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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) | |
54514a70 DM |
9 | * |
10 | * Remote softirq infrastructure is by Jens Axboe. | |
1da177e4 LT |
11 | */ |
12 | ||
13 | #include <linux/module.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> | |
83144186 | 21 | #include <linux/freezer.h> |
1da177e4 LT |
22 | #include <linux/kthread.h> |
23 | #include <linux/rcupdate.h> | |
7e49fcce | 24 | #include <linux/ftrace.h> |
78eef01b | 25 | #include <linux/smp.h> |
79bf2bb3 | 26 | #include <linux/tick.h> |
a0e39ed3 HC |
27 | |
28 | #define CREATE_TRACE_POINTS | |
ad8d75ff | 29 | #include <trace/events/irq.h> |
1da177e4 LT |
30 | |
31 | #include <asm/irq.h> | |
32 | /* | |
33 | - No shared variables, all the data are CPU local. | |
34 | - If a softirq needs serialization, let it serialize itself | |
35 | by its own spinlocks. | |
36 | - Even if softirq is serialized, only local cpu is marked for | |
37 | execution. Hence, we get something sort of weak cpu binding. | |
38 | Though it is still not clear, will it result in better locality | |
39 | or will not. | |
40 | ||
41 | Examples: | |
42 | - NET RX softirq. It is multithreaded and does not require | |
43 | any global serialization. | |
44 | - NET TX softirq. It kicks software netdevice queues, hence | |
45 | it is logically serialized per device, but this serialization | |
46 | is invisible to common code. | |
47 | - Tasklets: serialized wrt itself. | |
48 | */ | |
49 | ||
50 | #ifndef __ARCH_IRQ_STAT | |
51 | irq_cpustat_t irq_stat[NR_CPUS] ____cacheline_aligned; | |
52 | EXPORT_SYMBOL(irq_stat); | |
53 | #endif | |
54 | ||
978b0116 | 55 | static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp; |
1da177e4 LT |
56 | |
57 | static DEFINE_PER_CPU(struct task_struct *, ksoftirqd); | |
58 | ||
5d592b44 | 59 | char *softirq_to_name[NR_SOFTIRQS] = { |
899039e8 SR |
60 | "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", |
61 | "TASKLET", "SCHED", "HRTIMER", "RCU" | |
5d592b44 JB |
62 | }; |
63 | ||
1da177e4 LT |
64 | /* |
65 | * we cannot loop indefinitely here to avoid userspace starvation, | |
66 | * but we also don't want to introduce a worst case 1/HZ latency | |
67 | * to the pending events, so lets the scheduler to balance | |
68 | * the softirq load for us. | |
69 | */ | |
7f1e2ca9 | 70 | void wakeup_softirqd(void) |
1da177e4 LT |
71 | { |
72 | /* Interrupts are disabled: no need to stop preemption */ | |
73 | struct task_struct *tsk = __get_cpu_var(ksoftirqd); | |
74 | ||
75 | if (tsk && tsk->state != TASK_RUNNING) | |
76 | wake_up_process(tsk); | |
77 | } | |
78 | ||
de30a2b3 IM |
79 | /* |
80 | * This one is for softirq.c-internal use, | |
81 | * where hardirqs are disabled legitimately: | |
82 | */ | |
3c829c36 | 83 | #ifdef CONFIG_TRACE_IRQFLAGS |
de30a2b3 IM |
84 | static void __local_bh_disable(unsigned long ip) |
85 | { | |
86 | unsigned long flags; | |
87 | ||
88 | WARN_ON_ONCE(in_irq()); | |
89 | ||
90 | raw_local_irq_save(flags); | |
7e49fcce SR |
91 | /* |
92 | * The preempt tracer hooks into add_preempt_count and will break | |
93 | * lockdep because it calls back into lockdep after SOFTIRQ_OFFSET | |
94 | * is set and before current->softirq_enabled is cleared. | |
95 | * We must manually increment preempt_count here and manually | |
96 | * call the trace_preempt_off later. | |
97 | */ | |
98 | preempt_count() += SOFTIRQ_OFFSET; | |
de30a2b3 IM |
99 | /* |
100 | * Were softirqs turned off above: | |
101 | */ | |
102 | if (softirq_count() == SOFTIRQ_OFFSET) | |
103 | trace_softirqs_off(ip); | |
