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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/kernel/softirq.c | |
3 | * | |
4 | * Copyright (C) 1992 Linus Torvalds | |
5 | * | |
b10db7f0 PM |
6 | * Distribute under GPLv2. |
7 | * | |
8 | * Rewritten. Old one was good in 2.2, but in 2.3 it was immoral. --ANK (990903) | |
54514a70 DM |
9 | * |
10 | * Remote softirq infrastructure is by Jens Axboe. | |
1da177e4 LT |
11 | */ |
12 | ||
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 | 31 | |
1da177e4 LT |
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 | { | |
d2e08473 | 129 | __local_bh_disable(_RET_IP_, SOFTIRQ_DISABLE_OFFSET); |
de30a2b3 IM |
130 | } |
131 | ||
132 | EXPORT_SYMBOL(local_bh_disable); | |
133 | ||
75e1056f VP |
134 | static void __local_bh_enable(unsigned int cnt) |
135 | { | |
75e1056f VP |
136 | WARN_ON_ONCE(!irqs_disabled()); |
137 | ||
138 | if (softirq_count() == cnt) | |
d2e08473 | 139 | trace_softirqs_on(_RET_IP_); |
75e1056f VP |
140 | sub_preempt_count(cnt); |
141 | } | |
142 | ||
de30a2b3 IM |
143 | /* |
144 | * Special-case - softirqs can safely be enabled in | |
145 | * cond_resched_softirq(), or by __do_softirq(), | |
146 | * without processing still-pending softirqs: | |
147 | */ | |
148 | void _local_bh_enable(void) | |
149 | { | |
5d60d3e7 | 150 | WARN_ON_ONCE(in_irq()); |
75e1056f | 151 | __local_bh_enable(SOFTIRQ_DISABLE_OFFSET); |
de30a2b3 IM |
152 | } |
153 | ||
154 | EXPORT_SYMBOL(_local_bh_enable); | |
155 | ||
0f476b6d | 156 | static inline void _local_bh_enable_ip(unsigned long ip) |
de30a2b3 | 157 | { |
0f476b6d | 158 | WARN_ON_ONCE(in_irq() || irqs_disabled()); |
3c829c36 | 159 | #ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d | 160 | local_irq_disable(); |
3c829c36 | 161 | #endif |
de30a2b3 IM |
162 | /* |
163 | * Are softirqs going to be turned on now: | |
164 | */ | |
75e1056f | 165 | if (softirq_count() == SOFTIRQ_DISABLE_OFFSET) |
0f476b6d | 166 | trace_softirqs_on(ip); |
de30a2b3 IM |
167 | /* |
168 | * Keep preemption disabled until we are done with | |
169 | * softirq processing: | |
170 | */ | |
75e1056f | 171 | sub_preempt_count(SOFTIRQ_DISABLE_OFFSET - 1); |
de30a2b3 | 172 | |
0bed698a FW |
173 | if (unlikely(!in_interrupt() && local_softirq_pending())) { |
174 | /* | |
175 | * Run softirq if any pending. And do it in its own stack | |
176 | * as we may be calling this deep in a task call stack already. | |
177 | */ | |
de30a2b3 | 178 | do_softirq(); |
0bed698a | 179 | } |
de30a2b3 IM |
180 | |
181 | dec_preempt_count(); | |
3c829c36 | 182 | #ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d | 183 | local_irq_enable(); |
3c829c36 | 184 | #endif |
de30a2b3 IM |
185 | preempt_check_resched(); |
186 | } | |
0f476b6d JB |
187 | |
188 | void local_bh_enable(void) | |
189 | { | |
d2e08473 | 190 | _local_bh_enable_ip(_RET_IP_); |
0f476b6d | 191 | } |
de30a2b3 IM |
192 | EXPORT_SYMBOL(local_bh_enable); |
193 | ||
194 | void local_bh_enable_ip(unsigned long ip) | |
195 | { | |
0f476b6d | 196 | _local_bh_enable_ip(ip); |
de30a2b3 IM |
197 | } |
198 | EXPORT_SYMBOL(local_bh_enable_ip); | |
199 | ||
1da177e4 | 200 | /* |
34376a50 BG |
201 | * We restart softirq processing for at most MAX_SOFTIRQ_RESTART times, |
202 | * but break the loop if need_resched() is set or after 2 ms. | |
203 | * The MAX_SOFTIRQ_TIME provides a nice upper bound in most cases, but in | |
204 | * certain cases, such as stop_machine(), jiffies may cease to | |
205 | * increment and so we need the MAX_SOFTIRQ_RESTART limit as | |
