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 |
0bd3a173 | 92 | void __local_bh_disable_ip(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 | */ | |
9ea4c380 | 110 | if (softirq_count() == (cnt & SOFTIRQ_MASK)) |
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 | } |
0bd3a173 | 117 | EXPORT_SYMBOL(__local_bh_disable_ip); |
3c829c36 | 118 | #endif /* CONFIG_TRACE_IRQFLAGS */ |
de30a2b3 | 119 | |
75e1056f VP |
120 | static void __local_bh_enable(unsigned int cnt) |
121 | { | |
75e1056f VP |
122 | WARN_ON_ONCE(!irqs_disabled()); |
123 | ||
9ea4c380 | 124 | if (softirq_count() == (cnt & SOFTIRQ_MASK)) |
d2e08473 | 125 | trace_softirqs_on(_RET_IP_); |
bdb43806 | 126 | preempt_count_sub(cnt); |
75e1056f VP |
127 | } |
128 | ||
de30a2b3 IM |
129 | /* |
130 | * Special-case - softirqs can safely be enabled in | |
131 | * cond_resched_softirq(), or by __do_softirq(), | |
132 | * without processing still-pending softirqs: | |
133 | */ | |
134 | void _local_bh_enable(void) | |
135 | { | |
5d60d3e7 | 136 | WARN_ON_ONCE(in_irq()); |
75e1056f | 137 | __local_bh_enable(SOFTIRQ_DISABLE_OFFSET); |
de30a2b3 IM |
138 | } |
139 | ||
140 | EXPORT_SYMBOL(_local_bh_enable); | |
141 | ||
0bd3a173 | 142 | void __local_bh_enable_ip(unsigned long ip, unsigned int cnt) |
de30a2b3 | 143 | { |
0f476b6d | 144 | WARN_ON_ONCE(in_irq() || irqs_disabled()); |
3c829c36 | 145 | #ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d | 146 | local_irq_disable(); |
3c829c36 | 147 | #endif |
de30a2b3 IM |
148 | /* |
149 | * Are softirqs going to be turned on now: | |
150 | */ | |
75e1056f | 151 | if (softirq_count() == SOFTIRQ_DISABLE_OFFSET) |
0f476b6d | 152 | trace_softirqs_on(ip); |
de30a2b3 IM |
153 | /* |
154 | * Keep preemption disabled until we are done with | |
155 | * softirq processing: | |
156 | */ | |
0bd3a173 | 157 | preempt_count_sub(cnt - 1); |
de30a2b3 | 158 | |
0bed698a FW |
159 | if (unlikely(!in_interrupt() && local_softirq_pending())) { |
160 | /* | |
161 | * Run softirq if any pending. And do it in its own stack | |
162 | * as we may be calling this deep in a task call stack already. | |
163 | */ | |
de30a2b3 | 164 | do_softirq(); |
0bed698a | 165 | } |
de30a2b3 | 166 | |
bdb43806 | 167 | preempt_count_dec(); |
3c829c36 | 168 | #ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d | 169 | local_irq_enable(); |
3c829c36 | 170 | #endif |
de30a2b3 IM |
171 | preempt_check_resched(); |
172 | } | |
0bd3a173 | 173 | EXPORT_SYMBOL(__local_bh_enable_ip); |
de30a2b3 | 174 | |
1da177e4 | 175 | /* |
34376a50 BG |
176 | * We restart softirq processing for at most MAX_SOFTIRQ_RESTART times, |
177 | * but break the loop if need_resched() is set or after 2 ms. | |
178 | * The MAX_SOFTIRQ_TIME provides a nice upper bound in most cases, but in | |
179 | * certain cases, such as stop_machine(), jiffies may cease to | |
180 | * increment and so we need the MAX_SOFTIRQ_RESTART limit as | |
181 | * well to make sure we eventually return from this method. | |
1da177e4 | 182 | * |
