Root/
1 | /* |
2 | * linux/kernel/softirq.c |
3 | * |
4 | * Copyright (C) 1992 Linus Torvalds |
5 | * |
6 | * Distribute under GPLv2. |
7 | * |
8 | * Rewritten. Old one was good in 2.2, but in 2.3 it was immoral. --ANK (990903) |
9 | * |
10 | * Remote softirq infrastructure is by Jens Axboe. |
11 | */ |
12 | |
13 | #include <linux/export.h> |
14 | #include <linux/kernel_stat.h> |
15 | #include <linux/interrupt.h> |
16 | #include <linux/init.h> |
17 | #include <linux/mm.h> |
18 | #include <linux/notifier.h> |
19 | #include <linux/percpu.h> |
20 | #include <linux/cpu.h> |
21 | #include <linux/freezer.h> |
22 | #include <linux/kthread.h> |
23 | #include <linux/rcupdate.h> |
24 | #include <linux/ftrace.h> |
25 | #include <linux/smp.h> |
26 | #include <linux/smpboot.h> |
27 | #include <linux/tick.h> |
28 | |
29 | #define CREATE_TRACE_POINTS |
30 | #include <trace/events/irq.h> |
31 | |
32 | #include <asm/irq.h> |
33 | /* |
34 | - No shared variables, all the data are CPU local. |
35 | - If a softirq needs serialization, let it serialize itself |
36 | by its own spinlocks. |
37 | - Even if softirq is serialized, only local cpu is marked for |
38 | execution. Hence, we get something sort of weak cpu binding. |
39 | Though it is still not clear, will it result in better locality |
40 | or will not. |
41 | |
42 | Examples: |
43 | - NET RX softirq. It is multithreaded and does not require |
44 | any global serialization. |
45 | - NET TX softirq. It kicks software netdevice queues, hence |
46 | it is logically serialized per device, but this serialization |
47 | is invisible to common code. |
48 | - Tasklets: serialized wrt itself. |
49 | */ |
50 | |
51 | #ifndef __ARCH_IRQ_STAT |
52 | irq_cpustat_t irq_stat[NR_CPUS] ____cacheline_aligned; |
53 | EXPORT_SYMBOL(irq_stat); |
54 | #endif |
55 | |
56 | static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp; |
57 | |
58 | DEFINE_PER_CPU(struct task_struct *, ksoftirqd); |
59 | |
60 | char *softirq_to_name[NR_SOFTIRQS] = { |
61 | "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "BLOCK_IOPOLL", |
62 | "TASKLET", "SCHED", "HRTIMER", "RCU" |
63 | }; |
64 | |
65 | /* |
66 | * we cannot loop indefinitely here to avoid userspace starvation, |
67 | * but we also don't want to introduce a worst case 1/HZ latency |
68 | * to the pending events, so lets the scheduler to balance |
69 | * the softirq load for us. |
70 | */ |
71 | static void wakeup_softirqd(void) |
72 | { |
73 | /* Interrupts are disabled: no need to stop preemption */ |
74 | struct task_struct *tsk = __this_cpu_read(ksoftirqd); |
75 | |
76 | if (tsk && tsk->state != TASK_RUNNING) |
77 | wake_up_process(tsk); |
78 | } |
79 | |
80 | /* |
81 | * preempt_count and SOFTIRQ_OFFSET usage: |
82 | * - preempt_count is changed by SOFTIRQ_OFFSET on entering or leaving |
83 | * softirq processing. |
84 | * - preempt_count is changed by SOFTIRQ_DISABLE_OFFSET (= 2 * SOFTIRQ_OFFSET) |
85 | * on local_bh_disable or local_bh_enable. |
86 | * This lets us distinguish between whether we are currently processing |
87 | * softirq and whether we just have bh disabled. |
88 | */ |
89 | |
90 | /* |
91 | * This one is for softirq.c-internal use, |
92 | * where hardirqs are disabled legitimately: |
93 | */ |
94 | #ifdef CONFIG_TRACE_IRQFLAGS |
95 | static void __local_bh_disable(unsigned long ip, unsigned int cnt) |
96 | { |
97 | unsigned long flags; |