104 | raw_local_irq_restore(flags); | |
7e49fcce SR |
105 | |
106 | if (preempt_count() == SOFTIRQ_OFFSET) | |
107 | trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); | |
de30a2b3 | 108 | } |
3c829c36 TC |
109 | #else /* !CONFIG_TRACE_IRQFLAGS */ |
110 | static inline void __local_bh_disable(unsigned long ip) | |
111 | { | |
112 | add_preempt_count(SOFTIRQ_OFFSET); | |
113 | barrier(); | |
114 | } | |
115 | #endif /* CONFIG_TRACE_IRQFLAGS */ | |
de30a2b3 IM |
116 | |
117 | void local_bh_disable(void) | |
118 | { | |
119 | __local_bh_disable((unsigned long)__builtin_return_address(0)); | |
120 | } | |
121 | ||
122 | EXPORT_SYMBOL(local_bh_disable); | |
123 | ||
de30a2b3 IM |
124 | /* |
125 | * Special-case - softirqs can safely be enabled in | |
126 | * cond_resched_softirq(), or by __do_softirq(), | |
127 | * without processing still-pending softirqs: | |
128 | */ | |
129 | void _local_bh_enable(void) | |
130 | { | |
131 | WARN_ON_ONCE(in_irq()); | |
132 | WARN_ON_ONCE(!irqs_disabled()); | |
133 | ||
134 | if (softirq_count() == SOFTIRQ_OFFSET) | |
135 | trace_softirqs_on((unsigned long)__builtin_return_address(0)); | |
136 | sub_preempt_count(SOFTIRQ_OFFSET); | |
137 | } | |
138 | ||
139 | EXPORT_SYMBOL(_local_bh_enable); | |
140 | ||
0f476b6d | 141 | static inline void _local_bh_enable_ip(unsigned long ip) |
de30a2b3 | 142 | { |
0f476b6d | 143 | WARN_ON_ONCE(in_irq() || irqs_disabled()); |
3c829c36 | 144 | #ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d | 145 | local_irq_disable(); |
3c829c36 | 146 | #endif |
de30a2b3 IM |
147 | /* |
148 | * Are softirqs going to be turned on now: | |
149 | */ | |
150 | if (softirq_count() == SOFTIRQ_OFFSET) | |
0f476b6d | 151 | trace_softirqs_on(ip); |
de30a2b3 IM |
152 | /* |
153 | * Keep preemption disabled until we are done with | |
154 | * softirq processing: | |
155 | */ | |
156 | sub_preempt_count(SOFTIRQ_OFFSET - 1); | |
157 | ||
158 | if (unlikely(!in_interrupt() && local_softirq_pending())) | |
159 | do_softirq(); | |
160 | ||
161 | dec_preempt_count(); | |
3c829c36 | 162 | #ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d | 163 | local_irq_enable(); |
3c829c36 | 164 | #endif |
de30a2b3 IM |
165 | preempt_check_resched(); |
166 | } | |
0f476b6d JB |
167 | |
168 | void local_bh_enable(void) | |
169 | { | |
170 | _local_bh_enable_ip((unsigned long)__builtin_return_address(0)); | |
171 | } | |
de30a2b3 IM |
172 | EXPORT_SYMBOL(local_bh_enable); |
173 | ||
174 | void local_bh_enable_ip(unsigned long ip) | |
175 | { | |
0f476b6d | 176 | _local_bh_enable_ip(ip); |
de30a2b3 IM |
177 | } |
178 | EXPORT_SYMBOL(local_bh_enable_ip); | |
179 | ||
1da177e4 LT |
180 | /* |
181 | * We restart softirq processing MAX_SOFTIRQ_RESTART times, | |
182 | * and we fall back to softirqd after that. | |
183 | * | |
184 | * This number has been established via experimentation. | |
185 | * The two things to balance is latency against fairness - | |
186 | * we want to handle softirqs as soon as possible, but they | |
187 | * should not be able to lock up the box. | |
188 | */ | |
189 | #define MAX_SOFTIRQ_RESTART 10 | |
190 | ||
191 | asmlinkage void __do_softirq(void) | |
192 | { | |
193 | struct softirq_action *h; | |
194 | __u32 pending; | |
195 | int max_restart = MAX_SOFTIRQ_RESTART; | |
196 | int cpu; | |
197 | ||
198 | pending = local_softirq_pending(); | |
829035fd PM |
199 | account_system_vtime(current); |
200 | ||
de30a2b3 | 201 | __local_bh_disable((unsigned long)__builtin_return_address(0)); |
d820ac4c | 202 | lockdep_softirq_enter(); |
1da177e4 | 203 | |
1da177e4 LT |
204 | cpu = smp_processor_id(); |
