu); |
221 | } | |
222 | h++; | |
223 | pending >>= 1; | |
224 | } while (pending); | |
225 | ||
c70f5d66 | 226 | local_irq_disable(); |
1da177e4 LT |
227 | |
228 | pending = local_softirq_pending(); | |
229 | if (pending && --max_restart) | |
230 | goto restart; | |
231 | ||
232 | if (pending) | |
233 | wakeup_softirqd(); | |
234 | ||
de30a2b3 | 235 | trace_softirq_exit(); |
829035fd PM |
236 | |
237 | account_system_vtime(current); | |
de30a2b3 | 238 | _local_bh_enable(); |
1da177e4 LT |
239 | } |
240 | ||
241 | #ifndef __ARCH_HAS_DO_SOFTIRQ | |
242 | ||
243 | asmlinkage void do_softirq(void) | |
244 | { | |
245 | __u32 pending; | |
246 | unsigned long flags; | |
247 | ||
248 | if (in_interrupt()) | |
249 | return; | |
250 | ||
251 | local_irq_save(flags); | |
252 | ||
253 | pending = local_softirq_pending(); | |
254 | ||
255 | if (pending) | |
256 | __do_softirq(); | |
257 | ||
258 | local_irq_restore(flags); | |
259 | } | |
260 | ||
1da177e4 LT |
261 | #endif |
262 | ||
dde4b2b5 IM |
263 | /* |
264 | * Enter an interrupt context. | |
265 | */ | |
266 | void irq_enter(void) | |
267 | { | |
6378ddb5 VP |
268 | #ifdef CONFIG_NO_HZ |
269 | int cpu = smp_processor_id(); | |
270 | if (idle_cpu(cpu) && !in_interrupt()) | |
271 | tick_nohz_stop_idle(cpu); | |
272 | #endif | |
79bf2bb3 TG |
273 | __irq_enter(); |
274 | #ifdef CONFIG_NO_HZ | |
6378ddb5 | 275 | if (idle_cpu(cpu)) |
79bf2bb3 TG |
276 | tick_nohz_update_jiffies(); |
277 | #endif | |
dde4b2b5 IM |
278 | } |
279 | ||
1da177e4 LT |
280 | #ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED |
281 | # define invoke_softirq() __do_softirq() | |
282 | #else | |
283 | # define invoke_softirq() do_softirq() | |
284 | #endif | |
285 | ||
286 | /* | |
287 | * Exit an interrupt context. Process softirqs if needed and possible: | |
288 | */ | |
289 | void irq_exit(void) | |
290 | { | |
291 | account_system_vtime(current); | |
de30a2b3 | 292 | trace_hardirq_exit(); |
1da177e4 LT |
293 | sub_preempt_count(IRQ_EXIT_OFFSET); |
294 | if (!in_interrupt() && local_softirq_pending()) | |
295 | invoke_softirq(); | |
79bf2bb3 TG |
296 | |
297 | #ifdef CONFIG_NO_HZ | |
298 | /* Make sure that timer wheel updates are propagated */ | |
299 | if (!in_interrupt() && idle_cpu(smp_processor_id()) && !need_resched()) | |
b8f8c3cf | 300 | tick_nohz_stop_sched_tick(0); |
2232c2d8 | 301 | rcu_irq_exit(); |
79bf2bb3 | 302 | #endif |
1da177e4 LT |
303 | preempt_enable_no_resched(); |
304 | } | |
305 | ||
306 | /* | |
307 | * This function must run with irqs disabled! | |
308 | */ | |
7ad5b3a5 | 309 | inline void raise_softirq_irqoff(unsigned int nr) |
1da177e4 LT |
310 | { |
311 | __raise_softirq_irqoff(nr); | |
312 | ||
313 | /* | |
314 | * If we're in an interrupt or softirq, we're done | |
315 | * (this also catches softirq-disabled code). We will | |
316 | * actually run the softirq once we return from | |
317 | * the irq or softirq. | |
318 | * | |
319 | * Otherwise we wake up ksoftirqd to make sure we | |
