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 | ||
9984de1a | 13 | #include <linux/export.h> |
1da177e4 LT |
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 | 56 | |
4dd53d89 | 57 | DEFINE_PER_CPU(struct task_struct *, ksoftirqd); |
1da177e4 | 58 | |
5d592b44 | 59 | char *softirq_to_name[NR_SOFTIRQS] = { |
5dd4de58 | 60 | "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "BLOCK_IOPOLL", |
09223371 | 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 | */ | |
676cb02d | 70 | static void wakeup_softirqd(void) |
1da177e4 LT |
71 | { |
72 | /* Interrupts are disabled: no need to stop preemption */ | |
909ea964 | 73 | struct task_struct *tsk = __this_cpu_read(ksoftirqd); |
1da177e4 LT |
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; | |
907aed48 MG |
213 | unsigned long old_flags = current->flags; |
214 | ||
215 | /* | |
216 | * Mask out PF_MEMALLOC s current task context is borrowed for the | |
217 | * softirq. A softirq handled such as network RX might set PF_MEMALLOC | |
218 | * again if the socket is related to swap | |
219 | */ | |
220 | current->flags &= ~PF_MEMALLOC; | |
1da177e4 LT |
221 | |
222 | pending = local_softirq_pending(); | |
829035fd PM |
223 | account_system_vtime(current); |
224 | ||
75e1056f VP |
225 | __local_bh_disable((unsigned long)__builtin_return_address(0), |
226 | SOFTIRQ_OFFSET); | |
d820ac4c | 227 | lockdep_softirq_enter(); |
1da177e4 | 228 | |
1da177e4 LT |
229 | cpu = smp_processor_id(); |
230 | restart: | |
231 | /* Reset the pending bitmask before enabling irqs */ | |
3f74478b | 232 | set_softirq_pending(0); |
1da177e4 | 233 | |
c70f5d66 | 234 | local_irq_enable(); |
1da177e4 LT |
235 | |
236 | h = softirq_vec; | |
237 | ||
238 | do { | |
239 | if (pending & 1) { | |
f4bc6bb2 | 240 | unsigned int vec_nr = h - softirq_vec; |
8e85b4b5 TG |
241 | int prev_count = preempt_count(); |
242 | ||
f4bc6bb2 TG |
243 | kstat_incr_softirqs_this_cpu(vec_nr); |
244 | ||
245 | trace_softirq_entry(vec_nr); | |
1da177e4 | 246 | h->action(h); |
f4bc6bb2 | 247 | trace_softirq_exit(vec_nr); |
8e85b4b5 | 248 | if (unlikely(prev_count != preempt_count())) { |
f4bc6bb2 | 249 | printk(KERN_ERR "huh, entered softirq %u %s %p" |
8e85b4b5 | 250 | "with preempt_count %08x," |
f4bc6bb2 TG |
251 | " exited with %08x?\n", vec_nr, |
252 | softirq_to_name[vec_nr], h->action, | |
253 | prev_count, preempt_count()); | |
8e85b4b5 TG |
254 | preempt_count() = prev_count; |
255 | } | |
256 | ||
d6714c22 | 257 | rcu_bh_qs(cpu); |
1da177e4 LT |
258 | } |
259 | h++; | |
260 | pending >>= 1; | |
261 | } while (pending); | |
262 | ||
c70f5d66 | 263 | local_irq_disable(); |
1da177e4 LT |
264 | |
265 | pending = local_softirq_pending(); | |
266 | if (pending && --max_restart) | |
267 | goto restart; | |
268 | ||
269 | if (pending) | |
270 | wakeup_softirqd(); | |
271 | ||
d820ac4c | 272 | lockdep_softirq_exit(); |
829035fd PM |
273 | |
274 | account_system_vtime(current); | |
75e1056f | 275 | __local_bh_enable(SOFTIRQ_OFFSET); |
907aed48 | 276 | tsk_restore_flags(current, old_flags, PF_MEMALLOC); |
1da177e4 LT |
277 | } |
278 | ||
279 | #ifndef __ARCH_HAS_DO_SOFTIRQ | |
280 | ||
281 | asmlinkage void do_softirq(void) | |
282 | { | |
283 | __u32 pending; | |
284 | unsigned long flags; | |
