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) | |
1da177e4 LT |
9 | */ |
10 | ||
9984de1a | 11 | #include <linux/export.h> |
1da177e4 LT |
12 | #include <linux/kernel_stat.h> |
13 | #include <linux/interrupt.h> | |
14 | #include <linux/init.h> | |
15 | #include <linux/mm.h> | |
16 | #include <linux/notifier.h> | |
17 | #include <linux/percpu.h> | |
18 | #include <linux/cpu.h> | |
83144186 | 19 | #include <linux/freezer.h> |
1da177e4 LT |
20 | #include <linux/kthread.h> |
21 | #include <linux/rcupdate.h> | |
7e49fcce | 22 | #include <linux/ftrace.h> |
78eef01b | 23 | #include <linux/smp.h> |
3e339b5d | 24 | #include <linux/smpboot.h> |
79bf2bb3 | 25 | #include <linux/tick.h> |
a0e39ed3 HC |
26 | |
27 | #define CREATE_TRACE_POINTS | |
ad8d75ff | 28 | #include <trace/events/irq.h> |
1da177e4 | 29 | |
1da177e4 LT |
30 | /* |
31 | - No shared variables, all the data are CPU local. | |
32 | - If a softirq needs serialization, let it serialize itself | |
33 | by its own spinlocks. | |
34 | - Even if softirq is serialized, only local cpu is marked for | |
35 | execution. Hence, we get something sort of weak cpu binding. | |
36 | Though it is still not clear, will it result in better locality | |
37 | or will not. | |
38 | ||
39 | Examples: | |
40 | - NET RX softirq. It is multithreaded and does not require | |
41 | any global serialization. | |
42 | - NET TX softirq. It kicks software netdevice queues, hence | |
43 | it is logically serialized per device, but this serialization | |
44 | is invisible to common code. | |
45 | - Tasklets: serialized wrt itself. | |
46 | */ | |
47 | ||
48 | #ifndef __ARCH_IRQ_STAT | |
49 | irq_cpustat_t irq_stat[NR_CPUS] ____cacheline_aligned; | |
50 | EXPORT_SYMBOL(irq_stat); | |
51 | #endif | |
52 | ||
978b0116 | 53 | static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp; |
1da177e4 | 54 | |
4dd53d89 | 55 | DEFINE_PER_CPU(struct task_struct *, ksoftirqd); |
1da177e4 | 56 | |
5d592b44 | 57 | char *softirq_to_name[NR_SOFTIRQS] = { |
5dd4de58 | 58 | "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "BLOCK_IOPOLL", |
09223371 | 59 | "TASKLET", "SCHED", "HRTIMER", "RCU" |
5d592b44 JB |
60 | }; |
61 | ||
1da177e4 LT |
62 | /* |
63 | * we cannot loop indefinitely here to avoid userspace starvation, | |
64 | * but we also don't want to introduce a worst case 1/HZ latency | |
65 | * to the pending events, so lets the scheduler to balance | |
66 | * the softirq load for us. | |
67 | */ | |
676cb02d | 68 | static void wakeup_softirqd(void) |
1da177e4 LT |
69 | { |
70 | /* Interrupts are disabled: no need to stop preemption */ | |
909ea964 | 71 | struct task_struct *tsk = __this_cpu_read(ksoftirqd); |
1da177e4 LT |
72 | |
73 | if (tsk && tsk->state != TASK_RUNNING) | |
74 | wake_up_process(tsk); | |
75 | } | |
76 | ||
75e1056f VP |
77 | /* |
78 | * preempt_count and SOFTIRQ_OFFSET usage: | |
79 | * - preempt_count is changed by SOFTIRQ_OFFSET on entering or leaving | |
80 | * softirq processing. | |
81 | * - preempt_count is changed by SOFTIRQ_DISABLE_OFFSET (= 2 * SOFTIRQ_OFFSET) | |
82 | * on local_bh_disable or local_bh_enable. | |
83 | * This lets us distinguish between whether we are currently processing | |
84 | * softirq and whether we just have bh disabled. | |
85 | */ | |
86 | ||
de30a2b3 IM |
87 | /* |
88 | * This one is for softirq.c-internal use, | |
89 | * where hardirqs are disabled legitimately: | |
90 | */ | |
3c829c36 | 91 | #ifdef CONFIG_TRACE_IRQFLAGS |
