Commit | Line | Data |
---|---|---|
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> |
3e339b5d | 26 | #include <linux/smpboot.h> |
79bf2bb3 | 27 | #include <linux/tick.h> |
a0e39ed3 HC |
28 | |
29 | #define CREATE_TRACE_POINTS | |
ad8d75ff | 30 | #include <trace/events/irq.h> |
1da177e4 LT |
31 | |
32 | #include <asm/irq.h> | |
33 | /* | |
34 | - No shared variables, all the data are CPU local. | |
35 | - If a softirq needs serialization, let it serialize itself | |
36 | by its own spinlocks. | |
37 | - Even if softirq is serialized, only local cpu is marked for | |
38 | execution. Hence, we get something sort of weak cpu binding. | |
39 | Though it is still not clear, will it result in better locality | |
40 | or will not. | |
41 | ||
42 | Examples: | |
43 | - NET RX softirq. It is multithreaded and does not require | |
44 | any global serialization. | |
45 | - NET TX softirq. It kicks software netdevice queues, hence | |
46 | it is logically serialized per device, but this serialization | |
47 | is invisible to common code. | |
48 | - Tasklets: serialized wrt itself. | |
49 | */ | |
50 | ||
51 | #ifndef __ARCH_IRQ_STAT | |
52 | irq_cpustat_t irq_stat[NR_CPUS] ____cacheline_aligned; | |
53 | EXPORT_SYMBOL(irq_stat); | |
54 | #endif | |
55 | ||
978b0116 | 56 | static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp; |
1da177e4 | 57 | |
4dd53d89 | 58 | DEFINE_PER_CPU(struct task_struct *, ksoftirqd); |
1da177e4 | 59 | |
5d592b44 | 60 | char *softirq_to_name[NR_SOFTIRQS] = { |
5dd4de58 | 61 | "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "BLOCK_IOPOLL", |
09223371 | 62 | "TASKLET", "SCHED", "HRTIMER", "RCU" |
5d592b44 JB |
63 | }; |
64 | ||
1da177e4 LT |
65 | /* |
66 | * we cannot loop indefinitely here to avoid userspace starvation, | |
67 | * but we also don't want to introduce a worst case 1/HZ latency | |
68 | * to the pending events, so lets the scheduler to balance | |
69 | * the softirq load for us. | |
70 | */ | |
676cb02d | 71 | static void wakeup_softirqd(void) |
1da177e4 LT |
72 | { |
73 | /* Interrupts are disabled: no need to stop preemption */ | |
909ea964 | 74 | struct task_struct *tsk = __this_cpu_read(ksoftirqd); |
1da177e4 LT |
75 | |
76 | if (tsk && tsk->state != TASK_RUNNING) | |
77 | wake_up_process(tsk); | |
78 | } | |
79 | ||
75e1056f VP |
80 | /* |
81 | * preempt_count and SOFTIRQ_OFFSET usage: | |
82 | * - preempt_count is changed by SOFTIRQ_OFFSET on entering or leaving | |
83 | * softirq processing. | |
84 | * - preempt_count is changed by SOFTIRQ_DISABLE_OFFSET (= 2 * SOFTIRQ_OFFSET) | |
85 | * on local_bh_disable or local_bh_enable. | |
86 | * This lets us distinguish between whether we are currently processing | |
87 | * softirq and whether we just have bh disabled. | |
88 | */ | |
89 | ||
de30a2b3 IM |
90 | /* |
91 | * This one is for softirq.c-internal use, | |
92 | * where hardirqs are disabled legitimately: | |
93 | */ | |
3c829c36 | 94 | #ifdef CONFIG_TRACE_IRQFLAGS |
75e1056f | 95 | static void __local_bh_disable(unsigned long ip, unsigned int cnt) |
de30a2b3 IM |
96 | { |
97 | unsigned long flags; | |
98 | ||
99 | WARN_ON_ONCE(in_irq()); | |
100 | ||
101 | raw_local_irq_save(flags); | |
7e49fcce SR |
102 | /* |
103 | * The preempt tracer hooks into add_preempt_count and will break | |
104 | * lockdep because it calls back into lockdep after SOFTIRQ_OFFSET | |
105 | * is set and before current->softirq_enabled is cleared. | |
106 | * We must manually increment preempt_count here and manually | |
107 | * call the trace_preempt_off later. | |
108 | */ | |
75e1056f | 109 | preempt_count() += cnt; |
de30a2b3 IM |
110 | /* |
111 | * Were softirqs turned off above: | |
112 | */ | |
75e1056f | 113 | if (softirq_count() == cnt) |
de30a2b3 IM |
114 | trace_softirqs_off(ip); |
115 | raw_local_irq_restore(flags); | |