205 | restart: | |
206 | /* Reset the pending bitmask before enabling irqs */ | |
3f74478b | 207 | set_softirq_pending(0); |
1da177e4 | 208 | |
c70f5d66 | 209 | local_irq_enable(); |
1da177e4 LT |
210 | |
211 | h = softirq_vec; | |
212 | ||
213 | do { | |
214 | if (pending & 1) { | |
8e85b4b5 | 215 | int prev_count = preempt_count(); |
aa0ce5bb | 216 | kstat_incr_softirqs_this_cpu(h - softirq_vec); |
8e85b4b5 | 217 | |
39842323 | 218 | trace_softirq_entry(h, softirq_vec); |
1da177e4 | 219 | h->action(h); |
39842323 | 220 | trace_softirq_exit(h, softirq_vec); |
8e85b4b5 | 221 | if (unlikely(prev_count != preempt_count())) { |
5d592b44 | 222 | printk(KERN_ERR "huh, entered softirq %td %s %p" |
8e85b4b5 TG |
223 | "with preempt_count %08x," |
224 | " exited with %08x?\n", h - softirq_vec, | |
5d592b44 | 225 | softirq_to_name[h - softirq_vec], |
8e85b4b5 TG |
226 | h->action, prev_count, preempt_count()); |
227 | preempt_count() = prev_count; | |
228 | } | |
229 | ||
1da177e4 LT |
230 | rcu_bh_qsctr_inc(cpu); |
231 | } | |
232 | h++; | |
233 | pending >>= 1; | |
234 | } while (pending); | |
235 | ||
c70f5d66 | 236 | local_irq_disable(); |
1da177e4 LT |
237 | |
238 | pending = local_softirq_pending(); | |
239 | if (pending && --max_restart) | |
240 | goto restart; | |
241 | ||
242 | if (pending) | |
243 | wakeup_softirqd(); | |
244 | ||
d820ac4c | 245 | lockdep_softirq_exit(); |
829035fd PM |
246 | |
247 | account_system_vtime(current); | |
de30a2b3 | 248 | _local_bh_enable(); |
1da177e4 LT |
249 | } |
250 | ||
251 | #ifndef __ARCH_HAS_DO_SOFTIRQ | |
252 | ||
253 | asmlinkage void do_softirq(void) | |
254 | { | |
255 | __u32 pending; | |
256 | unsigned long flags; | |
257 | ||
258 | if (in_interrupt()) | |
259 | return; | |
260 | ||
261 | local_irq_save(flags); | |
262 | ||
263 | pending = local_softirq_pending(); | |
264 | ||
265 | if (pending) | |
266 | __do_softirq(); | |
267 | ||
268 | local_irq_restore(flags); | |
269 | } | |
270 | ||
1da177e4 LT |
271 | #endif |
272 | ||
dde4b2b5 IM |
273 | /* |
274 | * Enter an interrupt context. | |
275 | */ | |
276 | void irq_enter(void) | |
277 | { | |
6378ddb5 | 278 | int cpu = smp_processor_id(); |
719254fa | 279 | |
64db4cff | 280 | rcu_irq_enter(); |
ee5f80a9 TG |
281 | if (idle_cpu(cpu) && !in_interrupt()) { |
282 | __irq_enter(); | |
719254fa | 283 | tick_check_idle(cpu); |
ee5f80a9 TG |
284 | } else |
285 | __irq_enter(); | |
dde4b2b5 IM |
286 | } |
287 | ||
1da177e4 LT |
288 | #ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED |
289 | # define invoke_softirq() __do_softirq() | |
290 | #else | |
291 | # define invoke_softirq() do_softirq() | |
292 | #endif | |
293 | ||
294 | /* | |
295 | * Exit an interrupt context. Process softirqs if needed and possible: | |
296 | */ | |
297 | void irq_exit(void) | |
298 | { | |
299 | account_system_vtime(current); | |
de30a2b3 | 300 | trace_hardirq_exit(); |
1da177e4 LT |
301 | sub_preempt_count(IRQ_EXIT_OFFSET); |
302 | if (!in_interrupt() && local_softirq_pending()) | |
303 | invoke_softirq(); | |
79bf2bb3 TG |
304 | |
305 | #ifdef CONFIG_NO_HZ | |
306 | /* Make sure that timer wheel updates are propagated */ | |
2232c2d8 | 307 | rcu_irq_exit(); |
64db4cff PM |
308 | if (idle_cpu(smp_processor_id()) && !in_interrupt() && !need_resched()) |
309 | tick_nohz_stop_sched_tick(0); | |
79bf2bb3 | 310 | #endif |
1da177e4 LT |
311 | preempt_enable_no_resched(); |
312 | } | |
313 | ||
314 | /* | |
315 | * This function must run with irqs disabled! | |
316 | */ | |
7ad5b3a5 | 317 | inline void raise_softirq_irqoff(unsigned int nr) |
1da177e4 LT |
318 | { |
