Blame view
kernel/softirq.c
21 KB
1da177e4c
|
1 2 3 4 5 |
/* * linux/kernel/softirq.c * * Copyright (C) 1992 Linus Torvalds * |
b10db7f0d
|
6 7 8 |
* Distribute under GPLv2. * * Rewritten. Old one was good in 2.2, but in 2.3 it was immoral. --ANK (990903) |
54514a70a
|
9 10 |
* * Remote softirq infrastructure is by Jens Axboe. |
1da177e4c
|
11 |
*/ |
9984de1a5
|
12 |
#include <linux/export.h> |
1da177e4c
|
13 14 15 16 17 18 19 |
#include <linux/kernel_stat.h> #include <linux/interrupt.h> #include <linux/init.h> #include <linux/mm.h> #include <linux/notifier.h> #include <linux/percpu.h> #include <linux/cpu.h> |
831441862
|
20 |
#include <linux/freezer.h> |
1da177e4c
|
21 22 |
#include <linux/kthread.h> #include <linux/rcupdate.h> |
7e49fcce1
|
23 |
#include <linux/ftrace.h> |
78eef01b0
|
24 |
#include <linux/smp.h> |
3e339b5da
|
25 |
#include <linux/smpboot.h> |
79bf2bb33
|
26 |
#include <linux/tick.h> |
a0e39ed37
|
27 28 |
#define CREATE_TRACE_POINTS |
ad8d75fff
|
29 |
#include <trace/events/irq.h> |
1da177e4c
|
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 |
#include <asm/irq.h> /* - No shared variables, all the data are CPU local. - If a softirq needs serialization, let it serialize itself by its own spinlocks. - Even if softirq is serialized, only local cpu is marked for execution. Hence, we get something sort of weak cpu binding. Though it is still not clear, will it result in better locality or will not. Examples: - NET RX softirq. It is multithreaded and does not require any global serialization. - NET TX softirq. It kicks software netdevice queues, hence it is logically serialized per device, but this serialization is invisible to common code. - Tasklets: serialized wrt itself. */ #ifndef __ARCH_IRQ_STAT irq_cpustat_t irq_stat[NR_CPUS] ____cacheline_aligned; EXPORT_SYMBOL(irq_stat); #endif |
978b0116c
|
54 |
static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp; |
1da177e4c
|
55 |
|
4dd53d891
|
56 |
DEFINE_PER_CPU(struct task_struct *, ksoftirqd); |
1da177e4c
|
57 |
|
5d592b44b
|
58 |
char *softirq_to_name[NR_SOFTIRQS] = { |
5dd4de587
|
59 |
"HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "BLOCK_IOPOLL", |
09223371d
|
60 |
"TASKLET", "SCHED", "HRTIMER", "RCU" |
5d592b44b
|
61 |
}; |
1da177e4c
|
62 63 64 65 66 67 |
/* * we cannot loop indefinitely here to avoid userspace starvation, * but we also don't want to introduce a worst case 1/HZ latency * to the pending events, so lets the scheduler to balance * the softirq load for us. */ |
676cb02dc
|
68 |
static void wakeup_softirqd(void) |
1da177e4c
|
69 70 |
{ /* Interrupts are disabled: no need to stop preemption */ |
909ea9646
|
71 |
struct task_struct *tsk = __this_cpu_read(ksoftirqd); |
1da177e4c
|
72 73 74 75 76 77 |
if (tsk && tsk->state != TASK_RUNNING) wake_up_process(tsk); } /* |
75e1056f5
|
78 79 80 81 82 83 84 85 86 87 |
* preempt_count and SOFTIRQ_OFFSET usage: * - preempt_count is changed by SOFTIRQ_OFFSET on entering or leaving * softirq processing. * - preempt_count is changed by SOFTIRQ_DISABLE_OFFSET (= 2 * SOFTIRQ_OFFSET) * on local_bh_disable or local_bh_enable. * This lets us distinguish between whether we are currently processing * softirq and whether we just have bh disabled. */ /* |
de30a2b35
|
88 89 90 |
* This one is for softirq.c-internal use, * where hardirqs are disabled legitimately: */ |
3c829c367
|
91 |
#ifdef CONFIG_TRACE_IRQFLAGS |
75e1056f5
|
92 |
static void __local_bh_disable(unsigned long ip, unsigned int cnt) |
