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] = { |
5dd4de58 | 60 | "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "BLOCK_IOPOLL", |
899039e8 | 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 | ||
75e1056f VP |
79 | /* |
80 | * preempt_count and SOFTIRQ_OFFSET usage: | |
81 | * - preempt_count is changed by SOFTIRQ_OFFSET on entering or leaving | |
82 | * softirq processing. | |
83 | * - preempt_count is changed by SOFTIRQ_DISABLE_OFFSET (= 2 * SOFTIRQ_OFFSET) | |
84 | * on local_bh_disable or local_bh_enable. | |
85 | * This lets us distinguish between whether we are currently processing | |
86 | * softirq and whether we just have bh disabled. | |
87 | */ | |
88 | ||
de30a2b3 IM |
89 | /* |
90 | * This one is for softirq.c-internal use, | |
91 | * where hardirqs are disabled legitimately: | |
92 | */ | |
3c829c36 | 93 | #ifdef CONFIG_TRACE_IRQFLAGS |
75e1056f | 94 | static void __local_bh_disable(unsigned long ip, unsigned int cnt) |
de30a2b3 IM |
95 | { |
96 | unsigned long flags; | |
97 | ||
98 | WARN_ON_ONCE(in_irq()); | |
99 | ||
100 | raw_local_irq_save(flags); | |
7e49fcce SR |
101 | /* |
102 | * The preempt tracer hooks into add_preempt_count and will break | |
103 | * lockdep because it calls back into lockdep after SOFTIRQ_OFFSET | |
104 | * is set and before current->softirq_enabled is cleared. | |
105 | * We must manually increment preempt_count here and manually | |
106 | * call the trace_preempt_off later. | |
107 | */ | |
75e1056f | 108 | preempt_count() += cnt; |
de30a2b3 IM |
109 | /* |
110 | * Were softirqs turned off above: | |
111 | */ | |
75e1056f | 112 | if (softirq_count() == cnt) |
de30a2b3 IM |
113 | trace_softirqs_off(ip); |
114 | raw_local_irq_restore(flags); | |
7e49fcce | 115 | |
75e1056f | 116 | if (preempt_count() == cnt) |
7e49fcce | 117 | trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); |
de30a2b3 | 118 | } |
3c829c36 | 119 | #else /* !CONFIG_TRACE_IRQFLAGS */ |
75e1056f | 120 | static inline void __local_bh_disable(unsigned long ip, unsigned int cnt) |
3c829c36 | 121 | { |
75e1056f | 122 | add_preempt_count(cnt); |
3c829c36 TC |
123 | barrier(); |
124 | } | |
125 | #endif /* CONFIG_TRACE_IRQFLAGS */ | |
de30a2b3 IM |
126 | |
127 | void local_bh_disable(void) | |
128 | { | |
75e1056f VP |
129 | __local_bh_disable((unsigned long)__builtin_return_address(0), |
130 | SOFTIRQ_DISABLE_OFFSET); | |
de30a2b3 IM |
131 | } |
132 | ||
133 | EXPORT_SYMBOL(local_bh_disable); | |
134 | ||
75e1056f VP |
135 | static void __local_bh_enable(unsigned int cnt) |
136 | { | |
137 | WARN_ON_ONCE(in_irq()); | |
138 | WARN_ON_ONCE(!irqs_disabled()); | |
139 | ||
140 | if (softirq_count() == cnt) | |
141 | trace_softirqs_on((unsigned long)__builtin_return_address(0)); | |
142 | sub_preempt_count(cnt); | |
143 | } | |
144 | ||
de30a2b3 IM |
145 | /* |
146 | * Special-case - softirqs can safely be enabled in | |
147 | * cond_resched_softirq(), or by __do_softirq(), | |
148 | * without processing still-pending softirqs: | |
149 | */ | |
150 | void _local_bh_enable(void) | |
151 | { | |
75e1056f | 152 | __local_bh_enable(SOFTIRQ_DISABLE_OFFSET); |
de30a2b3 IM |
153 | } |
154 | ||
155 | EXPORT_SYMBOL(_local_bh_enable); | |
156 | ||
0f476b6d | 157 | static inline void _local_bh_enable_ip(unsigned long ip) |
de30a2b3 | 158 | { |
0f476b6d | 159 | WARN_ON_ONCE(in_irq() || irqs_disabled()); |
3c829c36 | 160 | #ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d | 161 | local_irq_disable(); |
3c829c36 | 162 | #endif |
de30a2b3 IM |
163 | /* |
164 | * Are softirqs going to be turned on now: | |
165 | */ | |
75e1056f | 166 | if (softirq_count() == SOFTIRQ_DISABLE_OFFSET) |
0f476b6d | 167 | trace_softirqs_on(ip); |