98 | |
99 | WARN_ON_ONCE(in_irq()); |
100 | |
101 | raw_local_irq_save(flags); |
102 | /* |
103 | * The preempt tracer hooks into add_preempt_count and will break |
104 | * lockdep because it calls back into lockdep after SOFTIRQ_OFFSET |
105 | * is set and before current->softirq_enabled is cleared. |
106 | * We must manually increment preempt_count here and manually |
107 | * call the trace_preempt_off later. |
108 | */ |
109 | preempt_count() += cnt; |
110 | /* |
111 | * Were softirqs turned off above: |
112 | */ |
113 | if (softirq_count() == cnt) |
114 | trace_softirqs_off(ip); |
115 | raw_local_irq_restore(flags); |
116 | |
117 | if (preempt_count() == cnt) |
118 | trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); |
119 | } |
120 | #else /* !CONFIG_TRACE_IRQFLAGS */ |
121 | static inline void __local_bh_disable(unsigned long ip, unsigned int cnt) |
122 | { |
123 | add_preempt_count(cnt); |
124 | barrier(); |
125 | } |
126 | #endif /* CONFIG_TRACE_IRQFLAGS */ |
127 | |
128 | void local_bh_disable(void) |
129 | { |
130 | __local_bh_disable((unsigned long)__builtin_return_address(0), |
131 | SOFTIRQ_DISABLE_OFFSET); |
132 | } |
133 | |
134 | EXPORT_SYMBOL(local_bh_disable); |
135 | |
136 | static void __local_bh_enable(unsigned int cnt) |
137 | { |
138 | WARN_ON_ONCE(in_irq()); |
139 | WARN_ON_ONCE(!irqs_disabled()); |
140 | |
141 | if (softirq_count() == cnt) |
142 | trace_softirqs_on((unsigned long)__builtin_return_address(0)); |
143 | sub_preempt_count(cnt); |
144 | } |
145 | |
146 | /* |
147 | * Special-case - softirqs can safely be enabled in |
148 | * cond_resched_softirq(), or by __do_softirq(), |
149 | * without processing still-pending softirqs: |
150 | */ |
151 | void _local_bh_enable(void) |
152 | { |
153 | __local_bh_enable(SOFTIRQ_DISABLE_OFFSET); |
154 | } |
155 | |
156 | EXPORT_SYMBOL(_local_bh_enable); |
157 | |
158 | static inline void _local_bh_enable_ip(unsigned long ip) |
159 | { |
160 | WARN_ON_ONCE(in_irq() || irqs_disabled()); |
161 | #ifdef CONFIG_TRACE_IRQFLAGS |
162 | local_irq_disable(); |
163 | #endif |
164 | /* |
165 | * Are softirqs going to be turned on now: |
166 | */ |
167 | if (softirq_count() == SOFTIRQ_DISABLE_OFFSET) |
168 | trace_softirqs_on(ip); |
169 | /* |
170 | * Keep preemption disabled until we are done with |
171 | * softirq processing: |
172 | */ |
173 | sub_preempt_count(SOFTIRQ_DISABLE_OFFSET - 1); |
174 | |
175 | if (unlikely(!in_interrupt() && local_softirq_pending())) |
176 | do_softirq(); |
177 | |
178 | dec_preempt_count(); |
179 | #ifdef CONFIG_TRACE_IRQFLAGS |
180 | local_irq_enable(); |
181 | #endif |
182 | preempt_check_resched(); |
183 | } |
184 | |
185 | void local_bh_enable(void) |
186 | { |
187 | _local_bh_enable_ip((unsigned long)__builtin_return_address(0)); |
188 | } |
189 | EXPORT_SYMBOL(local_bh_enable); |
190 | |
191 | void local_bh_enable_ip(unsigned long ip) |
192 | { |
193 | _local_bh_enable_ip(ip); |
194 | } |
195 | EXPORT_SYMBOL(local_bh_enable_ip); |
196 | |
197 | /* |
198 | * We restart softirq processing for at most 2 ms, |
199 | * and if need_resched() is not set. |
200 | * |
201 | * These limits have been established via experimentation. |
202 | * The two things to balance is latency against fairness - |
203 | * we want to handle softirqs as soon as possible, but they |
204 | * should not be able to lock up the box. |