319 | __raise_softirq_irqoff(nr); | |
320 | ||
321 | /* | |
322 | * If we're in an interrupt or softirq, we're done | |
323 | * (this also catches softirq-disabled code). We will | |
324 | * actually run the softirq once we return from | |
325 | * the irq or softirq. | |
326 | * | |
327 | * Otherwise we wake up ksoftirqd to make sure we | |
328 | * schedule the softirq soon. | |
329 | */ | |
330 | if (!in_interrupt()) | |
331 | wakeup_softirqd(); | |
332 | } | |
333 | ||
7ad5b3a5 | 334 | void raise_softirq(unsigned int nr) |
1da177e4 LT |
335 | { |
336 | unsigned long flags; | |
337 | ||
338 | local_irq_save(flags); | |
339 | raise_softirq_irqoff(nr); | |
340 | local_irq_restore(flags); | |
341 | } | |
342 | ||
962cf36c | 343 | void open_softirq(int nr, void (*action)(struct softirq_action *)) |
1da177e4 | 344 | { |
1da177e4 LT |
345 | softirq_vec[nr].action = action; |
346 | } | |
347 | ||
1da177e4 LT |
348 | /* Tasklets */ |
349 | struct tasklet_head | |
350 | { | |
48f20a9a OJ |
351 | struct tasklet_struct *head; |
352 | struct tasklet_struct **tail; | |
1da177e4 LT |
353 | }; |
354 | ||
4620b49f VN |
355 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec); |
356 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec); | |
1da177e4 | 357 | |
7ad5b3a5 | 358 | void __tasklet_schedule(struct tasklet_struct *t) |
1da177e4 LT |
359 | { |
360 | unsigned long flags; | |
361 | ||
362 | local_irq_save(flags); | |
48f20a9a OJ |
363 | t->next = NULL; |
364 | *__get_cpu_var(tasklet_vec).tail = t; | |
365 | __get_cpu_var(tasklet_vec).tail = &(t->next); | |
1da177e4 LT |
366 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
367 | local_irq_restore(flags); | |
368 | } | |
369 | ||
370 | EXPORT_SYMBOL(__tasklet_schedule); | |
371 | ||
7ad5b3a5 | 372 | void __tasklet_hi_schedule(struct tasklet_struct *t) |
1da177e4 LT |
373 | { |
374 | unsigned long flags; | |
375 | ||
376 | local_irq_save(flags); | |
48f20a9a OJ |
377 | t->next = NULL; |
378 | *__get_cpu_var(tasklet_hi_vec).tail = t; | |
379 | __get_cpu_var(tasklet_hi_vec).tail = &(t->next); | |
1da177e4 LT |
380 | raise_softirq_irqoff(HI_SOFTIRQ); |
381 | local_irq_restore(flags); | |
382 | } | |
383 | ||
384 | EXPORT_SYMBOL(__tasklet_hi_schedule); | |
385 | ||
7c692cba VN |
386 | void __tasklet_hi_schedule_first(struct tasklet_struct *t) |
387 | { | |
388 | BUG_ON(!irqs_disabled()); | |
389 | ||
390 | t->next = __get_cpu_var(tasklet_hi_vec).head; | |
391 | __get_cpu_var(tasklet_hi_vec).head = t; | |
392 | __raise_softirq_irqoff(HI_SOFTIRQ); | |
393 | } | |
394 | ||
395 | EXPORT_SYMBOL(__tasklet_hi_schedule_first); | |
396 | ||
1da177e4 LT |
397 | static void tasklet_action(struct softirq_action *a) |
398 | { | |
399 | struct tasklet_struct *list; | |
400 | ||
401 | local_irq_disable(); | |
48f20a9a OJ |
402 | list = __get_cpu_var(tasklet_vec).head; |
403 | __get_cpu_var(tasklet_vec).head = NULL; | |
404 | __get_cpu_var(tasklet_vec).tail = &__get_cpu_var(tasklet_vec).head; | |
1da177e4 LT |
405 | local_irq_enable(); |
406 | ||
407 | while (list) { | |
408 | struct tasklet_struct *t = list; | |
409 | ||
410 | list = list->next; | |
411 | ||
412 | if (tasklet_trylock(t)) { | |
413 | if (!atomic_read(&t->count)) { | |
414 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
415 | BUG(); | |
416 | t->func(t->data); | |
417 | tasklet_unlock(t); | |
418 | continue; | |
419 | } | |
420 | tasklet_unlock(t); | |
421 | } | |
422 | ||
423 | local_irq_disable(); | |
48f20a9a OJ |
424 | t->next = NULL; |
425 | *__get_cpu_var(tasklet_vec).tail = t; | |
426 | __get_cpu_var(tasklet_vec).tail = &(t->next); | |
