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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 | ||
134 | void local_bh_enable(void) | |
135 | { | |
3c829c36 | 136 | #ifdef CONFIG_TRACE_IRQFLAGS |
de30a2b3 IM |
137 | unsigned long flags; |
138 | ||
139 | WARN_ON_ONCE(in_irq()); | |
3c829c36 | 140 | #endif |
de30a2b3 IM |
141 | WARN_ON_ONCE(irqs_disabled()); |
142 | ||
3c829c36 | 143 | #ifdef CONFIG_TRACE_IRQFLAGS |
de30a2b3 | 144 | local_irq_save(flags); |
3c829c36 | 145 | #endif |
de30a2b3 IM |
146 | /* |
147 | * Are softirqs going to be turned on now: | |
148 | */ | |
149 | if (softirq_count() == SOFTIRQ_OFFSET) | |
150 | trace_softirqs_on((unsigned long)__builtin_return_address(0)); | |
151 | /* | |
152 | * Keep preemption disabled until we are done with | |
153 | * softirq processing: | |
154 | */ | |
155 | sub_preempt_count(SOFTIRQ_OFFSET - 1); | |
156 | ||
157 | if (unlikely(!in_interrupt() && local_softirq_pending())) | |
158 | do_softirq(); | |
159 | ||
160 | dec_preempt_count(); | |
3c829c36 | 161 | #ifdef CONFIG_TRACE_IRQFLAGS |
de30a2b3 | 162 | local_irq_restore(flags); |
3c829c36 | 163 | #endif |
de30a2b3 IM |
164 | preempt_check_resched(); |
165 | } | |
166 | EXPORT_SYMBOL(local_bh_enable); | |
167 | ||
168 | void local_bh_enable_ip(unsigned long ip) | |
169 | { | |
3c829c36 | 170 | #ifdef CONFIG_TRACE_IRQFLAGS |
de30a2b3 IM |
171 | unsigned long flags; |
172 | ||
173 | WARN_ON_ONCE(in_irq()); | |
174 | ||
175 | local_irq_save(flags); | |
3c829c36 | 176 | #endif |
de30a2b3 IM |
177 | /* |
178 | * Are softirqs going to be turned on now: | |
179 | */ | |
180 | if (softirq_count() == SOFTIRQ_OFFSET) | |
181 | trace_softirqs_on(ip); | |
182 | /* | |
183 | * Keep preemption disabled until we are done with | |
184 | * softirq processing: | |
185 | */ | |
186 | sub_preempt_count(SOFTIRQ_OFFSET - 1); | |
187 | ||
188 | if (unlikely(!in_interrupt() && local_softirq_pending())) | |
189 | do_softirq(); | |
190 | ||
191 | dec_preempt_count(); | |
3c829c36 | 192 | #ifdef CONFIG_TRACE_IRQFLAGS |
de30a2b3 | 193 | local_irq_restore(flags); |
3c829c36 | 194 | #endif |
de30a2b3 IM |
195 | preempt_check_resched(); |
196 | } | |
197 | EXPORT_SYMBOL(local_bh_enable_ip); | |
198 | ||
1da177e4 LT |
199 | /* |
200 | * We restart softirq processing MAX_SOFTIRQ_RESTART times, | |
201 | * and we fall back to softirqd after that. | |
202 | * | |
203 | * This number has been established via experimentation. | |
204 | * The two things to balance is latency against fairness - | |
205 | * we want to handle softirqs as soon as possible, but they | |
206 | * should not be able to lock up the box. | |
207 | */ | |
208 | #define MAX_SOFTIRQ_RESTART 10 | |
209 | ||
210 | asmlinkage void __do_softirq(void) | |
211 | { | |
212 | struct softirq_action *h; | |
213 | __u32 pending; | |
214 | int max_restart = MAX_SOFTIRQ_RESTART; | |
215 | int cpu; | |
216 | ||
217 | pending = local_softirq_pending(); | |
829035fd PM |
218 | account_system_vtime(current); |
219 | ||
de30a2b3 IM |
220 | __local_bh_disable((unsigned long)__builtin_return_address(0)); |