285 | ||
286 | if (in_interrupt()) | |
287 | return; | |
288 | ||
289 | local_irq_save(flags); | |
290 | ||
291 | pending = local_softirq_pending(); | |
292 | ||
293 | if (pending) | |
294 | __do_softirq(); | |
295 | ||
296 | local_irq_restore(flags); | |
297 | } | |
298 | ||
1da177e4 LT |
299 | #endif |
300 | ||
dde4b2b5 IM |
301 | /* |
302 | * Enter an interrupt context. | |
303 | */ | |
304 | void irq_enter(void) | |
305 | { | |
6378ddb5 | 306 | int cpu = smp_processor_id(); |
719254fa | 307 | |
64db4cff | 308 | rcu_irq_enter(); |
0a8a2e78 | 309 | if (is_idle_task(current) && !in_interrupt()) { |
d267f87f VP |
310 | /* |
311 | * Prevent raise_softirq from needlessly waking up ksoftirqd | |
312 | * here, as softirq will be serviced on return from interrupt. | |
313 | */ | |
314 | local_bh_disable(); | |
719254fa | 315 | tick_check_idle(cpu); |
d267f87f VP |
316 | _local_bh_enable(); |
317 | } | |
318 | ||
319 | __irq_enter(); | |
dde4b2b5 IM |
320 | } |
321 | ||
8d32a307 TG |
322 | static inline void invoke_softirq(void) |
323 | { | |
b2a00178 HC |
324 | if (!force_irqthreads) { |
325 | #ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED | |
8d32a307 | 326 | __do_softirq(); |
1da177e4 | 327 | #else |
8d32a307 | 328 | do_softirq(); |
b2a00178 HC |
329 | #endif |
330 | } else { | |
ec433f0c PZ |
331 | __local_bh_disable((unsigned long)__builtin_return_address(0), |
332 | SOFTIRQ_OFFSET); | |
8d32a307 | 333 | wakeup_softirqd(); |
ec433f0c PZ |
334 | __local_bh_enable(SOFTIRQ_OFFSET); |
335 | } | |
8d32a307 | 336 | } |
1da177e4 LT |
337 | |
338 | /* | |
339 | * Exit an interrupt context. Process softirqs if needed and possible: | |
340 | */ | |
341 | void irq_exit(void) | |
342 | { | |
343 | account_system_vtime(current); | |
de30a2b3 | 344 | trace_hardirq_exit(); |
1da177e4 LT |
345 | sub_preempt_count(IRQ_EXIT_OFFSET); |
346 | if (!in_interrupt() && local_softirq_pending()) | |
347 | invoke_softirq(); | |
79bf2bb3 TG |
348 | |
349 | #ifdef CONFIG_NO_HZ | |
350 | /* Make sure that timer wheel updates are propagated */ | |
64db4cff | 351 | if (idle_cpu(smp_processor_id()) && !in_interrupt() && !need_resched()) |
280f0677 | 352 | tick_nohz_irq_exit(); |
79bf2bb3 | 353 | #endif |
416eb33c | 354 | rcu_irq_exit(); |
ba74c144 | 355 | sched_preempt_enable_no_resched(); |
1da177e4 LT |
356 | } |
357 | ||
358 | /* | |
359 | * This function must run with irqs disabled! | |
360 | */ | |
7ad5b3a5 | 361 | inline void raise_softirq_irqoff(unsigned int nr) |
1da177e4 LT |
362 | { |
363 | __raise_softirq_irqoff(nr); | |
364 | ||
365 | /* | |
366 | * If we're in an interrupt or softirq, we're done | |
367 | * (this also catches softirq-disabled code). We will | |
368 | * actually run the softirq once we return from | |
369 | * the irq or softirq. | |
370 | * | |
371 | * Otherwise we wake up ksoftirqd to make sure we | |
372 | * schedule the softirq soon. | |
373 | */ | |
374 | if (!in_interrupt()) | |
375 | wakeup_softirqd(); | |
376 | } | |
377 | ||
7ad5b3a5 | 378 | void raise_softirq(unsigned int nr) |
1da177e4 LT |
379 | { |
380 | unsigned long flags; | |
381 | ||
382 | local_irq_save(flags); | |
383 | raise_softirq_irqoff(nr); | |
384 | local_irq_restore(flags); | |
385 | } | |
386 | ||
f069686e SR |