206 | * well to make sure we eventually return from this method. | |
1da177e4 | 207 | * |
c10d7367 | 208 | * These limits have been established via experimentation. |
1da177e4 LT |
209 | * The two things to balance is latency against fairness - |
210 | * we want to handle softirqs as soon as possible, but they | |
211 | * should not be able to lock up the box. | |
212 | */ | |
c10d7367 | 213 | #define MAX_SOFTIRQ_TIME msecs_to_jiffies(2) |
34376a50 | 214 | #define MAX_SOFTIRQ_RESTART 10 |
1da177e4 LT |
215 | |
216 | asmlinkage void __do_softirq(void) | |
217 | { | |
218 | struct softirq_action *h; | |
219 | __u32 pending; | |
c10d7367 | 220 | unsigned long end = jiffies + MAX_SOFTIRQ_TIME; |
1da177e4 | 221 | int cpu; |
907aed48 | 222 | unsigned long old_flags = current->flags; |
34376a50 | 223 | int max_restart = MAX_SOFTIRQ_RESTART; |
907aed48 MG |
224 | |
225 | /* | |
226 | * Mask out PF_MEMALLOC s current task context is borrowed for the | |
227 | * softirq. A softirq handled such as network RX might set PF_MEMALLOC | |
228 | * again if the socket is related to swap | |
229 | */ | |
230 | current->flags &= ~PF_MEMALLOC; | |
1da177e4 LT |
231 | |
232 | pending = local_softirq_pending(); | |
6a61671b | 233 | account_irq_enter_time(current); |
829035fd | 234 | |
d2e08473 | 235 | __local_bh_disable(_RET_IP_, SOFTIRQ_OFFSET); |
d820ac4c | 236 | lockdep_softirq_enter(); |
1da177e4 | 237 | |
1da177e4 LT |
238 | cpu = smp_processor_id(); |
239 | restart: | |
240 | /* Reset the pending bitmask before enabling irqs */ | |
3f74478b | 241 | set_softirq_pending(0); |
1da177e4 | 242 | |
c70f5d66 | 243 | local_irq_enable(); |
1da177e4 LT |
244 | |
245 | h = softirq_vec; | |
246 | ||
247 | do { | |
248 | if (pending & 1) { | |
f4bc6bb2 | 249 | unsigned int vec_nr = h - softirq_vec; |
8e85b4b5 TG |
250 | int prev_count = preempt_count(); |
251 | ||
f4bc6bb2 TG |
252 | kstat_incr_softirqs_this_cpu(vec_nr); |
253 | ||
254 | trace_softirq_entry(vec_nr); | |
1da177e4 | 255 | h->action(h); |
f4bc6bb2 | 256 | trace_softirq_exit(vec_nr); |
8e85b4b5 | 257 | if (unlikely(prev_count != preempt_count())) { |
f4bc6bb2 | 258 | printk(KERN_ERR "huh, entered softirq %u %s %p" |
8e85b4b5 | 259 | "with preempt_count %08x," |
f4bc6bb2 TG |
260 | " exited with %08x?\n", vec_nr, |
261 | softirq_to_name[vec_nr], h->action, | |
262 | prev_count, preempt_count()); | |
8e85b4b5 TG |
263 | preempt_count() = prev_count; |
264 | } | |
265 | ||
d6714c22 | 266 | rcu_bh_qs(cpu); |
1da177e4 LT |
267 | } |
268 | h++; | |
269 | pending >>= 1; | |
270 | } while (pending); | |
271 | ||
c70f5d66 | 272 | local_irq_disable(); |
1da177e4 LT |
273 | |
274 | pending = local_softirq_pending(); | |
c10d7367 | 275 | if (pending) { |
34376a50 BG |
276 | if (time_before(jiffies, end) && !need_resched() && |
277 | --max_restart) | |
c10d7367 | 278 | goto restart; |
1da177e4 | 279 | |
1da177e4 | 280 | wakeup_softirqd(); |
c10d7367 | 281 | } |
1da177e4 | 282 | |
d820ac4c | 283 | lockdep_softirq_exit(); |
829035fd | 284 | |
6a61671b | 285 | account_irq_exit_time(current); |
75e1056f | 286 | __local_bh_enable(SOFTIRQ_OFFSET); |
5d60d3e7 | 287 | WARN_ON_ONCE(in_interrupt()); |
907aed48 | 288 | tsk_restore_flags(current, old_flags, PF_MEMALLOC); |
1da177e4 LT |
289 | } |
290 | ||
7d65f4a6 | 291 | |
1da177e4 LT |
292 | |
293 | asmlinkage void do_softirq(void) | |
294 | { | |
295 | __u32 pending; | |
296 | unsigned long flags; | |
297 | ||
298 | if (in_interrupt()) | |
299 | return; | |
300 | ||
301 | local_irq_save(flags); | |
302 | ||