c10d7367 | 183 | * These limits have been established via experimentation. |
1da177e4 LT |
184 | * The two things to balance is latency against fairness - |
185 | * we want to handle softirqs as soon as possible, but they | |
186 | * should not be able to lock up the box. | |
187 | */ | |
c10d7367 | 188 | #define MAX_SOFTIRQ_TIME msecs_to_jiffies(2) |
34376a50 | 189 | #define MAX_SOFTIRQ_RESTART 10 |
1da177e4 | 190 | |
f1a83e65 PZ |
191 | #ifdef CONFIG_TRACE_IRQFLAGS |
192 | /* | |
f1a83e65 PZ |
193 | * When we run softirqs from irq_exit() and thus on the hardirq stack we need |
194 | * to keep the lockdep irq context tracking as tight as possible in order to | |
195 | * not miss-qualify lock contexts and miss possible deadlocks. | |
196 | */ | |
f1a83e65 | 197 | |
5c4853b6 | 198 | static inline bool lockdep_softirq_start(void) |
f1a83e65 | 199 | { |
5c4853b6 | 200 | bool in_hardirq = false; |
f1a83e65 | 201 | |
5c4853b6 FW |
202 | if (trace_hardirq_context(current)) { |
203 | in_hardirq = true; | |
f1a83e65 | 204 | trace_hardirq_exit(); |
5c4853b6 FW |
205 | } |
206 | ||
f1a83e65 | 207 | lockdep_softirq_enter(); |
5c4853b6 FW |
208 | |
209 | return in_hardirq; | |
f1a83e65 PZ |
210 | } |
211 | ||
5c4853b6 | 212 | static inline void lockdep_softirq_end(bool in_hardirq) |
f1a83e65 PZ |
213 | { |
214 | lockdep_softirq_exit(); | |
5c4853b6 FW |
215 | |
216 | if (in_hardirq) | |
f1a83e65 | 217 | trace_hardirq_enter(); |
f1a83e65 | 218 | } |
f1a83e65 | 219 | #else |
5c4853b6 FW |
220 | static inline bool lockdep_softirq_start(void) { return false; } |
221 | static inline void lockdep_softirq_end(bool in_hardirq) { } | |
f1a83e65 PZ |
222 | #endif |
223 | ||
1da177e4 LT |
224 | asmlinkage void __do_softirq(void) |
225 | { | |
c10d7367 | 226 | unsigned long end = jiffies + MAX_SOFTIRQ_TIME; |
907aed48 | 227 | unsigned long old_flags = current->flags; |
34376a50 | 228 | int max_restart = MAX_SOFTIRQ_RESTART; |
f1a83e65 | 229 | struct softirq_action *h; |
5c4853b6 | 230 | bool in_hardirq; |
f1a83e65 PZ |
231 | __u32 pending; |
232 | int cpu; | |
907aed48 MG |
233 | |
234 | /* | |
235 | * Mask out PF_MEMALLOC s current task context is borrowed for the | |
236 | * softirq. A softirq handled such as network RX might set PF_MEMALLOC | |
237 | * again if the socket is related to swap | |
238 | */ | |
239 | current->flags &= ~PF_MEMALLOC; | |
1da177e4 LT |
240 | |
241 | pending = local_softirq_pending(); | |
6a61671b | 242 | account_irq_enter_time(current); |
829035fd | 243 | |
0bd3a173 | 244 | __local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET); |
5c4853b6 | 245 | in_hardirq = lockdep_softirq_start(); |
1da177e4 | 246 | |
1da177e4 LT |
247 | cpu = smp_processor_id(); |
248 | restart: | |
249 | /* Reset the pending bitmask before enabling irqs */ | |
3f74478b | 250 | set_softirq_pending(0); |
1da177e4 | 251 | |
c70f5d66 | 252 | local_irq_enable(); |
1da177e4 LT |
253 | |
254 | h = softirq_vec; | |
255 | ||
256 | do { | |
257 | if (pending & 1) { | |
f4bc6bb2 | 258 | unsigned int vec_nr = h - softirq_vec; |
8e85b4b5 TG |