205 | */ |
206 | #define MAX_SOFTIRQ_TIME msecs_to_jiffies(2) |
207 | |
208 | asmlinkage void __do_softirq(void) |
209 | { |
210 | struct softirq_action *h; |
211 | __u32 pending; |
212 | unsigned long end = jiffies + MAX_SOFTIRQ_TIME; |
213 | int cpu; |
214 | unsigned long old_flags = current->flags; |
215 | |
216 | /* |
217 | * Mask out PF_MEMALLOC s current task context is borrowed for the |
218 | * softirq. A softirq handled such as network RX might set PF_MEMALLOC |
219 | * again if the socket is related to swap |
220 | */ |
221 | current->flags &= ~PF_MEMALLOC; |
222 | |
223 | pending = local_softirq_pending(); |
224 | account_irq_enter_time(current); |
225 | |
226 | __local_bh_disable((unsigned long)__builtin_return_address(0), |
227 | SOFTIRQ_OFFSET); |
228 | lockdep_softirq_enter(); |
229 | |
230 | cpu = smp_processor_id(); |
231 | restart: |
232 | /* Reset the pending bitmask before enabling irqs */ |
233 | set_softirq_pending(0); |
234 | |
235 | local_irq_enable(); |
236 | |
237 | h = softirq_vec; |
238 | |
239 | do { |
240 | if (pending & 1) { |
241 | unsigned int vec_nr = h - softirq_vec; |
242 | int prev_count = preempt_count(); |
243 | |
244 | kstat_incr_softirqs_this_cpu(vec_nr); |
245 | |
246 | trace_softirq_entry(vec_nr); |
247 | h->action(h); |
248 | trace_softirq_exit(vec_nr); |
249 | if (unlikely(prev_count != preempt_count())) { |
250 | printk(KERN_ERR "huh, entered softirq %u %s %p" |
251 | "with preempt_count %08x," |
252 | " exited with %08x?\n", vec_nr, |
253 | softirq_to_name[vec_nr], h->action, |
254 | prev_count, preempt_count()); |
255 | preempt_count() = prev_count; |
256 | } |
257 | |
258 | rcu_bh_qs(cpu); |
259 | } |
260 | h++; |
261 | pending >>= 1; |
262 | } while (pending); |
263 | |
264 | local_irq_disable(); |
265 | |
266 | pending = local_softirq_pending(); |
267 | if (pending) { |
268 | if (time_before(jiffies, end) && !need_resched()) |
269 | goto restart; |
270 | |
271 | wakeup_softirqd(); |
272 | } |
273 | |
274 | lockdep_softirq_exit(); |
275 | |
276 | account_irq_exit_time(current); |
277 | __local_bh_enable(SOFTIRQ_OFFSET); |
278 | tsk_restore_flags(current, old_flags, PF_MEMALLOC); |
279 | } |
280 | |
281 | #ifndef __ARCH_HAS_DO_SOFTIRQ |
282 | |
283 | asmlinkage void do_softirq(void) |
284 | { |
285 | __u32 pending; |
286 | unsigned long flags; |
287 | |
288 | if (in_interrupt()) |
289 | return; |
290 | |
291 | local_irq_save(flags); |
292 | |
293 | pending = local_softirq_pending(); |
294 | |
295 | if (pending) |
296 | __do_softirq(); |
297 | |
298 | local_irq_restore(flags); |
299 | } |
300 | |
301 | #endif |
302 | |
303 | /* |
304 | * Enter an interrupt context. |
305 | */ |
306 | void irq_enter(void) |
307 | { |
308 | int cpu = smp_processor_id(); |
309 | |
310 | rcu_irq_enter(); |
311 | if (is_idle_task(current) && !in_interrupt()) { |
312 | /* |
313 | * Prevent raise_softirq from needlessly waking up ksoftirqd |
314 | * here, as softirq will be serviced on return from interrupt. |
315 | */ |
316 | local_bh_disable(); |
317 | tick_check_idle(cpu); |
318 | _local_bh_enable(); |
319 | } |
320 | |
321 | __irq_enter(); |
322 | } |
323 | |
324 | static inline void invoke_softirq(void) |
325 | { |
326 | if (!force_irqthreads) |
327 | __do_softirq(); |
328 | else |
329 | wakeup_softirqd(); |
330 | } |
331 | |
332 | /* |
333 | * Exit an interrupt context. Process softirqs if needed and possible: |