387 | void __raise_softirq_irqoff(unsigned int nr) |
388 | { | |
389 | trace_softirq_raise(nr); | |
390 | or_softirq_pending(1UL << nr); | |
391 | } | |
392 | ||
962cf36c | 393 | void open_softirq(int nr, void (*action)(struct softirq_action *)) |
1da177e4 | 394 | { |
1da177e4 LT |
395 | softirq_vec[nr].action = action; |
396 | } | |
397 | ||
9ba5f005 PZ |
398 | /* |
399 | * Tasklets | |
400 | */ | |
1da177e4 LT |
401 | struct tasklet_head |
402 | { | |
48f20a9a OJ |
403 | struct tasklet_struct *head; |
404 | struct tasklet_struct **tail; | |
1da177e4 LT |
405 | }; |
406 | ||
4620b49f VN |
407 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec); |
408 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec); | |
1da177e4 | 409 | |
7ad5b3a5 | 410 | void __tasklet_schedule(struct tasklet_struct *t) |
1da177e4 LT |
411 | { |
412 | unsigned long flags; | |
413 | ||
414 | local_irq_save(flags); | |
48f20a9a | 415 | t->next = NULL; |
909ea964 CL |
416 | *__this_cpu_read(tasklet_vec.tail) = t; |
417 | __this_cpu_write(tasklet_vec.tail, &(t->next)); | |
1da177e4 LT |
418 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
419 | local_irq_restore(flags); | |
420 | } | |
421 | ||
422 | EXPORT_SYMBOL(__tasklet_schedule); | |
423 | ||
7ad5b3a5 | 424 | void __tasklet_hi_schedule(struct tasklet_struct *t) |
1da177e4 LT |
425 | { |
426 | unsigned long flags; | |
427 | ||
428 | local_irq_save(flags); | |
48f20a9a | 429 | t->next = NULL; |
909ea964 CL |
430 | *__this_cpu_read(tasklet_hi_vec.tail) = t; |
431 | __this_cpu_write(tasklet_hi_vec.tail, &(t->next)); | |
1da177e4 LT |
432 | raise_softirq_irqoff(HI_SOFTIRQ); |
433 | local_irq_restore(flags); | |
434 | } | |
435 | ||
436 | EXPORT_SYMBOL(__tasklet_hi_schedule); | |
437 | ||
7c692cba VN |
438 | void __tasklet_hi_schedule_first(struct tasklet_struct *t) |
439 | { | |
440 | BUG_ON(!irqs_disabled()); | |
441 | ||
909ea964 CL |
442 | t->next = __this_cpu_read(tasklet_hi_vec.head); |
443 | __this_cpu_write(tasklet_hi_vec.head, t); | |
7c692cba VN |
444 | __raise_softirq_irqoff(HI_SOFTIRQ); |
445 | } | |
446 | ||
447 | EXPORT_SYMBOL(__tasklet_hi_schedule_first); | |
448 | ||
1da177e4 LT |
449 | static void tasklet_action(struct softirq_action *a) |
450 | { | |
451 | struct tasklet_struct *list; | |
452 | ||
453 | local_irq_disable(); | |
909ea964 CL |
454 | list = __this_cpu_read(tasklet_vec.head); |
455 | __this_cpu_write(tasklet_vec.head, NULL); | |
456 | __this_cpu_write(tasklet_vec.tail, &__get_cpu_var(tasklet_vec).head); | |
1da177e4 LT |
457 | local_irq_enable(); |
458 | ||
459 | while (list) { | |
460 | struct tasklet_struct *t = list; | |
461 | ||
462 | list = list->next; | |
463 | ||
464 | if (tasklet_trylock(t)) { | |
465 | if (!atomic_read(&t->count)) { | |
466 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
467 | BUG(); | |
468 | t->func(t->data); | |
469 | tasklet_unlock(t); | |
470 | continue; | |
471 | } | |
472 | tasklet_unlock(t); | |
473 | } | |
474 | ||
475 | local_irq_disable(); | |
48f20a9a | 476 | t->next = NULL; |
909ea964 CL |
477 | *__this_cpu_read(tasklet_vec.tail) = t; |
478 | __this_cpu_write(tasklet_vec.tail, &(t->next)); | |
1da177e4 LT |
479 | __raise_softirq_irqoff(TASKLET_SOFTIRQ); |
480 | local_irq_enable(); | |
481 | } | |
482 | } | |