7e49fcce | 116 | |
75e1056f | 117 | if (preempt_count() == cnt) |
7e49fcce | 118 | trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); |
de30a2b3 | 119 | } |
3c829c36 | 120 | #else /* !CONFIG_TRACE_IRQFLAGS */ |
75e1056f | 121 | static inline void __local_bh_disable(unsigned long ip, unsigned int cnt) |
3c829c36 | 122 | { |
75e1056f | 123 | add_preempt_count(cnt); |
3c829c36 TC |
124 | barrier(); |
125 | } | |
126 | #endif /* CONFIG_TRACE_IRQFLAGS */ | |
de30a2b3 IM |
127 | |
128 | void local_bh_disable(void) | |
129 | { | |
75e1056f VP |
130 | __local_bh_disable((unsigned long)__builtin_return_address(0), |
131 | SOFTIRQ_DISABLE_OFFSET); | |
de30a2b3 IM |
132 | } |
133 | ||
134 | EXPORT_SYMBOL(local_bh_disable); | |
135 | ||
75e1056f VP |
136 | static void __local_bh_enable(unsigned int cnt) |
137 | { | |
138 | WARN_ON_ONCE(in_irq()); | |
139 | WARN_ON_ONCE(!irqs_disabled()); | |
140 | ||
141 | if (softirq_count() == cnt) | |
142 | trace_softirqs_on((unsigned long)__builtin_return_address(0)); | |
143 | sub_preempt_count(cnt); | |
144 | } | |
145 | ||
de30a2b3 IM |
146 | /* |
147 | * Special-case - softirqs can safely be enabled in | |
148 | * cond_resched_softirq(), or by __do_softirq(), | |
149 | * without processing still-pending softirqs: | |
150 | */ | |
151 | void _local_bh_enable(void) | |
152 | { | |
75e1056f | 153 | __local_bh_enable(SOFTIRQ_DISABLE_OFFSET); |
de30a2b3 IM |
154 | } |
155 | ||
156 | EXPORT_SYMBOL(_local_bh_enable); | |
157 | ||
0f476b6d | 158 | static inline void _local_bh_enable_ip(unsigned long ip) |
de30a2b3 | 159 | { |
0f476b6d | 160 | WARN_ON_ONCE(in_irq() || irqs_disabled()); |
3c829c36 | 161 | #ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d | 162 | local_irq_disable(); |
3c829c36 | 163 | #endif |
de30a2b3 IM |
164 | /* |
165 | * Are softirqs going to be turned on now: | |
166 | */ | |
75e1056f | 167 | if (softirq_count() == SOFTIRQ_DISABLE_OFFSET) |
0f476b6d | 168 | trace_softirqs_on(ip); |
de30a2b3 IM |
169 | /* |
170 | * Keep preemption disabled until we are done with | |
171 | * softirq processing: | |
172 | */ | |
75e1056f | 173 | sub_preempt_count(SOFTIRQ_DISABLE_OFFSET - 1); |
de30a2b3 IM |
174 | |
175 | if (unlikely(!in_interrupt() && local_softirq_pending())) | |
176 | do_softirq(); | |
177 | ||
178 | dec_preempt_count(); | |
3c829c36 | 179 | #ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d | 180 | local_irq_enable(); |
3c829c36 | 181 | #endif |
de30a2b3 IM |
182 | preempt_check_resched(); |
183 | } | |
0f476b6d JB |
184 | |
185 | void local_bh_enable(void) | |
186 | { | |
187 | _local_bh_enable_ip((unsigned long)__builtin_return_address(0)); | |
188 | } | |
de30a2b3 IM |
189 | EXPORT_SYMBOL(local_bh_enable); |
190 | ||
191 | void local_bh_enable_ip(unsigned long ip) | |
192 | { | |
0f476b6d | 193 | _local_bh_enable_ip(ip); |
de30a2b3 IM |
194 | } |
195 | EXPORT_SYMBOL(local_bh_enable_ip); | |
196 | ||
1da177e4 LT |
197 | /* |
198 | * We restart softirq processing MAX_SOFTIRQ_RESTART times, | |
199 | * and we fall back to softirqd after that. | |
200 | * | |
201 | * This number has been established via experimentation. | |
202 | * The two things to balance is latency against fairness - | |
203 | * we want to handle softirqs as soon as possible, but they | |
204 | * should not be able to lock up the box. | |
205 | */ | |
206 | #define MAX_SOFTIRQ_RESTART 10 | |
207 | ||
208 | asmlinkage void __do_softirq(void) | |
209 | { | |
210 | struct softirq_action *h; | |
211 | __u32 pending; | |
212 | int max_restart = MAX_SOFTIRQ_RESTART; | |
213 | int cpu; | |
907aed48 MG |
214 | unsigned long old_flags = current->flags; |
215 | ||
216 | /* | |
217 | * Mask out PF_MEMALLOC s current task context is borrowed for the | |
218 | * softirq. A softirq handled such as network RX might set PF_MEMALLOC | |