75e1056f | 92 | static void __local_bh_disable(unsigned long ip, unsigned int cnt) |
de30a2b3 IM |
93 | { |
94 | unsigned long flags; | |
95 | ||
96 | WARN_ON_ONCE(in_irq()); | |
97 | ||
98 | raw_local_irq_save(flags); | |
7e49fcce | 99 | /* |
bdb43806 | 100 | * The preempt tracer hooks into preempt_count_add and will break |
7e49fcce SR |
101 | * lockdep because it calls back into lockdep after SOFTIRQ_OFFSET |
102 | * is set and before current->softirq_enabled is cleared. | |
103 | * We must manually increment preempt_count here and manually | |
104 | * call the trace_preempt_off later. | |
105 | */ | |
bdb43806 | 106 | __preempt_count_add(cnt); |
de30a2b3 IM |
107 | /* |
108 | * Were softirqs turned off above: | |
109 | */ | |
75e1056f | 110 | if (softirq_count() == cnt) |
de30a2b3 IM |
111 | trace_softirqs_off(ip); |
112 | raw_local_irq_restore(flags); | |
7e49fcce | 113 | |
75e1056f | 114 | if (preempt_count() == cnt) |
7e49fcce | 115 | trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); |
de30a2b3 | 116 | } |
3c829c36 | 117 | #else /* !CONFIG_TRACE_IRQFLAGS */ |
75e1056f | 118 | static inline void __local_bh_disable(unsigned long ip, unsigned int cnt) |
3c829c36 | 119 | { |
bdb43806 | 120 | preempt_count_add(cnt); |
3c829c36 TC |
121 | barrier(); |
122 | } | |
123 | #endif /* CONFIG_TRACE_IRQFLAGS */ | |
de30a2b3 IM |
124 | |
125 | void local_bh_disable(void) | |
126 | { | |
d2e08473 | 127 | __local_bh_disable(_RET_IP_, SOFTIRQ_DISABLE_OFFSET); |
de30a2b3 IM |
128 | } |
129 | ||
130 | EXPORT_SYMBOL(local_bh_disable); | |
131 | ||
75e1056f VP |
132 | static void __local_bh_enable(unsigned int cnt) |
133 | { | |
75e1056f VP |
134 | WARN_ON_ONCE(!irqs_disabled()); |
135 | ||
136 | if (softirq_count() == cnt) | |
d2e08473 | 137 | trace_softirqs_on(_RET_IP_); |
bdb43806 | 138 | preempt_count_sub(cnt); |
75e1056f VP |
139 | } |
140 | ||
de30a2b3 IM |
141 | /* |
142 | * Special-case - softirqs can safely be enabled in | |
143 | * cond_resched_softirq(), or by __do_softirq(), | |
144 | * without processing still-pending softirqs: | |
145 | */ | |
146 | void _local_bh_enable(void) | |
147 | { | |
5d60d3e7 | 148 | WARN_ON_ONCE(in_irq()); |
75e1056f | 149 | __local_bh_enable(SOFTIRQ_DISABLE_OFFSET); |
de30a2b3 IM |
150 | } |
151 | ||
152 | EXPORT_SYMBOL(_local_bh_enable); | |
153 | ||
0f476b6d | 154 | static inline void _local_bh_enable_ip(unsigned long ip) |
de30a2b3 | 155 | { |
0f476b6d | 156 | WARN_ON_ONCE(in_irq() || irqs_disabled()); |
3c829c36 | 157 | #ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d | 158 | local_irq_disable(); |
3c829c36 | 159 | #endif |
de30a2b3 IM |
160 | /* |
161 | * Are softirqs going to be turned on now: | |
162 | */ | |
75e1056f | 163 | if (softirq_count() == SOFTIRQ_DISABLE_OFFSET) |
0f476b6d | 164 | trace_softirqs_on(ip); |
de30a2b3 IM |
165 | /* |
166 | * Keep preemption disabled until we are done with | |
167 | * softirq processing: | |
168 | */ | |
bdb43806 | 169 | preempt_count_sub(SOFTIRQ_DISABLE_OFFSET - 1); |
de30a2b3 | 170 | |
0bed698a FW |
171 | if (unlikely(!in_interrupt() && local_softirq_pending())) { |
172 | /* | |
173 | * Run softirq if any pending. And do it in its own stack | |
174 | * as we may be calling this deep in a task call stack already. | |
175 | */ | |
de30a2b3 | 176 | do_softirq(); |
0bed698a | 177 | } |
de30a2b3 | 178 | |
bdb43806 | 179 | preempt_count_dec(); |
3c829c36 | 180 | #ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d | 181 | local_irq_enable(); |
3c829c36 | 182 | #endif |
de30a2b3 IM |
