Commit | Line | Data |
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767a67b0 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* |
3 | * linux/kernel/softirq.c | |
4 | * | |
5 | * Copyright (C) 1992 Linus Torvalds | |
6 | * | |
b10db7f0 | 7 | * Rewritten. Old one was good in 2.2, but in 2.3 it was immoral. --ANK (990903) |
1da177e4 LT |
8 | */ |
9 | ||
40322764 JP |
10 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
11 | ||
9984de1a | 12 | #include <linux/export.h> |
1da177e4 LT |
13 | #include <linux/kernel_stat.h> |
14 | #include <linux/interrupt.h> | |
15 | #include <linux/init.h> | |
8b1c04ac | 16 | #include <linux/local_lock.h> |
1da177e4 LT |
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> |
d532676c | 28 | #include <linux/irq.h> |
da044747 | 29 | #include <linux/wait_bit.h> |
a0e39ed3 | 30 | |
db1cc7ae TG |
31 | #include <asm/softirq_stack.h> |
32 | ||
a0e39ed3 | 33 | #define CREATE_TRACE_POINTS |
ad8d75ff | 34 | #include <trace/events/irq.h> |
1da177e4 | 35 | |
1da177e4 LT |
36 | /* |
37 | - No shared variables, all the data are CPU local. | |
38 | - If a softirq needs serialization, let it serialize itself | |
39 | by its own spinlocks. | |
40 | - Even if softirq is serialized, only local cpu is marked for | |
41 | execution. Hence, we get something sort of weak cpu binding. | |
42 | Though it is still not clear, will it result in better locality | |
43 | or will not. | |
44 | ||
45 | Examples: | |
46 | - NET RX softirq. It is multithreaded and does not require | |
47 | any global serialization. | |
48 | - NET TX softirq. It kicks software netdevice queues, hence | |
49 | it is logically serialized per device, but this serialization | |
50 | is invisible to common code. | |
51 | - Tasklets: serialized wrt itself. | |
52 | */ | |
53 | ||
54 | #ifndef __ARCH_IRQ_STAT | |
0f6f47ba FW |
55 | DEFINE_PER_CPU_ALIGNED(irq_cpustat_t, irq_stat); |
56 | EXPORT_PER_CPU_SYMBOL(irq_stat); | |
1da177e4 LT |
57 | #endif |
58 | ||
978b0116 | 59 | static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp; |
1da177e4 | 60 | |
4dd53d89 | 61 | DEFINE_PER_CPU(struct task_struct *, ksoftirqd); |
1da177e4 | 62 | |
ce85b4f2 | 63 | const char * const softirq_to_name[NR_SOFTIRQS] = { |
f660f606 | 64 | "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "IRQ_POLL", |
09223371 | 65 | "TASKLET", "SCHED", "HRTIMER", "RCU" |
5d592b44 JB |
66 | }; |
67 | ||
1da177e4 LT |
68 | /* |
69 | * we cannot loop indefinitely here to avoid userspace starvation, | |
70 | * but we also don't want to introduce a worst case 1/HZ latency | |
71 | * to the pending events, so lets the scheduler to balance | |
72 | * the softirq load for us. | |
73 | */ | |
676cb02d | 74 | static void wakeup_softirqd(void) |
1da177e4 LT |
75 | { |
76 | /* Interrupts are disabled: no need to stop preemption */ | |
909ea964 | 77 | struct task_struct *tsk = __this_cpu_read(ksoftirqd); |
1da177e4 | 78 | |
37aadc68 | 79 | if (tsk) |
1da177e4 LT |
80 | wake_up_process(tsk); |
81 | } | |
82 | ||
4cd13c21 ED |
83 | /* |
84 | * If ksoftirqd is scheduled, we do not want to process pending softirqs | |
3c53776e LT |
85 | * right now. Let ksoftirqd handle this at its own rate, to get fairness, |
86 | * unless we're doing some of the synchronous softirqs. | |