de30a2b3 IM |
168 | /* |
169 | * Keep preemption disabled until we are done with | |
170 | * softirq processing: | |
171 | */ | |
75e1056f | 172 | sub_preempt_count(SOFTIRQ_DISABLE_OFFSET - 1); |
de30a2b3 IM |
173 | |
174 | if (unlikely(!in_interrupt() && local_softirq_pending())) | |
175 | do_softirq(); | |
176 | ||
177 | dec_preempt_count(); | |
3c829c36 | 178 | #ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d | 179 | local_irq_enable(); |
3c829c36 | 180 | #endif |
de30a2b3 IM |
181 | preempt_check_resched(); |
182 | } | |
0f476b6d JB |
183 | |
184 | void local_bh_enable(void) | |
185 | { | |
186 | _local_bh_enable_ip((unsigned long)__builtin_return_address(0)); | |
187 | } | |
de30a2b3 IM |
188 | EXPORT_SYMBOL(local_bh_enable); |
189 | ||
190 | void local_bh_enable_ip(unsigned long ip) | |
191 | { | |
0f476b6d | 192 | _local_bh_enable_ip(ip); |
de30a2b3 IM |
193 | } |
194 | EXPORT_SYMBOL(local_bh_enable_ip); | |
195 | ||
1da177e4 LT |
196 | /* |
197 | * We restart softirq processing MAX_SOFTIRQ_RESTART times, | |
198 | * and we fall back to softirqd after that. | |
199 | * | |
200 | * This number has been established via experimentation. | |
201 | * The two things to balance is latency against fairness - | |
202 | * we want to handle softirqs as soon as possible, but they | |
203 | * should not be able to lock up the box. | |
204 | */ | |
205 | #define MAX_SOFTIRQ_RESTART 10 | |
206 | ||
207 | asmlinkage void __do_softirq(void) | |
208 | { | |
209 | struct softirq_action *h; | |
210 | __u32 pending; | |
211 | int max_restart = MAX_SOFTIRQ_RESTART; | |
212 | int cpu; | |
213 | ||
214 | pending = local_softirq_pending(); | |
829035fd PM |
215 | account_system_vtime(current); |
216 | ||
75e1056f VP |
217 | __local_bh_disable((unsigned long)__builtin_return_address(0), |
218 | SOFTIRQ_OFFSET); | |
d820ac4c | 219 | lockdep_softirq_enter(); |
1da177e4 | 220 | |
1da177e4 LT |
221 | cpu = smp_processor_id(); |
222 | restart: | |
223 | /* Reset the pending bitmask before enabling irqs */ | |
3f74478b | 224 | set_softirq_pending(0); |
1da177e4 | 225 | |
c70f5d66 | 226 | local_irq_enable(); |
1da177e4 LT |
227 | |
228 | h = softirq_vec; | |
229 | ||
230 | do { | |
231 | if (pending & 1) { | |
8e85b4b5 | 232 | int prev_count = preempt_count(); |
aa0ce5bb | 233 | kstat_incr_softirqs_this_cpu(h - softirq_vec); |
8e85b4b5 | 234 | |
39842323 | 235 | trace_softirq_entry(h, softirq_vec); |
1da177e4 | 236 | h->action(h); |
39842323 | 237 | trace_softirq_exit(h, softirq_vec); |
8e85b4b5 | 238 | if (unlikely(prev_count != preempt_count())) { |
5d592b44 | 239 | printk(KERN_ERR "huh, entered softirq %td %s %p" |
8e85b4b5 TG |
240 | "with preempt_count %08x," |
241 | " exited with %08x?\n", h - softirq_vec, | |
5d592b44 | 242 | softirq_to_name[h - softirq_vec], |
8e85b4b5 TG |
243 | h->action, prev_count, preempt_count()); |
244 | preempt_count() = prev_count; | |
245 | } | |
246 | ||
d6714c22 | 247 | rcu_bh_qs(cpu); |
1da177e4 LT |
248 | } |
249 | h++; | |
250 | pending >>= 1; | |
251 | } while (pending); | |
252 | ||
c70f5d66 | 253 | local_irq_disable(); |
1da177e4 LT |
254 | |
255 | pending = local_softirq_pending(); | |
256 | if (pending && --max_restart) | |
257 | goto restart; | |
258 | ||
259 | if (pending) | |
260 | wakeup_softirqd(); | |
261 | ||
d820ac4c | 262 | lockdep_softirq_exit(); |
829035fd PM |
263 | |
264 | account_system_vtime(current); | |
75e1056f | 265 | __local_bh_enable(SOFTIRQ_OFFSET); |
1da177e4 LT |
266 | } |
267 | ||
268 | #ifndef __ARCH_HAS_DO_SOFTIRQ | |
269 | ||
270 | asmlinkage void do_softirq(void) | |
271 | { | |
272 | __u32 pending; | |
273 | unsigned long flags; | |
274 | ||
275 | if (in_interrupt()) | |
276 | return; | |