183 | preempt_check_resched(); |
184 | } | |
0f476b6d JB |
185 | |
186 | void local_bh_enable(void) | |
187 | { | |
d2e08473 | 188 | _local_bh_enable_ip(_RET_IP_); |
0f476b6d | 189 | } |
de30a2b3 IM |
190 | EXPORT_SYMBOL(local_bh_enable); |
191 | ||
192 | void local_bh_enable_ip(unsigned long ip) | |
193 | { | |
0f476b6d | 194 | _local_bh_enable_ip(ip); |
de30a2b3 IM |
195 | } |
196 | EXPORT_SYMBOL(local_bh_enable_ip); | |
197 | ||
1da177e4 | 198 | /* |
34376a50 BG |
199 | * We restart softirq processing for at most MAX_SOFTIRQ_RESTART times, |
200 | * but break the loop if need_resched() is set or after 2 ms. | |
201 | * The MAX_SOFTIRQ_TIME provides a nice upper bound in most cases, but in | |
202 | * certain cases, such as stop_machine(), jiffies may cease to | |
203 | * increment and so we need the MAX_SOFTIRQ_RESTART limit as | |
204 | * well to make sure we eventually return from this method. | |
1da177e4 | 205 | * |
c10d7367 | 206 | * These limits have been established via experimentation. |
1da177e4 LT |
207 | * The two things to balance is latency against fairness - |
208 | * we want to handle softirqs as soon as possible, but they | |
209 | * should not be able to lock up the box. | |
210 | */ | |
c10d7367 | 211 | #define MAX_SOFTIRQ_TIME msecs_to_jiffies(2) |
34376a50 | 212 | #define MAX_SOFTIRQ_RESTART 10 |
1da177e4 LT |
213 | |
214 | asmlinkage void __do_softirq(void) | |
215 | { | |
216 | struct softirq_action *h; | |
217 | __u32 pending; | |
c10d7367 | 218 | unsigned long end = jiffies + MAX_SOFTIRQ_TIME; |
1da177e4 | 219 | int cpu; |
907aed48 | 220 | unsigned long old_flags = current->flags; |
34376a50 | 221 | int max_restart = MAX_SOFTIRQ_RESTART; |
907aed48 MG |
222 | |
223 | /* | |
224 | * Mask out PF_MEMALLOC s current task context is borrowed for the | |
225 | * softirq. A softirq handled such as network RX might set PF_MEMALLOC | |
226 | * again if the socket is related to swap | |
227 | */ | |
228 | current->flags &= ~PF_MEMALLOC; | |
1da177e4 LT |
229 | |
230 | pending = local_softirq_pending(); | |
6a61671b | 231 | account_irq_enter_time(current); |
829035fd | 232 | |
d2e08473 | 233 | __local_bh_disable(_RET_IP_, SOFTIRQ_OFFSET); |
d820ac4c | 234 | lockdep_softirq_enter(); |
1da177e4 | 235 | |
1da177e4 LT |
236 | cpu = smp_processor_id(); |
237 | restart: | |
238 | /* Reset the pending bitmask before enabling irqs */ | |
3f74478b | 239 | set_softirq_pending(0); |
1da177e4 | 240 | |
c70f5d66 | 241 | local_irq_enable(); |
1da177e4 LT |
242 | |
243 | h = softirq_vec; | |
244 | ||
245 | do { | |
246 | if (pending & 1) { | |
f4bc6bb2 | 247 | unsigned int vec_nr = h - softirq_vec; |
8e85b4b5 TG |
248 | int prev_count = preempt_count(); |
249 | ||
f4bc6bb2 TG |
250 | kstat_incr_softirqs_this_cpu(vec_nr); |
251 | ||
252 | trace_softirq_entry(vec_nr); | |
1da177e4 | 253 | h->action(h); |
f4bc6bb2 | 254 | trace_softirq_exit(vec_nr); |
8e85b4b5 | 255 | if (unlikely(prev_count != preempt_count())) { |
f4bc6bb2 | 256 | printk(KERN_ERR "huh, entered softirq %u %s %p" |
8e85b4b5 | 257 | "with preempt_count %08x," |
f4bc6bb2 TG |
258 | " exited with %08x?\n", vec_nr, |
259 | softirq_to_name[vec_nr], h->action, | |
260 | prev_count, preempt_count()); | |
4a2b4b22 | 261 | preempt_count_set(prev_count); |
8e85b4b5 TG |
262 | } |
263 | ||
d6714c22 | 264 | rcu_bh_qs(cpu); |
1da177e4 LT |
265 | } |
266 | h++; | |
267 | pending >>= 1; | |
268 | } while (pending); | |
269 | ||
c70f5d66 | 270 | local_irq_disable(); |
1da177e4 LT |
271 | |