320 | * schedule the softirq soon. | |
321 | */ | |
322 | if (!in_interrupt()) | |
323 | wakeup_softirqd(); | |
324 | } | |
325 | ||
7ad5b3a5 | 326 | void raise_softirq(unsigned int nr) |
1da177e4 LT |
327 | { |
328 | unsigned long flags; | |
329 | ||
330 | local_irq_save(flags); | |
331 | raise_softirq_irqoff(nr); | |
332 | local_irq_restore(flags); | |
333 | } | |
334 | ||
962cf36c | 335 | void open_softirq(int nr, void (*action)(struct softirq_action *)) |
1da177e4 | 336 | { |
1da177e4 LT |
337 | softirq_vec[nr].action = action; |
338 | } | |
339 | ||
1da177e4 LT |
340 | /* Tasklets */ |
341 | struct tasklet_head | |
342 | { | |
48f20a9a OJ |
343 | struct tasklet_struct *head; |
344 | struct tasklet_struct **tail; | |
1da177e4 LT |
345 | }; |
346 | ||
4620b49f VN |
347 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec); |
348 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec); | |
1da177e4 | 349 | |
7ad5b3a5 | 350 | void __tasklet_schedule(struct tasklet_struct *t) |
1da177e4 LT |
351 | { |
352 | unsigned long flags; | |
353 | ||
354 | local_irq_save(flags); | |
48f20a9a OJ |
355 | t->next = NULL; |
356 | *__get_cpu_var(tasklet_vec).tail = t; | |
357 | __get_cpu_var(tasklet_vec).tail = &(t->next); | |
1da177e4 LT |
358 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
359 | local_irq_restore(flags); | |
360 | } | |
361 | ||
362 | EXPORT_SYMBOL(__tasklet_schedule); | |
363 | ||
7ad5b3a5 | 364 | void __tasklet_hi_schedule(struct tasklet_struct *t) |
1da177e4 LT |
365 | { |
366 | unsigned long flags; | |
367 | ||
368 | local_irq_save(flags); | |
48f20a9a OJ |
369 | t->next = NULL; |
370 | *__get_cpu_var(tasklet_hi_vec).tail = t; | |
371 | __get_cpu_var(tasklet_hi_vec).tail = &(t->next); | |
1da177e4 LT |
372 | raise_softirq_irqoff(HI_SOFTIRQ); |
373 | local_irq_restore(flags); | |
374 | } | |
375 | ||
376 | EXPORT_SYMBOL(__tasklet_hi_schedule); | |
377 | ||
378 | static void tasklet_action(struct softirq_action *a) | |
379 | { | |
380 | struct tasklet_struct *list; | |
381 | ||
382 | local_irq_disable(); | |
48f20a9a OJ |
383 | list = __get_cpu_var(tasklet_vec).head; |
384 | __get_cpu_var(tasklet_vec).head = NULL; | |
385 | __get_cpu_var(tasklet_vec).tail = &__get_cpu_var(tasklet_vec).head; | |
1da177e4 LT |
386 | local_irq_enable(); |
387 | ||
388 | while (list) { | |
389 | struct tasklet_struct *t = list; | |
390 | ||
391 | list = list->next; | |
392 | ||
393 | if (tasklet_trylock(t)) { | |
394 | if (!atomic_read(&t->count)) { | |
395 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
396 | BUG(); | |
397 | t->func(t->data); | |
398 | tasklet_unlock(t); | |
399 | continue; | |
400 | } | |
401 | tasklet_unlock(t); | |
402 | } | |
403 | ||
404 | local_irq_disable(); | |
48f20a9a OJ |
405 | t->next = NULL; |
406 | *__get_cpu_var(tasklet_vec).tail = t; | |
407 | __get_cpu_var(tasklet_vec).tail = &(t->next); | |
1da177e4 LT |
408 | __raise_softirq_irqoff(TASKLET_SOFTIRQ); |
409 | local_irq_enable(); | |
410 | } | |
411 | } | |
412 | ||