221 | trace_softirq_enter(); | |
1da177e4 | 222 | |
1da177e4 LT |
223 | cpu = smp_processor_id(); |
224 | restart: | |
225 | /* Reset the pending bitmask before enabling irqs */ | |
3f74478b | 226 | set_softirq_pending(0); |
1da177e4 | 227 | |
c70f5d66 | 228 | local_irq_enable(); |
1da177e4 LT |
229 | |
230 | h = softirq_vec; | |
231 | ||
232 | do { | |
233 | if (pending & 1) { | |
234 | h->action(h); | |
235 | rcu_bh_qsctr_inc(cpu); | |
236 | } | |
237 | h++; | |
238 | pending >>= 1; | |
239 | } while (pending); | |
240 | ||
c70f5d66 | 241 | local_irq_disable(); |
1da177e4 LT |
242 | |
243 | pending = local_softirq_pending(); | |
244 | if (pending && --max_restart) | |
245 | goto restart; | |
246 | ||
247 | if (pending) | |
248 | wakeup_softirqd(); | |
249 | ||
de30a2b3 | 250 | trace_softirq_exit(); |
829035fd PM |
251 | |
252 | account_system_vtime(current); | |
de30a2b3 | 253 | _local_bh_enable(); |
1da177e4 LT |
254 | } |
255 | ||
256 | #ifndef __ARCH_HAS_DO_SOFTIRQ | |
257 | ||
258 | asmlinkage void do_softirq(void) | |
259 | { | |
260 | __u32 pending; | |
261 | unsigned long flags; | |
262 | ||
263 | if (in_interrupt()) | |
264 | return; | |
265 | ||
266 | local_irq_save(flags); | |
267 | ||
268 | pending = local_softirq_pending(); | |
269 | ||
270 | if (pending) | |
271 | __do_softirq(); | |
272 | ||
273 | local_irq_restore(flags); | |
274 | } | |
275 | ||
1da177e4 LT |
276 | #endif |
277 | ||
dde4b2b5 IM |
278 | /* |
279 | * Enter an interrupt context. | |
280 | */ | |
281 | void irq_enter(void) | |
282 | { | |
6378ddb5 VP |
283 | #ifdef CONFIG_NO_HZ |
284 | int cpu = smp_processor_id(); | |
285 | if (idle_cpu(cpu) && !in_interrupt()) | |
286 | tick_nohz_stop_idle(cpu); | |
287 | #endif | |
79bf2bb3 TG |
288 | __irq_enter(); |
289 | #ifdef CONFIG_NO_HZ | |
6378ddb5 | 290 | if (idle_cpu(cpu)) |
79bf2bb3 TG |
291 | tick_nohz_update_jiffies(); |
292 | #endif | |
dde4b2b5 IM |
293 | } |
294 | ||
1da177e4 LT |
295 | #ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED |
296 | # define invoke_softirq() __do_softirq() | |
297 | #else | |
298 | # define invoke_softirq() do_softirq() | |
299 | #endif | |
300 | ||
301 | /* | |
302 | * Exit an interrupt context. Process softirqs if needed and possible: | |
303 | */ | |
304 | void irq_exit(void) | |
305 | { | |
306 | account_system_vtime(current); | |
de30a2b3 | 307 | trace_hardirq_exit(); |
1da177e4 LT |
308 | sub_preempt_count(IRQ_EXIT_OFFSET); |
309 | if (!in_interrupt() && local_softirq_pending()) | |
310 | invoke_softirq(); | |
79bf2bb3 TG |
311 | |
312 | #ifdef CONFIG_NO_HZ | |
313 | /* Make sure that timer wheel updates are propagated */ | |
314 | if (!in_interrupt() && idle_cpu(smp_processor_id()) && !need_resched()) | |
315 | tick_nohz_stop_sched_tick(); | |
2232c2d8 | 316 | rcu_irq_exit(); |
79bf2bb3 | 317 | #endif |
1da177e4 LT |
318 | preempt_enable_no_resched(); |
319 | } | |
320 | ||
321 | /* | |
322 | * This function must run with irqs disabled! | |
323 | */ | |
7ad5b3a5 | 324 | inline void raise_softirq_irqoff(unsigned int nr) |
1da177e4 LT |
325 | { |