272 | pending = local_softirq_pending(); | |
c10d7367 | 273 | if (pending) { |
34376a50 BG |
274 | if (time_before(jiffies, end) && !need_resched() && |
275 | --max_restart) | |
c10d7367 | 276 | goto restart; |
1da177e4 | 277 | |
1da177e4 | 278 | wakeup_softirqd(); |
c10d7367 | 279 | } |
1da177e4 | 280 | |
d820ac4c | 281 | lockdep_softirq_exit(); |
829035fd | 282 | |
6a61671b | 283 | account_irq_exit_time(current); |
75e1056f | 284 | __local_bh_enable(SOFTIRQ_OFFSET); |
5d60d3e7 | 285 | WARN_ON_ONCE(in_interrupt()); |
907aed48 | 286 | tsk_restore_flags(current, old_flags, PF_MEMALLOC); |
1da177e4 LT |
287 | } |
288 | ||
7d65f4a6 | 289 | |
1da177e4 LT |
290 | |
291 | asmlinkage void do_softirq(void) | |
292 | { | |
293 | __u32 pending; | |
294 | unsigned long flags; | |
295 | ||
296 | if (in_interrupt()) | |
297 | return; | |
298 | ||
299 | local_irq_save(flags); | |
300 | ||
301 | pending = local_softirq_pending(); | |
302 | ||
303 | if (pending) | |
7d65f4a6 | 304 | do_softirq_own_stack(); |
1da177e4 LT |
305 | |
306 | local_irq_restore(flags); | |
307 | } | |
308 | ||
dde4b2b5 IM |
309 | /* |
310 | * Enter an interrupt context. | |
311 | */ | |
312 | void irq_enter(void) | |
313 | { | |
6378ddb5 | 314 | int cpu = smp_processor_id(); |
719254fa | 315 | |
64db4cff | 316 | rcu_irq_enter(); |
0a8a2e78 | 317 | if (is_idle_task(current) && !in_interrupt()) { |
d267f87f VP |
318 | /* |
319 | * Prevent raise_softirq from needlessly waking up ksoftirqd | |
320 | * here, as softirq will be serviced on return from interrupt. | |
321 | */ | |
322 | local_bh_disable(); | |
719254fa | 323 | tick_check_idle(cpu); |
d267f87f VP |
324 | _local_bh_enable(); |
325 | } | |
326 | ||
327 | __irq_enter(); | |
dde4b2b5 IM |
328 | } |
329 | ||
8d32a307 TG |
330 | static inline void invoke_softirq(void) |
331 | { | |
ded79754 | 332 | if (!force_irqthreads) { |
cc1f0274 | 333 | #ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK |
ded79754 FW |
334 | /* |
335 | * We can safely execute softirq on the current stack if | |
336 | * it is the irq stack, because it should be near empty | |
cc1f0274 FW |
337 | * at this stage. |
338 | */ | |
339 | __do_softirq(); | |
340 | #else | |
341 | /* | |
342 | * Otherwise, irq_exit() is called on the task stack that can | |
343 | * be potentially deep already. So call softirq in its own stack | |
344 | * to prevent from any overrun. | |
ded79754 | 345 | */ |
be6e1016 | 346 | do_softirq_own_stack(); |
cc1f0274 | 347 | #endif |
ded79754 | 348 | } else { |
8d32a307 | 349 | wakeup_softirqd(); |
ded79754 | 350 | } |
8d32a307 | 351 | } |
1da177e4 | 352 | |
67826eae FW |
353 | static inline void tick_irq_exit(void) |
354 | { | |
355 | #ifdef CONFIG_NO_HZ_COMMON | |
356 | int cpu = smp_processor_id(); | |
357 | ||
358 | /* Make sure that timer wheel updates are propagated */ | |
359 | if ((idle_cpu(cpu) && !need_resched()) || tick_nohz_full_cpu(cpu)) { | |
360 | if (!in_interrupt()) | |
361 | tick_nohz_irq_exit(); | |
362 | } | |
363 | #endif | |
364 | } | |
365 | ||
1da177e4 LT |
366 | /* |
367 | * Exit an interrupt context. Process softirqs if needed and possible: | |
368 | */ | |
369 | void irq_exit(void) | |
370 | { | |
74eed016 | 371 | #ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED |
4cd5d111 | 372 | local_irq_disable(); |
74eed016 TG |
373 | #else |
374 | WARN_ON_ONCE(!irqs_disabled()); | |
375 | #endif | |
376 | ||
6a61671b | 377 | account_irq_exit_time(current); |
de30a2b3 | 378 | trace_hardirq_exit(); |
bdb43806 | 379 | preempt_count_sub(HARDIRQ_OFFSET); |