413 | static void tasklet_hi_action(struct softirq_action *a) | |
414 | { | |
415 | struct tasklet_struct *list; | |
416 | ||
417 | local_irq_disable(); | |
48f20a9a OJ |
418 | list = __get_cpu_var(tasklet_hi_vec).head; |
419 | __get_cpu_var(tasklet_hi_vec).head = NULL; | |
420 | __get_cpu_var(tasklet_hi_vec).tail = &__get_cpu_var(tasklet_hi_vec).head; | |
1da177e4 LT |
421 | local_irq_enable(); |
422 | ||
423 | while (list) { | |
424 | struct tasklet_struct *t = list; | |
425 | ||
426 | list = list->next; | |
427 | ||
428 | if (tasklet_trylock(t)) { | |
429 | if (!atomic_read(&t->count)) { | |
430 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
431 | BUG(); | |
432 | t->func(t->data); | |
433 | tasklet_unlock(t); | |
434 | continue; | |
435 | } | |
436 | tasklet_unlock(t); | |
437 | } | |
438 | ||
439 | local_irq_disable(); | |
48f20a9a OJ |
440 | t->next = NULL; |
441 | *__get_cpu_var(tasklet_hi_vec).tail = t; | |
442 | __get_cpu_var(tasklet_hi_vec).tail = &(t->next); | |
1da177e4 LT |
443 | __raise_softirq_irqoff(HI_SOFTIRQ); |
444 | local_irq_enable(); | |
445 | } | |
446 | } | |
447 | ||
448 | ||
449 | void tasklet_init(struct tasklet_struct *t, | |
450 | void (*func)(unsigned long), unsigned long data) | |
451 | { | |
452 | t->next = NULL; | |
453 | t->state = 0; | |
454 | atomic_set(&t->count, 0); | |
455 | t->func = func; | |
456 | t->data = data; | |
457 | } | |
458 | ||
459 | EXPORT_SYMBOL(tasklet_init); | |
460 | ||
461 | void tasklet_kill(struct tasklet_struct *t) | |
462 | { | |
463 | if (in_interrupt()) | |
464 | printk("Attempt to kill tasklet from interrupt\n"); | |
465 | ||
466 | while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { | |
467 | do | |
468 | yield(); | |
469 | while (test_bit(TASKLET_STATE_SCHED, &t->state)); | |
470 | } | |
471 | tasklet_unlock_wait(t); | |
472 | clear_bit(TASKLET_STATE_SCHED, &t->state); | |
473 | } | |
474 | ||
475 | EXPORT_SYMBOL(tasklet_kill); | |
476 | ||
477 | void __init softirq_init(void) | |
478 | { | |
48f20a9a OJ |
479 | int cpu; |
480 | ||
481 | for_each_possible_cpu(cpu) { | |
482 | per_cpu(tasklet_vec, cpu).tail = | |
483 | &per_cpu(tasklet_vec, cpu).head; | |
484 | per_cpu(tasklet_hi_vec, cpu).tail = | |
485 | &per_cpu(tasklet_hi_vec, cpu).head; | |
486 | } | |
487 | ||
962cf36c CM |
488 | open_softirq(TASKLET_SOFTIRQ, tasklet_action); |
489 | open_softirq(HI_SOFTIRQ, tasklet_hi_action); | |
1da177e4 LT |
490 | } |
491 | ||
492 | static int ksoftirqd(void * __bind_cpu) | |
493 | { | |
1da177e4 LT |
494 | set_current_state(TASK_INTERRUPTIBLE); |
495 | ||
496 | while (!kthread_should_stop()) { | |
497 | preempt_disable(); | |
498 | if (!local_softirq_pending()) { | |
499 | preempt_enable_no_resched(); | |
500 | schedule(); | |
501 | preempt_disable(); | |
502 | } | |
503 | ||
504 | __set_current_state(TASK_RUNNING); | |
505 | ||
506 | while (local_softirq_pending()) { | |
507 | /* Preempt disable stops cpu going offline. | |
508 | If already offline, we'll be on wrong CPU: | |