326 | __raise_softirq_irqoff(nr); | |
327 | ||
328 | /* | |
329 | * If we're in an interrupt or softirq, we're done | |
330 | * (this also catches softirq-disabled code). We will | |
331 | * actually run the softirq once we return from | |
332 | * the irq or softirq. | |
333 | * | |
334 | * Otherwise we wake up ksoftirqd to make sure we | |
335 | * schedule the softirq soon. | |
336 | */ | |
337 | if (!in_interrupt()) | |
338 | wakeup_softirqd(); | |
339 | } | |
340 | ||
7ad5b3a5 | 341 | void raise_softirq(unsigned int nr) |
1da177e4 LT |
342 | { |
343 | unsigned long flags; | |
344 | ||
345 | local_irq_save(flags); | |
346 | raise_softirq_irqoff(nr); | |
347 | local_irq_restore(flags); | |
348 | } | |
349 | ||
962cf36c | 350 | void open_softirq(int nr, void (*action)(struct softirq_action *)) |
1da177e4 | 351 | { |
1da177e4 LT |
352 | softirq_vec[nr].action = action; |
353 | } | |
354 | ||
1da177e4 LT |
355 | /* Tasklets */ |
356 | struct tasklet_head | |
357 | { | |
48f20a9a OJ |
358 | struct tasklet_struct *head; |
359 | struct tasklet_struct **tail; | |
1da177e4 LT |
360 | }; |
361 | ||
362 | /* Some compilers disobey section attribute on statics when not | |
363 | initialized -- RR */ | |
364 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec) = { NULL }; | |
365 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec) = { NULL }; | |
366 | ||
7ad5b3a5 | 367 | void __tasklet_schedule(struct tasklet_struct *t) |
1da177e4 LT |
368 | { |
369 | unsigned long flags; | |
370 | ||
371 | local_irq_save(flags); | |
48f20a9a OJ |
372 | t->next = NULL; |
373 | *__get_cpu_var(tasklet_vec).tail = t; | |
374 | __get_cpu_var(tasklet_vec).tail = &(t->next); | |
1da177e4 LT |
375 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
376 | local_irq_restore(flags); | |
377 | } | |
378 | ||
379 | EXPORT_SYMBOL(__tasklet_schedule); | |
380 | ||
7ad5b3a5 | 381 | void __tasklet_hi_schedule(struct tasklet_struct *t) |
1da177e4 LT |
382 | { |
383 | unsigned long flags; | |
384 | ||
385 | local_irq_save(flags); | |
48f20a9a OJ |
386 | t->next = NULL; |
387 | *__get_cpu_var(tasklet_hi_vec).tail = t; | |
388 | __get_cpu_var(tasklet_hi_vec).tail = &(t->next); | |
1da177e4 LT |
389 | raise_softirq_irqoff(HI_SOFTIRQ); |
390 | local_irq_restore(flags); | |
391 | } | |
392 | ||
393 | EXPORT_SYMBOL(__tasklet_hi_schedule); | |
394 | ||
395 | static void tasklet_action(struct softirq_action *a) | |
396 | { | |
397 | struct tasklet_struct *list; | |
398 | ||
399 | local_irq_disable(); | |
48f20a9a OJ |
400 | list = __get_cpu_var(tasklet_vec).head; |
401 | __get_cpu_var(tasklet_vec).head = NULL; | |
402 | __get_cpu_var(tasklet_vec).tail = &__get_cpu_var(tasklet_vec).head; | |
1da177e4 LT |
403 | local_irq_enable(); |
404 | ||
405 | while (list) { | |
406 | struct tasklet_struct *t = list; | |
407 | ||
408 | list = list->next; | |
409 | ||
410 | if (tasklet_trylock(t)) { | |
411 | if (!atomic_read(&t->count)) { | |
412 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
413 | BUG(); | |
414 | t->func(t->data); | |
415 | tasklet_unlock(t); | |
416 | continue; | |