4cd13c21 | 87 | */ |
3c53776e LT |
88 | #define SOFTIRQ_NOW_MASK ((1 << HI_SOFTIRQ) | (1 << TASKLET_SOFTIRQ)) |
89 | static bool ksoftirqd_running(unsigned long pending) | |
4cd13c21 ED |
90 | { |
91 | struct task_struct *tsk = __this_cpu_read(ksoftirqd); | |
92 | ||
3c53776e LT |
93 | if (pending & SOFTIRQ_NOW_MASK) |
94 | return false; | |
b03fbd4f | 95 | return tsk && task_is_running(tsk) && !__kthread_should_park(tsk); |
4cd13c21 ED |
96 | } |
97 | ||
ae9ef589 TG |
98 | #ifdef CONFIG_TRACE_IRQFLAGS |
99 | DEFINE_PER_CPU(int, hardirqs_enabled); | |
100 | DEFINE_PER_CPU(int, hardirq_context); | |
101 | EXPORT_PER_CPU_SYMBOL_GPL(hardirqs_enabled); | |
102 | EXPORT_PER_CPU_SYMBOL_GPL(hardirq_context); | |
103 | #endif | |
104 | ||
75e1056f | 105 | /* |
8b1c04ac TG |
106 | * SOFTIRQ_OFFSET usage: |
107 | * | |
108 | * On !RT kernels 'count' is the preempt counter, on RT kernels this applies | |
109 | * to a per CPU counter and to task::softirqs_disabled_cnt. | |
110 | * | |
111 | * - count is changed by SOFTIRQ_OFFSET on entering or leaving softirq | |
112 | * processing. | |
113 | * | |
114 | * - count is changed by SOFTIRQ_DISABLE_OFFSET (= 2 * SOFTIRQ_OFFSET) | |
75e1056f | 115 | * on local_bh_disable or local_bh_enable. |
8b1c04ac | 116 | * |
75e1056f VP |
117 | * This lets us distinguish between whether we are currently processing |
118 | * softirq and whether we just have bh disabled. | |
119 | */ | |
8b1c04ac TG |
120 | #ifdef CONFIG_PREEMPT_RT |
121 | ||
122 | /* | |
123 | * RT accounts for BH disabled sections in task::softirqs_disabled_cnt and | |
124 | * also in per CPU softirq_ctrl::cnt. This is necessary to allow tasks in a | |
125 | * softirq disabled section to be preempted. | |
126 | * | |
127 | * The per task counter is used for softirq_count(), in_softirq() and | |
128 | * in_serving_softirqs() because these counts are only valid when the task | |
129 | * holding softirq_ctrl::lock is running. | |
130 | * | |
131 | * The per CPU counter prevents pointless wakeups of ksoftirqd in case that | |
132 | * the task which is in a softirq disabled section is preempted or blocks. | |
133 | */ | |
134 | struct softirq_ctrl { | |
135 | local_lock_t lock; | |
136 | int cnt; | |
137 | }; | |
138 | ||
139 | static DEFINE_PER_CPU(struct softirq_ctrl, softirq_ctrl) = { | |
140 | .lock = INIT_LOCAL_LOCK(softirq_ctrl.lock), | |
141 | }; | |
142 | ||
47c218dc TG |
143 | /** |
144 | * local_bh_blocked() - Check for idle whether BH processing is blocked | |
145 | * | |
146 | * Returns false if the per CPU softirq::cnt is 0 otherwise true. | |
147 | * | |
148 | * This is invoked from the idle task to guard against false positive | |
149 | * softirq pending warnings, which would happen when the task which holds | |
150 | * softirq_ctrl::lock was the only running task on the CPU and blocks on | |
151 | * some other lock. | |
152 | */ | |
153 | bool local_bh_blocked(void) | |
154 | { | |
155 | return __this_cpu_read(softirq_ctrl.cnt) != 0; | |
156 | } | |
157 | ||
8b1c04ac TG |
158 | void __local_bh_disable_ip(unsigned long ip, unsigned int cnt) |
159 | { | |
160 | unsigned long flags; | |
161 | int newcnt; | |
162 | ||
163 | WARN_ON_ONCE(in_hardirq()); | |
164 | ||