303 | pending = local_softirq_pending(); | |
304 | ||
305 | if (pending) | |
7d65f4a6 | 306 | do_softirq_own_stack(); |
1da177e4 LT |
307 | |
308 | local_irq_restore(flags); | |
309 | } | |
310 | ||
dde4b2b5 IM |
311 | /* |
312 | * Enter an interrupt context. | |
313 | */ | |
314 | void irq_enter(void) | |
315 | { | |
6378ddb5 | 316 | int cpu = smp_processor_id(); |
719254fa | 317 | |
64db4cff | 318 | rcu_irq_enter(); |
0a8a2e78 | 319 | if (is_idle_task(current) && !in_interrupt()) { |
d267f87f VP |
320 | /* |
321 | * Prevent raise_softirq from needlessly waking up ksoftirqd | |
322 | * here, as softirq will be serviced on return from interrupt. | |
323 | */ | |
324 | local_bh_disable(); | |
719254fa | 325 | tick_check_idle(cpu); |
d267f87f VP |
326 | _local_bh_enable(); |
327 | } | |
328 | ||
329 | __irq_enter(); | |
dde4b2b5 IM |
330 | } |
331 | ||
8d32a307 TG |
332 | static inline void invoke_softirq(void) |
333 | { | |
ded79754 | 334 | if (!force_irqthreads) { |
cc1f0274 | 335 | #ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK |
ded79754 FW |
336 | /* |
337 | * We can safely execute softirq on the current stack if | |
338 | * it is the irq stack, because it should be near empty | |
cc1f0274 FW |
339 | * at this stage. |
340 | */ | |
341 | __do_softirq(); | |
342 | #else | |
343 | /* | |
344 | * Otherwise, irq_exit() is called on the task stack that can | |
345 | * be potentially deep already. So call softirq in its own stack | |
346 | * to prevent from any overrun. | |
ded79754 | 347 | */ |
be6e1016 | 348 | do_softirq_own_stack(); |
cc1f0274 | 349 | #endif |
ded79754 | 350 | } else { |
8d32a307 | 351 | wakeup_softirqd(); |
ded79754 | 352 | } |
8d32a307 | 353 | } |
1da177e4 | 354 | |
67826eae FW |
355 | static inline void tick_irq_exit(void) |
356 | { | |
357 | #ifdef CONFIG_NO_HZ_COMMON | |
358 | int cpu = smp_processor_id(); | |
359 | ||
360 | /* Make sure that timer wheel updates are propagated */ | |
361 | if ((idle_cpu(cpu) && !need_resched()) || tick_nohz_full_cpu(cpu)) { | |
362 | if (!in_interrupt()) | |
363 | tick_nohz_irq_exit(); | |
364 | } | |
365 | #endif | |
366 | } | |
367 | ||
1da177e4 LT |
368 | /* |
369 | * Exit an interrupt context. Process softirqs if needed and possible: | |
370 | */ | |
371 | void irq_exit(void) | |
372 | { | |
74eed016 | 373 | #ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED |
4cd5d111 | 374 | local_irq_disable(); |
74eed016 TG |
375 | #else |
376 | WARN_ON_ONCE(!irqs_disabled()); | |
377 | #endif | |
378 | ||
6a61671b | 379 | account_irq_exit_time(current); |
de30a2b3 | 380 | trace_hardirq_exit(); |
4d4c4e24 | 381 | sub_preempt_count(HARDIRQ_OFFSET); |
1da177e4 LT |
382 | if (!in_interrupt() && local_softirq_pending()) |
383 | invoke_softirq(); | |
79bf2bb3 | 384 | |
67826eae | 385 | tick_irq_exit(); |
416eb33c | 386 | rcu_irq_exit(); |
1da177e4 LT |
387 | } |
388 | ||
389 | /* | |
390 | * This function must run with irqs disabled! | |
391 | */ | |
7ad5b3a5 | 392 | inline void raise_softirq_irqoff(unsigned int nr) |
1da177e4 LT |
393 | { |
394 | __raise_softirq_irqoff(nr); | |
395 | ||
396 | /* | |
397 | * If we're in an interrupt or softirq, we're done | |
398 | * (this also catches softirq-disabled code). We will | |
399 | * actually run the softirq once we return from | |
400 | * the irq or softirq. | |
401 | * | |
402 | * Otherwise we wake up ksoftirqd to make sure we | |
403 | * schedule the softirq soon. | |
404 | */ | |
405 | if (!in_interrupt()) | |
406 | wakeup_softirqd(); | |
407 | } | |
408 | ||