417 | } | |
418 | tasklet_unlock(t); | |
419 | } | |
420 | ||
421 | local_irq_disable(); | |
48f20a9a OJ |
422 | t->next = NULL; |
423 | *__get_cpu_var(tasklet_vec).tail = t; | |
424 | __get_cpu_var(tasklet_vec).tail = &(t->next); | |
1da177e4 LT |
425 | __raise_softirq_irqoff(TASKLET_SOFTIRQ); |
426 | local_irq_enable(); | |
427 | } | |
428 | } | |
429 | ||
430 | static void tasklet_hi_action(struct softirq_action *a) | |
431 | { | |
432 | struct tasklet_struct *list; | |
433 | ||
434 | local_irq_disable(); | |
48f20a9a OJ |
435 | list = __get_cpu_var(tasklet_hi_vec).head; |
436 | __get_cpu_var(tasklet_hi_vec).head = NULL; | |
437 | __get_cpu_var(tasklet_hi_vec).tail = &__get_cpu_var(tasklet_hi_vec).head; | |
1da177e4 LT |
438 | local_irq_enable(); |
439 | ||
440 | while (list) { | |
441 | struct tasklet_struct *t = list; | |
442 | ||
443 | list = list->next; | |
444 | ||
445 | if (tasklet_trylock(t)) { | |
446 | if (!atomic_read(&t->count)) { | |
447 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
448 | BUG(); | |
449 | t->func(t->data); | |
450 | tasklet_unlock(t); | |
451 | continue; | |
452 | } | |
453 | tasklet_unlock(t); | |
454 | } | |
455 | ||
456 | local_irq_disable(); | |
48f20a9a OJ |
457 | t->next = NULL; |
458 | *__get_cpu_var(tasklet_hi_vec).tail = t; | |
459 | __get_cpu_var(tasklet_hi_vec).tail = &(t->next); | |
1da177e4 LT |
460 | __raise_softirq_irqoff(HI_SOFTIRQ); |
461 | local_irq_enable(); | |
462 | } | |
463 | } | |
464 | ||
465 | ||
466 | void tasklet_init(struct tasklet_struct *t, | |
467 | void (*func)(unsigned long), unsigned long data) | |
468 | { | |
469 | t->next = NULL; | |
470 | t->state = 0; | |
471 | atomic_set(&t->count, 0); | |
472 | t->func = func; | |
473 | t->data = data; | |
474 | } | |
475 | ||
476 | EXPORT_SYMBOL(tasklet_init); | |
477 | ||
478 | void tasklet_kill(struct tasklet_struct *t) | |
479 | { | |
480 | if (in_interrupt()) | |
481 | printk("Attempt to kill tasklet from interrupt\n"); | |
482 | ||
483 | while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { | |
484 | do | |
485 | yield(); | |
486 | while (test_bit(TASKLET_STATE_SCHED, &t->state)); | |
487 | } | |
488 | tasklet_unlock_wait(t); | |
489 | clear_bit(TASKLET_STATE_SCHED, &t->state); | |
490 | } | |
491 | ||
492 | EXPORT_SYMBOL(tasklet_kill); | |
493 | ||
494 | void __init softirq_init(void) | |
495 | { | |
48f20a9a OJ |
496 | int cpu; |
497 | ||
498 | for_each_possible_cpu(cpu) { | |
499 | per_cpu(tasklet_vec, cpu).tail = | |
500 | &per_cpu(tasklet_vec, cpu).head; | |
501 | per_cpu(tasklet_hi_vec, cpu).tail = | |
502 | &per_cpu(tasklet_hi_vec, cpu).head; | |
503 | } | |
504 | ||
962cf36c CM |
505 | open_softirq(TASKLET_SOFTIRQ, tasklet_action); |
506 | open_softirq(HI_SOFTIRQ, tasklet_hi_action); | |
1da177e4 LT |
507 | } |
508 | ||
509 | static int ksoftirqd(void * __bind_cpu) | |
510 | { | |
1da177e4 LT |
511 | set_current_state(TASK_INTERRUPTIBLE); |
512 | ||
513 | while (!kthread_should_stop()) { | |
514 | preempt_disable(); | |
515 | if (!local_softirq_pending()) { | |
516 | preempt_enable_no_resched(); | |