de30a2b35
|
93 94 95 96 97 98 |
{ unsigned long flags; WARN_ON_ONCE(in_irq()); raw_local_irq_save(flags); |
7e49fcce1
|
99 100 101 102 103 104 105 |
/* * The preempt tracer hooks into add_preempt_count and will break * lockdep because it calls back into lockdep after SOFTIRQ_OFFSET * is set and before current->softirq_enabled is cleared. * We must manually increment preempt_count here and manually * call the trace_preempt_off later. */ |
75e1056f5
|
106 |
preempt_count() += cnt; |
de30a2b35
|
107 108 109 |
/* * Were softirqs turned off above: */ |
75e1056f5
|
110 |
if (softirq_count() == cnt) |
de30a2b35
|
111 112 |
trace_softirqs_off(ip); raw_local_irq_restore(flags); |
7e49fcce1
|
113 |
|
75e1056f5
|
114 |
if (preempt_count() == cnt) |
7e49fcce1
|
115 |
trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); |
de30a2b35
|
116 |
} |
3c829c367
|
117 |
#else /* !CONFIG_TRACE_IRQFLAGS */ |
75e1056f5
|
118 |
static inline void __local_bh_disable(unsigned long ip, unsigned int cnt) |
3c829c367
|
119 |
{ |
75e1056f5
|
120 |
add_preempt_count(cnt); |
3c829c367
|
121 122 123 |
barrier(); } #endif /* CONFIG_TRACE_IRQFLAGS */ |
de30a2b35
|
124 125 126 |
void local_bh_disable(void) { |
d2e08473f
|
127 |
__local_bh_disable(_RET_IP_, SOFTIRQ_DISABLE_OFFSET); |
de30a2b35
|
128 129 130 |
} EXPORT_SYMBOL(local_bh_disable); |
75e1056f5
|
131 132 133 134 135 136 |
static void __local_bh_enable(unsigned int cnt) { WARN_ON_ONCE(in_irq()); WARN_ON_ONCE(!irqs_disabled()); if (softirq_count() == cnt) |
d2e08473f
|
137 |
trace_softirqs_on(_RET_IP_); |
75e1056f5
|
138 139 |
sub_preempt_count(cnt); } |
de30a2b35
|
140 141 142 143 144 145 146 |
/* * Special-case - softirqs can safely be enabled in * cond_resched_softirq(), or by __do_softirq(), * without processing still-pending softirqs: */ void _local_bh_enable(void) { |
75e1056f5
|
147 |
__local_bh_enable(SOFTIRQ_DISABLE_OFFSET); |
de30a2b35
|
148 149 150 |
} EXPORT_SYMBOL(_local_bh_enable); |
0f476b6d9
|
151 |
static inline void _local_bh_enable_ip(unsigned long ip) |
de30a2b35
|
152 |
{ |
0f476b6d9
|
153 |
WARN_ON_ONCE(in_irq() || irqs_disabled()); |
3c829c367
|
154 |
#ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d9
|
155 |
local_irq_disable(); |
3c829c367
|
156 |
#endif |
de30a2b35
|
157 158 159 |
/* * Are softirqs going to be turned on now: */ |
75e1056f5
|
160 |
if (softirq_count() == SOFTIRQ_DISABLE_OFFSET) |
0f476b6d9
|
161 |
trace_softirqs_on(ip); |
de30a2b35
|
162 163 164 165 |
/* * Keep preemption disabled until we are done with * softirq processing: */ |
75e1056f5
|
166 |
sub_preempt_count(SOFTIRQ_DISABLE_OFFSET - 1); |
de30a2b35
|
167 168 169 170 171 |
if (unlikely(!in_interrupt() && local_softirq_pending())) do_softirq(); dec_preempt_count(); |
3c829c367
|
172 |
#ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d9
|
173 |
local_irq_enable(); |
3c829c367
|
174 |
#endif |
de30a2b35
|
175 176 |
preempt_check_resched(); } |
0f476b6d9
|
177 178 179 |
void local_bh_enable(void) { |
d2e08473f
|
180 |
_local_bh_enable_ip(_RET_IP_); |
0f476b6d9
|
181 |
} |
de30a2b35
|
182 183 184 185 |
EXPORT_SYMBOL(local_bh_enable); void local_bh_enable_ip(unsigned long ip) { |
0f476b6d9
|
186 |
_local_bh_enable_ip(ip); |
de30a2b35
|
187 188 189 190 |
} EXPORT_SYMBOL(local_bh_enable_ip); /* |
34376a50f
|
191 192 193 194 195 196 |