483 | ||
484 | static void tasklet_hi_action(struct softirq_action *a) | |
485 | { | |
486 | struct tasklet_struct *list; | |
487 | ||
488 | local_irq_disable(); | |
909ea964 CL |
489 | list = __this_cpu_read(tasklet_hi_vec.head); |
490 | __this_cpu_write(tasklet_hi_vec.head, NULL); | |
491 | __this_cpu_write(tasklet_hi_vec.tail, &__get_cpu_var(tasklet_hi_vec).head); | |
1da177e4 LT |
492 | local_irq_enable(); |
493 | ||
494 | while (list) { | |
495 | struct tasklet_struct *t = list; | |
496 | ||
497 | list = list->next; | |
498 | ||
499 | if (tasklet_trylock(t)) { | |
500 | if (!atomic_read(&t->count)) { | |
501 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
502 | BUG(); | |
503 | t->func(t->data); | |
504 | tasklet_unlock(t); | |
505 | continue; | |
506 | } | |
507 | tasklet_unlock(t); | |
508 | } | |
509 | ||
510 | local_irq_disable(); | |
48f20a9a | 511 | t->next = NULL; |
909ea964 CL |
512 | *__this_cpu_read(tasklet_hi_vec.tail) = t; |
513 | __this_cpu_write(tasklet_hi_vec.tail, &(t->next)); | |
1da177e4 LT |
514 | __raise_softirq_irqoff(HI_SOFTIRQ); |
515 | local_irq_enable(); | |
516 | } | |
517 | } | |
518 | ||
519 | ||
520 | void tasklet_init(struct tasklet_struct *t, | |
521 | void (*func)(unsigned long), unsigned long data) | |
522 | { | |
523 | t->next = NULL; | |
524 | t->state = 0; | |
525 | atomic_set(&t->count, 0); | |
526 | t->func = func; | |
527 | t->data = data; | |
528 | } | |
529 | ||
530 | EXPORT_SYMBOL(tasklet_init); | |
531 | ||
532 | void tasklet_kill(struct tasklet_struct *t) | |
533 | { | |
534 | if (in_interrupt()) | |
535 | printk("Attempt to kill tasklet from interrupt\n"); | |
536 | ||
537 | while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { | |
79d381c9 | 538 | do { |
1da177e4 | 539 | yield(); |
79d381c9 | 540 | } while (test_bit(TASKLET_STATE_SCHED, &t->state)); |
1da177e4 LT |
541 | } |
542 | tasklet_unlock_wait(t); | |
543 | clear_bit(TASKLET_STATE_SCHED, &t->state); | |
544 | } | |
545 | ||
546 | EXPORT_SYMBOL(tasklet_kill); | |
547 | ||
9ba5f005 PZ |
548 | /* |
549 | * tasklet_hrtimer | |
550 | */ | |
551 | ||
552 | /* | |
b9c30322 PZ |
553 | * The trampoline is called when the hrtimer expires. It schedules a tasklet |
554 | * to run __tasklet_hrtimer_trampoline() which in turn will call the intended | |
555 | * hrtimer callback, but from softirq context. | |
9ba5f005 PZ |
556 | */ |
557 | static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer) | |
558 | { | |
559 | struct tasklet_hrtimer *ttimer = | |
560 | container_of(timer, struct tasklet_hrtimer, timer); | |
561 | ||
b9c30322 PZ |
562 | tasklet_hi_schedule(&ttimer->tasklet); |
563 | return HRTIMER_NORESTART; | |
9ba5f005 PZ |
564 | } |
565 | ||
566 | /* | |
567 | * Helper function which calls the hrtimer callback from | |
568 | * tasklet/softirq context | |
569 | */ | |
570 | static void __tasklet_hrtimer_trampoline(unsigned long data) | |
571 | { | |
572 | struct tasklet_hrtimer *ttimer = (void *)data; | |
573 | enum hrtimer_restart restart; | |
574 | ||
575 | restart = ttimer->function(&ttimer->timer); | |
576 | if (restart != HRTIMER_NORESTART) | |
577 | hrtimer_restart(&ttimer->timer); | |
578 | } | |
579 | ||
580 | /** | |
581 | * tasklet_hrtimer_init - Init a tasklet/hrtimer combo for softirq callbacks | |