1da177e4 LT |
380 | if (!in_interrupt() && local_softirq_pending()) |
381 | invoke_softirq(); | |
79bf2bb3 | 382 | |
67826eae | 383 | tick_irq_exit(); |
416eb33c | 384 | rcu_irq_exit(); |
1da177e4 LT |
385 | } |
386 | ||
387 | /* | |
388 | * This function must run with irqs disabled! | |
389 | */ | |
7ad5b3a5 | 390 | inline void raise_softirq_irqoff(unsigned int nr) |
1da177e4 LT |
391 | { |
392 | __raise_softirq_irqoff(nr); | |
393 | ||
394 | /* | |
395 | * If we're in an interrupt or softirq, we're done | |
396 | * (this also catches softirq-disabled code). We will | |
397 | * actually run the softirq once we return from | |
398 | * the irq or softirq. | |
399 | * | |
400 | * Otherwise we wake up ksoftirqd to make sure we | |
401 | * schedule the softirq soon. | |
402 | */ | |
403 | if (!in_interrupt()) | |
404 | wakeup_softirqd(); | |
405 | } | |
406 | ||
7ad5b3a5 | 407 | void raise_softirq(unsigned int nr) |
1da177e4 LT |
408 | { |
409 | unsigned long flags; | |
410 | ||
411 | local_irq_save(flags); | |
412 | raise_softirq_irqoff(nr); | |
413 | local_irq_restore(flags); | |
414 | } | |
415 | ||
f069686e SR |
416 | void __raise_softirq_irqoff(unsigned int nr) |
417 | { | |
418 | trace_softirq_raise(nr); | |
419 | or_softirq_pending(1UL << nr); | |
420 | } | |
421 | ||
962cf36c | 422 | void open_softirq(int nr, void (*action)(struct softirq_action *)) |
1da177e4 | 423 | { |
1da177e4 LT |
424 | softirq_vec[nr].action = action; |
425 | } | |
426 | ||
9ba5f005 PZ |
427 | /* |
428 | * Tasklets | |
429 | */ | |
1da177e4 LT |
430 | struct tasklet_head |
431 | { | |
48f20a9a OJ |
432 | struct tasklet_struct *head; |
433 | struct tasklet_struct **tail; | |
1da177e4 LT |
434 | }; |
435 | ||
4620b49f VN |
436 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec); |
437 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec); | |
1da177e4 | 438 | |
7ad5b3a5 | 439 | void __tasklet_schedule(struct tasklet_struct *t) |
1da177e4 LT |
440 | { |
441 | unsigned long flags; | |
442 | ||
443 | local_irq_save(flags); | |
48f20a9a | 444 | t->next = NULL; |
909ea964 CL |
445 | *__this_cpu_read(tasklet_vec.tail) = t; |
446 | __this_cpu_write(tasklet_vec.tail, &(t->next)); | |
1da177e4 LT |
447 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
448 | local_irq_restore(flags); | |
449 | } | |
450 | ||
451 | EXPORT_SYMBOL(__tasklet_schedule); | |
452 | ||
7ad5b3a5 | 453 | void __tasklet_hi_schedule(struct tasklet_struct *t) |
1da177e4 LT |
454 | { |
455 | unsigned long flags; | |
456 | ||
457 | local_irq_save(flags); | |
48f20a9a | 458 | t->next = NULL; |
909ea964 CL |
459 | *__this_cpu_read(tasklet_hi_vec.tail) = t; |
460 | __this_cpu_write(tasklet_hi_vec.tail, &(t->next)); | |
1da177e4 LT |
461 | raise_softirq_irqoff(HI_SOFTIRQ); |
462 | local_irq_restore(flags); | |
463 | } | |
464 | ||
465 | EXPORT_SYMBOL(__tasklet_hi_schedule); | |
466 | ||
7c692cba VN |
467 | void __tasklet_hi_schedule_first(struct tasklet_struct *t) |
468 | { | |
469 | BUG_ON(!irqs_disabled()); | |
470 | ||
909ea964 CL |
471 | t->next = __this_cpu_read(tasklet_hi_vec.head); |
472 | __this_cpu_write(tasklet_hi_vec.head, t); | |
7c692cba VN |
473 | __raise_softirq_irqoff(HI_SOFTIRQ); |
474 | } | |
475 | ||
476 | EXPORT_SYMBOL(__tasklet_hi_schedule_first); | |
477 | ||
1da177e4 LT |
478 | static void tasklet_action(struct softirq_action *a) |
479 | { | |
480 | struct tasklet_struct *list; | |
481 | ||
482 | local_irq_disable(); | |
909ea964 CL |
483 | list = __this_cpu_read(tasklet_vec.head); |