277 | ||
278 | local_irq_save(flags); | |
279 | ||
280 | pending = local_softirq_pending(); | |
281 | ||
282 | if (pending) | |
283 | __do_softirq(); | |
284 | ||
285 | local_irq_restore(flags); | |
286 | } | |
287 | ||
1da177e4 LT |
288 | #endif |
289 | ||
dde4b2b5 IM |
290 | /* |
291 | * Enter an interrupt context. | |
292 | */ | |
293 | void irq_enter(void) | |
294 | { | |
6378ddb5 | 295 | int cpu = smp_processor_id(); |
719254fa | 296 | |
64db4cff | 297 | rcu_irq_enter(); |
ee5f80a9 TG |
298 | if (idle_cpu(cpu) && !in_interrupt()) { |
299 | __irq_enter(); | |
719254fa | 300 | tick_check_idle(cpu); |
ee5f80a9 TG |
301 | } else |
302 | __irq_enter(); | |
dde4b2b5 IM |
303 | } |
304 | ||
1da177e4 LT |
305 | #ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED |
306 | # define invoke_softirq() __do_softirq() | |
307 | #else | |
308 | # define invoke_softirq() do_softirq() | |
309 | #endif | |
310 | ||
311 | /* | |
312 | * Exit an interrupt context. Process softirqs if needed and possible: | |
313 | */ | |
314 | void irq_exit(void) | |
315 | { | |
316 | account_system_vtime(current); | |
de30a2b3 | 317 | trace_hardirq_exit(); |
1da177e4 LT |
318 | sub_preempt_count(IRQ_EXIT_OFFSET); |
319 | if (!in_interrupt() && local_softirq_pending()) | |
320 | invoke_softirq(); | |
79bf2bb3 | 321 | |
c5e0cb3d | 322 | rcu_irq_exit(); |
79bf2bb3 TG |
323 | #ifdef CONFIG_NO_HZ |
324 | /* Make sure that timer wheel updates are propagated */ | |
64db4cff PM |
325 | if (idle_cpu(smp_processor_id()) && !in_interrupt() && !need_resched()) |
326 | tick_nohz_stop_sched_tick(0); | |
79bf2bb3 | 327 | #endif |
1da177e4 LT |
328 | preempt_enable_no_resched(); |
329 | } | |
330 | ||
331 | /* | |
332 | * This function must run with irqs disabled! | |
333 | */ | |
7ad5b3a5 | 334 | inline void raise_softirq_irqoff(unsigned int nr) |
1da177e4 LT |
335 | { |
336 | __raise_softirq_irqoff(nr); | |
337 | ||
338 | /* | |
339 | * If we're in an interrupt or softirq, we're done | |
340 | * (this also catches softirq-disabled code). We will | |
341 | * actually run the softirq once we return from | |
342 | * the irq or softirq. | |
343 | * | |
344 | * Otherwise we wake up ksoftirqd to make sure we | |
345 | * schedule the softirq soon. | |
346 | */ | |
347 | if (!in_interrupt()) | |
348 | wakeup_softirqd(); | |
349 | } | |
350 | ||
7ad5b3a5 | 351 | void raise_softirq(unsigned int nr) |
1da177e4 LT |
352 | { |
353 | unsigned long flags; | |
354 | ||
355 | local_irq_save(flags); | |
356 | raise_softirq_irqoff(nr); | |
357 | local_irq_restore(flags); | |
358 | } | |
359 | ||
962cf36c | 360 | void open_softirq(int nr, void (*action)(struct softirq_action *)) |
1da177e4 | 361 | { |
1da177e4 LT |
362 | softirq_vec[nr].action = action; |
363 | } | |
364 | ||
9ba5f005 PZ |
365 | /* |
366 | * Tasklets | |
367 | */ | |
1da177e4 LT |
368 | struct tasklet_head |
369 | { | |
48f20a9a OJ |
370 | struct tasklet_struct *head; |
371 | struct tasklet_struct **tail; | |
1da177e4 LT |
372 | }; |
373 | ||
4620b49f VN |
374 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec); |
375 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec); | |
1da177e4 | 376 | |
7ad5b3a5 | 377 | void __tasklet_schedule(struct tasklet_struct *t) |
1da177e4 LT |
378 | { |
379 | unsigned long flags; | |
380 | ||
381 | local_irq_save(flags); | |
48f20a9a OJ |
382 | t->next = NULL; |
383 | *__get_cpu_var(tasklet_vec).tail = t; | |
384 | __get_cpu_var(tasklet_vec).tail = &(t->next); | |
1da177e4 LT |
385 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
386 | local_irq_restore(flags); | |
387 | } | |
388 | ||
389 | EXPORT_SYMBOL(__tasklet_schedule); | |
390 | ||
7ad5b3a5 | 391 | void __tasklet_hi_schedule(struct tasklet_struct *t) |