* We restart softirq processing for at most MAX_SOFTIRQ_RESTART times, * but break the loop if need_resched() is set or after 2 ms. * The MAX_SOFTIRQ_TIME provides a nice upper bound in most cases, but in * certain cases, such as stop_machine(), jiffies may cease to * increment and so we need the MAX_SOFTIRQ_RESTART limit as * well to make sure we eventually return from this method. |
1da177e4c
|
197 |
* |
c10d73671
|
198 |
* These limits have been established via experimentation. |
1da177e4c
|
199 200 201 202 |
* The two things to balance is latency against fairness - * we want to handle softirqs as soon as possible, but they * should not be able to lock up the box. */ |
c10d73671
|
203 |
#define MAX_SOFTIRQ_TIME msecs_to_jiffies(2) |
34376a50f
|
204 |
#define MAX_SOFTIRQ_RESTART 10 |
1da177e4c
|
205 206 207 208 209 |
asmlinkage void __do_softirq(void) { struct softirq_action *h; __u32 pending; |
c10d73671
|
210 |
unsigned long end = jiffies + MAX_SOFTIRQ_TIME; |
1da177e4c
|
211 |
int cpu; |
907aed48f
|
212 |
unsigned long old_flags = current->flags; |
34376a50f
|
213 |
int max_restart = MAX_SOFTIRQ_RESTART; |
907aed48f
|
214 215 216 217 218 219 220 |
/* * Mask out PF_MEMALLOC s current task context is borrowed for the * softirq. A softirq handled such as network RX might set PF_MEMALLOC * again if the socket is related to swap */ current->flags &= ~PF_MEMALLOC; |
1da177e4c
|
221 222 |
pending = local_softirq_pending(); |
6a61671bb
|
223 |
account_irq_enter_time(current); |
829035fd7
|
224 |
|
d2e08473f
|
225 |
__local_bh_disable(_RET_IP_, SOFTIRQ_OFFSET); |
d820ac4c2
|
226 |
lockdep_softirq_enter(); |
1da177e4c
|
227 |
|
1da177e4c
|
228 229 230 |
cpu = smp_processor_id(); restart: /* Reset the pending bitmask before enabling irqs */ |
3f74478b5
|
231 |
set_softirq_pending(0); |
1da177e4c
|
232 |
|
c70f5d661
|
233 |
local_irq_enable(); |
1da177e4c
|
234 235 236 237 238 |
h = softirq_vec; do { if (pending & 1) { |
f4bc6bb2d
|
239 |
unsigned int vec_nr = h - softirq_vec; |
8e85b4b55
|
240 |
int prev_count = preempt_count(); |
f4bc6bb2d
|
241 242 243 |
kstat_incr_softirqs_this_cpu(vec_nr); trace_softirq_entry(vec_nr); |
1da177e4c
|
244 |
h->action(h); |
f4bc6bb2d
|
245 |
trace_softirq_exit(vec_nr); |
8e85b4b55
|
246 |
if (unlikely(prev_count != preempt_count())) { |
f4bc6bb2d
|
247 |
printk(KERN_ERR "huh, entered softirq %u %s %p" |
8e85b4b55
|
248 |
"with preempt_count %08x," |
f4bc6bb2d
|
249 250 251 252 |
" exited with %08x? ", vec_nr, softirq_to_name[vec_nr], h->action, prev_count, preempt_count()); |
8e85b4b55
|
253 254 |
preempt_count() = prev_count; } |
d6714c22b
|
255 |
rcu_bh_qs(cpu); |
1da177e4c
|
256 257 258 259 |
} h++; pending >>= 1; } while (pending); |
c70f5d661
|
260 |
local_irq_disable(); |
1da177e4c
|
261 262 |
pending = local_softirq_pending(); |
c10d73671
|
263 |
if (pending) { |
34376a50f
|
264 265 |
if (time_before(jiffies, end) && !need_resched() && --max_restart) |
c10d73671
|
266 |
goto restart; |
1da177e4c
|
267 |
|
1da177e4c
|
268 |
wakeup_softirqd(); |
c10d73671
|
269 |
} |
1da177e4c
|
270 |
|
d820ac4c2
|
271 |
lockdep_softirq_exit(); |
829035fd7
|
272 |
|
6a61671bb
|
273 |
account_irq_exit_time(current); |
75e1056f5
|
274 |
__local_bh_enable(SOFTIRQ_OFFSET); |
907aed48f
|
275 |
tsk_restore_flags(current, old_flags, PF_MEMALLOC); |
1da177e4c
|
276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 |
} #ifndef __ARCH_HAS_DO_SOFTIRQ asmlinkage void do_softirq(void) { __u32 pending; unsigned long flags; if (in_interrupt()) return; local_irq_save(flags); pending = local_softirq_pending(); if (pending) __do_softirq(); local_irq_restore(flags); } |