484 | __this_cpu_write(tasklet_vec.head, NULL); | |
485 | __this_cpu_write(tasklet_vec.tail, &__get_cpu_var(tasklet_vec).head); | |
1da177e4 LT |
486 | local_irq_enable(); |
487 | ||
488 | while (list) { | |
489 | struct tasklet_struct *t = list; | |
490 | ||
491 | list = list->next; | |
492 | ||
493 | if (tasklet_trylock(t)) { | |
494 | if (!atomic_read(&t->count)) { | |
495 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
496 | BUG(); | |
497 | t->func(t->data); | |
498 | tasklet_unlock(t); | |
499 | continue; | |
500 | } | |
501 | tasklet_unlock(t); | |
502 | } | |
503 | ||
504 | local_irq_disable(); | |
48f20a9a | 505 | t->next = NULL; |
909ea964 CL |
506 | *__this_cpu_read(tasklet_vec.tail) = t; |
507 | __this_cpu_write(tasklet_vec.tail, &(t->next)); | |
1da177e4 LT |
508 | __raise_softirq_irqoff(TASKLET_SOFTIRQ); |
509 | local_irq_enable(); | |
510 | } | |
511 | } | |
512 | ||
513 | static void tasklet_hi_action(struct softirq_action *a) | |
514 | { | |
515 | struct tasklet_struct *list; | |
516 | ||
517 | local_irq_disable(); | |
909ea964 CL |
518 | list = __this_cpu_read(tasklet_hi_vec.head); |
519 | __this_cpu_write(tasklet_hi_vec.head, NULL); | |
520 | __this_cpu_write(tasklet_hi_vec.tail, &__get_cpu_var(tasklet_hi_vec).head); | |
1da177e4 LT |
521 | local_irq_enable(); |
522 | ||
523 | while (list) { | |
524 | struct tasklet_struct *t = list; | |
525 | ||
526 | list = list->next; | |
527 | ||
528 | if (tasklet_trylock(t)) { | |
529 | if (!atomic_read(&t->count)) { | |
530 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
531 | BUG(); | |
532 | t->func(t->data); | |
533 | tasklet_unlock(t); | |
534 | continue; | |
535 | } | |
536 | tasklet_unlock(t); | |
537 | } | |
538 | ||
539 | local_irq_disable(); | |
48f20a9a | 540 | t->next = NULL; |
909ea964 CL |
541 | *__this_cpu_read(tasklet_hi_vec.tail) = t; |
542 | __this_cpu_write(tasklet_hi_vec.tail, &(t->next)); | |
1da177e4 LT |
543 | __raise_softirq_irqoff(HI_SOFTIRQ); |
544 | local_irq_enable(); | |
545 | } | |
546 | } | |
547 | ||
548 | ||
549 | void tasklet_init(struct tasklet_struct *t, | |
550 | void (*func)(unsigned long), unsigned long data) | |
551 | { | |
552 | t->next = NULL; | |
553 | t->state = 0; | |
554 | atomic_set(&t->count, 0); | |
555 | t->func = func; | |
556 | t->data = data; | |
557 | } | |
558 | ||
559 | EXPORT_SYMBOL(tasklet_init); | |
560 | ||
561 | void tasklet_kill(struct tasklet_struct *t) | |
562 | { | |
563 | if (in_interrupt()) | |
564 | printk("Attempt to kill tasklet from interrupt\n"); | |
565 | ||
566 | while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { | |
79d381c9 | 567 | do { |
1da177e4 | 568 | yield(); |
79d381c9 | 569 | } while (test_bit(TASKLET_STATE_SCHED, &t->state)); |
1da177e4 LT |
570 | } |
571 | tasklet_unlock_wait(t); | |
572 | clear_bit(TASKLET_STATE_SCHED, &t->state); | |
573 | } | |
574 | ||
575 | EXPORT_SYMBOL(tasklet_kill); | |
576 | ||
9ba5f005 PZ |
577 | /* |
578 | * tasklet_hrtimer | |
579 | */ | |
580 | ||
581 | /* | |
b9c30322 PZ |
582 | * The trampoline is called when the hrtimer expires. It schedules a tasklet |
583 | * to run __tasklet_hrtimer_trampoline() which in turn will call the intended | |
584 | * hrtimer callback, but from softirq context. | |
9ba5f005 PZ |
585 | */ |
586 | static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer) | |
587 | { | |
588 | struct tasklet_hrtimer *ttimer = | |
589 | container_of(timer, struct tasklet_hrtimer, timer); | |
590 | ||
b9c30322 PZ |