219 | * again if the socket is related to swap | |
220 | */ | |
221 | current->flags &= ~PF_MEMALLOC; | |
1da177e4 LT |
222 | |
223 | pending = local_softirq_pending(); | |
bf9fae9f | 224 | vtime_account(current); |
829035fd | 225 | |
75e1056f VP |
226 | __local_bh_disable((unsigned long)__builtin_return_address(0), |
227 | SOFTIRQ_OFFSET); | |
d820ac4c | 228 | lockdep_softirq_enter(); |
1da177e4 | 229 | |
1da177e4 LT |
230 | cpu = smp_processor_id(); |
231 | restart: | |
232 | /* Reset the pending bitmask before enabling irqs */ | |
3f74478b | 233 | set_softirq_pending(0); |
1da177e4 | 234 | |
c70f5d66 | 235 | local_irq_enable(); |
1da177e4 LT |
236 | |
237 | h = softirq_vec; | |
238 | ||
239 | do { | |
240 | if (pending & 1) { | |
f4bc6bb2 | 241 | unsigned int vec_nr = h - softirq_vec; |
8e85b4b5 TG |
242 | int prev_count = preempt_count(); |
243 | ||
f4bc6bb2 TG |
244 | kstat_incr_softirqs_this_cpu(vec_nr); |
245 | ||
246 | trace_softirq_entry(vec_nr); | |
1da177e4 | 247 | h->action(h); |
f4bc6bb2 | 248 | trace_softirq_exit(vec_nr); |
8e85b4b5 | 249 | if (unlikely(prev_count != preempt_count())) { |
f4bc6bb2 | 250 | printk(KERN_ERR "huh, entered softirq %u %s %p" |
8e85b4b5 | 251 | "with preempt_count %08x," |
f4bc6bb2 TG |
252 | " exited with %08x?\n", vec_nr, |
253 | softirq_to_name[vec_nr], h->action, | |
254 | prev_count, preempt_count()); | |
8e85b4b5 TG |
255 | preempt_count() = prev_count; |
256 | } | |
257 | ||
d6714c22 | 258 | rcu_bh_qs(cpu); |
1da177e4 LT |
259 | } |
260 | h++; | |
261 | pending >>= 1; | |
262 | } while (pending); | |
263 | ||
c70f5d66 | 264 | local_irq_disable(); |
1da177e4 LT |
265 | |
266 | pending = local_softirq_pending(); | |
267 | if (pending && --max_restart) | |
268 | goto restart; | |
269 | ||
270 | if (pending) | |
271 | wakeup_softirqd(); | |
272 | ||
d820ac4c | 273 | lockdep_softirq_exit(); |
829035fd | 274 | |
bf9fae9f | 275 | vtime_account(current); |
75e1056f | 276 | __local_bh_enable(SOFTIRQ_OFFSET); |
907aed48 | 277 | tsk_restore_flags(current, old_flags, PF_MEMALLOC); |
1da177e4 LT |
278 | } |
279 | ||
280 | #ifndef __ARCH_HAS_DO_SOFTIRQ | |
281 | ||
282 | asmlinkage void do_softirq(void) | |
283 | { | |
284 | __u32 pending; | |
285 | unsigned long flags; | |
286 | ||
287 | if (in_interrupt()) | |
288 | return; | |
289 | ||
290 | local_irq_save(flags); | |
291 | ||
292 | pending = local_softirq_pending(); | |
293 | ||
294 | if (pending) | |
295 | __do_softirq(); | |
296 | ||
297 | local_irq_restore(flags); | |
298 | } | |
299 | ||
1da177e4 LT |
300 | #endif |
301 | ||
dde4b2b5 IM |
302 | /* |
303 | * Enter an interrupt context. | |
304 | */ | |
305 | void irq_enter(void) | |
306 | { | |
6378ddb5 | 307 | int cpu = smp_processor_id(); |
719254fa | 308 | |
64db4cff | 309 | rcu_irq_enter(); |
0a8a2e78 | 310 | if (is_idle_task(current) && !in_interrupt()) { |
d267f87f VP |
311 | /* |
312 | * Prevent raise_softirq from needlessly waking up ksoftirqd | |
313 | * here, as softirq will be serviced on return from interrupt. | |
314 | */ | |
315 | local_bh_disable(); | |
719254fa | 316 | tick_check_idle(cpu); |
d267f87f VP |
317 | _local_bh_enable(); |
318 | } | |
319 | ||
320 | __irq_enter(); | |
dde4b2b5 IM |
321 | } |
322 | ||
8d32a307 TG |
323 | static inline void invoke_softirq(void) |
324 | { | |
b2a00178 HC |
325 | if (!force_irqthreads) { |
326 | #ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED | |
8d32a307 | 327 | __do_softirq(); |
1da177e4 | 328 | #else |
8d32a307 | 329 | do_softirq(); |
b2a00178 HC |
330 | #endif |
331 | } else { | |
ec433f0c PZ |
332 | __local_bh_disable((unsigned long)__builtin_return_address(0), |
333 | SOFTIRQ_OFFSET); | |
8d32a307 | 334 | wakeup_softirqd(); |
ec433f0c PZ |
335 | __local_bh_enable(SOFTIRQ_OFFSET); |
336 | } | |
8d32a307 | 337 | } |