1da177e4 LT |
392 | { |
393 | unsigned long flags; | |
394 | ||
395 | local_irq_save(flags); | |
48f20a9a OJ |
396 | t->next = NULL; |
397 | *__get_cpu_var(tasklet_hi_vec).tail = t; | |
398 | __get_cpu_var(tasklet_hi_vec).tail = &(t->next); | |
1da177e4 LT |
399 | raise_softirq_irqoff(HI_SOFTIRQ); |
400 | local_irq_restore(flags); | |
401 | } | |
402 | ||
403 | EXPORT_SYMBOL(__tasklet_hi_schedule); | |
404 | ||
7c692cba VN |
405 | void __tasklet_hi_schedule_first(struct tasklet_struct *t) |
406 | { | |
407 | BUG_ON(!irqs_disabled()); | |
408 | ||
409 | t->next = __get_cpu_var(tasklet_hi_vec).head; | |
410 | __get_cpu_var(tasklet_hi_vec).head = t; | |
411 | __raise_softirq_irqoff(HI_SOFTIRQ); | |
412 | } | |
413 | ||
414 | EXPORT_SYMBOL(__tasklet_hi_schedule_first); | |
415 | ||
1da177e4 LT |
416 | static void tasklet_action(struct softirq_action *a) |
417 | { | |
418 | struct tasklet_struct *list; | |
419 | ||
420 | local_irq_disable(); | |
48f20a9a OJ |
421 | list = __get_cpu_var(tasklet_vec).head; |
422 | __get_cpu_var(tasklet_vec).head = NULL; | |
423 | __get_cpu_var(tasklet_vec).tail = &__get_cpu_var(tasklet_vec).head; | |
1da177e4 LT |
424 | local_irq_enable(); |
425 | ||
426 | while (list) { | |
427 | struct tasklet_struct *t = list; | |
428 | ||
429 | list = list->next; | |
430 | ||
431 | if (tasklet_trylock(t)) { | |
432 | if (!atomic_read(&t->count)) { | |
433 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
434 | BUG(); | |
435 | t->func(t->data); | |
436 | tasklet_unlock(t); | |
437 | continue; | |
438 | } | |
439 | tasklet_unlock(t); | |
440 | } | |
441 | ||
442 | local_irq_disable(); | |
48f20a9a OJ |
443 | t->next = NULL; |
444 | *__get_cpu_var(tasklet_vec).tail = t; | |
445 | __get_cpu_var(tasklet_vec).tail = &(t->next); | |
1da177e4 LT |
446 | __raise_softirq_irqoff(TASKLET_SOFTIRQ); |
447 | local_irq_enable(); | |
448 | } | |
449 | } | |
450 | ||
451 | static void tasklet_hi_action(struct softirq_action *a) | |
452 | { | |
453 | struct tasklet_struct *list; | |
454 | ||
455 | local_irq_disable(); | |
48f20a9a OJ |
456 | list = __get_cpu_var(tasklet_hi_vec).head; |
457 | __get_cpu_var(tasklet_hi_vec).head = NULL; | |
458 | __get_cpu_var(tasklet_hi_vec).tail = &__get_cpu_var(tasklet_hi_vec).head; | |
1da177e4 LT |
459 | local_irq_enable(); |
460 | ||
461 | while (list) { | |
462 | struct tasklet_struct *t = list; | |
463 | ||
464 | list = list->next; | |
465 | ||
466 | if (tasklet_trylock(t)) { | |
467 | if (!atomic_read(&t->count)) { | |
468 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
469 | BUG(); | |
470 | t->func(t->data); | |
471 | tasklet_unlock(t); | |
472 | continue; | |
473 | } | |
474 | tasklet_unlock(t); | |
475 | } | |
476 | ||
477 | local_irq_disable(); | |
48f20a9a OJ |
478 | t->next = NULL; |
479 | *__get_cpu_var(tasklet_hi_vec).tail = t; | |
480 | __get_cpu_var(tasklet_hi_vec).tail = &(t->next); | |
1da177e4 LT |
481 | __raise_softirq_irqoff(HI_SOFTIRQ); |
482 | local_irq_enable(); | |
483 | } | |
484 | } | |
485 | ||
486 | ||
487 | void tasklet_init(struct tasklet_struct *t, | |
488 | void (*func)(unsigned long), unsigned long data) | |
489 | { | |
490 | t->next = NULL; | |
491 | t->state = 0; | |
492 | atomic_set(&t->count, 0); | |
493 | t->func = func; | |
494 | t->data = data; | |
495 | } | |
496 | ||
497 | EXPORT_SYMBOL(tasklet_init); | |
498 | ||
499 | void tasklet_kill(struct tasklet_struct *t) | |
500 | { | |
501 | if (in_interrupt()) | |
502 | printk("Attempt to kill tasklet from interrupt\n"); | |
503 | ||
504 | while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { | |
79d381c9 | 505 | do { |
1da177e4 | 506 | yield(); |
79d381c9 | 507 | } while (test_bit(TASKLET_STATE_SCHED, &t->state)); |