7ad5b3a5 | 409 | void raise_softirq(unsigned int nr) |
1da177e4 LT |
410 | { |
411 | unsigned long flags; | |
412 | ||
413 | local_irq_save(flags); | |
414 | raise_softirq_irqoff(nr); | |
415 | local_irq_restore(flags); | |
416 | } | |
417 | ||
f069686e SR |
418 | void __raise_softirq_irqoff(unsigned int nr) |
419 | { | |
420 | trace_softirq_raise(nr); | |
421 | or_softirq_pending(1UL << nr); | |
422 | } | |
423 | ||
962cf36c | 424 | void open_softirq(int nr, void (*action)(struct softirq_action *)) |
1da177e4 | 425 | { |
1da177e4 LT |
426 | softirq_vec[nr].action = action; |
427 | } | |
428 | ||
9ba5f005 PZ |
429 | /* |
430 | * Tasklets | |
431 | */ | |
1da177e4 LT |
432 | struct tasklet_head |
433 | { | |
48f20a9a OJ |
434 | struct tasklet_struct *head; |
435 | struct tasklet_struct **tail; | |
1da177e4 LT |
436 | }; |
437 | ||
4620b49f VN |
438 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec); |
439 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec); | |
1da177e4 | 440 | |
7ad5b3a5 | 441 | void __tasklet_schedule(struct tasklet_struct *t) |
1da177e4 LT |
442 | { |
443 | unsigned long flags; | |
444 | ||
445 | local_irq_save(flags); | |
48f20a9a | 446 | t->next = NULL; |
909ea964 CL |
447 | *__this_cpu_read(tasklet_vec.tail) = t; |
448 | __this_cpu_write(tasklet_vec.tail, &(t->next)); | |
1da177e4 LT |
449 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
450 | local_irq_restore(flags); | |
451 | } | |
452 | ||
453 | EXPORT_SYMBOL(__tasklet_schedule); | |
454 | ||
7ad5b3a5 | 455 | void __tasklet_hi_schedule(struct tasklet_struct *t) |
1da177e4 LT |
456 | { |
457 | unsigned long flags; | |
458 | ||
459 | local_irq_save(flags); | |
48f20a9a | 460 | t->next = NULL; |
909ea964 CL |
461 | *__this_cpu_read(tasklet_hi_vec.tail) = t; |
462 | __this_cpu_write(tasklet_hi_vec.tail, &(t->next)); | |
1da177e4 LT |
463 | raise_softirq_irqoff(HI_SOFTIRQ); |
464 | local_irq_restore(flags); | |
465 | } | |
466 | ||
467 | EXPORT_SYMBOL(__tasklet_hi_schedule); | |
468 | ||
7c692cba VN |
469 | void __tasklet_hi_schedule_first(struct tasklet_struct *t) |
470 | { | |
471 | BUG_ON(!irqs_disabled()); | |
472 | ||
909ea964 CL |
473 | t->next = __this_cpu_read(tasklet_hi_vec.head); |
474 | __this_cpu_write(tasklet_hi_vec.head, t); | |
7c692cba VN |
475 | __raise_softirq_irqoff(HI_SOFTIRQ); |
476 | } | |
477 | ||
478 | EXPORT_SYMBOL(__tasklet_hi_schedule_first); | |
479 | ||
1da177e4 LT |
480 | static void tasklet_action(struct softirq_action *a) |
481 | { | |
482 | struct tasklet_struct *list; | |
483 | ||
484 | local_irq_disable(); | |
909ea964 CL |
485 | list = __this_cpu_read(tasklet_vec.head); |
486 | __this_cpu_write(tasklet_vec.head, NULL); | |
487 | __this_cpu_write(tasklet_vec.tail, &__get_cpu_var(tasklet_vec).head); | |
1da177e4 LT |
488 | local_irq_enable(); |
489 | ||
490 | while (list) { | |
491 | struct tasklet_struct *t = list; | |
492 | ||
493 | list = list->next; | |
494 | ||
495 | if (tasklet_trylock(t)) { | |
496 | if (!atomic_read(&t->count)) { | |
497 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
498 | BUG(); | |
499 | t->func(t->data); | |
500 | tasklet_unlock(t); | |
501 | continue; | |
502 | } | |
503 | tasklet_unlock(t); | |
504 | } | |
505 | ||
506 | local_irq_disable(); | |
48f20a9a | 507 | t->next = NULL; |
909ea964 CL |
508 | *__this_cpu_read(tasklet_vec.tail) = t; |
509 | __this_cpu_write(tasklet_vec.tail, &(t->next)); | |
1da177e4 LT |
510 | __raise_softirq_irqoff(TASKLET_SOFTIRQ); |
511 | local_irq_enable(); | |
512 | } | |
513 | } | |
514 | ||