1da177e4 LT |
338 | |
339 | /* | |
340 | * Exit an interrupt context. Process softirqs if needed and possible: | |
341 | */ | |
342 | void irq_exit(void) | |
343 | { | |
bf9fae9f | 344 | vtime_account(current); |
de30a2b3 | 345 | trace_hardirq_exit(); |
1da177e4 LT |
346 | sub_preempt_count(IRQ_EXIT_OFFSET); |
347 | if (!in_interrupt() && local_softirq_pending()) | |
348 | invoke_softirq(); | |
79bf2bb3 TG |
349 | |
350 | #ifdef CONFIG_NO_HZ | |
351 | /* Make sure that timer wheel updates are propagated */ | |
64db4cff | 352 | if (idle_cpu(smp_processor_id()) && !in_interrupt() && !need_resched()) |
280f0677 | 353 | tick_nohz_irq_exit(); |
79bf2bb3 | 354 | #endif |
416eb33c | 355 | rcu_irq_exit(); |
ba74c144 | 356 | sched_preempt_enable_no_resched(); |
1da177e4 LT |
357 | } |
358 | ||
359 | /* | |
360 | * This function must run with irqs disabled! | |
361 | */ | |
7ad5b3a5 | 362 | inline void raise_softirq_irqoff(unsigned int nr) |
1da177e4 LT |
363 | { |
364 | __raise_softirq_irqoff(nr); | |
365 | ||
366 | /* | |
367 | * If we're in an interrupt or softirq, we're done | |
368 | * (this also catches softirq-disabled code). We will | |
369 | * actually run the softirq once we return from | |
370 | * the irq or softirq. | |
371 | * | |
372 | * Otherwise we wake up ksoftirqd to make sure we | |
373 | * schedule the softirq soon. | |
374 | */ | |
375 | if (!in_interrupt()) | |
376 | wakeup_softirqd(); | |
377 | } | |
378 | ||
7ad5b3a5 | 379 | void raise_softirq(unsigned int nr) |
1da177e4 LT |
380 | { |
381 | unsigned long flags; | |
382 | ||
383 | local_irq_save(flags); | |
384 | raise_softirq_irqoff(nr); | |
385 | local_irq_restore(flags); | |
386 | } | |
387 | ||
f069686e SR |
388 | void __raise_softirq_irqoff(unsigned int nr) |
389 | { | |
390 | trace_softirq_raise(nr); | |
391 | or_softirq_pending(1UL << nr); | |
392 | } | |
393 | ||
962cf36c | 394 | void open_softirq(int nr, void (*action)(struct softirq_action *)) |
1da177e4 | 395 | { |
1da177e4 LT |
396 | softirq_vec[nr].action = action; |
397 | } | |
398 | ||
9ba5f005 PZ |
399 | /* |
400 | * Tasklets | |
401 | */ | |
1da177e4 LT |
402 | struct tasklet_head |
403 | { | |
48f20a9a OJ |
404 | struct tasklet_struct *head; |
405 | struct tasklet_struct **tail; | |
1da177e4 LT |
406 | }; |
407 | ||
4620b49f VN |
408 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec); |
409 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec); | |
1da177e4 | 410 | |
7ad5b3a5 | 411 | void __tasklet_schedule(struct tasklet_struct *t) |
1da177e4 LT |
412 | { |
413 | unsigned long flags; | |
414 | ||
415 | local_irq_save(flags); | |
48f20a9a | 416 | t->next = NULL; |
909ea964 CL |
417 | *__this_cpu_read(tasklet_vec.tail) = t; |
418 | __this_cpu_write(tasklet_vec.tail, &(t->next)); | |
1da177e4 LT |
419 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
420 | local_irq_restore(flags); | |
421 | } | |
422 | ||
423 | EXPORT_SYMBOL(__tasklet_schedule); | |
424 | ||
7ad5b3a5 | 425 | void __tasklet_hi_schedule(struct tasklet_struct *t) |
1da177e4 LT |
426 | { |
427 | unsigned long flags; | |
428 | ||
429 | local_irq_save(flags); | |
48f20a9a | 430 | t->next = NULL; |
909ea964 CL |
431 | *__this_cpu_read(tasklet_hi_vec.tail) = t; |
432 | __this_cpu_write(tasklet_hi_vec.tail, &(t->next)); | |
1da177e4 LT |
433 | raise_softirq_irqoff(HI_SOFTIRQ); |
434 | local_irq_restore(flags); | |
435 | } | |
436 | ||
437 | EXPORT_SYMBOL(__tasklet_hi_schedule); | |
438 | ||
7c692cba VN |
439 | void __tasklet_hi_schedule_first(struct tasklet_struct *t) |
440 | { | |
441 | BUG_ON(!irqs_disabled()); | |
442 | ||
909ea964 CL |
443 | t->next = __this_cpu_read(tasklet_hi_vec.head); |
444 | __this_cpu_write(tasklet_hi_vec.head, t); | |
7c692cba VN |
445 | __raise_softirq_irqoff(HI_SOFTIRQ); |
446 | } | |
447 | ||