1da177e4 LT |
508 | } |
509 | tasklet_unlock_wait(t); | |
510 | clear_bit(TASKLET_STATE_SCHED, &t->state); | |
511 | } | |
512 | ||
513 | EXPORT_SYMBOL(tasklet_kill); | |
514 | ||
9ba5f005 PZ |
515 | /* |
516 | * tasklet_hrtimer | |
517 | */ | |
518 | ||
519 | /* | |
b9c30322 PZ |
520 | * The trampoline is called when the hrtimer expires. It schedules a tasklet |
521 | * to run __tasklet_hrtimer_trampoline() which in turn will call the intended | |
522 | * hrtimer callback, but from softirq context. | |
9ba5f005 PZ |
523 | */ |
524 | static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer) | |
525 | { | |
526 | struct tasklet_hrtimer *ttimer = | |
527 | container_of(timer, struct tasklet_hrtimer, timer); | |
528 | ||
b9c30322 PZ |
529 | tasklet_hi_schedule(&ttimer->tasklet); |
530 | return HRTIMER_NORESTART; | |
9ba5f005 PZ |
531 | } |
532 | ||
533 | /* | |
534 | * Helper function which calls the hrtimer callback from | |
535 | * tasklet/softirq context | |
536 | */ | |
537 | static void __tasklet_hrtimer_trampoline(unsigned long data) | |
538 | { | |
539 | struct tasklet_hrtimer *ttimer = (void *)data; | |
540 | enum hrtimer_restart restart; | |
541 | ||
542 | restart = ttimer->function(&ttimer->timer); | |
543 | if (restart != HRTIMER_NORESTART) | |
544 | hrtimer_restart(&ttimer->timer); | |
545 | } | |
546 | ||
547 | /** | |
548 | * tasklet_hrtimer_init - Init a tasklet/hrtimer combo for softirq callbacks | |
549 | * @ttimer: tasklet_hrtimer which is initialized | |
550 | * @function: hrtimer callback funtion which gets called from softirq context | |
551 | * @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME) | |
552 | * @mode: hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL) | |
553 | */ | |
554 | void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer, | |
555 | enum hrtimer_restart (*function)(struct hrtimer *), | |
556 | clockid_t which_clock, enum hrtimer_mode mode) | |
557 | { | |
558 | hrtimer_init(&ttimer->timer, which_clock, mode); | |
559 | ttimer->timer.function = __hrtimer_tasklet_trampoline; | |
560 | tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline, | |
561 | (unsigned long)ttimer); | |
562 | ttimer->function = function; | |
563 | } | |
564 | EXPORT_SYMBOL_GPL(tasklet_hrtimer_init); | |
565 | ||
566 | /* | |
567 | * Remote softirq bits | |
568 | */ | |
569 | ||
54514a70 DM |
570 | DEFINE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list); |
571 | EXPORT_PER_CPU_SYMBOL(softirq_work_list); | |
572 | ||
573 | static void __local_trigger(struct call_single_data *cp, int softirq) | |
574 | { | |
575 | struct list_head *head = &__get_cpu_var(softirq_work_list[softirq]); | |
576 | ||
577 | list_add_tail(&cp->list, head); | |
578 | ||
579 | /* Trigger the softirq only if the list was previously empty. */ | |
580 | if (head->next == &cp->list) | |
581 | raise_softirq_irqoff(softirq); | |
582 | } | |
583 | ||
584 | #ifdef CONFIG_USE_GENERIC_SMP_HELPERS | |
585 | static void remote_softirq_receive(void *data) | |
586 | { | |
587 | struct call_single_data *cp = data; | |
588 | unsigned long flags; | |
589 | int softirq; | |
590 | ||
591 | softirq = cp->priv; | |
592 | ||
593 | local_irq_save(flags); | |
594 | __local_trigger(cp, softirq); | |
595 | local_irq_restore(flags); | |
596 | } | |
597 | ||
598 | static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) | |
599 | { | |
600 | if (cpu_online(cpu)) { | |
601 | cp->func = remote_softirq_receive; | |
602 | cp->info = cp; | |
603 | cp->flags = 0; | |
604 | cp->priv = softirq; | |
605 | ||
6e275637 | 606 | __smp_call_function_single(cpu, cp, 0); |
54514a70 DM |
607 | return 0; |
608 | } | |
609 | return 1; | |