1da177e4c
|
297 |
#endif |
dde4b2b5f
|
298 299 300 301 302 |
/* * Enter an interrupt context. */ void irq_enter(void) { |
6378ddb59
|
303 |
int cpu = smp_processor_id(); |
719254faa
|
304 |
|
64db4cfff
|
305 |
rcu_irq_enter(); |
0a8a2e78b
|
306 |
if (is_idle_task(current) && !in_interrupt()) { |
d267f87fb
|
307 308 309 310 311 |
/* * Prevent raise_softirq from needlessly waking up ksoftirqd * here, as softirq will be serviced on return from interrupt. */ local_bh_disable(); |
719254faa
|
312 |
tick_check_idle(cpu); |
d267f87fb
|
313 314 315 316 |
_local_bh_enable(); } __irq_enter(); |
dde4b2b5f
|
317 |
} |
8d32a307e
|
318 319 |
static inline void invoke_softirq(void) { |
facd8b80c
|
320 |
if (!force_irqthreads) |
8d32a307e
|
321 |
__do_softirq(); |
facd8b80c
|
322 |
else |
8d32a307e
|
323 324 |
wakeup_softirqd(); } |
1da177e4c
|
325 |
|
67826eae8
|
326 327 328 329 330 331 332 333 334 335 336 337 |
static inline void tick_irq_exit(void) { #ifdef CONFIG_NO_HZ_COMMON int cpu = smp_processor_id(); /* Make sure that timer wheel updates are propagated */ if ((idle_cpu(cpu) && !need_resched()) || tick_nohz_full_cpu(cpu)) { if (!in_interrupt()) tick_nohz_irq_exit(); } #endif } |
1da177e4c
|
338 339 340 341 342 |
/* * Exit an interrupt context. Process softirqs if needed and possible: */ void irq_exit(void) { |
74eed0163
|
343 |
#ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED |
4cd5d1115
|
344 |
local_irq_disable(); |
74eed0163
|
345 346 347 |
#else WARN_ON_ONCE(!irqs_disabled()); #endif |
6a61671bb
|
348 |
account_irq_exit_time(current); |
de30a2b35
|
349 |
trace_hardirq_exit(); |
4d4c4e24c
|
350 |
sub_preempt_count(HARDIRQ_OFFSET); |
1da177e4c
|
351 352 |
if (!in_interrupt() && local_softirq_pending()) invoke_softirq(); |
79bf2bb33
|
353 |
|
67826eae8
|
354 |
tick_irq_exit(); |
416eb33cd
|
355 |
rcu_irq_exit(); |
1da177e4c
|
356 357 358 359 360 |
} /* * This function must run with irqs disabled! */ |
7ad5b3a50
|
361 |
inline void raise_softirq_irqoff(unsigned int nr) |
1da177e4c
|
362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 |
{ __raise_softirq_irqoff(nr); /* * If we're in an interrupt or softirq, we're done * (this also catches softirq-disabled code). We will * actually run the softirq once we return from * the irq or softirq. * * Otherwise we wake up ksoftirqd to make sure we * schedule the softirq soon. */ if (!in_interrupt()) wakeup_softirqd(); } |
7ad5b3a50
|
377 |
void raise_softirq(unsigned int nr) |
1da177e4c
|
378 379 380 381 382 383 384 |
{ unsigned long flags; local_irq_save(flags); raise_softirq_irqoff(nr); local_irq_restore(flags); } |
f069686e4
|
385 386 387 388 389 |
void __raise_softirq_irqoff(unsigned int nr) { trace_softirq_raise(nr); or_softirq_pending(1UL << nr); } |
962cf36c5
|
390 |
void open_softirq(int nr, void (*action)(struct softirq_action *)) |
1da177e4c
|
391 |
{ |
1da177e4c
|
392 393 |
softirq_vec[nr].action = action; } |
9ba5f005c
|
394 395 396 |
/* * Tasklets */ |
1da177e4c
|
397 398 |
struct tasklet_head { |
48f20a9a9
|
399 400 |
struct tasklet_struct *head; struct tasklet_struct **tail; |
1da177e4c
|
401 |
}; |
4620b49f7
|
402 403 |
static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec); static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec); |
1da177e4c
|
404 |
|
7ad5b3a50
|
405 |
void __tasklet_schedule(struct tasklet_struct *t) |
1da177e4c
|