591 | tasklet_hi_schedule(&ttimer->tasklet); |
592 | return HRTIMER_NORESTART; | |
9ba5f005 PZ |
593 | } |
594 | ||
595 | /* | |
596 | * Helper function which calls the hrtimer callback from | |
597 | * tasklet/softirq context | |
598 | */ | |
599 | static void __tasklet_hrtimer_trampoline(unsigned long data) | |
600 | { | |
601 | struct tasklet_hrtimer *ttimer = (void *)data; | |
602 | enum hrtimer_restart restart; | |
603 | ||
604 | restart = ttimer->function(&ttimer->timer); | |
605 | if (restart != HRTIMER_NORESTART) | |
606 | hrtimer_restart(&ttimer->timer); | |
607 | } | |
608 | ||
609 | /** | |
610 | * tasklet_hrtimer_init - Init a tasklet/hrtimer combo for softirq callbacks | |
611 | * @ttimer: tasklet_hrtimer which is initialized | |
25985edc | 612 | * @function: hrtimer callback function which gets called from softirq context |
9ba5f005 PZ |
613 | * @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME) |
614 | * @mode: hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL) | |
615 | */ | |
616 | void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer, | |
617 | enum hrtimer_restart (*function)(struct hrtimer *), | |
618 | clockid_t which_clock, enum hrtimer_mode mode) | |
619 | { | |
620 | hrtimer_init(&ttimer->timer, which_clock, mode); | |
621 | ttimer->timer.function = __hrtimer_tasklet_trampoline; | |
622 | tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline, | |
623 | (unsigned long)ttimer); | |
624 | ttimer->function = function; | |
625 | } | |
626 | EXPORT_SYMBOL_GPL(tasklet_hrtimer_init); | |
627 | ||
1da177e4 LT |
628 | void __init softirq_init(void) |
629 | { | |
48f20a9a OJ |
630 | int cpu; |
631 | ||
632 | for_each_possible_cpu(cpu) { | |
633 | per_cpu(tasklet_vec, cpu).tail = | |
634 | &per_cpu(tasklet_vec, cpu).head; | |
635 | per_cpu(tasklet_hi_vec, cpu).tail = | |
636 | &per_cpu(tasklet_hi_vec, cpu).head; | |
637 | } | |
638 | ||
962cf36c CM |
639 | open_softirq(TASKLET_SOFTIRQ, tasklet_action); |
640 | open_softirq(HI_SOFTIRQ, tasklet_hi_action); | |
1da177e4 LT |
641 | } |
642 | ||
3e339b5d | 643 | static int ksoftirqd_should_run(unsigned int cpu) |
1da177e4 | 644 | { |
3e339b5d TG |
645 | return local_softirq_pending(); |
646 | } | |
1da177e4 | 647 | |
3e339b5d TG |
648 | static void run_ksoftirqd(unsigned int cpu) |
649 | { | |
650 | local_irq_disable(); | |
651 | if (local_softirq_pending()) { | |
0bed698a FW |
652 | /* |
653 | * We can safely run softirq on inline stack, as we are not deep | |
654 | * in the task stack here. | |
655 | */ | |
3e339b5d TG |
656 | __do_softirq(); |
657 | rcu_note_context_switch(cpu); | |
658 | local_irq_enable(); | |
659 | cond_resched(); | |
660 | return; | |
1da177e4 | 661 | } |
3e339b5d | 662 | local_irq_enable(); |
1da177e4 LT |
663 | } |
664 | ||
665 | #ifdef CONFIG_HOTPLUG_CPU | |
666 | /* | |
667 | * tasklet_kill_immediate is called to remove a tasklet which can already be | |
668 | * scheduled for execution on @cpu. | |
669 | * | |
670 | * Unlike tasklet_kill, this function removes the tasklet | |
671 | * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state. | |
672 | * | |
673 | * When this function is called, @cpu must be in the CPU_DEAD state. | |
674 | */ | |
675 | void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu) | |
676 | { | |
677 | struct tasklet_struct **i; | |
678 | ||
679 | BUG_ON(cpu_online(cpu)); | |
680 | BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state)); | |
681 | ||
682 | if (!test_bit(TASKLET_STATE_SCHED, &t->state)) | |