517 | schedule(); | |
518 | preempt_disable(); | |
519 | } | |
520 | ||
521 | __set_current_state(TASK_RUNNING); | |
522 | ||
523 | while (local_softirq_pending()) { | |
524 | /* Preempt disable stops cpu going offline. | |
525 | If already offline, we'll be on wrong CPU: | |
526 | don't process */ | |
527 | if (cpu_is_offline((long)__bind_cpu)) | |
528 | goto wait_to_die; | |
529 | do_softirq(); | |
530 | preempt_enable_no_resched(); | |
531 | cond_resched(); | |
532 | preempt_disable(); | |
533 | } | |
534 | preempt_enable(); | |
535 | set_current_state(TASK_INTERRUPTIBLE); | |
536 | } | |
537 | __set_current_state(TASK_RUNNING); | |
538 | return 0; | |
539 | ||
540 | wait_to_die: | |
541 | preempt_enable(); | |
542 | /* Wait for kthread_stop */ | |
543 | set_current_state(TASK_INTERRUPTIBLE); | |
544 | while (!kthread_should_stop()) { | |
545 | schedule(); | |
546 | set_current_state(TASK_INTERRUPTIBLE); | |
547 | } | |
548 | __set_current_state(TASK_RUNNING); | |
549 | return 0; | |
550 | } | |
551 | ||
552 | #ifdef CONFIG_HOTPLUG_CPU | |
553 | /* | |
554 | * tasklet_kill_immediate is called to remove a tasklet which can already be | |
555 | * scheduled for execution on @cpu. | |
556 | * | |
557 | * Unlike tasklet_kill, this function removes the tasklet | |
558 | * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state. | |
559 | * | |
560 | * When this function is called, @cpu must be in the CPU_DEAD state. | |
561 | */ | |
562 | void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu) | |
563 | { | |
564 | struct tasklet_struct **i; | |
565 | ||
566 | BUG_ON(cpu_online(cpu)); | |
567 | BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state)); | |
568 | ||
569 | if (!test_bit(TASKLET_STATE_SCHED, &t->state)) | |
570 | return; | |
571 | ||
572 | /* CPU is dead, so no lock needed. */ | |
48f20a9a | 573 | for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) { |
1da177e4 LT |
574 | if (*i == t) { |
575 | *i = t->next; | |
48f20a9a OJ |
576 | /* If this was the tail element, move the tail ptr */ |
577 | if (*i == NULL) | |
578 | per_cpu(tasklet_vec, cpu).tail = i; | |
1da177e4 LT |
579 | return; |
580 | } | |
581 | } | |
582 | BUG(); | |
583 | } | |
584 | ||
585 | static void takeover_tasklets(unsigned int cpu) | |
586 | { | |
1da177e4 LT |
587 | /* CPU is dead, so no lock needed. */ |
588 | local_irq_disable(); | |
589 | ||
590 | /* Find end, append list for that CPU. */ | |
e5e41723 CB |
591 | if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) { |
592 | *(__get_cpu_var(tasklet_vec).tail) = per_cpu(tasklet_vec, cpu).head; | |
593 | __get_cpu_var(tasklet_vec).tail = per_cpu(tasklet_vec, cpu).tail; | |
594 | per_cpu(tasklet_vec, cpu).head = NULL; | |
595 | per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; | |
596 | } | |
1da177e4 LT |
597 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
598 | ||
e5e41723 CB |
599 | if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) { |
600 | *__get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).head; | |
601 | __get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).tail; | |