406 407 408 409 |
{ unsigned long flags; local_irq_save(flags); |
48f20a9a9
|
410 |
t->next = NULL; |
909ea9646
|
411 412 |
*__this_cpu_read(tasklet_vec.tail) = t; __this_cpu_write(tasklet_vec.tail, &(t->next)); |
1da177e4c
|
413 414 415 416 417 |
raise_softirq_irqoff(TASKLET_SOFTIRQ); local_irq_restore(flags); } EXPORT_SYMBOL(__tasklet_schedule); |
7ad5b3a50
|
418 |
void __tasklet_hi_schedule(struct tasklet_struct *t) |
1da177e4c
|
419 420 421 422 |
{ unsigned long flags; local_irq_save(flags); |
48f20a9a9
|
423 |
t->next = NULL; |
909ea9646
|
424 425 |
*__this_cpu_read(tasklet_hi_vec.tail) = t; __this_cpu_write(tasklet_hi_vec.tail, &(t->next)); |
1da177e4c
|
426 427 428 429 430 |
raise_softirq_irqoff(HI_SOFTIRQ); local_irq_restore(flags); } EXPORT_SYMBOL(__tasklet_hi_schedule); |
7c692cbad
|
431 432 433 |
void __tasklet_hi_schedule_first(struct tasklet_struct *t) { BUG_ON(!irqs_disabled()); |
909ea9646
|
434 435 |
t->next = __this_cpu_read(tasklet_hi_vec.head); __this_cpu_write(tasklet_hi_vec.head, t); |
7c692cbad
|
436 437 438 439 |
__raise_softirq_irqoff(HI_SOFTIRQ); } EXPORT_SYMBOL(__tasklet_hi_schedule_first); |
1da177e4c
|
440 441 442 443 444 |
static void tasklet_action(struct softirq_action *a) { struct tasklet_struct *list; local_irq_disable(); |
909ea9646
|
445 446 447 |
list = __this_cpu_read(tasklet_vec.head); __this_cpu_write(tasklet_vec.head, NULL); __this_cpu_write(tasklet_vec.tail, &__get_cpu_var(tasklet_vec).head); |
1da177e4c
|
448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 |
local_irq_enable(); while (list) { struct tasklet_struct *t = list; list = list->next; if (tasklet_trylock(t)) { if (!atomic_read(&t->count)) { if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) BUG(); t->func(t->data); tasklet_unlock(t); continue; } tasklet_unlock(t); } local_irq_disable(); |
48f20a9a9
|
467 |
t->next = NULL; |
909ea9646
|
468 469 |
*__this_cpu_read(tasklet_vec.tail) = t; __this_cpu_write(tasklet_vec.tail, &(t->next)); |
1da177e4c
|
470 471 472 473 474 475 476 477 478 479 |
__raise_softirq_irqoff(TASKLET_SOFTIRQ); local_irq_enable(); } } static void tasklet_hi_action(struct softirq_action *a) { struct tasklet_struct *list; local_irq_disable(); |
909ea9646
|
480 481 482 |
list = __this_cpu_read(tasklet_hi_vec.head); __this_cpu_write(tasklet_hi_vec.head, NULL); __this_cpu_write(tasklet_hi_vec.tail, &__get_cpu_var(tasklet_hi_vec).head); |
1da177e4c
|
483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 |
local_irq_enable(); while (list) { struct tasklet_struct *t = list; list = list->next; if (tasklet_trylock(t)) { if (!atomic_read(&t->count)) { if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) BUG(); t->func(t->data); tasklet_unlock(t); continue; } tasklet_unlock(t); } local_irq_disable(); |
48f20a9a9
|
502 |
t->next = NULL; |
909ea9646
|
503 504 |
*__this_cpu_read(tasklet_hi_vec.tail) = t; __this_cpu_write(tasklet_hi_vec.tail, &(t->next)); |
1da177e4c
|
505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 |
__raise_softirq_irqoff(HI_SOFTIRQ); local_irq_enable(); } } void tasklet_init(struct tasklet_struct *t, void (*func)(unsigned long), unsigned long data) { t->next = NULL; t->state = 0; atomic_set(&t->count, 0); t->func = func; t->data = data; } EXPORT_SYMBOL(tasklet_init); void tasklet_kill(struct tasklet_struct *t) { if (in_interrupt()) printk("Attempt to kill tasklet from interrupt "); while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { |
79d381c9f