334 | */ |
335 | void irq_exit(void) |
336 | { |
337 | #ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED |
338 | local_irq_disable(); |
339 | #else |
340 | WARN_ON_ONCE(!irqs_disabled()); |
341 | #endif |
342 | |
343 | account_irq_exit_time(current); |
344 | trace_hardirq_exit(); |
345 | sub_preempt_count(HARDIRQ_OFFSET); |
346 | if (!in_interrupt() && local_softirq_pending()) |
347 | invoke_softirq(); |
348 | |
349 | #ifdef CONFIG_NO_HZ |
350 | /* Make sure that timer wheel updates are propagated */ |
351 | if (idle_cpu(smp_processor_id()) && !in_interrupt() && !need_resched()) |
352 | tick_nohz_irq_exit(); |
353 | #endif |
354 | rcu_irq_exit(); |
355 | } |
356 | |
357 | /* |
358 | * This function must run with irqs disabled! |
359 | */ |
360 | inline void raise_softirq_irqoff(unsigned int nr) |
361 | { |
362 | __raise_softirq_irqoff(nr); |
363 | |
364 | /* |
365 | * If we're in an interrupt or softirq, we're done |
366 | * (this also catches softirq-disabled code). We will |
367 | * actually run the softirq once we return from |
368 | * the irq or softirq. |
369 | * |
370 | * Otherwise we wake up ksoftirqd to make sure we |
371 | * schedule the softirq soon. |
372 | */ |
373 | if (!in_interrupt()) |
374 | wakeup_softirqd(); |
375 | } |
376 | |
377 | void raise_softirq(unsigned int nr) |
378 | { |
379 | unsigned long flags; |
380 | |
381 | local_irq_save(flags); |
382 | raise_softirq_irqoff(nr); |
383 | local_irq_restore(flags); |
384 | } |
385 | |
386 | void __raise_softirq_irqoff(unsigned int nr) |
387 | { |
388 | trace_softirq_raise(nr); |
389 | or_softirq_pending(1UL << nr); |
390 | } |
391 | |
392 | void open_softirq(int nr, void (*action)(struct softirq_action *)) |
393 | { |
394 | softirq_vec[nr].action = action; |
395 | } |
396 | |
397 | /* |
398 | * Tasklets |
399 | */ |
400 | struct tasklet_head |
401 | { |
402 | struct tasklet_struct *head; |
403 | struct tasklet_struct **tail; |
404 | }; |
405 | |
406 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec); |
407 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec); |
408 | |
409 | void __tasklet_schedule(struct tasklet_struct *t) |
410 | { |
411 | unsigned long flags; |
412 | |
413 | local_irq_save(flags); |
414 | t->next = NULL; |
415 | *__this_cpu_read(tasklet_vec.tail) = t; |
416 | __this_cpu_write(tasklet_vec.tail, &(t->next)); |
417 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
418 | local_irq_restore(flags); |
419 | } |
420 | |
421 | EXPORT_SYMBOL(__tasklet_schedule); |
422 | |
423 | void __tasklet_hi_schedule(struct tasklet_struct *t) |
424 | { |
425 | unsigned long flags; |
426 | |
427 | local_irq_save(flags); |
428 | t->next = NULL; |
429 | *__this_cpu_read(tasklet_hi_vec.tail) = t; |
430 | __this_cpu_write(tasklet_hi_vec.tail, &(t->next)); |
431 | raise_softirq_irqoff(HI_SOFTIRQ); |
432 | local_irq_restore(flags); |
433 | } |
434 | |
435 | EXPORT_SYMBOL(__tasklet_hi_schedule); |
436 | |
437 | void __tasklet_hi_schedule_first(struct tasklet_struct *t) |
438 | { |
439 | BUG_ON(!irqs_disabled()); |
440 | |
441 | t->next = __this_cpu_read(tasklet_hi_vec.head); |
442 | __this_cpu_write(tasklet_hi_vec.head, t); |
443 | __raise_softirq_irqoff(HI_SOFTIRQ); |
444 | } |
445 | |
446 | EXPORT_SYMBOL(__tasklet_hi_schedule_first); |
447 | |
448 | static void tasklet_action(struct softirq_action *a) |
449 | { |