259 | int prev_count = preempt_count(); |
260 | ||
f4bc6bb2 TG |
261 | kstat_incr_softirqs_this_cpu(vec_nr); |
262 | ||
263 | trace_softirq_entry(vec_nr); | |
1da177e4 | 264 | h->action(h); |
f4bc6bb2 | 265 | trace_softirq_exit(vec_nr); |
8e85b4b5 | 266 | if (unlikely(prev_count != preempt_count())) { |
f4bc6bb2 | 267 | printk(KERN_ERR "huh, entered softirq %u %s %p" |
8e85b4b5 | 268 | "with preempt_count %08x," |
f4bc6bb2 TG |
269 | " exited with %08x?\n", vec_nr, |
270 | softirq_to_name[vec_nr], h->action, | |
271 | prev_count, preempt_count()); | |
4a2b4b22 | 272 | preempt_count_set(prev_count); |
8e85b4b5 TG |
273 | } |
274 | ||
d6714c22 | 275 | rcu_bh_qs(cpu); |
1da177e4 LT |
276 | } |
277 | h++; | |
278 | pending >>= 1; | |
279 | } while (pending); | |
280 | ||
c70f5d66 | 281 | local_irq_disable(); |
1da177e4 LT |
282 | |
283 | pending = local_softirq_pending(); | |
c10d7367 | 284 | if (pending) { |
34376a50 BG |
285 | if (time_before(jiffies, end) && !need_resched() && |
286 | --max_restart) | |
c10d7367 | 287 | goto restart; |
1da177e4 | 288 | |
1da177e4 | 289 | wakeup_softirqd(); |
c10d7367 | 290 | } |
1da177e4 | 291 | |
5c4853b6 | 292 | lockdep_softirq_end(in_hardirq); |
6a61671b | 293 | account_irq_exit_time(current); |
75e1056f | 294 | __local_bh_enable(SOFTIRQ_OFFSET); |
5d60d3e7 | 295 | WARN_ON_ONCE(in_interrupt()); |
907aed48 | 296 | tsk_restore_flags(current, old_flags, PF_MEMALLOC); |
1da177e4 LT |
297 | } |
298 | ||
1da177e4 LT |
299 | asmlinkage void do_softirq(void) |
300 | { | |
301 | __u32 pending; | |
302 | unsigned long flags; | |
303 | ||
304 | if (in_interrupt()) | |
305 | return; | |
306 | ||
307 | local_irq_save(flags); | |
308 | ||
309 | pending = local_softirq_pending(); | |
310 | ||
311 | if (pending) | |
7d65f4a6 | 312 | do_softirq_own_stack(); |
1da177e4 LT |
313 | |
314 | local_irq_restore(flags); | |
315 | } | |
316 | ||
dde4b2b5 IM |
317 | /* |
318 | * Enter an interrupt context. | |
319 | */ | |
320 | void irq_enter(void) | |
321 | { | |
64db4cff | 322 | rcu_irq_enter(); |
0a8a2e78 | 323 | if (is_idle_task(current) && !in_interrupt()) { |
d267f87f VP |
324 | /* |
325 | * Prevent raise_softirq from needlessly waking up ksoftirqd | |
326 | * here, as softirq will be serviced on return from interrupt. | |
327 | */ | |
328 | local_bh_disable(); | |
e8fcaa5c | 329 | tick_check_idle(); |
d267f87f VP |
330 | _local_bh_enable(); |
331 | } | |
332 | ||
333 | __irq_enter(); | |
dde4b2b5 IM |
334 | } |
335 | ||
8d32a307 TG |
336 | static inline void invoke_softirq(void) |
337 | { | |
ded79754 | 338 | if (!force_irqthreads) { |
cc1f0274 | 339 | #ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK |
ded79754 FW |
340 | /* |
341 | * We can safely execute softirq on the current stack if | |
342 | * it is the irq stack, because it should be near empty | |
cc1f0274 FW |
343 | * at this stage. |
344 | */ | |
345 | __do_softirq(); | |
346 | #else | |
347 | /* | |
348 | * Otherwise, irq_exit() is called on the task stack that can | |
349 | * be potentially deep already. So call softirq in its own stack | |