448 | EXPORT_SYMBOL(__tasklet_hi_schedule_first); | |
449 | ||
1da177e4 LT |
450 | static void tasklet_action(struct softirq_action *a) |
451 | { | |
452 | struct tasklet_struct *list; | |
453 | ||
454 | local_irq_disable(); | |
909ea964 CL |
455 | list = __this_cpu_read(tasklet_vec.head); |
456 | __this_cpu_write(tasklet_vec.head, NULL); | |
457 | __this_cpu_write(tasklet_vec.tail, &__get_cpu_var(tasklet_vec).head); | |
1da177e4 LT |
458 | local_irq_enable(); |
459 | ||
460 | while (list) { | |
461 | struct tasklet_struct *t = list; | |
462 | ||
463 | list = list->next; | |
464 | ||
465 | if (tasklet_trylock(t)) { | |
466 | if (!atomic_read(&t->count)) { | |
467 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
468 | BUG(); | |
469 | t->func(t->data); | |
470 | tasklet_unlock(t); | |
471 | continue; | |
472 | } | |
473 | tasklet_unlock(t); | |
474 | } | |
475 | ||
476 | local_irq_disable(); | |
48f20a9a | 477 | t->next = NULL; |
909ea964 CL |
478 | *__this_cpu_read(tasklet_vec.tail) = t; |
479 | __this_cpu_write(tasklet_vec.tail, &(t->next)); | |
1da177e4 LT |
480 | __raise_softirq_irqoff(TASKLET_SOFTIRQ); |
481 | local_irq_enable(); | |
482 | } | |
483 | } | |
484 | ||
485 | static void tasklet_hi_action(struct softirq_action *a) | |
486 | { | |
487 | struct tasklet_struct *list; | |
488 | ||
489 | local_irq_disable(); | |
909ea964 CL |
490 | list = __this_cpu_read(tasklet_hi_vec.head); |
491 | __this_cpu_write(tasklet_hi_vec.head, NULL); | |
492 | __this_cpu_write(tasklet_hi_vec.tail, &__get_cpu_var(tasklet_hi_vec).head); | |
1da177e4 LT |
493 | local_irq_enable(); |
494 | ||
495 | while (list) { | |
496 | struct tasklet_struct *t = list; | |
497 | ||
498 | list = list->next; | |
499 | ||
500 | if (tasklet_trylock(t)) { | |
501 | if (!atomic_read(&t->count)) { | |
502 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
503 | BUG(); | |
504 | t->func(t->data); | |
505 | tasklet_unlock(t); | |
506 | continue; | |
507 | } | |
508 | tasklet_unlock(t); | |
509 | } | |
510 | ||
511 | local_irq_disable(); | |
48f20a9a | 512 | t->next = NULL; |
909ea964 CL |
513 | *__this_cpu_read(tasklet_hi_vec.tail) = t; |
514 | __this_cpu_write(tasklet_hi_vec.tail, &(t->next)); | |
1da177e4 LT |
515 | __raise_softirq_irqoff(HI_SOFTIRQ); |
516 | local_irq_enable(); | |
517 | } | |
518 | } | |
519 | ||
520 | ||
521 | void tasklet_init(struct tasklet_struct *t, | |
522 | void (*func)(unsigned long), unsigned long data) | |
523 | { | |
524 | t->next = NULL; | |
525 | t->state = 0; | |
526 | atomic_set(&t->count, 0); | |
527 | t->func = func; | |
528 | t->data = data; | |
529 | } | |
530 | ||
531 | EXPORT_SYMBOL(tasklet_init); | |
532 | ||
533 | void tasklet_kill(struct tasklet_struct *t) | |
534 | { | |
535 | if (in_interrupt()) | |
536 | printk("Attempt to kill tasklet from interrupt\n"); | |
537 | ||
538 | while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { | |
79d381c9 | 539 | do { |
1da177e4 | 540 | yield(); |
79d381c9 | 541 | } while (test_bit(TASKLET_STATE_SCHED, &t->state)); |
1da177e4 LT |
542 | } |
543 | tasklet_unlock_wait(t); | |
544 | clear_bit(TASKLET_STATE_SCHED, &t->state); | |
545 | } | |
546 | ||
547 | EXPORT_SYMBOL(tasklet_kill); | |
548 | ||
9ba5f005 PZ |
549 | /* |
550 | * tasklet_hrtimer | |
551 | */ | |
552 | ||
553 | /* | |
b9c30322 PZ |
554 | * The trampoline is called when the hrtimer expires. It schedules a tasklet |
555 | * to run __tasklet_hrtimer_trampoline() which in turn will call the intended | |
556 | * hrtimer callback, but from softirq context. | |
9ba5f005 PZ |
557 | */ |
558 | static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer) | |
559 | { | |
560 | struct tasklet_hrtimer *ttimer = | |
561 | container_of(timer, struct tasklet_hrtimer, timer); | |
562 | ||
b9c30322 PZ |
563 | tasklet_hi_schedule(&ttimer->tasklet); |