602 | per_cpu(tasklet_hi_vec, cpu).head = NULL; | |
603 | per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; | |
604 | } | |
1da177e4 LT |
605 | raise_softirq_irqoff(HI_SOFTIRQ); |
606 | ||
607 | local_irq_enable(); | |
608 | } | |
609 | #endif /* CONFIG_HOTPLUG_CPU */ | |
610 | ||
8c78f307 | 611 | static int __cpuinit cpu_callback(struct notifier_block *nfb, |
1da177e4 LT |
612 | unsigned long action, |
613 | void *hcpu) | |
614 | { | |
615 | int hotcpu = (unsigned long)hcpu; | |
616 | struct task_struct *p; | |
617 | ||
618 | switch (action) { | |
619 | case CPU_UP_PREPARE: | |
8bb78442 | 620 | case CPU_UP_PREPARE_FROZEN: |
1da177e4 LT |
621 | p = kthread_create(ksoftirqd, hcpu, "ksoftirqd/%d", hotcpu); |
622 | if (IS_ERR(p)) { | |
623 | printk("ksoftirqd for %i failed\n", hotcpu); | |
624 | return NOTIFY_BAD; | |
625 | } | |
626 | kthread_bind(p, hotcpu); | |
627 | per_cpu(ksoftirqd, hotcpu) = p; | |
628 | break; | |
629 | case CPU_ONLINE: | |
8bb78442 | 630 | case CPU_ONLINE_FROZEN: |
1da177e4 LT |
631 | wake_up_process(per_cpu(ksoftirqd, hotcpu)); |
632 | break; | |
633 | #ifdef CONFIG_HOTPLUG_CPU | |
634 | case CPU_UP_CANCELED: | |
8bb78442 | 635 | case CPU_UP_CANCELED_FROZEN: |
fc75cdfa HC |
636 | if (!per_cpu(ksoftirqd, hotcpu)) |
637 | break; | |
1da177e4 | 638 | /* Unbind so it can run. Fall thru. */ |
a4c4af7c HC |
639 | kthread_bind(per_cpu(ksoftirqd, hotcpu), |
640 | any_online_cpu(cpu_online_map)); | |
1da177e4 | 641 | case CPU_DEAD: |
1c6b4aa9 ST |
642 | case CPU_DEAD_FROZEN: { |
643 | struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; | |
644 | ||
1da177e4 LT |
645 | p = per_cpu(ksoftirqd, hotcpu); |
646 | per_cpu(ksoftirqd, hotcpu) = NULL; | |
1c6b4aa9 | 647 | sched_setscheduler(p, SCHED_FIFO, ¶m); |
1da177e4 LT |
648 | kthread_stop(p); |
649 | takeover_tasklets(hotcpu); | |
650 | break; | |
1c6b4aa9 | 651 | } |
1da177e4 LT |
652 | #endif /* CONFIG_HOTPLUG_CPU */ |
653 | } | |
654 | return NOTIFY_OK; | |
655 | } | |
656 | ||
8c78f307 | 657 | static struct notifier_block __cpuinitdata cpu_nfb = { |
1da177e4 LT |
658 | .notifier_call = cpu_callback |
659 | }; | |
660 | ||
661 | __init int spawn_ksoftirqd(void) | |
662 | { | |
663 | void *cpu = (void *)(long)smp_processor_id(); | |
07dccf33 AM |
664 | int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu); |
665 | ||
666 | BUG_ON(err == NOTIFY_BAD); | |
1da177e4 LT |
667 | cpu_callback(&cpu_nfb, CPU_ONLINE, cpu); |
668 | register_cpu_notifier(&cpu_nfb); | |
669 | return 0; | |
670 | } | |
78eef01b AM |
671 | |
672 | #ifdef CONFIG_SMP | |
673 | /* | |
674 | * Call a function on all processors | |
675 | */ | |
676 | int on_each_cpu(void (*func) (void *info), void *info, int retry, int wait) | |
677 | { | |
678 | int ret = 0; | |
679 | ||
680 | preempt_disable(); | |
681 | ret = smp_call_function(func, info, retry, wait); | |
682 | local_irq_disable(); | |
683 | func(info); | |
684 | local_irq_enable(); | |
685 | preempt_enable(); | |
686 | return ret; | |
687 | } | |
688 | EXPORT_SYMBOL(on_each_cpu); | |
689 | #endif |