509 | don't process */ | |
510 | if (cpu_is_offline((long)__bind_cpu)) | |
511 | goto wait_to_die; | |
512 | do_softirq(); | |
513 | preempt_enable_no_resched(); | |
514 | cond_resched(); | |
515 | preempt_disable(); | |
516 | } | |
517 | preempt_enable(); | |
518 | set_current_state(TASK_INTERRUPTIBLE); | |
519 | } | |
520 | __set_current_state(TASK_RUNNING); | |
521 | return 0; | |
522 | ||
523 | wait_to_die: | |
524 | preempt_enable(); | |
525 | /* Wait for kthread_stop */ | |
526 | set_current_state(TASK_INTERRUPTIBLE); | |
527 | while (!kthread_should_stop()) { | |
528 | schedule(); | |
529 | set_current_state(TASK_INTERRUPTIBLE); | |
530 | } | |
531 | __set_current_state(TASK_RUNNING); | |
532 | return 0; | |
533 | } | |
534 | ||
535 | #ifdef CONFIG_HOTPLUG_CPU | |
536 | /* | |
537 | * tasklet_kill_immediate is called to remove a tasklet which can already be | |
538 | * scheduled for execution on @cpu. | |
539 | * | |
540 | * Unlike tasklet_kill, this function removes the tasklet | |
541 | * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state. | |
542 | * | |
543 | * When this function is called, @cpu must be in the CPU_DEAD state. | |
544 | */ | |
545 | void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu) | |
546 | { | |
547 | struct tasklet_struct **i; | |
548 | ||
549 | BUG_ON(cpu_online(cpu)); | |
550 | BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state)); | |
551 | ||
552 | if (!test_bit(TASKLET_STATE_SCHED, &t->state)) | |
553 | return; | |
554 | ||
555 | /* CPU is dead, so no lock needed. */ | |
48f20a9a | 556 | for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) { |
1da177e4 LT |
557 | if (*i == t) { |
558 | *i = t->next; | |
48f20a9a OJ |
559 | /* If this was the tail element, move the tail ptr */ |
560 | if (*i == NULL) | |
561 | per_cpu(tasklet_vec, cpu).tail = i; | |
1da177e4 LT |
562 | return; |
563 | } | |
564 | } | |
565 | BUG(); | |
566 | } | |
567 | ||
568 | static void takeover_tasklets(unsigned int cpu) | |
569 | { | |
1da177e4 LT |
570 | /* CPU is dead, so no lock needed. */ |
571 | local_irq_disable(); | |
572 | ||
573 | /* Find end, append list for that CPU. */ | |
e5e41723 CB |
574 | if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) { |
575 | *(__get_cpu_var(tasklet_vec).tail) = per_cpu(tasklet_vec, cpu).head; | |
576 | __get_cpu_var(tasklet_vec).tail = per_cpu(tasklet_vec, cpu).tail; | |
577 | per_cpu(tasklet_vec, cpu).head = NULL; | |
578 | per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; | |
579 | } | |
1da177e4 LT |
580 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
581 | ||
e5e41723 CB |
582 | if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) { |
583 | *__get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).head; | |
584 | __get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).tail; | |
585 | per_cpu(tasklet_hi_vec, cpu).head = NULL; | |
586 | per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; | |
587 | } | |
1da177e4 LT |
588 | raise_softirq_irqoff(HI_SOFTIRQ); |