350 | * to prevent from any overrun. | |
ded79754 | 351 | */ |
be6e1016 | 352 | do_softirq_own_stack(); |
cc1f0274 | 353 | #endif |
ded79754 | 354 | } else { |
8d32a307 | 355 | wakeup_softirqd(); |
ded79754 | 356 | } |
8d32a307 | 357 | } |
1da177e4 | 358 | |
67826eae FW |
359 | static inline void tick_irq_exit(void) |
360 | { | |
361 | #ifdef CONFIG_NO_HZ_COMMON | |
362 | int cpu = smp_processor_id(); | |
363 | ||
364 | /* Make sure that timer wheel updates are propagated */ | |
365 | if ((idle_cpu(cpu) && !need_resched()) || tick_nohz_full_cpu(cpu)) { | |
366 | if (!in_interrupt()) | |
367 | tick_nohz_irq_exit(); | |
368 | } | |
369 | #endif | |
370 | } | |
371 | ||
1da177e4 LT |
372 | /* |
373 | * Exit an interrupt context. Process softirqs if needed and possible: | |
374 | */ | |
375 | void irq_exit(void) | |
376 | { | |
74eed016 | 377 | #ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED |
4cd5d111 | 378 | local_irq_disable(); |
74eed016 TG |
379 | #else |
380 | WARN_ON_ONCE(!irqs_disabled()); | |
381 | #endif | |
382 | ||
6a61671b | 383 | account_irq_exit_time(current); |
bdb43806 | 384 | preempt_count_sub(HARDIRQ_OFFSET); |
1da177e4 LT |
385 | if (!in_interrupt() && local_softirq_pending()) |
386 | invoke_softirq(); | |
79bf2bb3 | 387 | |
67826eae | 388 | tick_irq_exit(); |
416eb33c | 389 | rcu_irq_exit(); |
f1a83e65 | 390 | trace_hardirq_exit(); /* must be last! */ |
1da177e4 LT |
391 | } |
392 | ||
393 | /* | |
394 | * This function must run with irqs disabled! | |
395 | */ | |
7ad5b3a5 | 396 | inline void raise_softirq_irqoff(unsigned int nr) |
1da177e4 LT |
397 | { |
398 | __raise_softirq_irqoff(nr); | |
399 | ||
400 | /* | |
401 | * If we're in an interrupt or softirq, we're done | |
402 | * (this also catches softirq-disabled code). We will | |
403 | * actually run the softirq once we return from | |
404 | * the irq or softirq. | |
405 | * | |
406 | * Otherwise we wake up ksoftirqd to make sure we | |
407 | * schedule the softirq soon. | |
408 | */ | |
409 | if (!in_interrupt()) | |
410 | wakeup_softirqd(); | |
411 | } | |
412 | ||
7ad5b3a5 | 413 | void raise_softirq(unsigned int nr) |
1da177e4 LT |
414 | { |
415 | unsigned long flags; | |
416 | ||
417 | local_irq_save(flags); | |
418 | raise_softirq_irqoff(nr); | |
419 | local_irq_restore(flags); | |
420 | } | |
421 | ||
f069686e SR |
422 | void __raise_softirq_irqoff(unsigned int nr) |
423 | { | |
424 | trace_softirq_raise(nr); | |
425 | or_softirq_pending(1UL << nr); | |
426 | } | |
427 | ||
962cf36c | 428 | void open_softirq(int nr, void (*action)(struct softirq_action *)) |
1da177e4 | 429 | { |
1da177e4 LT |
430 | softirq_vec[nr].action = action; |
431 | } | |
432 | ||
9ba5f005 PZ |
433 | /* |
434 | * Tasklets | |
435 | */ | |
1da177e4 LT |
436 | struct tasklet_head |
437 | { | |
48f20a9a OJ |
438 | struct tasklet_struct *head; |
439 | struct tasklet_struct **tail; | |
1da177e4 LT |
440 | }; |
441 | ||
4620b49f VN |
442 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec); |