165 | /* First entry of a task into a BH disabled section? */ | |
166 | if (!current->softirq_disable_cnt) { | |
167 | if (preemptible()) { | |
168 | local_lock(&softirq_ctrl.lock); | |
169 | /* Required to meet the RCU bottomhalf requirements. */ | |
170 | rcu_read_lock(); | |
171 | } else { | |
172 | DEBUG_LOCKS_WARN_ON(this_cpu_read(softirq_ctrl.cnt)); | |
173 | } | |
174 | } | |
175 | ||
176 | /* | |
177 | * Track the per CPU softirq disabled state. On RT this is per CPU | |
178 | * state to allow preemption of bottom half disabled sections. | |
179 | */ | |
180 | newcnt = __this_cpu_add_return(softirq_ctrl.cnt, cnt); | |
181 | /* | |
182 | * Reflect the result in the task state to prevent recursion on the | |
183 | * local lock and to make softirq_count() & al work. | |
184 | */ | |
185 | current->softirq_disable_cnt = newcnt; | |
186 | ||
187 | if (IS_ENABLED(CONFIG_TRACE_IRQFLAGS) && newcnt == cnt) { | |
188 | raw_local_irq_save(flags); | |
189 | lockdep_softirqs_off(ip); | |
190 | raw_local_irq_restore(flags); | |
191 | } | |
192 | } | |
193 | EXPORT_SYMBOL(__local_bh_disable_ip); | |
194 | ||
195 | static void __local_bh_enable(unsigned int cnt, bool unlock) | |
196 | { | |
197 | unsigned long flags; | |
198 | int newcnt; | |
199 | ||
200 | DEBUG_LOCKS_WARN_ON(current->softirq_disable_cnt != | |
201 | this_cpu_read(softirq_ctrl.cnt)); | |
202 | ||
203 | if (IS_ENABLED(CONFIG_TRACE_IRQFLAGS) && softirq_count() == cnt) { | |
204 | raw_local_irq_save(flags); | |
205 | lockdep_softirqs_on(_RET_IP_); | |
206 | raw_local_irq_restore(flags); | |
207 | } | |
208 | ||
209 | newcnt = __this_cpu_sub_return(softirq_ctrl.cnt, cnt); | |
210 | current->softirq_disable_cnt = newcnt; | |
211 | ||
212 | if (!newcnt && unlock) { | |
213 | rcu_read_unlock(); | |
214 | local_unlock(&softirq_ctrl.lock); | |
215 | } | |
216 | } | |
217 | ||
218 | void __local_bh_enable_ip(unsigned long ip, unsigned int cnt) | |
219 | { | |
220 | bool preempt_on = preemptible(); | |
221 | unsigned long flags; | |
222 | u32 pending; | |
223 | int curcnt; | |
224 | ||
fe13889c | 225 | WARN_ON_ONCE(in_hardirq()); |
8b1c04ac TG |
226 | lockdep_assert_irqs_enabled(); |
227 | ||
228 | local_irq_save(flags); | |
229 | curcnt = __this_cpu_read(softirq_ctrl.cnt); | |
230 | ||
231 | /* | |
232 | * If this is not reenabling soft interrupts, no point in trying to | |
233 | * run pending ones. | |
234 | */ | |
235 | if (curcnt != cnt) | |
236 | goto out; | |
237 | ||
238 | pending = local_softirq_pending(); | |
239 | if (!pending || ksoftirqd_running(pending)) | |
240 | goto out; | |
241 | ||
242 | /* | |
243 | * If this was called from non preemptible context, wake up the | |
244 | * softirq daemon. | |
245 | */ | |
246 | if (!preempt_on) { | |
247 | wakeup_softirqd(); | |
248 | goto out; | |
249 | } | |
250 | ||
251 | /* | |
252 | * Adjust softirq count to SOFTIRQ_OFFSET which makes | |
253 | * in_serving_softirq() become true. | |
254 | */ | |
255 | cnt = SOFTIRQ_OFFSET; | |
256 | __local_bh_enable(cnt, false); | |
257 | __do_softirq(); | |
258 | ||
259 | out: | |
260 | __local_bh_enable(cnt, preempt_on); | |
261 | local_irq_restore(flags); | |
262 | } | |
263 | EXPORT_SYMBOL(__local_bh_enable_ip); | |
75e1056f | 264 | |