564 | return HRTIMER_NORESTART; | |
9ba5f005 PZ |
565 | } |
566 | ||
567 | /* | |
568 | * Helper function which calls the hrtimer callback from | |
569 | * tasklet/softirq context | |
570 | */ | |
571 | static void __tasklet_hrtimer_trampoline(unsigned long data) | |
572 | { | |
573 | struct tasklet_hrtimer *ttimer = (void *)data; | |
574 | enum hrtimer_restart restart; | |
575 | ||
576 | restart = ttimer->function(&ttimer->timer); | |
577 | if (restart != HRTIMER_NORESTART) | |
578 | hrtimer_restart(&ttimer->timer); | |
579 | } | |
580 | ||
581 | /** | |
582 | * tasklet_hrtimer_init - Init a tasklet/hrtimer combo for softirq callbacks | |
583 | * @ttimer: tasklet_hrtimer which is initialized | |
25985edc | 584 | * @function: hrtimer callback function which gets called from softirq context |
9ba5f005 PZ |
585 | * @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME) |
586 | * @mode: hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL) | |
587 | */ | |
588 | void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer, | |
589 | enum hrtimer_restart (*function)(struct hrtimer *), | |
590 | clockid_t which_clock, enum hrtimer_mode mode) | |
591 | { | |
592 | hrtimer_init(&ttimer->timer, which_clock, mode); | |
593 | ttimer->timer.function = __hrtimer_tasklet_trampoline; | |
594 | tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline, | |
595 | (unsigned long)ttimer); | |
596 | ttimer->function = function; | |
597 | } | |
598 | EXPORT_SYMBOL_GPL(tasklet_hrtimer_init); | |
599 | ||
600 | /* | |
601 | * Remote softirq bits | |
602 | */ | |
603 | ||
54514a70 DM |
604 | DEFINE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list); |
605 | EXPORT_PER_CPU_SYMBOL(softirq_work_list); | |
606 | ||
607 | static void __local_trigger(struct call_single_data *cp, int softirq) | |
608 | { | |
609 | struct list_head *head = &__get_cpu_var(softirq_work_list[softirq]); | |
610 | ||
611 | list_add_tail(&cp->list, head); | |
612 | ||
613 | /* Trigger the softirq only if the list was previously empty. */ | |
614 | if (head->next == &cp->list) | |
615 | raise_softirq_irqoff(softirq); | |
616 | } | |
617 | ||
618 | #ifdef CONFIG_USE_GENERIC_SMP_HELPERS | |
619 | static void remote_softirq_receive(void *data) | |
620 | { | |
621 | struct call_single_data *cp = data; | |
622 | unsigned long flags; | |
623 | int softirq; | |
624 | ||
625 | softirq = cp->priv; | |
626 | ||
627 | local_irq_save(flags); | |
628 | __local_trigger(cp, softirq); | |
629 | local_irq_restore(flags); | |
630 | } | |
631 | ||
632 | static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) | |
633 | { | |
634 | if (cpu_online(cpu)) { | |
635 | cp->func = remote_softirq_receive; | |
636 | cp->info = cp; | |
637 | cp->flags = 0; | |
638 | cp->priv = softirq; | |
639 | ||
6e275637 | 640 | __smp_call_function_single(cpu, cp, 0); |
54514a70 DM |
641 | return 0; |
642 | } | |
643 | return 1; | |
644 | } | |
645 | #else /* CONFIG_USE_GENERIC_SMP_HELPERS */ | |
646 | static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) | |
647 | { | |
648 | return 1; | |
649 | } | |
650 | #endif | |
651 | ||
652 | /** | |
653 | * __send_remote_softirq - try to schedule softirq work on a remote cpu | |
654 | * @cp: private SMP call function data area | |
655 | * @cpu: the remote cpu | |
656 | * @this_cpu: the currently executing cpu | |
657 | * @softirq: the softirq for the work | |
658 | * | |
659 | * Attempt to schedule softirq work on a remote cpu. If this cannot be | |
660 | * done, the work is instead queued up on the local cpu. | |
661 | * | |
662 | * Interrupts must be disabled. | |
663 | */ | |
664 | void __send_remote_softirq(struct call_single_data *cp, int cpu, int this_cpu, int softirq) | |
665 | { | |
666 | if (cpu == this_cpu || __try_remote_softirq(cp, cpu, softirq)) | |
667 | __local_trigger(cp, softirq); | |