515 | static void tasklet_hi_action(struct softirq_action *a) | |
516 | { | |
517 | struct tasklet_struct *list; | |
518 | ||
519 | local_irq_disable(); | |
909ea964 CL |
520 | list = __this_cpu_read(tasklet_hi_vec.head); |
521 | __this_cpu_write(tasklet_hi_vec.head, NULL); | |
522 | __this_cpu_write(tasklet_hi_vec.tail, &__get_cpu_var(tasklet_hi_vec).head); | |
1da177e4 LT |
523 | local_irq_enable(); |
524 | ||
525 | while (list) { | |
526 | struct tasklet_struct *t = list; | |
527 | ||
528 | list = list->next; | |
529 | ||
530 | if (tasklet_trylock(t)) { | |
531 | if (!atomic_read(&t->count)) { | |
532 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
533 | BUG(); | |
534 | t->func(t->data); | |
535 | tasklet_unlock(t); | |
536 | continue; | |
537 | } | |
538 | tasklet_unlock(t); | |
539 | } | |
540 | ||
541 | local_irq_disable(); | |
48f20a9a | 542 | t->next = NULL; |
909ea964 CL |
543 | *__this_cpu_read(tasklet_hi_vec.tail) = t; |
544 | __this_cpu_write(tasklet_hi_vec.tail, &(t->next)); | |
1da177e4 LT |
545 | __raise_softirq_irqoff(HI_SOFTIRQ); |
546 | local_irq_enable(); | |
547 | } | |
548 | } | |
549 | ||
550 | ||
551 | void tasklet_init(struct tasklet_struct *t, | |
552 | void (*func)(unsigned long), unsigned long data) | |
553 | { | |
554 | t->next = NULL; | |
555 | t->state = 0; | |
556 | atomic_set(&t->count, 0); | |
557 | t->func = func; | |
558 | t->data = data; | |
559 | } | |
560 | ||
561 | EXPORT_SYMBOL(tasklet_init); | |
562 | ||
563 | void tasklet_kill(struct tasklet_struct *t) | |
564 | { | |
565 | if (in_interrupt()) | |
566 | printk("Attempt to kill tasklet from interrupt\n"); | |
567 | ||
568 | while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { | |
79d381c9 | 569 | do { |
1da177e4 | 570 | yield(); |
79d381c9 | 571 | } while (test_bit(TASKLET_STATE_SCHED, &t->state)); |
1da177e4 LT |
572 | } |
573 | tasklet_unlock_wait(t); | |
574 | clear_bit(TASKLET_STATE_SCHED, &t->state); | |
575 | } | |
576 | ||
577 | EXPORT_SYMBOL(tasklet_kill); | |
578 | ||
9ba5f005 PZ |
579 | /* |
580 | * tasklet_hrtimer | |
581 | */ | |
582 | ||
583 | /* | |
b9c30322 PZ |
584 | * The trampoline is called when the hrtimer expires. It schedules a tasklet |
585 | * to run __tasklet_hrtimer_trampoline() which in turn will call the intended | |
586 | * hrtimer callback, but from softirq context. | |
9ba5f005 PZ |
587 | */ |
588 | static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer) | |
589 | { | |
590 | struct tasklet_hrtimer *ttimer = | |
591 | container_of(timer, struct tasklet_hrtimer, timer); | |
592 | ||
b9c30322 PZ |
593 | tasklet_hi_schedule(&ttimer->tasklet); |
594 | return HRTIMER_NORESTART; | |
9ba5f005 PZ |
595 | } |
596 | ||
597 | /* | |
598 | * Helper function which calls the hrtimer callback from | |
599 | * tasklet/softirq context | |
600 | */ | |
601 | static void __tasklet_hrtimer_trampoline(unsigned long data) | |
602 | { | |
603 | struct tasklet_hrtimer *ttimer = (void *)data; | |
604 | enum hrtimer_restart restart; | |
605 | ||
606 | restart = ttimer->function(&ttimer->timer); | |
607 | if (restart != HRTIMER_NORESTART) | |
608 | hrtimer_restart(&ttimer->timer); | |
609 | } | |
610 | ||
611 | /** | |
612 | * tasklet_hrtimer_init - Init a tasklet/hrtimer combo for softirq callbacks | |
613 | * @ttimer: tasklet_hrtimer which is initialized | |
25985edc | 614 | * @function: hrtimer callback function which gets called from softirq context |
9ba5f005 PZ |
615 | * @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME) |
616 | * @mode: hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL) | |