582 | * @ttimer: tasklet_hrtimer which is initialized | |
25985edc | 583 | * @function: hrtimer callback function which gets called from softirq context |
9ba5f005 PZ |
584 | * @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME) |
585 | * @mode: hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL) | |
586 | */ | |
587 | void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer, | |
588 | enum hrtimer_restart (*function)(struct hrtimer *), | |
589 | clockid_t which_clock, enum hrtimer_mode mode) | |
590 | { | |
591 | hrtimer_init(&ttimer->timer, which_clock, mode); | |
592 | ttimer->timer.function = __hrtimer_tasklet_trampoline; | |
593 | tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline, | |
594 | (unsigned long)ttimer); | |
595 | ttimer->function = function; | |
596 | } | |
597 | EXPORT_SYMBOL_GPL(tasklet_hrtimer_init); | |
598 | ||
599 | /* | |
600 | * Remote softirq bits | |
601 | */ | |
602 | ||
54514a70 DM |
603 | DEFINE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list); |
604 | EXPORT_PER_CPU_SYMBOL(softirq_work_list); | |
605 | ||
606 | static void __local_trigger(struct call_single_data *cp, int softirq) | |
607 | { | |
608 | struct list_head *head = &__get_cpu_var(softirq_work_list[softirq]); | |
609 | ||
610 | list_add_tail(&cp->list, head); | |
611 | ||
612 | /* Trigger the softirq only if the list was previously empty. */ | |
613 | if (head->next == &cp->list) | |
614 | raise_softirq_irqoff(softirq); | |
615 | } | |
616 | ||
617 | #ifdef CONFIG_USE_GENERIC_SMP_HELPERS | |
618 | static void remote_softirq_receive(void *data) | |
619 | { | |
620 | struct call_single_data *cp = data; | |
621 | unsigned long flags; | |
622 | int softirq; | |
623 | ||
624 | softirq = cp->priv; | |
625 | ||
626 | local_irq_save(flags); | |
627 | __local_trigger(cp, softirq); | |
628 | local_irq_restore(flags); | |
629 | } | |
630 | ||
631 | static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) | |
632 | { | |
633 | if (cpu_online(cpu)) { | |
634 | cp->func = remote_softirq_receive; | |
635 | cp->info = cp; | |
636 | cp->flags = 0; | |
637 | cp->priv = softirq; | |
638 | ||
6e275637 | 639 | __smp_call_function_single(cpu, cp, 0); |
54514a70 DM |
640 | return 0; |
641 | } | |
642 | return 1; | |
643 | } | |
644 | #else /* CONFIG_USE_GENERIC_SMP_HELPERS */ | |
645 | static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) | |
646 | { | |
647 | return 1; | |
648 | } | |
649 | #endif | |
650 | ||
651 | /** | |
652 | * __send_remote_softirq - try to schedule softirq work on a remote cpu | |
653 | * @cp: private SMP call function data area | |
654 | * @cpu: the remote cpu | |
655 | * @this_cpu: the currently executing cpu | |
656 | * @softirq: the softirq for the work | |
657 | * | |
658 | * Attempt to schedule softirq work on a remote cpu. If this cannot be | |
659 | * done, the work is instead queued up on the local cpu. | |
660 | * | |
661 | * Interrupts must be disabled. | |
662 | */ | |
663 | void __send_remote_softirq(struct call_single_data *cp, int cpu, int this_cpu, int softirq) | |
664 | { | |
665 | if (cpu == this_cpu || __try_remote_softirq(cp, cpu, softirq)) | |
666 | __local_trigger(cp, softirq); | |
667 | } | |
668 | EXPORT_SYMBOL(__send_remote_softirq); | |