450 | struct tasklet_struct *list; |
451 | |
452 | local_irq_disable(); |
453 | list = __this_cpu_read(tasklet_vec.head); |
454 | __this_cpu_write(tasklet_vec.head, NULL); |
455 | __this_cpu_write(tasklet_vec.tail, &__get_cpu_var(tasklet_vec).head); |
456 | local_irq_enable(); |
457 | |
458 | while (list) { |
459 | struct tasklet_struct *t = list; |
460 | |
461 | list = list->next; |
462 | |
463 | if (tasklet_trylock(t)) { |
464 | if (!atomic_read(&t->count)) { |
465 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) |
466 | BUG(); |
467 | t->func(t->data); |
468 | tasklet_unlock(t); |
469 | continue; |
470 | } |
471 | tasklet_unlock(t); |
472 | } |
473 | |
474 | local_irq_disable(); |
475 | t->next = NULL; |
476 | *__this_cpu_read(tasklet_vec.tail) = t; |
477 | __this_cpu_write(tasklet_vec.tail, &(t->next)); |
478 | __raise_softirq_irqoff(TASKLET_SOFTIRQ); |
479 | local_irq_enable(); |
480 | } |
481 | } |
482 | |
483 | static void tasklet_hi_action(struct softirq_action *a) |
484 | { |
485 | struct tasklet_struct *list; |
486 | |
487 | local_irq_disable(); |
488 | list = __this_cpu_read(tasklet_hi_vec.head); |
489 | __this_cpu_write(tasklet_hi_vec.head, NULL); |
490 | __this_cpu_write(tasklet_hi_vec.tail, &__get_cpu_var(tasklet_hi_vec).head); |
491 | local_irq_enable(); |
492 | |
493 | while (list) { |
494 | struct tasklet_struct *t = list; |
495 | |
496 | list = list->next; |
497 | |
498 | if (tasklet_trylock(t)) { |
499 | if (!atomic_read(&t->count)) { |
500 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) |
501 | BUG(); |
502 | t->func(t->data); |
503 | tasklet_unlock(t); |
504 | continue; |
505 | } |
506 | tasklet_unlock(t); |
507 | } |
508 | |
509 | local_irq_disable(); |
510 | t->next = NULL; |
511 | *__this_cpu_read(tasklet_hi_vec.tail) = t; |
512 | __this_cpu_write(tasklet_hi_vec.tail, &(t->next)); |
513 | __raise_softirq_irqoff(HI_SOFTIRQ); |
514 | local_irq_enable(); |
515 | } |
516 | } |
517 | |
518 | |
519 | void tasklet_init(struct tasklet_struct *t, |
520 | void (*func)(unsigned long), unsigned long data) |
521 | { |
522 | t->next = NULL; |
523 | t->state = 0; |
524 | atomic_set(&t->count, 0); |
525 | t->func = func; |
526 | t->data = data; |
527 | } |
528 | |
529 | EXPORT_SYMBOL(tasklet_init); |
530 | |
531 | void tasklet_kill(struct tasklet_struct *t) |
532 | { |
533 | if (in_interrupt()) |
534 | printk("Attempt to kill tasklet from interrupt\n"); |
535 | |
536 | while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { |
537 | do { |
538 | yield(); |
539 | } while (test_bit(TASKLET_STATE_SCHED, &t->state)); |
540 | } |
541 | tasklet_unlock_wait(t); |
542 | clear_bit(TASKLET_STATE_SCHED, &t->state); |
543 | } |
544 | |
545 | EXPORT_SYMBOL(tasklet_kill); |
546 | |
547 | /* |
548 | * tasklet_hrtimer |
549 | */ |
550 | |
551 | /* |
552 | * The trampoline is called when the hrtimer expires. It schedules a tasklet |
553 | * to run __tasklet_hrtimer_trampoline() which in turn will call the intended |
554 | * hrtimer callback, but from softirq context. |
555 | */ |
556 | static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer) |
557 | { |
558 | struct tasklet_hrtimer *ttimer = |
559 | container_of(timer, struct tasklet_hrtimer, timer); |
560 | |
561 | tasklet_hi_schedule(&ttimer->tasklet); |
562 | return HRTIMER_NORESTART; |
563 | } |
564 | |
565 | /* |
566 | * Helper function which calls the hrtimer callback from |