617 | */ | |
618 | void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer, | |
619 | enum hrtimer_restart (*function)(struct hrtimer *), | |
620 | clockid_t which_clock, enum hrtimer_mode mode) | |
621 | { | |
622 | hrtimer_init(&ttimer->timer, which_clock, mode); | |
623 | ttimer->timer.function = __hrtimer_tasklet_trampoline; | |
624 | tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline, | |
625 | (unsigned long)ttimer); | |
626 | ttimer->function = function; | |
627 | } | |
628 | EXPORT_SYMBOL_GPL(tasklet_hrtimer_init); | |
629 | ||
630 | /* | |
631 | * Remote softirq bits | |
632 | */ | |
633 | ||
54514a70 DM |
634 | DEFINE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list); |
635 | EXPORT_PER_CPU_SYMBOL(softirq_work_list); | |
636 | ||
637 | static void __local_trigger(struct call_single_data *cp, int softirq) | |
638 | { | |
639 | struct list_head *head = &__get_cpu_var(softirq_work_list[softirq]); | |
640 | ||
641 | list_add_tail(&cp->list, head); | |
642 | ||
643 | /* Trigger the softirq only if the list was previously empty. */ | |
644 | if (head->next == &cp->list) | |
645 | raise_softirq_irqoff(softirq); | |
646 | } | |
647 | ||
648 | #ifdef CONFIG_USE_GENERIC_SMP_HELPERS | |
649 | static void remote_softirq_receive(void *data) | |
650 | { | |
651 | struct call_single_data *cp = data; | |
652 | unsigned long flags; | |
653 | int softirq; | |
654 | ||
3440a1ca | 655 | softirq = *(int *)cp->info; |
54514a70 DM |
656 | local_irq_save(flags); |
657 | __local_trigger(cp, softirq); | |
658 | local_irq_restore(flags); | |
659 | } | |
660 | ||
661 | static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) | |
662 | { | |
663 | if (cpu_online(cpu)) { | |
664 | cp->func = remote_softirq_receive; | |
3440a1ca | 665 | cp->info = &softirq; |
54514a70 | 666 | cp->flags = 0; |
54514a70 | 667 | |
6e275637 | 668 | __smp_call_function_single(cpu, cp, 0); |
54514a70 DM |
669 | return 0; |
670 | } | |
671 | return 1; | |
672 | } | |
673 | #else /* CONFIG_USE_GENERIC_SMP_HELPERS */ | |
674 | static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) | |
675 | { | |
676 | return 1; | |
677 | } | |
678 | #endif | |
679 | ||
680 | /** | |
681 | * __send_remote_softirq - try to schedule softirq work on a remote cpu | |
682 | * @cp: private SMP call function data area | |
683 | * @cpu: the remote cpu | |
684 | * @this_cpu: the currently executing cpu | |
685 | * @softirq: the softirq for the work | |
686 | * | |
687 | * Attempt to schedule softirq work on a remote cpu. If this cannot be | |
688 | * done, the work is instead queued up on the local cpu. | |
689 | * | |
690 | * Interrupts must be disabled. | |
691 | */ | |
692 | void __send_remote_softirq(struct call_single_data *cp, int cpu, int this_cpu, int softirq) | |
693 | { | |
694 | if (cpu == this_cpu || __try_remote_softirq(cp, cpu, softirq)) | |
695 | __local_trigger(cp, softirq); | |
696 | } | |
697 | EXPORT_SYMBOL(__send_remote_softirq); | |
698 | ||
699 | /** | |
700 | * send_remote_softirq - try to schedule softirq work on a remote cpu | |
701 | * @cp: private SMP call function data area | |
702 | * @cpu: the remote cpu | |
703 | * @softirq: the softirq for the work | |
704 | * | |
705 | * Like __send_remote_softirq except that disabling interrupts and | |
706 | * computing the current cpu is done for the caller. | |
707 | */ | |
708 | void send_remote_softirq(struct call_single_data *cp, int cpu, int softirq) | |
709 | { | |
710 | unsigned long flags; | |
711 | int this_cpu; | |