1da177e4 LT |
427 | __raise_softirq_irqoff(TASKLET_SOFTIRQ); |
428 | local_irq_enable(); | |
429 | } | |
430 | } | |
431 | ||
432 | static void tasklet_hi_action(struct softirq_action *a) | |
433 | { | |
434 | struct tasklet_struct *list; | |
435 | ||
436 | local_irq_disable(); | |
48f20a9a OJ |
437 | list = __get_cpu_var(tasklet_hi_vec).head; |
438 | __get_cpu_var(tasklet_hi_vec).head = NULL; | |
439 | __get_cpu_var(tasklet_hi_vec).tail = &__get_cpu_var(tasklet_hi_vec).head; | |
1da177e4 LT |
440 | local_irq_enable(); |
441 | ||
442 | while (list) { | |
443 | struct tasklet_struct *t = list; | |
444 | ||
445 | list = list->next; | |
446 | ||
447 | if (tasklet_trylock(t)) { | |
448 | if (!atomic_read(&t->count)) { | |
449 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
450 | BUG(); | |
451 | t->func(t->data); | |
452 | tasklet_unlock(t); | |
453 | continue; | |
454 | } | |
455 | tasklet_unlock(t); | |
456 | } | |
457 | ||
458 | local_irq_disable(); | |
48f20a9a OJ |
459 | t->next = NULL; |
460 | *__get_cpu_var(tasklet_hi_vec).tail = t; | |
461 | __get_cpu_var(tasklet_hi_vec).tail = &(t->next); | |
1da177e4 LT |
462 | __raise_softirq_irqoff(HI_SOFTIRQ); |
463 | local_irq_enable(); | |
464 | } | |
465 | } | |
466 | ||
467 | ||
468 | void tasklet_init(struct tasklet_struct *t, | |
469 | void (*func)(unsigned long), unsigned long data) | |
470 | { | |
471 | t->next = NULL; | |
472 | t->state = 0; | |
473 | atomic_set(&t->count, 0); | |
474 | t->func = func; | |
475 | t->data = data; | |
476 | } | |
477 | ||
478 | EXPORT_SYMBOL(tasklet_init); | |
479 | ||
480 | void tasklet_kill(struct tasklet_struct *t) | |
481 | { | |
482 | if (in_interrupt()) | |
483 | printk("Attempt to kill tasklet from interrupt\n"); | |
484 | ||
485 | while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { | |
79d381c9 | 486 | do { |
1da177e4 | 487 | yield(); |
79d381c9 | 488 | } while (test_bit(TASKLET_STATE_SCHED, &t->state)); |
1da177e4 LT |
489 | } |
490 | tasklet_unlock_wait(t); | |
491 | clear_bit(TASKLET_STATE_SCHED, &t->state); | |
492 | } | |
493 | ||
494 | EXPORT_SYMBOL(tasklet_kill); | |
495 | ||
54514a70 DM |
496 | DEFINE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list); |
497 | EXPORT_PER_CPU_SYMBOL(softirq_work_list); | |
498 | ||
499 | static void __local_trigger(struct call_single_data *cp, int softirq) | |
500 | { | |
501 | struct list_head *head = &__get_cpu_var(softirq_work_list[softirq]); | |
502 | ||
503 | list_add_tail(&cp->list, head); | |
504 | ||
505 | /* Trigger the softirq only if the list was previously empty. */ | |
506 | if (head->next == &cp->list) | |
507 | raise_softirq_irqoff(softirq); | |
508 | } | |
509 | ||
510 | #ifdef CONFIG_USE_GENERIC_SMP_HELPERS | |
511 | static void remote_softirq_receive(void *data) | |
512 | { | |
513 | struct call_single_data *cp = data; | |
514 | unsigned long flags; | |
515 | int softirq; | |
516 | ||
517 | softirq = cp->priv; | |
518 | ||
519 | local_irq_save(flags); | |
520 | __local_trigger(cp, softirq); | |
521 | local_irq_restore(flags); | |
522 | } | |
523 | ||
524 | static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) | |
525 | { | |
526 | if (cpu_online(cpu)) { | |
527 | cp->func = remote_softirq_receive; | |
528 | cp->info = cp; | |
529 | cp->flags = 0; | |
530 | cp->priv = softirq; | |
531 | ||
6e275637 | 532 | __smp_call_function_single(cpu, cp, 0); |
54514a70 DM |
533 | return 0; |
534 | } | |
535 | return 1; | |
536 | } | |
537 | #else /* CONFIG_USE_GENERIC_SMP_HELPERS */ | |
538 | static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) | |
539 | { | |