669 | ||
670 | /** | |
671 | * send_remote_softirq - try to schedule softirq work on a remote cpu | |
672 | * @cp: private SMP call function data area | |
673 | * @cpu: the remote cpu | |
674 | * @softirq: the softirq for the work | |
675 | * | |
676 | * Like __send_remote_softirq except that disabling interrupts and | |
677 | * computing the current cpu is done for the caller. | |
678 | */ | |
679 | void send_remote_softirq(struct call_single_data *cp, int cpu, int softirq) | |
680 | { | |
681 | unsigned long flags; | |
682 | int this_cpu; | |
683 | ||
684 | local_irq_save(flags); | |
685 | this_cpu = smp_processor_id(); | |
686 | __send_remote_softirq(cp, cpu, this_cpu, softirq); | |
687 | local_irq_restore(flags); | |
688 | } | |
689 | EXPORT_SYMBOL(send_remote_softirq); | |
690 | ||
691 | static int __cpuinit remote_softirq_cpu_notify(struct notifier_block *self, | |
692 | unsigned long action, void *hcpu) | |
693 | { | |
694 | /* | |
695 | * If a CPU goes away, splice its entries to the current CPU | |
696 | * and trigger a run of the softirq | |
697 | */ | |
698 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { | |
699 | int cpu = (unsigned long) hcpu; | |
700 | int i; | |
701 | ||
702 | local_irq_disable(); | |
703 | for (i = 0; i < NR_SOFTIRQS; i++) { | |
704 | struct list_head *head = &per_cpu(softirq_work_list[i], cpu); | |
705 | struct list_head *local_head; | |
706 | ||
707 | if (list_empty(head)) | |
708 | continue; | |
709 | ||
710 | local_head = &__get_cpu_var(softirq_work_list[i]); | |
711 | list_splice_init(head, local_head); | |
712 | raise_softirq_irqoff(i); | |
713 | } | |
714 | local_irq_enable(); | |
715 | } | |
716 | ||
717 | return NOTIFY_OK; | |
718 | } | |
719 | ||
720 | static struct notifier_block __cpuinitdata remote_softirq_cpu_notifier = { | |
721 | .notifier_call = remote_softirq_cpu_notify, | |
722 | }; | |
723 | ||
1da177e4 LT |
724 | void __init softirq_init(void) |
725 | { | |
48f20a9a OJ |
726 | int cpu; |
727 | ||
728 | for_each_possible_cpu(cpu) { | |
54514a70 DM |
729 | int i; |
730 | ||
48f20a9a OJ |
731 | per_cpu(tasklet_vec, cpu).tail = |
732 | &per_cpu(tasklet_vec, cpu).head; | |
733 | per_cpu(tasklet_hi_vec, cpu).tail = | |
734 | &per_cpu(tasklet_hi_vec, cpu).head; | |
54514a70 DM |
735 | for (i = 0; i < NR_SOFTIRQS; i++) |
736 | INIT_LIST_HEAD(&per_cpu(softirq_work_list[i], cpu)); | |
48f20a9a OJ |
737 | } |
738 | ||
54514a70 DM |
739 | register_hotcpu_notifier(&remote_softirq_cpu_notifier); |
740 | ||
962cf36c CM |
741 | open_softirq(TASKLET_SOFTIRQ, tasklet_action); |
742 | open_softirq(HI_SOFTIRQ, tasklet_hi_action); | |
1da177e4 LT |
743 | } |
744 | ||
1871e52c | 745 | static int run_ksoftirqd(void * __bind_cpu) |
1da177e4 | 746 | { |
1da177e4 LT |
747 | set_current_state(TASK_INTERRUPTIBLE); |
748 | ||
749 | while (!kthread_should_stop()) { | |
750 | preempt_disable(); | |
751 | if (!local_softirq_pending()) { | |
bd2f5536 | 752 | schedule_preempt_disabled(); |
1da177e4 LT |
753 | } |
754 | ||
755 | __set_current_state(TASK_RUNNING); | |
756 | ||
757 | while (local_softirq_pending()) { | |
758 | /* Preempt disable stops cpu going offline. | |
759 | If already offline, we'll be on wrong CPU: | |
760 | don't process */ | |