443 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec); | |
1da177e4 | 444 | |
7ad5b3a5 | 445 | void __tasklet_schedule(struct tasklet_struct *t) |
1da177e4 LT |
446 | { |
447 | unsigned long flags; | |
448 | ||
449 | local_irq_save(flags); | |
48f20a9a | 450 | t->next = NULL; |
909ea964 CL |
451 | *__this_cpu_read(tasklet_vec.tail) = t; |
452 | __this_cpu_write(tasklet_vec.tail, &(t->next)); | |
1da177e4 LT |
453 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
454 | local_irq_restore(flags); | |
455 | } | |
456 | ||
457 | EXPORT_SYMBOL(__tasklet_schedule); | |
458 | ||
7ad5b3a5 | 459 | void __tasklet_hi_schedule(struct tasklet_struct *t) |
1da177e4 LT |
460 | { |
461 | unsigned long flags; | |
462 | ||
463 | local_irq_save(flags); | |
48f20a9a | 464 | t->next = NULL; |
909ea964 CL |
465 | *__this_cpu_read(tasklet_hi_vec.tail) = t; |
466 | __this_cpu_write(tasklet_hi_vec.tail, &(t->next)); | |
1da177e4 LT |
467 | raise_softirq_irqoff(HI_SOFTIRQ); |
468 | local_irq_restore(flags); | |
469 | } | |
470 | ||
471 | EXPORT_SYMBOL(__tasklet_hi_schedule); | |
472 | ||
7c692cba VN |
473 | void __tasklet_hi_schedule_first(struct tasklet_struct *t) |
474 | { | |
475 | BUG_ON(!irqs_disabled()); | |
476 | ||
909ea964 CL |
477 | t->next = __this_cpu_read(tasklet_hi_vec.head); |
478 | __this_cpu_write(tasklet_hi_vec.head, t); | |
7c692cba VN |
479 | __raise_softirq_irqoff(HI_SOFTIRQ); |
480 | } | |
481 | ||
482 | EXPORT_SYMBOL(__tasklet_hi_schedule_first); | |
483 | ||
1da177e4 LT |
484 | static void tasklet_action(struct softirq_action *a) |
485 | { | |
486 | struct tasklet_struct *list; | |
487 | ||
488 | local_irq_disable(); | |
909ea964 CL |
489 | list = __this_cpu_read(tasklet_vec.head); |
490 | __this_cpu_write(tasklet_vec.head, NULL); | |
491 | __this_cpu_write(tasklet_vec.tail, &__get_cpu_var(tasklet_vec).head); | |
1da177e4 LT |
492 | local_irq_enable(); |
493 | ||
494 | while (list) { | |
495 | struct tasklet_struct *t = list; | |
496 | ||
497 | list = list->next; | |
498 | ||
499 | if (tasklet_trylock(t)) { | |
500 | if (!atomic_read(&t->count)) { | |
501 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
502 | BUG(); | |
503 | t->func(t->data); | |
504 | tasklet_unlock(t); | |
505 | continue; | |
506 | } | |
507 | tasklet_unlock(t); | |
508 | } | |
509 | ||
510 | local_irq_disable(); | |
48f20a9a | 511 | t->next = NULL; |
909ea964 CL |
512 | *__this_cpu_read(tasklet_vec.tail) = t; |
513 | __this_cpu_write(tasklet_vec.tail, &(t->next)); | |
1da177e4 LT |
514 | __raise_softirq_irqoff(TASKLET_SOFTIRQ); |
515 | local_irq_enable(); | |
516 | } | |
517 | } | |
518 | ||
519 | static void tasklet_hi_action(struct softirq_action *a) | |
520 | { | |
521 | struct tasklet_struct *list; | |
522 | ||
523 | local_irq_disable(); | |
909ea964 CL |
524 | list = __this_cpu_read(tasklet_hi_vec.head); |
525 | __this_cpu_write(tasklet_hi_vec.head, NULL); | |
526 | __this_cpu_write(tasklet_hi_vec.tail, &__get_cpu_var(tasklet_hi_vec).head); | |
1da177e4 LT |
527 | local_irq_enable(); |
528 | ||
529 | while (list) { | |