668 | } | |
669 | EXPORT_SYMBOL(__send_remote_softirq); | |
670 | ||
671 | /** | |
672 | * send_remote_softirq - try to schedule softirq work on a remote cpu | |
673 | * @cp: private SMP call function data area | |
674 | * @cpu: the remote cpu | |
675 | * @softirq: the softirq for the work | |
676 | * | |
677 | * Like __send_remote_softirq except that disabling interrupts and | |
678 | * computing the current cpu is done for the caller. | |
679 | */ | |
680 | void send_remote_softirq(struct call_single_data *cp, int cpu, int softirq) | |
681 | { | |
682 | unsigned long flags; | |
683 | int this_cpu; | |
684 | ||
685 | local_irq_save(flags); | |
686 | this_cpu = smp_processor_id(); | |
687 | __send_remote_softirq(cp, cpu, this_cpu, softirq); | |
688 | local_irq_restore(flags); | |
689 | } | |
690 | EXPORT_SYMBOL(send_remote_softirq); | |
691 | ||
692 | static int __cpuinit remote_softirq_cpu_notify(struct notifier_block *self, | |
693 | unsigned long action, void *hcpu) | |
694 | { | |
695 | /* | |
696 | * If a CPU goes away, splice its entries to the current CPU | |
697 | * and trigger a run of the softirq | |
698 | */ | |
699 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { | |
700 | int cpu = (unsigned long) hcpu; | |
701 | int i; | |
702 | ||
703 | local_irq_disable(); | |
704 | for (i = 0; i < NR_SOFTIRQS; i++) { | |
705 | struct list_head *head = &per_cpu(softirq_work_list[i], cpu); | |
706 | struct list_head *local_head; | |
707 | ||
708 | if (list_empty(head)) | |
709 | continue; | |
710 | ||
711 | local_head = &__get_cpu_var(softirq_work_list[i]); | |
712 | list_splice_init(head, local_head); | |
713 | raise_softirq_irqoff(i); | |
714 | } | |
715 | local_irq_enable(); | |
716 | } | |
717 | ||
718 | return NOTIFY_OK; | |
719 | } | |
720 | ||
721 | static struct notifier_block __cpuinitdata remote_softirq_cpu_notifier = { | |
722 | .notifier_call = remote_softirq_cpu_notify, | |
723 | }; | |
724 | ||
1da177e4 LT |
725 | void __init softirq_init(void) |
726 | { | |
48f20a9a OJ |
727 | int cpu; |
728 | ||
729 | for_each_possible_cpu(cpu) { | |
54514a70 DM |
730 | int i; |
731 | ||
48f20a9a OJ |
732 | per_cpu(tasklet_vec, cpu).tail = |
733 | &per_cpu(tasklet_vec, cpu).head; | |
734 | per_cpu(tasklet_hi_vec, cpu).tail = | |
735 | &per_cpu(tasklet_hi_vec, cpu).head; | |
54514a70 DM |
736 | for (i = 0; i < NR_SOFTIRQS; i++) |
737 | INIT_LIST_HEAD(&per_cpu(softirq_work_list[i], cpu)); | |
48f20a9a OJ |
738 | } |
739 | ||
54514a70 DM |
740 | register_hotcpu_notifier(&remote_softirq_cpu_notifier); |
741 | ||
962cf36c CM |
742 | open_softirq(TASKLET_SOFTIRQ, tasklet_action); |
743 | open_softirq(HI_SOFTIRQ, tasklet_hi_action); | |
1da177e4 LT |
744 | } |
745 | ||
3e339b5d | 746 | static int ksoftirqd_should_run(unsigned int cpu) |
1da177e4 | 747 | { |
3e339b5d TG |
748 | return local_softirq_pending(); |
749 | } | |
1da177e4 | 750 | |
3e339b5d TG |
751 | static void run_ksoftirqd(unsigned int cpu) |
752 | { | |
753 | local_irq_disable(); | |
754 | if (local_softirq_pending()) { | |
755 | __do_softirq(); | |
756 | rcu_note_context_switch(cpu); | |
757 | local_irq_enable(); | |
758 | cond_resched(); | |
759 | return; | |
1da177e4 | 760 | } |
3e339b5d | 761 | local_irq_enable(); |
1da177e4 LT |
762 | } |
763 | ||
764 | #ifdef CONFIG_HOTPLUG_CPU | |
765 | /* | |
766 | * tasklet_kill_immediate is called to remove a tasklet which can already be | |
767 | * scheduled for execution on @cpu. | |
768 | * | |
769 | * Unlike tasklet_kill, this function removes the tasklet | |
770 | * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state. | |
771 | * | |
772 | * When this function is called, @cpu must be in the CPU_DEAD state. | |
773 | */ | |
774 | void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu) | |
775 | { | |