761 | if (cpu_is_offline((long)__bind_cpu)) | |
762 | goto wait_to_die; | |
c305d524 TG |
763 | local_irq_disable(); |
764 | if (local_softirq_pending()) | |
765 | __do_softirq(); | |
766 | local_irq_enable(); | |
ba74c144 | 767 | sched_preempt_enable_no_resched(); |
1da177e4 LT |
768 | cond_resched(); |
769 | preempt_disable(); | |
25502a6c | 770 | rcu_note_context_switch((long)__bind_cpu); |
1da177e4 LT |
771 | } |
772 | preempt_enable(); | |
773 | set_current_state(TASK_INTERRUPTIBLE); | |
774 | } | |
775 | __set_current_state(TASK_RUNNING); | |
776 | return 0; | |
777 | ||
778 | wait_to_die: | |
779 | preempt_enable(); | |
780 | /* Wait for kthread_stop */ | |
781 | set_current_state(TASK_INTERRUPTIBLE); | |
782 | while (!kthread_should_stop()) { | |
783 | schedule(); | |
784 | set_current_state(TASK_INTERRUPTIBLE); | |
785 | } | |
786 | __set_current_state(TASK_RUNNING); | |
787 | return 0; | |
788 | } | |
789 | ||
790 | #ifdef CONFIG_HOTPLUG_CPU | |
791 | /* | |
792 | * tasklet_kill_immediate is called to remove a tasklet which can already be | |
793 | * scheduled for execution on @cpu. | |
794 | * | |
795 | * Unlike tasklet_kill, this function removes the tasklet | |
796 | * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state. | |
797 | * | |
798 | * When this function is called, @cpu must be in the CPU_DEAD state. | |
799 | */ | |
800 | void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu) | |
801 | { | |
802 | struct tasklet_struct **i; | |
803 | ||
804 | BUG_ON(cpu_online(cpu)); | |
805 | BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state)); | |
806 | ||
807 | if (!test_bit(TASKLET_STATE_SCHED, &t->state)) | |
808 | return; | |
809 | ||
810 | /* CPU is dead, so no lock needed. */ | |
48f20a9a | 811 | for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) { |
1da177e4 LT |
812 | if (*i == t) { |
813 | *i = t->next; | |
48f20a9a OJ |
814 | /* If this was the tail element, move the tail ptr */ |
815 | if (*i == NULL) | |
816 | per_cpu(tasklet_vec, cpu).tail = i; | |
1da177e4 LT |
817 | return; |
818 | } | |
819 | } | |
820 | BUG(); | |
821 | } | |
822 | ||
823 | static void takeover_tasklets(unsigned int cpu) | |
824 | { | |
1da177e4 LT |
825 | /* CPU is dead, so no lock needed. */ |
826 | local_irq_disable(); | |
827 | ||
828 | /* Find end, append list for that CPU. */ | |
e5e41723 | 829 | if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) { |
909ea964 CL |
830 | *__this_cpu_read(tasklet_vec.tail) = per_cpu(tasklet_vec, cpu).head; |
831 | this_cpu_write(tasklet_vec.tail, per_cpu(tasklet_vec, cpu).tail); | |
e5e41723 CB |
832 | per_cpu(tasklet_vec, cpu).head = NULL; |
833 | per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; | |
834 | } | |
1da177e4 LT |
835 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
836 | ||
e5e41723 | 837 | if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) { |
909ea964 CL |
838 | *__this_cpu_read(tasklet_hi_vec.tail) = per_cpu(tasklet_hi_vec, cpu).head; |
839 | __this_cpu_write(tasklet_hi_vec.tail, per_cpu(tasklet_hi_vec, cpu).tail); | |
e5e41723 CB |
840 | per_cpu(tasklet_hi_vec, cpu).head = NULL; |
841 | per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; | |
842 | } | |
1da177e4 LT |
843 | raise_softirq_irqoff(HI_SOFTIRQ); |