530 | struct tasklet_struct *t = list; | |
531 | ||
532 | list = list->next; | |
533 | ||
534 | if (tasklet_trylock(t)) { | |
535 | if (!atomic_read(&t->count)) { | |
536 | if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) | |
537 | BUG(); | |
538 | t->func(t->data); | |
539 | tasklet_unlock(t); | |
540 | continue; | |
541 | } | |
542 | tasklet_unlock(t); | |
543 | } | |
544 | ||
545 | local_irq_disable(); | |
48f20a9a | 546 | t->next = NULL; |
909ea964 CL |
547 | *__this_cpu_read(tasklet_hi_vec.tail) = t; |
548 | __this_cpu_write(tasklet_hi_vec.tail, &(t->next)); | |
1da177e4 LT |
549 | __raise_softirq_irqoff(HI_SOFTIRQ); |
550 | local_irq_enable(); | |
551 | } | |
552 | } | |
553 | ||
554 | ||
555 | void tasklet_init(struct tasklet_struct *t, | |
556 | void (*func)(unsigned long), unsigned long data) | |
557 | { | |
558 | t->next = NULL; | |
559 | t->state = 0; | |
560 | atomic_set(&t->count, 0); | |
561 | t->func = func; | |
562 | t->data = data; | |
563 | } | |
564 | ||
565 | EXPORT_SYMBOL(tasklet_init); | |
566 | ||
567 | void tasklet_kill(struct tasklet_struct *t) | |
568 | { | |
569 | if (in_interrupt()) | |
570 | printk("Attempt to kill tasklet from interrupt\n"); | |
571 | ||
572 | while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { | |
79d381c9 | 573 | do { |
1da177e4 | 574 | yield(); |
79d381c9 | 575 | } while (test_bit(TASKLET_STATE_SCHED, &t->state)); |
1da177e4 LT |
576 | } |
577 | tasklet_unlock_wait(t); | |
578 | clear_bit(TASKLET_STATE_SCHED, &t->state); | |
579 | } | |
580 | ||
581 | EXPORT_SYMBOL(tasklet_kill); | |
582 | ||
9ba5f005 PZ |
583 | /* |
584 | * tasklet_hrtimer | |
585 | */ | |
586 | ||
587 | /* | |
b9c30322 PZ |
588 | * The trampoline is called when the hrtimer expires. It schedules a tasklet |
589 | * to run __tasklet_hrtimer_trampoline() which in turn will call the intended | |
590 | * hrtimer callback, but from softirq context. | |
9ba5f005 PZ |
591 | */ |
592 | static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer) | |
593 | { | |
594 | struct tasklet_hrtimer *ttimer = | |
595 | container_of(timer, struct tasklet_hrtimer, timer); | |
596 | ||
b9c30322 PZ |
597 | tasklet_hi_schedule(&ttimer->tasklet); |
598 | return HRTIMER_NORESTART; | |
9ba5f005 PZ |
599 | } |
600 | ||
601 | /* | |
602 | * Helper function which calls the hrtimer callback from | |
603 | * tasklet/softirq context | |
604 | */ | |
605 | static void __tasklet_hrtimer_trampoline(unsigned long data) | |
606 | { | |
607 | struct tasklet_hrtimer *ttimer = (void *)data; | |
608 | enum hrtimer_restart restart; | |
609 | ||
610 | restart = ttimer->function(&ttimer->timer); | |
611 | if (restart != HRTIMER_NORESTART) | |
612 | hrtimer_restart(&ttimer->timer); | |
613 | } | |
614 | ||
615 | /** | |
616 | * tasklet_hrtimer_init - Init a tasklet/hrtimer combo for softirq callbacks | |
617 | * @ttimer: tasklet_hrtimer which is initialized | |
25985edc | 618 | * @function: hrtimer callback function which gets called from softirq context |
9ba5f005 PZ |
619 | * @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME) |