589 | ||
590 | local_irq_enable(); | |
591 | } | |
592 | #endif /* CONFIG_HOTPLUG_CPU */ | |
593 | ||
8c78f307 | 594 | static int __cpuinit cpu_callback(struct notifier_block *nfb, |
1da177e4 LT |
595 | unsigned long action, |
596 | void *hcpu) | |
597 | { | |
598 | int hotcpu = (unsigned long)hcpu; | |
599 | struct task_struct *p; | |
600 | ||
601 | switch (action) { | |
602 | case CPU_UP_PREPARE: | |
8bb78442 | 603 | case CPU_UP_PREPARE_FROZEN: |
1da177e4 LT |
604 | p = kthread_create(ksoftirqd, hcpu, "ksoftirqd/%d", hotcpu); |
605 | if (IS_ERR(p)) { | |
606 | printk("ksoftirqd for %i failed\n", hotcpu); | |
607 | return NOTIFY_BAD; | |
608 | } | |
609 | kthread_bind(p, hotcpu); | |
610 | per_cpu(ksoftirqd, hotcpu) = p; | |
611 | break; | |
612 | case CPU_ONLINE: | |
8bb78442 | 613 | case CPU_ONLINE_FROZEN: |
1da177e4 LT |
614 | wake_up_process(per_cpu(ksoftirqd, hotcpu)); |
615 | break; | |
616 | #ifdef CONFIG_HOTPLUG_CPU | |
617 | case CPU_UP_CANCELED: | |
8bb78442 | 618 | case CPU_UP_CANCELED_FROZEN: |
fc75cdfa HC |
619 | if (!per_cpu(ksoftirqd, hotcpu)) |
620 | break; | |
1da177e4 | 621 | /* Unbind so it can run. Fall thru. */ |
a4c4af7c HC |
622 | kthread_bind(per_cpu(ksoftirqd, hotcpu), |
623 | any_online_cpu(cpu_online_map)); | |
1da177e4 | 624 | case CPU_DEAD: |
1c6b4aa9 ST |
625 | case CPU_DEAD_FROZEN: { |
626 | struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; | |
627 | ||
1da177e4 LT |
628 | p = per_cpu(ksoftirqd, hotcpu); |
629 | per_cpu(ksoftirqd, hotcpu) = NULL; | |
961ccddd | 630 | sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m); |
1da177e4 LT |
631 | kthread_stop(p); |
632 | takeover_tasklets(hotcpu); | |
633 | break; | |
1c6b4aa9 | 634 | } |
1da177e4 LT |
635 | #endif /* CONFIG_HOTPLUG_CPU */ |
636 | } | |
637 | return NOTIFY_OK; | |
638 | } | |
639 | ||
8c78f307 | 640 | static struct notifier_block __cpuinitdata cpu_nfb = { |
1da177e4 LT |
641 | .notifier_call = cpu_callback |
642 | }; | |
643 | ||
7babe8db | 644 | static __init int spawn_ksoftirqd(void) |
1da177e4 LT |
645 | { |
646 | void *cpu = (void *)(long)smp_processor_id(); | |
07dccf33 AM |
647 | int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu); |
648 | ||
649 | BUG_ON(err == NOTIFY_BAD); | |
1da177e4 LT |
650 | cpu_callback(&cpu_nfb, CPU_ONLINE, cpu); |
651 | register_cpu_notifier(&cpu_nfb); | |
652 | return 0; | |
653 | } | |
7babe8db | 654 | early_initcall(spawn_ksoftirqd); |
78eef01b AM |
655 | |
656 | #ifdef CONFIG_SMP | |
657 | /* | |
658 | * Call a function on all processors | |
659 | */ | |
15c8b6c1 | 660 | int on_each_cpu(void (*func) (void *info), void *info, int wait) |
78eef01b AM |
661 | { |
662 | int ret = 0; | |
663 | ||
664 | preempt_disable(); | |
8691e5a8 | 665 | ret = smp_call_function(func, info, wait); |
78eef01b AM |
666 | local_irq_disable(); |
667 | func(info); | |
668 | local_irq_enable(); | |
669 | preempt_enable(); | |
670 | return ret; | |
671 | } | |
672 | EXPORT_SYMBOL(on_each_cpu); | |
673 | #endif |