776 | struct tasklet_struct **i; | |
777 | ||
778 | BUG_ON(cpu_online(cpu)); | |
779 | BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state)); | |
780 | ||
781 | if (!test_bit(TASKLET_STATE_SCHED, &t->state)) | |
782 | return; | |
783 | ||
784 | /* CPU is dead, so no lock needed. */ | |
48f20a9a | 785 | for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) { |
1da177e4 LT |
786 | if (*i == t) { |
787 | *i = t->next; | |
48f20a9a OJ |
788 | /* If this was the tail element, move the tail ptr */ |
789 | if (*i == NULL) | |
790 | per_cpu(tasklet_vec, cpu).tail = i; | |
1da177e4 LT |
791 | return; |
792 | } | |
793 | } | |
794 | BUG(); | |
795 | } | |
796 | ||
797 | static void takeover_tasklets(unsigned int cpu) | |
798 | { | |
1da177e4 LT |
799 | /* CPU is dead, so no lock needed. */ |
800 | local_irq_disable(); | |
801 | ||
802 | /* Find end, append list for that CPU. */ | |
e5e41723 | 803 | if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) { |
909ea964 CL |
804 | *__this_cpu_read(tasklet_vec.tail) = per_cpu(tasklet_vec, cpu).head; |
805 | this_cpu_write(tasklet_vec.tail, per_cpu(tasklet_vec, cpu).tail); | |
e5e41723 CB |
806 | per_cpu(tasklet_vec, cpu).head = NULL; |
807 | per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; | |
808 | } | |
1da177e4 LT |
809 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
810 | ||
e5e41723 | 811 | if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) { |
909ea964 CL |
812 | *__this_cpu_read(tasklet_hi_vec.tail) = per_cpu(tasklet_hi_vec, cpu).head; |
813 | __this_cpu_write(tasklet_hi_vec.tail, per_cpu(tasklet_hi_vec, cpu).tail); | |
e5e41723 CB |
814 | per_cpu(tasklet_hi_vec, cpu).head = NULL; |
815 | per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; | |
816 | } | |
1da177e4 LT |
817 | raise_softirq_irqoff(HI_SOFTIRQ); |
818 | ||
819 | local_irq_enable(); | |
820 | } | |
821 | #endif /* CONFIG_HOTPLUG_CPU */ | |
822 | ||
8c78f307 | 823 | static int __cpuinit cpu_callback(struct notifier_block *nfb, |
1da177e4 LT |
824 | unsigned long action, |
825 | void *hcpu) | |
826 | { | |
1da177e4 | 827 | switch (action) { |
1da177e4 | 828 | #ifdef CONFIG_HOTPLUG_CPU |
1da177e4 | 829 | case CPU_DEAD: |
3e339b5d TG |
830 | case CPU_DEAD_FROZEN: |
831 | takeover_tasklets((unsigned long)hcpu); | |
1da177e4 LT |
832 | break; |
833 | #endif /* CONFIG_HOTPLUG_CPU */ | |
3e339b5d | 834 | } |
1da177e4 LT |
835 | return NOTIFY_OK; |
836 | } | |
837 | ||
8c78f307 | 838 | static struct notifier_block __cpuinitdata cpu_nfb = { |
1da177e4 LT |
839 | .notifier_call = cpu_callback |
840 | }; | |
841 | ||
3e339b5d TG |
842 | static struct smp_hotplug_thread softirq_threads = { |
843 | .store = &ksoftirqd, | |
844 | .thread_should_run = ksoftirqd_should_run, | |
845 | .thread_fn = run_ksoftirqd, | |
846 | .thread_comm = "ksoftirqd/%u", | |
847 | }; | |
848 | ||
7babe8db | 849 | static __init int spawn_ksoftirqd(void) |
1da177e4 | 850 | { |
1da177e4 | 851 | register_cpu_notifier(&cpu_nfb); |
3e339b5d TG |
852 | |
853 | BUG_ON(smpboot_register_percpu_thread(&softirq_threads)); | |
854 | ||
1da177e4 LT |
855 | return 0; |
856 | } | |
7babe8db | 857 | early_initcall(spawn_ksoftirqd); |
78eef01b | 858 | |
43a25632 YL |
859 | /* |
860 | * [ These __weak aliases are kept in a separate compilation unit, so that | |
861 | * GCC does not inline them incorrectly. ] | |
862 | */ | |
863 | ||
864 | int __init __weak early_irq_init(void) | |
865 | { | |
866 | return 0; | |
867 | } | |
868 | ||
b683de2b | 869 | #ifdef CONFIG_GENERIC_HARDIRQS |
4a046d17 YL |
870 | int __init __weak arch_probe_nr_irqs(void) |
871 | { | |
b683de2b | 872 | return NR_IRQS_LEGACY; |
4a046d17 YL |
873 | } |
874 | ||
43a25632 YL |
875 | int __init __weak arch_early_irq_init(void) |
876 | { | |
877 | return 0; | |
878 | } | |
b683de2b | 879 | #endif |