567 | * tasklet/softirq context |
568 | */ |
569 | static void __tasklet_hrtimer_trampoline(unsigned long data) |
570 | { |
571 | struct tasklet_hrtimer *ttimer = (void *)data; |
572 | enum hrtimer_restart restart; |
573 | |
574 | restart = ttimer->function(&ttimer->timer); |
575 | if (restart != HRTIMER_NORESTART) |
576 | hrtimer_restart(&ttimer->timer); |
577 | } |
578 | |
579 | /** |
580 | * tasklet_hrtimer_init - Init a tasklet/hrtimer combo for softirq callbacks |
581 | * @ttimer: tasklet_hrtimer which is initialized |
582 | * @function: hrtimer callback function which gets called from softirq context |
583 | * @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME) |
584 | * @mode: hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL) |
585 | */ |
586 | void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer, |
587 | enum hrtimer_restart (*function)(struct hrtimer *), |
588 | clockid_t which_clock, enum hrtimer_mode mode) |
589 | { |
590 | hrtimer_init(&ttimer->timer, which_clock, mode); |
591 | ttimer->timer.function = __hrtimer_tasklet_trampoline; |
592 | tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline, |
593 | (unsigned long)ttimer); |
594 | ttimer->function = function; |
595 | } |
596 | EXPORT_SYMBOL_GPL(tasklet_hrtimer_init); |
597 | |
598 | /* |
599 | * Remote softirq bits |
600 | */ |
601 | |
602 | DEFINE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list); |
603 | EXPORT_PER_CPU_SYMBOL(softirq_work_list); |
604 | |
605 | static void __local_trigger(struct call_single_data *cp, int softirq) |
606 | { |
607 | struct list_head *head = &__get_cpu_var(softirq_work_list[softirq]); |
608 | |
609 | list_add_tail(&cp->list, head); |
610 | |
611 | /* Trigger the softirq only if the list was previously empty. */ |
612 | if (head->next == &cp->list) |
613 | raise_softirq_irqoff(softirq); |
614 | } |
615 | |
616 | #ifdef CONFIG_USE_GENERIC_SMP_HELPERS |
617 | static void remote_softirq_receive(void *data) |
618 | { |
619 | struct call_single_data *cp = data; |
620 | unsigned long flags; |
621 | int softirq; |
622 | |
623 | softirq = cp->priv; |
624 | |
625 | local_irq_save(flags); |
626 | __local_trigger(cp, softirq); |
627 | local_irq_restore(flags); |
628 | } |
629 | |
630 | static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) |
631 | { |
632 | if (cpu_online(cpu)) { |
633 | cp->func = remote_softirq_receive; |
634 | cp->info = cp; |
635 | cp->flags = 0; |
636 | cp->priv = softirq; |
637 | |
638 | __smp_call_function_single(cpu, cp, 0); |
639 | return 0; |
640 | } |
641 | return 1; |
642 | } |
643 | #else /* CONFIG_USE_GENERIC_SMP_HELPERS */ |
644 | static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) |
645 | { |
646 | return 1; |
647 | } |
648 | #endif |
649 | |
650 | /** |
651 | * __send_remote_softirq - try to schedule softirq work on a remote cpu |
652 | * @cp: private SMP call function data area |
653 | * @cpu: the remote cpu |
654 | * @this_cpu: the currently executing cpu |
655 | * @softirq: the softirq for the work |
656 | * |
657 | * Attempt to schedule softirq work on a remote cpu. If this cannot be |
658 | * done, the work is instead queued up on the local cpu. |
659 | * |
660 | * Interrupts must be disabled. |
661 | */ |
662 | void __send_remote_softirq(struct call_single_data *cp, int cpu, int this_cpu, int softirq) |
663 | { |