712 | ||
713 | local_irq_save(flags); | |
714 | this_cpu = smp_processor_id(); | |
715 | __send_remote_softirq(cp, cpu, this_cpu, softirq); | |
716 | local_irq_restore(flags); | |
717 | } | |
718 | EXPORT_SYMBOL(send_remote_softirq); | |
719 | ||
0db0628d | 720 | static int remote_softirq_cpu_notify(struct notifier_block *self, |
54514a70 DM |
721 | unsigned long action, void *hcpu) |
722 | { | |
723 | /* | |
724 | * If a CPU goes away, splice its entries to the current CPU | |
725 | * and trigger a run of the softirq | |
726 | */ | |
727 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { | |
728 | int cpu = (unsigned long) hcpu; | |
729 | int i; | |
730 | ||
731 | local_irq_disable(); | |
732 | for (i = 0; i < NR_SOFTIRQS; i++) { | |
733 | struct list_head *head = &per_cpu(softirq_work_list[i], cpu); | |
734 | struct list_head *local_head; | |
735 | ||
736 | if (list_empty(head)) | |
737 | continue; | |
738 | ||
739 | local_head = &__get_cpu_var(softirq_work_list[i]); | |
740 | list_splice_init(head, local_head); | |
741 | raise_softirq_irqoff(i); | |
742 | } | |
743 | local_irq_enable(); | |
744 | } | |
745 | ||
746 | return NOTIFY_OK; | |
747 | } | |
748 | ||
0db0628d | 749 | static struct notifier_block remote_softirq_cpu_notifier = { |
54514a70 DM |
750 | .notifier_call = remote_softirq_cpu_notify, |
751 | }; | |
752 | ||
1da177e4 LT |
753 | void __init softirq_init(void) |
754 | { | |
48f20a9a OJ |
755 | int cpu; |
756 | ||
757 | for_each_possible_cpu(cpu) { | |
54514a70 DM |
758 | int i; |
759 | ||
48f20a9a OJ |
760 | per_cpu(tasklet_vec, cpu).tail = |
761 | &per_cpu(tasklet_vec, cpu).head; | |
762 | per_cpu(tasklet_hi_vec, cpu).tail = | |
763 | &per_cpu(tasklet_hi_vec, cpu).head; | |
54514a70 DM |
764 | for (i = 0; i < NR_SOFTIRQS; i++) |
765 | INIT_LIST_HEAD(&per_cpu(softirq_work_list[i], cpu)); | |
48f20a9a OJ |
766 | } |
767 | ||
54514a70 DM |
768 | register_hotcpu_notifier(&remote_softirq_cpu_notifier); |
769 | ||
962cf36c CM |
770 | open_softirq(TASKLET_SOFTIRQ, tasklet_action); |
771 | open_softirq(HI_SOFTIRQ, tasklet_hi_action); | |
1da177e4 LT |
772 | } |
773 | ||
3e339b5d | 774 | static int ksoftirqd_should_run(unsigned int cpu) |
1da177e4 | 775 | { |
3e339b5d TG |
776 | return local_softirq_pending(); |
777 | } | |
1da177e4 | 778 | |
3e339b5d TG |
779 | static void run_ksoftirqd(unsigned int cpu) |
780 | { | |
781 | local_irq_disable(); | |
782 | if (local_softirq_pending()) { | |
0bed698a FW |
783 | /* |
784 | * We can safely run softirq on inline stack, as we are not deep | |
785 | * in the task stack here. | |
786 | */ | |
3e339b5d TG |
787 | __do_softirq(); |
788 | rcu_note_context_switch(cpu); | |
789 | local_irq_enable(); | |
790 | cond_resched(); | |
791 | return; | |
1da177e4 | 792 | } |
3e339b5d | 793 | local_irq_enable(); |
1da177e4 LT |
794 | } |
795 | ||
796 | #ifdef CONFIG_HOTPLUG_CPU | |
797 | /* | |
798 | * tasklet_kill_immediate is called to remove a tasklet which can already be | |
799 | * scheduled for execution on @cpu. | |
800 | * | |
801 | * Unlike tasklet_kill, this function removes the tasklet | |
802 | * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state. | |
803 | * | |
804 | * When this function is called, @cpu must be in the CPU_DEAD state. | |
805 | */ | |
806 | void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu) | |
807 | { | |
808 | struct tasklet_struct **i; | |
809 | ||
810 | BUG_ON(cpu_online(cpu)); | |
811 | BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state)); | |
812 | ||