610 | } | |
611 | #else /* CONFIG_USE_GENERIC_SMP_HELPERS */ | |
612 | static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) | |
613 | { | |
614 | return 1; | |
615 | } | |
616 | #endif | |
617 | ||
618 | /** | |
619 | * __send_remote_softirq - try to schedule softirq work on a remote cpu | |
620 | * @cp: private SMP call function data area | |
621 | * @cpu: the remote cpu | |
622 | * @this_cpu: the currently executing cpu | |
623 | * @softirq: the softirq for the work | |
624 | * | |
625 | * Attempt to schedule softirq work on a remote cpu. If this cannot be | |
626 | * done, the work is instead queued up on the local cpu. | |
627 | * | |
628 | * Interrupts must be disabled. | |
629 | */ | |
630 | void __send_remote_softirq(struct call_single_data *cp, int cpu, int this_cpu, int softirq) | |
631 | { | |
632 | if (cpu == this_cpu || __try_remote_softirq(cp, cpu, softirq)) | |
633 | __local_trigger(cp, softirq); | |
634 | } | |
635 | EXPORT_SYMBOL(__send_remote_softirq); | |
636 | ||
637 | /** | |
638 | * send_remote_softirq - try to schedule softirq work on a remote cpu | |
639 | * @cp: private SMP call function data area | |
640 | * @cpu: the remote cpu | |
641 | * @softirq: the softirq for the work | |
642 | * | |
643 | * Like __send_remote_softirq except that disabling interrupts and | |
644 | * computing the current cpu is done for the caller. | |
645 | */ | |
646 | void send_remote_softirq(struct call_single_data *cp, int cpu, int softirq) | |
647 | { | |
648 | unsigned long flags; | |
649 | int this_cpu; | |
650 | ||
651 | local_irq_save(flags); | |
652 | this_cpu = smp_processor_id(); | |
653 | __send_remote_softirq(cp, cpu, this_cpu, softirq); | |
654 | local_irq_restore(flags); | |
655 | } | |
656 | EXPORT_SYMBOL(send_remote_softirq); | |
657 | ||
658 | static int __cpuinit remote_softirq_cpu_notify(struct notifier_block *self, | |
659 | unsigned long action, void *hcpu) | |
660 | { | |
661 | /* | |
662 | * If a CPU goes away, splice its entries to the current CPU | |
663 | * and trigger a run of the softirq | |
664 | */ | |
665 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { | |
666 | int cpu = (unsigned long) hcpu; | |
667 | int i; | |
668 | ||
669 | local_irq_disable(); | |
670 | for (i = 0; i < NR_SOFTIRQS; i++) { | |
671 | struct list_head *head = &per_cpu(softirq_work_list[i], cpu); | |
672 | struct list_head *local_head; | |
673 | ||
674 | if (list_empty(head)) | |
675 | continue; | |
676 | ||
677 | local_head = &__get_cpu_var(softirq_work_list[i]); | |
678 | list_splice_init(head, local_head); | |
679 | raise_softirq_irqoff(i); | |
680 | } | |
681 | local_irq_enable(); | |
682 | } | |
683 | ||
684 | return NOTIFY_OK; | |
685 | } | |
686 | ||
687 | static struct notifier_block __cpuinitdata remote_softirq_cpu_notifier = { | |
688 | .notifier_call = remote_softirq_cpu_notify, | |
689 | }; | |
690 | ||
1da177e4 LT |
691 | void __init softirq_init(void) |
692 | { | |
48f20a9a OJ |
693 | int cpu; |
694 | ||
695 | for_each_possible_cpu(cpu) { | |
54514a70 DM |
696 | int i; |
697 | ||
48f20a9a OJ |
698 | per_cpu(tasklet_vec, cpu).tail = |
699 | &per_cpu(tasklet_vec, cpu).head; | |
700 | per_cpu(tasklet_hi_vec, cpu).tail = | |
701 | &per_cpu(tasklet_hi_vec, cpu).head; | |
54514a70 DM |
702 | for (i = 0; i < NR_SOFTIRQS; i++) |
703 | INIT_LIST_HEAD(&per_cpu(softirq_work_list[i], cpu)); | |
48f20a9a OJ |
704 | } |
705 | ||
54514a70 DM |
706 | register_hotcpu_notifier(&remote_softirq_cpu_notifier); |
707 | ||
962cf36c CM |
708 | open_softirq(TASKLET_SOFTIRQ, tasklet_action); |
709 | open_softirq(HI_SOFTIRQ, tasklet_hi_action); | |
1da177e4 LT |
710 | } |
711 | ||
1871e52c | 712 | static int run_ksoftirqd(void * __bind_cpu) |