664 | if (cpu == this_cpu || __try_remote_softirq(cp, cpu, softirq)) |
665 | __local_trigger(cp, softirq); |
666 | } |
667 | EXPORT_SYMBOL(__send_remote_softirq); |
668 | |
669 | /** |
670 | * send_remote_softirq - try to schedule softirq work on a remote cpu |
671 | * @cp: private SMP call function data area |
672 | * @cpu: the remote cpu |
673 | * @softirq: the softirq for the work |
674 | * |
675 | * Like __send_remote_softirq except that disabling interrupts and |
676 | * computing the current cpu is done for the caller. |
677 | */ |
678 | void send_remote_softirq(struct call_single_data *cp, int cpu, int softirq) |
679 | { |
680 | unsigned long flags; |
681 | int this_cpu; |
682 | |
683 | local_irq_save(flags); |
684 | this_cpu = smp_processor_id(); |
685 | __send_remote_softirq(cp, cpu, this_cpu, softirq); |
686 | local_irq_restore(flags); |
687 | } |
688 | EXPORT_SYMBOL(send_remote_softirq); |
689 | |
690 | static int __cpuinit remote_softirq_cpu_notify(struct notifier_block *self, |
691 | unsigned long action, void *hcpu) |
692 | { |
693 | /* |
694 | * If a CPU goes away, splice its entries to the current CPU |
695 | * and trigger a run of the softirq |
696 | */ |
697 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { |
698 | int cpu = (unsigned long) hcpu; |
699 | int i; |
700 | |
701 | local_irq_disable(); |
702 | for (i = 0; i < NR_SOFTIRQS; i++) { |
703 | struct list_head *head = &per_cpu(softirq_work_list[i], cpu); |
704 | struct list_head *local_head; |
705 | |
706 | if (list_empty(head)) |
707 | continue; |
708 | |
709 | local_head = &__get_cpu_var(softirq_work_list[i]); |
710 | list_splice_init(head, local_head); |
711 | raise_softirq_irqoff(i); |
712 | } |
713 | local_irq_enable(); |
714 | } |
715 | |
716 | return NOTIFY_OK; |
717 | } |
718 | |
719 | static struct notifier_block __cpuinitdata remote_softirq_cpu_notifier = { |
720 | .notifier_call = remote_softirq_cpu_notify, |
721 | }; |
722 | |
723 | void __init softirq_init(void) |
724 | { |
725 | int cpu; |
726 | |
727 | for_each_possible_cpu(cpu) { |
728 | int i; |
729 | |
730 | per_cpu(tasklet_vec, cpu).tail = |
731 | &per_cpu(tasklet_vec, cpu).head; |
732 | per_cpu(tasklet_hi_vec, cpu).tail = |
733 | &per_cpu(tasklet_hi_vec, cpu).head; |
734 | for (i = 0; i < NR_SOFTIRQS; i++) |
735 | INIT_LIST_HEAD(&per_cpu(softirq_work_list[i], cpu)); |
736 | } |
737 | |
738 | register_hotcpu_notifier(&remote_softirq_cpu_notifier); |
739 | |
740 | open_softirq(TASKLET_SOFTIRQ, tasklet_action); |
741 | open_softirq(HI_SOFTIRQ, tasklet_hi_action); |
742 | } |
743 | |
744 | static int ksoftirqd_should_run(unsigned int cpu) |
745 | { |
746 | return local_softirq_pending(); |
747 | } |
748 | |
749 | static void run_ksoftirqd(unsigned int cpu) |
750 | { |
751 | local_irq_disable(); |
752 | if (local_softirq_pending()) { |
753 | __do_softirq(); |
754 | rcu_note_context_switch(cpu); |
755 | local_irq_enable(); |
756 | cond_resched(); |
757 | return; |
758 | } |
759 | local_irq_enable(); |
760 | } |
761 | |
762 | #ifdef CONFIG_HOTPLUG_CPU |
763 | /* |
764 | * tasklet_kill_immediate is called to remove a tasklet which can already be |
765 | * scheduled for execution on @cpu. |
766 | * |
767 | * Unlike tasklet_kill, this function removes the tasklet |
768 | * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state. |
769 | * |
770 | * When this function is called, @cpu must be in the CPU_DEAD state. |