540 | return 1; | |
541 | } | |
542 | #endif | |
543 | ||
544 | /** | |
545 | * __send_remote_softirq - try to schedule softirq work on a remote cpu | |
546 | * @cp: private SMP call function data area | |
547 | * @cpu: the remote cpu | |
548 | * @this_cpu: the currently executing cpu | |
549 | * @softirq: the softirq for the work | |
550 | * | |
551 | * Attempt to schedule softirq work on a remote cpu. If this cannot be | |
552 | * done, the work is instead queued up on the local cpu. | |
553 | * | |
554 | * Interrupts must be disabled. | |
555 | */ | |
556 | void __send_remote_softirq(struct call_single_data *cp, int cpu, int this_cpu, int softirq) | |
557 | { | |
558 | if (cpu == this_cpu || __try_remote_softirq(cp, cpu, softirq)) | |
559 | __local_trigger(cp, softirq); | |
560 | } | |
561 | EXPORT_SYMBOL(__send_remote_softirq); | |
562 | ||
563 | /** | |
564 | * send_remote_softirq - try to schedule softirq work on a remote cpu | |
565 | * @cp: private SMP call function data area | |
566 | * @cpu: the remote cpu | |
567 | * @softirq: the softirq for the work | |
568 | * | |
569 | * Like __send_remote_softirq except that disabling interrupts and | |
570 | * computing the current cpu is done for the caller. | |
571 | */ | |
572 | void send_remote_softirq(struct call_single_data *cp, int cpu, int softirq) | |
573 | { | |
574 | unsigned long flags; | |
575 | int this_cpu; | |
576 | ||
577 | local_irq_save(flags); | |
578 | this_cpu = smp_processor_id(); | |
579 | __send_remote_softirq(cp, cpu, this_cpu, softirq); | |
580 | local_irq_restore(flags); | |
581 | } | |
582 | EXPORT_SYMBOL(send_remote_softirq); | |
583 | ||
584 | static int __cpuinit remote_softirq_cpu_notify(struct notifier_block *self, | |
585 | unsigned long action, void *hcpu) | |
586 | { | |
587 | /* | |
588 | * If a CPU goes away, splice its entries to the current CPU | |
589 | * and trigger a run of the softirq | |
590 | */ | |
591 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { | |
592 | int cpu = (unsigned long) hcpu; | |
593 | int i; | |
594 | ||
595 | local_irq_disable(); | |
596 | for (i = 0; i < NR_SOFTIRQS; i++) { | |
597 | struct list_head *head = &per_cpu(softirq_work_list[i], cpu); | |
598 | struct list_head *local_head; | |
599 | ||
600 | if (list_empty(head)) | |
601 | continue; | |
602 | ||
603 | local_head = &__get_cpu_var(softirq_work_list[i]); | |
604 | list_splice_init(head, local_head); | |
605 | raise_softirq_irqoff(i); | |
606 | } | |
607 | local_irq_enable(); | |
608 | } | |
609 | ||
610 | return NOTIFY_OK; | |
611 | } | |
612 | ||
613 | static struct notifier_block __cpuinitdata remote_softirq_cpu_notifier = { | |
614 | .notifier_call = remote_softirq_cpu_notify, | |
615 | }; | |
616 | ||
1da177e4 LT |
617 | void __init softirq_init(void) |
618 | { | |
48f20a9a OJ |
619 | int cpu; |
620 | ||
621 | for_each_possible_cpu(cpu) { | |
54514a70 DM |
622 | int i; |
623 | ||
48f20a9a OJ |
624 | per_cpu(tasklet_vec, cpu).tail = |
625 | &per_cpu(tasklet_vec, cpu).head; | |
626 | per_cpu(tasklet_hi_vec, cpu).tail = | |
627 | &per_cpu(tasklet_hi_vec, cpu).head; | |
54514a70 DM |
628 | for (i = 0; i < NR_SOFTIRQS; i++) |
629 | INIT_LIST_HEAD(&per_cpu(softirq_work_list[i], cpu)); | |
48f20a9a OJ |
630 | } |
631 | ||
54514a70 DM |
632 | register_hotcpu_notifier(&remote_softirq_cpu_notifier); |
633 | ||
962cf36c CM |
634 | open_softirq(TASKLET_SOFTIRQ, tasklet_action); |
635 | open_softirq(HI_SOFTIRQ, tasklet_hi_action); | |
1da177e4 LT |
636 | } |
637 | ||
638 | static int ksoftirqd(void * __bind_cpu) | |
639 | { | |
1da177e4 LT |
640 | set_current_state(TASK_INTERRUPTIBLE); |