620 | * @mode: hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL) | |
621 | */ | |
622 | void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer, | |
623 | enum hrtimer_restart (*function)(struct hrtimer *), | |
624 | clockid_t which_clock, enum hrtimer_mode mode) | |
625 | { | |
626 | hrtimer_init(&ttimer->timer, which_clock, mode); | |
627 | ttimer->timer.function = __hrtimer_tasklet_trampoline; | |
628 | tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline, | |
629 | (unsigned long)ttimer); | |
630 | ttimer->function = function; | |
631 | } | |
632 | EXPORT_SYMBOL_GPL(tasklet_hrtimer_init); | |
633 | ||
1da177e4 LT |
634 | void __init softirq_init(void) |
635 | { | |
48f20a9a OJ |
636 | int cpu; |
637 | ||
638 | for_each_possible_cpu(cpu) { | |
639 | per_cpu(tasklet_vec, cpu).tail = | |
640 | &per_cpu(tasklet_vec, cpu).head; | |
641 | per_cpu(tasklet_hi_vec, cpu).tail = | |
642 | &per_cpu(tasklet_hi_vec, cpu).head; | |
643 | } | |
644 | ||
962cf36c CM |
645 | open_softirq(TASKLET_SOFTIRQ, tasklet_action); |
646 | open_softirq(HI_SOFTIRQ, tasklet_hi_action); | |
1da177e4 LT |
647 | } |
648 | ||
3e339b5d | 649 | static int ksoftirqd_should_run(unsigned int cpu) |
1da177e4 | 650 | { |
3e339b5d TG |
651 | return local_softirq_pending(); |
652 | } | |
1da177e4 | 653 | |
3e339b5d TG |
654 | static void run_ksoftirqd(unsigned int cpu) |
655 | { | |
656 | local_irq_disable(); | |
657 | if (local_softirq_pending()) { | |
0bed698a FW |
658 | /* |
659 | * We can safely run softirq on inline stack, as we are not deep | |
660 | * in the task stack here. | |
661 | */ | |
3e339b5d TG |
662 | __do_softirq(); |
663 | rcu_note_context_switch(cpu); | |
664 | local_irq_enable(); | |
665 | cond_resched(); | |
666 | return; | |
1da177e4 | 667 | } |
3e339b5d | 668 | local_irq_enable(); |
1da177e4 LT |
669 | } |
670 | ||
671 | #ifdef CONFIG_HOTPLUG_CPU | |
672 | /* | |
673 | * tasklet_kill_immediate is called to remove a tasklet which can already be | |
674 | * scheduled for execution on @cpu. | |
675 | * | |
676 | * Unlike tasklet_kill, this function removes the tasklet | |
677 | * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state. | |
678 | * | |
679 | * When this function is called, @cpu must be in the CPU_DEAD state. | |
680 | */ | |
681 | void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu) | |
682 | { | |
683 | struct tasklet_struct **i; | |
684 | ||
685 | BUG_ON(cpu_online(cpu)); | |
686 | BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state)); | |
687 | ||
688 | if (!test_bit(TASKLET_STATE_SCHED, &t->state)) | |
689 | return; | |
690 | ||
691 | /* CPU is dead, so no lock needed. */ | |
48f20a9a | 692 | for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) { |
1da177e4 LT |
693 | if (*i == t) { |
694 | *i = t->next; | |
48f20a9a OJ |
695 | /* If this was the tail element, move the tail ptr */ |
696 | if (*i == NULL) | |
697 | per_cpu(tasklet_vec, cpu).tail = i; | |
1da177e4 LT |
698 | return; |
699 | } | |
700 | } | |
701 | BUG(); | |
702 | } | |