1da177e4 | 713 | { |
1da177e4 LT |
714 | set_current_state(TASK_INTERRUPTIBLE); |
715 | ||
6cdd5199 | 716 | current->flags |= PF_KSOFTIRQD; |
1da177e4 LT |
717 | while (!kthread_should_stop()) { |
718 | preempt_disable(); | |
719 | if (!local_softirq_pending()) { | |
720 | preempt_enable_no_resched(); | |
721 | schedule(); | |
722 | preempt_disable(); | |
723 | } | |
724 | ||
725 | __set_current_state(TASK_RUNNING); | |
726 | ||
727 | while (local_softirq_pending()) { | |
728 | /* Preempt disable stops cpu going offline. | |
729 | If already offline, we'll be on wrong CPU: | |
730 | don't process */ | |
731 | if (cpu_is_offline((long)__bind_cpu)) | |
732 | goto wait_to_die; | |
733 | do_softirq(); | |
734 | preempt_enable_no_resched(); | |
735 | cond_resched(); | |
736 | preempt_disable(); | |
25502a6c | 737 | rcu_note_context_switch((long)__bind_cpu); |
1da177e4 LT |
738 | } |
739 | preempt_enable(); | |
740 | set_current_state(TASK_INTERRUPTIBLE); | |
741 | } | |
742 | __set_current_state(TASK_RUNNING); | |
743 | return 0; | |
744 | ||
745 | wait_to_die: | |
746 | preempt_enable(); | |
747 | /* Wait for kthread_stop */ | |
748 | set_current_state(TASK_INTERRUPTIBLE); | |
749 | while (!kthread_should_stop()) { | |
750 | schedule(); | |
751 | set_current_state(TASK_INTERRUPTIBLE); | |
752 | } | |
753 | __set_current_state(TASK_RUNNING); | |
754 | return 0; | |
755 | } | |
756 | ||
757 | #ifdef CONFIG_HOTPLUG_CPU | |
758 | /* | |
759 | * tasklet_kill_immediate is called to remove a tasklet which can already be | |
760 | * scheduled for execution on @cpu. | |
761 | * | |
762 | * Unlike tasklet_kill, this function removes the tasklet | |
763 | * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state. | |
764 | * | |
765 | * When this function is called, @cpu must be in the CPU_DEAD state. | |
766 | */ | |
767 | void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu) | |
768 | { | |
769 | struct tasklet_struct **i; | |
770 | ||
771 | BUG_ON(cpu_online(cpu)); | |
772 | BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state)); | |
773 | ||
774 | if (!test_bit(TASKLET_STATE_SCHED, &t->state)) | |
775 | return; | |
776 | ||
777 | /* CPU is dead, so no lock needed. */ | |
48f20a9a | 778 | for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) { |
1da177e4 LT |
779 | if (*i == t) { |
780 | *i = t->next; | |
48f20a9a OJ |
781 | /* If this was the tail element, move the tail ptr */ |
782 | if (*i == NULL) | |
783 | per_cpu(tasklet_vec, cpu).tail = i; | |
1da177e4 LT |
784 | return; |
785 | } | |
786 | } | |
787 | BUG(); | |
788 | } | |
789 | ||
790 | static void takeover_tasklets(unsigned int cpu) | |
791 | { | |
1da177e4 LT |
792 | /* CPU is dead, so no lock needed. */ |
793 | local_irq_disable(); | |
794 | ||
795 | /* Find end, append list for that CPU. */ | |
e5e41723 CB |
796 | if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) { |
797 | *(__get_cpu_var(tasklet_vec).tail) = per_cpu(tasklet_vec, cpu).head; | |
798 | __get_cpu_var(tasklet_vec).tail = per_cpu(tasklet_vec, cpu).tail; | |
799 | per_cpu(tasklet_vec, cpu).head = NULL; | |
800 | per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; | |
801 | } | |
1da177e4 LT |
802 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
803 | ||
e5e41723 CB |
804 | if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) { |
805 | *__get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).head; | |
806 | __get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).tail; | |
807 | per_cpu(tasklet_hi_vec, cpu).head = NULL; | |
808 | per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; | |
809 | } | |
1da177e4 LT |
810 | raise_softirq_irqoff(HI_SOFTIRQ); |
811 | ||