|
530 |
do { |
1da177e4c
|
531 |
yield(); |
79d381c9f
|
532 |
} while (test_bit(TASKLET_STATE_SCHED, &t->state)); |
1da177e4c
|
533 534 535 536 537 538 |
} tasklet_unlock_wait(t); clear_bit(TASKLET_STATE_SCHED, &t->state); } EXPORT_SYMBOL(tasklet_kill); |
9ba5f005c
|
539 540 541 542 543 |
/* * tasklet_hrtimer */ /* |
b9c303227
|
544 545 546 |
* The trampoline is called when the hrtimer expires. It schedules a tasklet * to run __tasklet_hrtimer_trampoline() which in turn will call the intended * hrtimer callback, but from softirq context. |
9ba5f005c
|
547 548 549 550 551 |
*/ static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer) { struct tasklet_hrtimer *ttimer = container_of(timer, struct tasklet_hrtimer, timer); |
b9c303227
|
552 553 |
tasklet_hi_schedule(&ttimer->tasklet); return HRTIMER_NORESTART; |
9ba5f005c
|
554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 |
} /* * Helper function which calls the hrtimer callback from * tasklet/softirq context */ static void __tasklet_hrtimer_trampoline(unsigned long data) { struct tasklet_hrtimer *ttimer = (void *)data; enum hrtimer_restart restart; restart = ttimer->function(&ttimer->timer); if (restart != HRTIMER_NORESTART) hrtimer_restart(&ttimer->timer); } /** * tasklet_hrtimer_init - Init a tasklet/hrtimer combo for softirq callbacks * @ttimer: tasklet_hrtimer which is initialized |
25985edce
|
573 |
* @function: hrtimer callback function which gets called from softirq context |
9ba5f005c
|
574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 |
* @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME) * @mode: hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL) */ void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer, enum hrtimer_restart (*function)(struct hrtimer *), clockid_t which_clock, enum hrtimer_mode mode) { hrtimer_init(&ttimer->timer, which_clock, mode); ttimer->timer.function = __hrtimer_tasklet_trampoline; tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline, (unsigned long)ttimer); ttimer->function = function; } EXPORT_SYMBOL_GPL(tasklet_hrtimer_init); /* * Remote softirq bits */ |
54514a70a
|
592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 |
DEFINE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list); EXPORT_PER_CPU_SYMBOL(softirq_work_list); static void __local_trigger(struct call_single_data *cp, int softirq) { struct list_head *head = &__get_cpu_var(softirq_work_list[softirq]); list_add_tail(&cp->list, head); /* Trigger the softirq only if the list was previously empty. */ if (head->next == &cp->list) raise_softirq_irqoff(softirq); } #ifdef CONFIG_USE_GENERIC_SMP_HELPERS static void remote_softirq_receive(void *data) { struct call_single_data *cp = data; unsigned long flags; int softirq; |
3440a1ca9
|
612 |
softirq = *(int *)cp->info; |
54514a70a
|
613 614 615 616 617 618 619 620 621 |
local_irq_save(flags); __local_trigger(cp, softirq); local_irq_restore(flags); } static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) { if (cpu_online(cpu)) { cp->func = remote_softirq_receive; |
3440a1ca9
|
622 |
cp->info = &softirq; |
54514a70a
|
623 |
cp->flags = 0; |
54514a70a
|
624 |
|
6e2756376
|
625 |
__smp_call_function_single(cpu, cp, 0); |
54514a70a
|
626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 |