de30a2b3 | 265 | /* |
8b1c04ac TG |
266 | * Invoked from ksoftirqd_run() outside of the interrupt disabled section |
267 | * to acquire the per CPU local lock for reentrancy protection. | |
268 | */ | |
269 | static inline void ksoftirqd_run_begin(void) | |
270 | { | |
271 | __local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET); | |
272 | local_irq_disable(); | |
273 | } | |
274 | ||
275 | /* Counterpart to ksoftirqd_run_begin() */ | |
276 | static inline void ksoftirqd_run_end(void) | |
277 | { | |
278 | __local_bh_enable(SOFTIRQ_OFFSET, true); | |
279 | WARN_ON_ONCE(in_interrupt()); | |
280 | local_irq_enable(); | |
281 | } | |
282 | ||
283 | static inline void softirq_handle_begin(void) { } | |
284 | static inline void softirq_handle_end(void) { } | |
285 | ||
286 | static inline bool should_wake_ksoftirqd(void) | |
287 | { | |
288 | return !this_cpu_read(softirq_ctrl.cnt); | |
289 | } | |
290 | ||
291 | static inline void invoke_softirq(void) | |
292 | { | |
293 | if (should_wake_ksoftirqd()) | |
294 | wakeup_softirqd(); | |
295 | } | |
296 | ||
1a90bfd2 SAS |
297 | /* |
298 | * flush_smp_call_function_queue() can raise a soft interrupt in a function | |
299 | * call. On RT kernels this is undesired and the only known functionality | |
300 | * in the block layer which does this is disabled on RT. If soft interrupts | |
301 | * get raised which haven't been raised before the flush, warn so it can be | |
302 | * investigated. | |
303 | */ | |
304 | void do_softirq_post_smp_call_flush(unsigned int was_pending) | |
305 | { | |
306 | if (WARN_ON_ONCE(was_pending != local_softirq_pending())) | |
307 | invoke_softirq(); | |
308 | } | |
309 | ||
8b1c04ac TG |
310 | #else /* CONFIG_PREEMPT_RT */ |
311 | ||
312 | /* | |
313 | * This one is for softirq.c-internal use, where hardirqs are disabled | |
ae9ef589 | 314 | * legitimately: |
de30a2b3 | 315 | */ |
8b1c04ac | 316 | #ifdef CONFIG_TRACE_IRQFLAGS |
0bd3a173 | 317 | void __local_bh_disable_ip(unsigned long ip, unsigned int cnt) |
de30a2b3 IM |
318 | { |
319 | unsigned long flags; | |
320 | ||
fe13889c | 321 | WARN_ON_ONCE(in_hardirq()); |
de30a2b3 IM |
322 | |
323 | raw_local_irq_save(flags); | |
7e49fcce | 324 | /* |
bdb43806 | 325 | * The preempt tracer hooks into preempt_count_add and will break |
7e49fcce SR |
326 | * lockdep because it calls back into lockdep after SOFTIRQ_OFFSET |
327 | * is set and before current->softirq_enabled is cleared. | |
328 | * We must manually increment preempt_count here and manually | |
329 | * call the trace_preempt_off later. | |
330 | */ | |
bdb43806 | 331 | __preempt_count_add(cnt); |
de30a2b3 IM |
332 | /* |
333 | * Were softirqs turned off above: | |
334 | */ | |
9ea4c380 | 335 | if (softirq_count() == (cnt & SOFTIRQ_MASK)) |
0d38453c | 336 | lockdep_softirqs_off(ip); |
de30a2b3 | 337 | raw_local_irq_restore(flags); |
7e49fcce | 338 | |
0f1ba9a2 HC |
339 | if (preempt_count() == cnt) { |
340 | #ifdef CONFIG_DEBUG_PREEMPT | |
f904f582 | 341 | current->preempt_disable_ip = get_lock_parent_ip(); |
0f1ba9a2 | 342 | #endif |
f904f582 | 343 | trace_preempt_off(CALLER_ADDR0, get_lock_parent_ip()); |
0f1ba9a2 | 344 | } |
de30a2b3 | 345 | } |
0bd3a173 | 346 | EXPORT_SYMBOL(__local_bh_disable_ip); |