844 | ||
845 | local_irq_enable(); | |
846 | } | |
847 | #endif /* CONFIG_HOTPLUG_CPU */ | |
848 | ||
8c78f307 | 849 | static int __cpuinit cpu_callback(struct notifier_block *nfb, |
1da177e4 LT |
850 | unsigned long action, |
851 | void *hcpu) | |
852 | { | |
853 | int hotcpu = (unsigned long)hcpu; | |
854 | struct task_struct *p; | |
855 | ||
856 | switch (action) { | |
857 | case CPU_UP_PREPARE: | |
8bb78442 | 858 | case CPU_UP_PREPARE_FROZEN: |
94dcf29a ED |
859 | p = kthread_create_on_node(run_ksoftirqd, |
860 | hcpu, | |
861 | cpu_to_node(hotcpu), | |
862 | "ksoftirqd/%d", hotcpu); | |
1da177e4 LT |
863 | if (IS_ERR(p)) { |
864 | printk("ksoftirqd for %i failed\n", hotcpu); | |
80b5184c | 865 | return notifier_from_errno(PTR_ERR(p)); |
1da177e4 LT |
866 | } |
867 | kthread_bind(p, hotcpu); | |
868 | per_cpu(ksoftirqd, hotcpu) = p; | |
869 | break; | |
870 | case CPU_ONLINE: | |
8bb78442 | 871 | case CPU_ONLINE_FROZEN: |
1da177e4 LT |
872 | wake_up_process(per_cpu(ksoftirqd, hotcpu)); |
873 | break; | |
874 | #ifdef CONFIG_HOTPLUG_CPU | |
875 | case CPU_UP_CANCELED: | |
8bb78442 | 876 | case CPU_UP_CANCELED_FROZEN: |
fc75cdfa HC |
877 | if (!per_cpu(ksoftirqd, hotcpu)) |
878 | break; | |
1da177e4 | 879 | /* Unbind so it can run. Fall thru. */ |
a4c4af7c | 880 | kthread_bind(per_cpu(ksoftirqd, hotcpu), |
f1fc057c | 881 | cpumask_any(cpu_online_mask)); |
1da177e4 | 882 | case CPU_DEAD: |
1c6b4aa9 | 883 | case CPU_DEAD_FROZEN: { |
c9b5f501 | 884 | static const struct sched_param param = { |
fe7de49f KM |
885 | .sched_priority = MAX_RT_PRIO-1 |
886 | }; | |
1c6b4aa9 | 887 | |
1da177e4 LT |
888 | p = per_cpu(ksoftirqd, hotcpu); |
889 | per_cpu(ksoftirqd, hotcpu) = NULL; | |
961ccddd | 890 | sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m); |
1da177e4 LT |
891 | kthread_stop(p); |
892 | takeover_tasklets(hotcpu); | |
893 | break; | |
1c6b4aa9 | 894 | } |
1da177e4 LT |
895 | #endif /* CONFIG_HOTPLUG_CPU */ |
896 | } | |
897 | return NOTIFY_OK; | |
898 | } | |
899 | ||
8c78f307 | 900 | static struct notifier_block __cpuinitdata cpu_nfb = { |
1da177e4 LT |
901 | .notifier_call = cpu_callback |
902 | }; | |
903 | ||
7babe8db | 904 | static __init int spawn_ksoftirqd(void) |
1da177e4 LT |
905 | { |
906 | void *cpu = (void *)(long)smp_processor_id(); | |
07dccf33 AM |
907 | int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu); |
908 | ||
9e506f7a | 909 | BUG_ON(err != NOTIFY_OK); |
1da177e4 LT |
910 | cpu_callback(&cpu_nfb, CPU_ONLINE, cpu); |
911 | register_cpu_notifier(&cpu_nfb); | |
912 | return 0; | |
913 | } | |
7babe8db | 914 | early_initcall(spawn_ksoftirqd); |
78eef01b | 915 | |
43a25632 YL |
916 | /* |
917 | * [ These __weak aliases are kept in a separate compilation unit, so that | |
918 | * GCC does not inline them incorrectly. ] | |
919 | */ | |
920 | ||
921 | int __init __weak early_irq_init(void) | |
922 | { | |
923 | return 0; | |
924 | } | |
925 | ||
b683de2b | 926 | #ifdef CONFIG_GENERIC_HARDIRQS |
4a046d17 YL |
927 | int __init __weak arch_probe_nr_irqs(void) |
928 | { | |
b683de2b | 929 | return NR_IRQS_LEGACY; |
4a046d17 YL |
930 | } |
931 | ||
43a25632 YL |
932 | int __init __weak arch_early_irq_init(void) |
933 | { | |
934 | return 0; | |
935 | } | |
b683de2b | 936 | #endif |