return 0; } return 1; } #else /* CONFIG_USE_GENERIC_SMP_HELPERS */ static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) { return 1; } #endif /** * __send_remote_softirq - try to schedule softirq work on a remote cpu * @cp: private SMP call function data area * @cpu: the remote cpu * @this_cpu: the currently executing cpu * @softirq: the softirq for the work * * Attempt to schedule softirq work on a remote cpu. If this cannot be * done, the work is instead queued up on the local cpu. * * Interrupts must be disabled. */ void __send_remote_softirq(struct call_single_data *cp, int cpu, int this_cpu, int softirq) { if (cpu == this_cpu || __try_remote_softirq(cp, cpu, softirq)) __local_trigger(cp, softirq); } EXPORT_SYMBOL(__send_remote_softirq); /** * send_remote_softirq - try to schedule softirq work on a remote cpu * @cp: private SMP call function data area * @cpu: the remote cpu * @softirq: the softirq for the work * * Like __send_remote_softirq except that disabling interrupts and * computing the current cpu is done for the caller. */ void send_remote_softirq(struct call_single_data *cp, int cpu, int softirq) { unsigned long flags; int this_cpu; local_irq_save(flags); this_cpu = smp_processor_id(); __send_remote_softirq(cp, cpu, this_cpu, softirq); local_irq_restore(flags); } EXPORT_SYMBOL(send_remote_softirq); |
0db0628d9
|
676 |
static int remote_softirq_cpu_notify(struct notifier_block *self, |
54514a70a
|
677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 |
unsigned long action, void *hcpu) { /* * If a CPU goes away, splice its entries to the current CPU * and trigger a run of the softirq */ if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { int cpu = (unsigned long) hcpu; int i; local_irq_disable(); for (i = 0; i < NR_SOFTIRQS; i++) { struct list_head *head = &per_cpu(softirq_work_list[i], cpu); struct list_head *local_head; if (list_empty(head)) continue; local_head = &__get_cpu_var(softirq_work_list[i]); list_splice_init(head, local_head); raise_softirq_irqoff(i); } local_irq_enable(); } return NOTIFY_OK; } |
0db0628d9
|
704 |
static struct notifier_block remote_softirq_cpu_notifier = { |
54514a70a
|
705 706 |
.notifier_call = remote_softirq_cpu_notify, }; |
1da177e4c
|
707 708 |
void __init softirq_init(void) { |
48f20a9a9
|
709 710 711 |
int cpu; for_each_possible_cpu(cpu) { |
54514a70a
|
712 |
int i; |
48f20a9a9
|
713 714 715 716 |
per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; |
54514a70a
|
717 718 |
for (i = 0; i < NR_SOFTIRQS; i++) INIT_LIST_HEAD(&per_cpu(softirq_work_list[i], cpu)); |
48f20a9a9
|
719 |
} |
54514a70a
|
720 |
register_hotcpu_notifier(&remote_softirq_cpu_notifier); |
962cf36c5
|
721 722 |
open_softirq(TASKLET_SOFTIRQ, tasklet_action); open_softirq(HI_SOFTIRQ, tasklet_hi_action); |
1da177e4c
|
723 |
} |
3e339b5da
|
724 |
static int ksoftirqd_should_run(unsigned int cpu) |
1da177e4c
|
725 |
{ |
3e339b5da
|
726 727 |
return local_softirq_pending(); } |
1da177e4c
|
728 |
|
3e339b5da
|
729 730 731 732 733 734 735 736 737 |
static void run_ksoftirqd(unsigned int cpu) { local_irq_disable(); if (local_softirq_pending()) { __do_softirq(); rcu_note_context_switch(cpu); local_irq_enable(); cond_resched(); return; |
1da177e4c
|
738 |
} |
3e339b5da
|
739 |
local_irq_enable(); |
1da177e4c
|
740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 |