641 | ||
642 | while (!kthread_should_stop()) { | |
643 | preempt_disable(); | |
644 | if (!local_softirq_pending()) { | |
645 | preempt_enable_no_resched(); | |
646 | schedule(); | |
647 | preempt_disable(); | |
648 | } | |
649 | ||
650 | __set_current_state(TASK_RUNNING); | |
651 | ||
652 | while (local_softirq_pending()) { | |
653 | /* Preempt disable stops cpu going offline. | |
654 | If already offline, we'll be on wrong CPU: | |
655 | don't process */ | |
656 | if (cpu_is_offline((long)__bind_cpu)) | |
657 | goto wait_to_die; | |
658 | do_softirq(); | |
659 | preempt_enable_no_resched(); | |
660 | cond_resched(); | |
661 | preempt_disable(); | |
64ca5ab9 | 662 | rcu_qsctr_inc((long)__bind_cpu); |
1da177e4 LT |
663 | } |
664 | preempt_enable(); | |
665 | set_current_state(TASK_INTERRUPTIBLE); | |
666 | } | |
667 | __set_current_state(TASK_RUNNING); | |
668 | return 0; | |
669 | ||
670 | wait_to_die: | |
671 | preempt_enable(); | |
672 | /* Wait for kthread_stop */ | |
673 | set_current_state(TASK_INTERRUPTIBLE); | |
674 | while (!kthread_should_stop()) { | |
675 | schedule(); | |
676 | set_current_state(TASK_INTERRUPTIBLE); | |
677 | } | |
678 | __set_current_state(TASK_RUNNING); | |
679 | return 0; | |
680 | } | |
681 | ||
682 | #ifdef CONFIG_HOTPLUG_CPU | |
683 | /* | |
684 | * tasklet_kill_immediate is called to remove a tasklet which can already be | |
685 | * scheduled for execution on @cpu. | |
686 | * | |
687 | * Unlike tasklet_kill, this function removes the tasklet | |
688 | * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state. | |
689 | * | |
690 | * When this function is called, @cpu must be in the CPU_DEAD state. | |
691 | */ | |
692 | void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu) | |
693 | { | |
694 | struct tasklet_struct **i; | |
695 | ||
696 | BUG_ON(cpu_online(cpu)); | |
697 | BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state)); | |
698 | ||
699 | if (!test_bit(TASKLET_STATE_SCHED, &t->state)) | |
700 | return; | |
701 | ||
702 | /* CPU is dead, so no lock needed. */ | |
48f20a9a | 703 | for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) { |
1da177e4 LT |
704 | if (*i == t) { |
705 | *i = t->next; | |
48f20a9a OJ |
706 | /* If this was the tail element, move the tail ptr */ |
707 | if (*i == NULL) | |
708 | per_cpu(tasklet_vec, cpu).tail = i; | |
1da177e4 LT |
709 | return; |
710 | } | |
711 | } | |
712 | BUG(); | |
713 | } | |
714 | ||
715 | static void takeover_tasklets(unsigned int cpu) | |
716 | { | |
1da177e4 LT |
717 | /* CPU is dead, so no lock needed. */ |
718 | local_irq_disable(); | |
719 | ||
720 | /* Find end, append list for that CPU. */ | |
e5e41723 CB |
721 | if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) { |
722 | *(__get_cpu_var(tasklet_vec).tail) = per_cpu(tasklet_vec, cpu).head; | |
723 | __get_cpu_var(tasklet_vec).tail = per_cpu(tasklet_vec, cpu).tail; | |
724 | per_cpu(tasklet_vec, cpu).head = NULL; | |
725 | per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; | |
726 | } | |
1da177e4 LT |
727 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
728 | ||
e5e41723 CB |
729 | if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) { |
730 | *__get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).head; | |
731 | __get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).tail; | |
732 | per_cpu(tasklet_hi_vec, cpu).head = NULL; | |
733 | per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; | |
734 | } | |
1da177e4 LT |
735 | raise_softirq_irqoff(HI_SOFTIRQ); |
736 | ||
737 | local_irq_enable(); | |
738 | } | |