771 | */ |
772 | void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu) |
773 | { |
774 | struct tasklet_struct **i; |
775 | |
776 | BUG_ON(cpu_online(cpu)); |
777 | BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state)); |
778 | |
779 | if (!test_bit(TASKLET_STATE_SCHED, &t->state)) |
780 | return; |
781 | |
782 | /* CPU is dead, so no lock needed. */ |
783 | for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) { |
784 | if (*i == t) { |
785 | *i = t->next; |
786 | /* If this was the tail element, move the tail ptr */ |
787 | if (*i == NULL) |
788 | per_cpu(tasklet_vec, cpu).tail = i; |
789 | return; |
790 | } |
791 | } |
792 | BUG(); |
793 | } |
794 | |
795 | static void takeover_tasklets(unsigned int cpu) |
796 | { |
797 | /* CPU is dead, so no lock needed. */ |
798 | local_irq_disable(); |
799 | |
800 | /* Find end, append list for that CPU. */ |
801 | if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) { |
802 | *__this_cpu_read(tasklet_vec.tail) = per_cpu(tasklet_vec, cpu).head; |
803 | this_cpu_write(tasklet_vec.tail, per_cpu(tasklet_vec, cpu).tail); |
804 | per_cpu(tasklet_vec, cpu).head = NULL; |
805 | per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; |
806 | } |
807 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
808 | |
809 | if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) { |
810 | *__this_cpu_read(tasklet_hi_vec.tail) = per_cpu(tasklet_hi_vec, cpu).head; |
811 | __this_cpu_write(tasklet_hi_vec.tail, per_cpu(tasklet_hi_vec, cpu).tail); |
812 | per_cpu(tasklet_hi_vec, cpu).head = NULL; |
813 | per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; |
814 | } |
815 | raise_softirq_irqoff(HI_SOFTIRQ); |
816 | |
817 | local_irq_enable(); |
818 | } |
819 | #endif /* CONFIG_HOTPLUG_CPU */ |
820 | |
821 | static int __cpuinit cpu_callback(struct notifier_block *nfb, |
822 | unsigned long action, |
823 | void *hcpu) |
824 | { |
825 | switch (action) { |
826 | #ifdef CONFIG_HOTPLUG_CPU |
827 | case CPU_DEAD: |
828 | case CPU_DEAD_FROZEN: |
829 | takeover_tasklets((unsigned long)hcpu); |
830 | break; |
831 | #endif /* CONFIG_HOTPLUG_CPU */ |
832 | } |
833 | return NOTIFY_OK; |
834 | } |
835 | |
836 | static struct notifier_block __cpuinitdata cpu_nfb = { |
837 | .notifier_call = cpu_callback |
838 | }; |
839 | |
840 | static struct smp_hotplug_thread softirq_threads = { |
841 | .store = &ksoftirqd, |
842 | .thread_should_run = ksoftirqd_should_run, |
843 | .thread_fn = run_ksoftirqd, |
844 | .thread_comm = "ksoftirqd/%u", |
845 | }; |
846 | |
847 | static __init int spawn_ksoftirqd(void) |
848 | { |
849 | register_cpu_notifier(&cpu_nfb); |
850 | |
851 | BUG_ON(smpboot_register_percpu_thread(&softirq_threads)); |
852 | |
853 | return 0; |
854 | } |
855 | early_initcall(spawn_ksoftirqd); |
856 | |
857 | /* |
858 | * [ These __weak aliases are kept in a separate compilation unit, so that |
859 | * GCC does not inline them incorrectly. ] |
860 | */ |
861 | |
862 | int __init __weak early_irq_init(void) |
863 | { |
864 | return 0; |
865 | } |
866 | |
867 | #ifdef CONFIG_GENERIC_HARDIRQS |
868 | int __init __weak arch_probe_nr_irqs(void) |
869 | { |
870 | return NR_IRQS_LEGACY; |
871 | } |
872 | |
873 | int __init __weak arch_early_irq_init(void) |
874 | { |
875 | return 0; |
876 | } |
877 | #endif |
878 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9