813 | if (!test_bit(TASKLET_STATE_SCHED, &t->state)) | |
814 | return; | |
815 | ||
816 | /* CPU is dead, so no lock needed. */ | |
48f20a9a | 817 | for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) { |
1da177e4 LT |
818 | if (*i == t) { |
819 | *i = t->next; | |
48f20a9a OJ |
820 | /* If this was the tail element, move the tail ptr */ |
821 | if (*i == NULL) | |
822 | per_cpu(tasklet_vec, cpu).tail = i; | |
1da177e4 LT |
823 | return; |
824 | } | |
825 | } | |
826 | BUG(); | |
827 | } | |
828 | ||
829 | static void takeover_tasklets(unsigned int cpu) | |
830 | { | |
1da177e4 LT |
831 | /* CPU is dead, so no lock needed. */ |
832 | local_irq_disable(); | |
833 | ||
834 | /* Find end, append list for that CPU. */ | |
e5e41723 | 835 | if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) { |
909ea964 CL |
836 | *__this_cpu_read(tasklet_vec.tail) = per_cpu(tasklet_vec, cpu).head; |
837 | this_cpu_write(tasklet_vec.tail, per_cpu(tasklet_vec, cpu).tail); | |
e5e41723 CB |
838 | per_cpu(tasklet_vec, cpu).head = NULL; |
839 | per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; | |
840 | } | |
1da177e4 LT |
841 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
842 | ||
e5e41723 | 843 | if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) { |
909ea964 CL |
844 | *__this_cpu_read(tasklet_hi_vec.tail) = per_cpu(tasklet_hi_vec, cpu).head; |
845 | __this_cpu_write(tasklet_hi_vec.tail, per_cpu(tasklet_hi_vec, cpu).tail); | |
e5e41723 CB |
846 | per_cpu(tasklet_hi_vec, cpu).head = NULL; |
847 | per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; | |
848 | } | |
1da177e4 LT |
849 | raise_softirq_irqoff(HI_SOFTIRQ); |
850 | ||
851 | local_irq_enable(); | |
852 | } | |
853 | #endif /* CONFIG_HOTPLUG_CPU */ | |
854 | ||
0db0628d | 855 | static int cpu_callback(struct notifier_block *nfb, |
1da177e4 LT |
856 | unsigned long action, |
857 | void *hcpu) | |
858 | { | |
1da177e4 | 859 | switch (action) { |
1da177e4 | 860 | #ifdef CONFIG_HOTPLUG_CPU |
1da177e4 | 861 | case CPU_DEAD: |
3e339b5d TG |
862 | case CPU_DEAD_FROZEN: |
863 | takeover_tasklets((unsigned long)hcpu); | |
1da177e4 LT |
864 | break; |
865 | #endif /* CONFIG_HOTPLUG_CPU */ | |
3e339b5d | 866 | } |
1da177e4 LT |
867 | return NOTIFY_OK; |
868 | } | |
869 | ||
0db0628d | 870 | static struct notifier_block cpu_nfb = { |
1da177e4 LT |
871 | .notifier_call = cpu_callback |
872 | }; | |
873 | ||
3e339b5d TG |
874 | static struct smp_hotplug_thread softirq_threads = { |
875 | .store = &ksoftirqd, | |
876 | .thread_should_run = ksoftirqd_should_run, | |
877 | .thread_fn = run_ksoftirqd, | |
878 | .thread_comm = "ksoftirqd/%u", | |
879 | }; | |
880 | ||
7babe8db | 881 | static __init int spawn_ksoftirqd(void) |
1da177e4 | 882 | { |
1da177e4 | 883 | register_cpu_notifier(&cpu_nfb); |
3e339b5d TG |
884 | |
885 | BUG_ON(smpboot_register_percpu_thread(&softirq_threads)); | |
886 | ||
1da177e4 LT |
887 | return 0; |
888 | } | |
7babe8db | 889 | early_initcall(spawn_ksoftirqd); |
78eef01b | 890 | |
43a25632 YL |
891 | /* |
892 | * [ These __weak aliases are kept in a separate compilation unit, so that | |
893 | * GCC does not inline them incorrectly. ] | |
894 | */ | |
895 | ||
896 | int __init __weak early_irq_init(void) | |
897 | { | |
898 | return 0; | |
899 | } | |
900 | ||
4a046d17 YL |
901 | int __init __weak arch_probe_nr_irqs(void) |
902 | { | |
b683de2b | 903 | return NR_IRQS_LEGACY; |
4a046d17 YL |
904 | } |
905 | ||
43a25632 YL |
906 | int __init __weak arch_early_irq_init(void) |
907 | { | |
908 | return 0; | |
909 | } |