812 | local_irq_enable(); | |
813 | } | |
814 | #endif /* CONFIG_HOTPLUG_CPU */ | |
815 | ||
8c78f307 | 816 | static int __cpuinit cpu_callback(struct notifier_block *nfb, |
1da177e4 LT |
817 | unsigned long action, |
818 | void *hcpu) | |
819 | { | |
820 | int hotcpu = (unsigned long)hcpu; | |
821 | struct task_struct *p; | |
822 | ||
823 | switch (action) { | |
824 | case CPU_UP_PREPARE: | |
8bb78442 | 825 | case CPU_UP_PREPARE_FROZEN: |
1871e52c | 826 | p = kthread_create(run_ksoftirqd, hcpu, "ksoftirqd/%d", hotcpu); |
1da177e4 LT |
827 | if (IS_ERR(p)) { |
828 | printk("ksoftirqd for %i failed\n", hotcpu); | |
80b5184c | 829 | return notifier_from_errno(PTR_ERR(p)); |
1da177e4 LT |
830 | } |
831 | kthread_bind(p, hotcpu); | |
832 | per_cpu(ksoftirqd, hotcpu) = p; | |
833 | break; | |
834 | case CPU_ONLINE: | |
8bb78442 | 835 | case CPU_ONLINE_FROZEN: |
1da177e4 LT |
836 | wake_up_process(per_cpu(ksoftirqd, hotcpu)); |
837 | break; | |
838 | #ifdef CONFIG_HOTPLUG_CPU | |
839 | case CPU_UP_CANCELED: | |
8bb78442 | 840 | case CPU_UP_CANCELED_FROZEN: |
fc75cdfa HC |
841 | if (!per_cpu(ksoftirqd, hotcpu)) |
842 | break; | |
1da177e4 | 843 | /* Unbind so it can run. Fall thru. */ |
a4c4af7c | 844 | kthread_bind(per_cpu(ksoftirqd, hotcpu), |
f1fc057c | 845 | cpumask_any(cpu_online_mask)); |
1da177e4 | 846 | case CPU_DEAD: |
1c6b4aa9 ST |
847 | case CPU_DEAD_FROZEN: { |
848 | struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; | |
849 | ||
1da177e4 LT |
850 | p = per_cpu(ksoftirqd, hotcpu); |
851 | per_cpu(ksoftirqd, hotcpu) = NULL; | |
961ccddd | 852 | sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m); |
1da177e4 LT |
853 | kthread_stop(p); |
854 | takeover_tasklets(hotcpu); | |
855 | break; | |
1c6b4aa9 | 856 | } |
1da177e4 LT |
857 | #endif /* CONFIG_HOTPLUG_CPU */ |
858 | } | |
859 | return NOTIFY_OK; | |
860 | } | |
861 | ||
8c78f307 | 862 | static struct notifier_block __cpuinitdata cpu_nfb = { |
1da177e4 LT |
863 | .notifier_call = cpu_callback |
864 | }; | |
865 | ||
7babe8db | 866 | static __init int spawn_ksoftirqd(void) |
1da177e4 LT |
867 | { |
868 | void *cpu = (void *)(long)smp_processor_id(); | |
07dccf33 AM |
869 | int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu); |
870 | ||
9e506f7a | 871 | BUG_ON(err != NOTIFY_OK); |
1da177e4 LT |
872 | cpu_callback(&cpu_nfb, CPU_ONLINE, cpu); |
873 | register_cpu_notifier(&cpu_nfb); | |
874 | return 0; | |
875 | } | |
7babe8db | 876 | early_initcall(spawn_ksoftirqd); |
78eef01b AM |
877 | |
878 | #ifdef CONFIG_SMP | |
879 | /* | |
880 | * Call a function on all processors | |
881 | */ | |
15c8b6c1 | 882 | int on_each_cpu(void (*func) (void *info), void *info, int wait) |
78eef01b AM |
883 | { |
884 | int ret = 0; | |
885 | ||
886 | preempt_disable(); | |
8691e5a8 | 887 | ret = smp_call_function(func, info, wait); |
78eef01b AM |
888 | local_irq_disable(); |
889 | func(info); | |
890 | local_irq_enable(); | |
891 | preempt_enable(); | |
892 | return ret; | |
893 | } | |
894 | EXPORT_SYMBOL(on_each_cpu); | |
895 | #endif | |
43a25632 YL |
896 | |
897 | /* | |
898 | * [ These __weak aliases are kept in a separate compilation unit, so that | |
899 | * GCC does not inline them incorrectly. ] | |
900 | */ | |
901 | ||
902 | int __init __weak early_irq_init(void) | |
903 | { | |
904 | return 0; | |
905 | } | |
906 | ||
4a046d17 YL |
907 | int __init __weak arch_probe_nr_irqs(void) |
908 | { | |
909 | return 0; | |
910 | } | |
911 | ||
43a25632 YL |
912 | int __init __weak arch_early_irq_init(void) |
913 | { | |
914 | return 0; | |
915 | } | |
916 | ||
85ac16d0 | 917 | int __weak arch_init_chip_data(struct irq_desc *desc, int node) |
43a25632 YL |
918 | { |
919 | return 0; | |
920 | } |