683 | return; | |
684 | ||
685 | /* CPU is dead, so no lock needed. */ | |
48f20a9a | 686 | for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) { |
1da177e4 LT |
687 | if (*i == t) { |
688 | *i = t->next; | |
48f20a9a OJ |
689 | /* If this was the tail element, move the tail ptr */ |
690 | if (*i == NULL) | |
691 | per_cpu(tasklet_vec, cpu).tail = i; | |
1da177e4 LT |
692 | return; |
693 | } | |
694 | } | |
695 | BUG(); | |
696 | } | |
697 | ||
698 | static void takeover_tasklets(unsigned int cpu) | |
699 | { | |
1da177e4 LT |
700 | /* CPU is dead, so no lock needed. */ |
701 | local_irq_disable(); | |
702 | ||
703 | /* Find end, append list for that CPU. */ | |
e5e41723 | 704 | if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) { |
909ea964 CL |
705 | *__this_cpu_read(tasklet_vec.tail) = per_cpu(tasklet_vec, cpu).head; |
706 | this_cpu_write(tasklet_vec.tail, per_cpu(tasklet_vec, cpu).tail); | |
e5e41723 CB |
707 | per_cpu(tasklet_vec, cpu).head = NULL; |
708 | per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; | |
709 | } | |
1da177e4 LT |
710 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
711 | ||
e5e41723 | 712 | if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) { |
909ea964 CL |
713 | *__this_cpu_read(tasklet_hi_vec.tail) = per_cpu(tasklet_hi_vec, cpu).head; |
714 | __this_cpu_write(tasklet_hi_vec.tail, per_cpu(tasklet_hi_vec, cpu).tail); | |
e5e41723 CB |
715 | per_cpu(tasklet_hi_vec, cpu).head = NULL; |
716 | per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; | |
717 | } | |
1da177e4 LT |
718 | raise_softirq_irqoff(HI_SOFTIRQ); |
719 | ||
720 | local_irq_enable(); | |
721 | } | |
722 | #endif /* CONFIG_HOTPLUG_CPU */ | |
723 | ||
0db0628d | 724 | static int cpu_callback(struct notifier_block *nfb, |
1da177e4 LT |
725 | unsigned long action, |
726 | void *hcpu) | |
727 | { | |
1da177e4 | 728 | switch (action) { |
1da177e4 | 729 | #ifdef CONFIG_HOTPLUG_CPU |
1da177e4 | 730 | case CPU_DEAD: |
3e339b5d TG |
731 | case CPU_DEAD_FROZEN: |
732 | takeover_tasklets((unsigned long)hcpu); | |
1da177e4 LT |
733 | break; |
734 | #endif /* CONFIG_HOTPLUG_CPU */ | |
3e339b5d | 735 | } |
1da177e4 LT |
736 | return NOTIFY_OK; |
737 | } | |
738 | ||
0db0628d | 739 | static struct notifier_block cpu_nfb = { |
1da177e4 LT |
740 | .notifier_call = cpu_callback |
741 | }; | |
742 | ||
3e339b5d TG |
743 | static struct smp_hotplug_thread softirq_threads = { |
744 | .store = &ksoftirqd, | |
745 | .thread_should_run = ksoftirqd_should_run, | |
746 | .thread_fn = run_ksoftirqd, | |
747 | .thread_comm = "ksoftirqd/%u", | |
748 | }; | |
749 | ||
7babe8db | 750 | static __init int spawn_ksoftirqd(void) |
1da177e4 | 751 | { |
1da177e4 | 752 | register_cpu_notifier(&cpu_nfb); |
3e339b5d TG |
753 | |
754 | BUG_ON(smpboot_register_percpu_thread(&softirq_threads)); | |
755 | ||
1da177e4 LT |
756 | return 0; |
757 | } | |
7babe8db | 758 | early_initcall(spawn_ksoftirqd); |
78eef01b | 759 | |
43a25632 YL |
760 | /* |
761 | * [ These __weak aliases are kept in a separate compilation unit, so that | |
762 | * GCC does not inline them incorrectly. ] | |
763 | */ | |
764 | ||
765 | int __init __weak early_irq_init(void) | |
766 | { | |
767 | return 0; | |
768 | } | |
769 | ||
4a046d17 YL |
770 | int __init __weak arch_probe_nr_irqs(void) |
771 | { | |
b683de2b | 772 | return NR_IRQS_LEGACY; |
4a046d17 YL |
773 | } |
774 | ||
43a25632 YL |
775 | int __init __weak arch_early_irq_init(void) |
776 | { | |
777 | return 0; | |
778 | } |