703 | ||
704 | static void takeover_tasklets(unsigned int cpu) | |
705 | { | |
1da177e4 LT |
706 | /* CPU is dead, so no lock needed. */ |
707 | local_irq_disable(); | |
708 | ||
709 | /* Find end, append list for that CPU. */ | |
e5e41723 | 710 | if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) { |
909ea964 CL |
711 | *__this_cpu_read(tasklet_vec.tail) = per_cpu(tasklet_vec, cpu).head; |
712 | this_cpu_write(tasklet_vec.tail, per_cpu(tasklet_vec, cpu).tail); | |
e5e41723 CB |
713 | per_cpu(tasklet_vec, cpu).head = NULL; |
714 | per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; | |
715 | } | |
1da177e4 LT |
716 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
717 | ||
e5e41723 | 718 | if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) { |
909ea964 CL |
719 | *__this_cpu_read(tasklet_hi_vec.tail) = per_cpu(tasklet_hi_vec, cpu).head; |
720 | __this_cpu_write(tasklet_hi_vec.tail, per_cpu(tasklet_hi_vec, cpu).tail); | |
e5e41723 CB |
721 | per_cpu(tasklet_hi_vec, cpu).head = NULL; |
722 | per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; | |
723 | } | |
1da177e4 LT |
724 | raise_softirq_irqoff(HI_SOFTIRQ); |
725 | ||
726 | local_irq_enable(); | |
727 | } | |
728 | #endif /* CONFIG_HOTPLUG_CPU */ | |
729 | ||
0db0628d | 730 | static int cpu_callback(struct notifier_block *nfb, |
1da177e4 LT |
731 | unsigned long action, |
732 | void *hcpu) | |
733 | { | |
1da177e4 | 734 | switch (action) { |
1da177e4 | 735 | #ifdef CONFIG_HOTPLUG_CPU |
1da177e4 | 736 | case CPU_DEAD: |
3e339b5d TG |
737 | case CPU_DEAD_FROZEN: |
738 | takeover_tasklets((unsigned long)hcpu); | |
1da177e4 LT |
739 | break; |
740 | #endif /* CONFIG_HOTPLUG_CPU */ | |
3e339b5d | 741 | } |
1da177e4 LT |
742 | return NOTIFY_OK; |
743 | } | |
744 | ||
0db0628d | 745 | static struct notifier_block cpu_nfb = { |
1da177e4 LT |
746 | .notifier_call = cpu_callback |
747 | }; | |
748 | ||
3e339b5d TG |
749 | static struct smp_hotplug_thread softirq_threads = { |
750 | .store = &ksoftirqd, | |
751 | .thread_should_run = ksoftirqd_should_run, | |
752 | .thread_fn = run_ksoftirqd, | |
753 | .thread_comm = "ksoftirqd/%u", | |
754 | }; | |
755 | ||
7babe8db | 756 | static __init int spawn_ksoftirqd(void) |
1da177e4 | 757 | { |
1da177e4 | 758 | register_cpu_notifier(&cpu_nfb); |
3e339b5d TG |
759 | |
760 | BUG_ON(smpboot_register_percpu_thread(&softirq_threads)); | |
761 | ||
1da177e4 LT |
762 | return 0; |
763 | } | |
7babe8db | 764 | early_initcall(spawn_ksoftirqd); |
78eef01b | 765 | |
43a25632 YL |
766 | /* |
767 | * [ These __weak aliases are kept in a separate compilation unit, so that | |
768 | * GCC does not inline them incorrectly. ] | |
769 | */ | |
770 | ||
771 | int __init __weak early_irq_init(void) | |
772 | { | |
773 | return 0; | |
774 | } | |
775 | ||
4a046d17 YL |
776 | int __init __weak arch_probe_nr_irqs(void) |
777 | { | |
b683de2b | 778 | return NR_IRQS_LEGACY; |
4a046d17 YL |
779 | } |
780 | ||
43a25632 YL |
781 | int __init __weak arch_early_irq_init(void) |
782 | { | |
783 | return 0; | |
784 | } |