739 | #endif /* CONFIG_HOTPLUG_CPU */ | |
740 | ||
8c78f307 | 741 | static int __cpuinit cpu_callback(struct notifier_block *nfb, |
1da177e4 LT |
742 | unsigned long action, |
743 | void *hcpu) | |
744 | { | |
745 | int hotcpu = (unsigned long)hcpu; | |
746 | struct task_struct *p; | |
747 | ||
748 | switch (action) { | |
749 | case CPU_UP_PREPARE: | |
8bb78442 | 750 | case CPU_UP_PREPARE_FROZEN: |
1da177e4 LT |
751 | p = kthread_create(ksoftirqd, hcpu, "ksoftirqd/%d", hotcpu); |
752 | if (IS_ERR(p)) { | |
753 | printk("ksoftirqd for %i failed\n", hotcpu); | |
754 | return NOTIFY_BAD; | |
755 | } | |
756 | kthread_bind(p, hotcpu); | |
757 | per_cpu(ksoftirqd, hotcpu) = p; | |
758 | break; | |
759 | case CPU_ONLINE: | |
8bb78442 | 760 | case CPU_ONLINE_FROZEN: |
1da177e4 LT |
761 | wake_up_process(per_cpu(ksoftirqd, hotcpu)); |
762 | break; | |
763 | #ifdef CONFIG_HOTPLUG_CPU | |
764 | case CPU_UP_CANCELED: | |
8bb78442 | 765 | case CPU_UP_CANCELED_FROZEN: |
fc75cdfa HC |
766 | if (!per_cpu(ksoftirqd, hotcpu)) |
767 | break; | |
1da177e4 | 768 | /* Unbind so it can run. Fall thru. */ |
a4c4af7c | 769 | kthread_bind(per_cpu(ksoftirqd, hotcpu), |
f1fc057c | 770 | cpumask_any(cpu_online_mask)); |
1da177e4 | 771 | case CPU_DEAD: |
1c6b4aa9 ST |
772 | case CPU_DEAD_FROZEN: { |
773 | struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; | |
774 | ||
1da177e4 LT |
775 | p = per_cpu(ksoftirqd, hotcpu); |
776 | per_cpu(ksoftirqd, hotcpu) = NULL; | |
961ccddd | 777 | sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m); |
1da177e4 LT |
778 | kthread_stop(p); |
779 | takeover_tasklets(hotcpu); | |
780 | break; | |
1c6b4aa9 | 781 | } |
1da177e4 LT |
782 | #endif /* CONFIG_HOTPLUG_CPU */ |
783 | } | |
784 | return NOTIFY_OK; | |
785 | } | |
786 | ||
8c78f307 | 787 | static struct notifier_block __cpuinitdata cpu_nfb = { |
1da177e4 LT |
788 | .notifier_call = cpu_callback |
789 | }; | |
790 | ||
7babe8db | 791 | static __init int spawn_ksoftirqd(void) |
1da177e4 LT |
792 | { |
793 | void *cpu = (void *)(long)smp_processor_id(); | |
07dccf33 AM |
794 | int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu); |
795 | ||
796 | BUG_ON(err == NOTIFY_BAD); | |
1da177e4 LT |
797 | cpu_callback(&cpu_nfb, CPU_ONLINE, cpu); |
798 | register_cpu_notifier(&cpu_nfb); | |
799 | return 0; | |
800 | } | |
7babe8db | 801 | early_initcall(spawn_ksoftirqd); |
78eef01b AM |
802 | |
803 | #ifdef CONFIG_SMP | |
804 | /* | |
805 | * Call a function on all processors | |
806 | */ | |
15c8b6c1 | 807 | int on_each_cpu(void (*func) (void *info), void *info, int wait) |
78eef01b AM |
808 | { |
809 | int ret = 0; | |
810 | ||
811 | preempt_disable(); | |
8691e5a8 | 812 | ret = smp_call_function(func, info, wait); |
78eef01b AM |
813 | local_irq_disable(); |
814 | func(info); | |
815 | local_irq_enable(); | |
816 | preempt_enable(); | |
817 | return ret; | |
818 | } | |
819 | EXPORT_SYMBOL(on_each_cpu); | |
820 | #endif | |
43a25632 YL |
821 | |
822 | /* | |
823 | * [ These __weak aliases are kept in a separate compilation unit, so that | |
824 | * GCC does not inline them incorrectly. ] | |
825 | */ | |
826 | ||
827 | int __init __weak early_irq_init(void) | |
828 | { | |
829 | return 0; | |
830 | } | |
831 | ||
4a046d17 YL |
832 | int __init __weak arch_probe_nr_irqs(void) |
833 | { | |
834 | return 0; | |
835 | } | |
836 | ||
43a25632 YL |
837 | int __init __weak arch_early_irq_init(void) |
838 | { | |
839 | return 0; | |
840 | } | |
841 | ||
85ac16d0 | 842 | int __weak arch_init_chip_data(struct irq_desc *desc, int node) |
43a25632 YL |
843 | { |
844 | return 0; | |
845 | } |