} #ifdef CONFIG_HOTPLUG_CPU /* * tasklet_kill_immediate is called to remove a tasklet which can already be * scheduled for execution on @cpu. * * Unlike tasklet_kill, this function removes the tasklet * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state. * * When this function is called, @cpu must be in the CPU_DEAD state. */ void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu) { struct tasklet_struct **i; BUG_ON(cpu_online(cpu)); BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state)); if (!test_bit(TASKLET_STATE_SCHED, &t->state)) return; /* CPU is dead, so no lock needed. */ |
48f20a9a9
|
763 |
for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) { |
1da177e4c
|
764 765 |
if (*i == t) { *i = t->next; |
48f20a9a9
|
766 767 768 |
/* If this was the tail element, move the tail ptr */ if (*i == NULL) per_cpu(tasklet_vec, cpu).tail = i; |
1da177e4c
|
769 770 771 772 773 774 775 776 |
return; } } BUG(); } static void takeover_tasklets(unsigned int cpu) { |
1da177e4c
|
777 778 779 780 |
/* CPU is dead, so no lock needed. */ local_irq_disable(); /* Find end, append list for that CPU. */ |
e5e417232
|
781 |
if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) { |
909ea9646
|
782 783 |
*__this_cpu_read(tasklet_vec.tail) = per_cpu(tasklet_vec, cpu).head; this_cpu_write(tasklet_vec.tail, per_cpu(tasklet_vec, cpu).tail); |
e5e417232
|
784 785 786 |
per_cpu(tasklet_vec, cpu).head = NULL; per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; } |
1da177e4c
|
787 |
raise_softirq_irqoff(TASKLET_SOFTIRQ); |
e5e417232
|
788 |
if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) { |
909ea9646
|
789 790 |
*__this_cpu_read(tasklet_hi_vec.tail) = per_cpu(tasklet_hi_vec, cpu).head; __this_cpu_write(tasklet_hi_vec.tail, per_cpu(tasklet_hi_vec, cpu).tail); |
e5e417232
|
791 792 793 |
per_cpu(tasklet_hi_vec, cpu).head = NULL; per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; } |
1da177e4c
|
794 795 796 797 798 |
raise_softirq_irqoff(HI_SOFTIRQ); local_irq_enable(); } #endif /* CONFIG_HOTPLUG_CPU */ |
0db0628d9
|
799 |
static int cpu_callback(struct notifier_block *nfb, |
1da177e4c
|
800 801 802 |
unsigned long action, void *hcpu) { |
1da177e4c
|
803 |
switch (action) { |
1da177e4c
|
804 |
#ifdef CONFIG_HOTPLUG_CPU |
1da177e4c
|
805 |
case CPU_DEAD: |
3e339b5da
|
806 807 |
case CPU_DEAD_FROZEN: takeover_tasklets((unsigned long)hcpu); |
1da177e4c
|
808 809 |
break; #endif /* CONFIG_HOTPLUG_CPU */ |
3e339b5da
|
810 |
} |
1da177e4c
|
811 812 |
return NOTIFY_OK; } |
0db0628d9
|
813 |
static struct notifier_block cpu_nfb = { |
1da177e4c
|
814 815 |
.notifier_call = cpu_callback }; |
3e339b5da
|
816 817 818 819 820 821 |
static struct smp_hotplug_thread softirq_threads = { .store = &ksoftirqd, .thread_should_run = ksoftirqd_should_run, .thread_fn = run_ksoftirqd, .thread_comm = "ksoftirqd/%u", }; |
7babe8db9
|
822 |
static __init int spawn_ksoftirqd(void) |
1da177e4c
|
823 |
{ |
1da177e4c
|
824 |
register_cpu_notifier(&cpu_nfb); |
3e339b5da
|
825 826 |
BUG_ON(smpboot_register_percpu_thread(&softirq_threads)); |
1da177e4c
|
827 828 |
return 0; } |
7babe8db9
|
829 |
early_initcall(spawn_ksoftirqd); |
78eef01b0
|
830 |
|
43a256322
|
831 832 833 834 835 836 837 838 839 |
/* * [ These __weak aliases are kept in a separate compilation unit, so that * GCC does not inline them incorrectly. ] */ int __init __weak early_irq_init(void) { return 0; } |
b683de2b3
|
840 |
#ifdef CONFIG_GENERIC_HARDIRQS |
4a046d175
|
841 842 |
int __init __weak arch_probe_nr_irqs(void) { |
b683de2b3
|
843 |
return NR_IRQS_LEGACY; |
4a046d175
|
844 |
} |
43a256322
|
845 846 847 848 |
int __init __weak arch_early_irq_init(void) { return 0; } |
b683de2b3
|
849 |
#endif |