3c829c36 | 347 | #endif /* CONFIG_TRACE_IRQFLAGS */ |
de30a2b3 | 348 | |
75e1056f VP |
349 | static void __local_bh_enable(unsigned int cnt) |
350 | { | |
f71b74bc | 351 | lockdep_assert_irqs_disabled(); |
75e1056f | 352 | |
1a63dcd8 JFG |
353 | if (preempt_count() == cnt) |
354 | trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip()); | |
355 | ||
9ea4c380 | 356 | if (softirq_count() == (cnt & SOFTIRQ_MASK)) |
0d38453c | 357 | lockdep_softirqs_on(_RET_IP_); |
1a63dcd8 JFG |
358 | |
359 | __preempt_count_sub(cnt); | |
75e1056f VP |
360 | } |
361 | ||
de30a2b3 | 362 | /* |
c3442697 | 363 | * Special-case - softirqs can safely be enabled by __do_softirq(), |
de30a2b3 IM |
364 | * without processing still-pending softirqs: |
365 | */ | |
366 | void _local_bh_enable(void) | |
367 | { | |
fe13889c | 368 | WARN_ON_ONCE(in_hardirq()); |
75e1056f | 369 | __local_bh_enable(SOFTIRQ_DISABLE_OFFSET); |
de30a2b3 | 370 | } |
de30a2b3 IM |
371 | EXPORT_SYMBOL(_local_bh_enable); |
372 | ||
0bd3a173 | 373 | void __local_bh_enable_ip(unsigned long ip, unsigned int cnt) |
de30a2b3 | 374 | { |
fe13889c | 375 | WARN_ON_ONCE(in_hardirq()); |
f71b74bc | 376 | lockdep_assert_irqs_enabled(); |
3c829c36 | 377 | #ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d | 378 | local_irq_disable(); |
3c829c36 | 379 | #endif |
de30a2b3 IM |
380 | /* |
381 | * Are softirqs going to be turned on now: | |
382 | */ | |
75e1056f | 383 | if (softirq_count() == SOFTIRQ_DISABLE_OFFSET) |
0d38453c | 384 | lockdep_softirqs_on(ip); |
de30a2b3 IM |
385 | /* |
386 | * Keep preemption disabled until we are done with | |
387 | * softirq processing: | |
ce85b4f2 | 388 | */ |
91ea62d5 | 389 | __preempt_count_sub(cnt - 1); |
de30a2b3 | 390 | |
0bed698a FW |
391 | if (unlikely(!in_interrupt() && local_softirq_pending())) { |
392 | /* | |
393 | * Run softirq if any pending. And do it in its own stack | |
394 | * as we may be calling this deep in a task call stack already. | |
395 | */ | |
de30a2b3 | 396 | do_softirq(); |
0bed698a | 397 | } |
de30a2b3 | 398 | |
bdb43806 | 399 | preempt_count_dec(); |
3c829c36 | 400 | #ifdef CONFIG_TRACE_IRQFLAGS |
0f476b6d | 401 | local_irq_enable(); |
3c829c36 | 402 | #endif |
de30a2b3 IM |
403 | preempt_check_resched(); |
404 | } | |
0bd3a173 | 405 | EXPORT_SYMBOL(__local_bh_enable_ip); |
de30a2b3 | 406 | |
f02fc963 TG |
407 | static inline void softirq_handle_begin(void) |
408 | { | |
409 | __local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET); | |
410 | } | |
411 | ||
412 | static inline void softirq_handle_end(void) | |
413 | { | |
414 | __local_bh_enable(SOFTIRQ_OFFSET); | |
415 | WARN_ON_ONCE(in_interrupt()); | |
416 | } | |
417 | ||
418 | static inline void ksoftirqd_run_begin(void) | |
419 | { | |
420 | local_irq_disable(); | |
421 | } | |
422 | ||
423 | static inline void ksoftirqd_run_end(void) | |
424 | { | |
425 | local_irq_enable(); | |
426 | } | |
427 | ||
428 | static inline bool should_wake_ksoftirqd(void) | |
429 | { | |
430 | return true; | |
431 | } | |
432 | ||
ae9ef589 TG |
433 | static inline void invoke_softirq(void) |
434 | { | |
435 | if (ksoftirqd_running(local_softirq_pending())) | |
436 | return; | |
437 | ||
91cc470e | 438 | if (!force_irqthreads() || !__this_cpu_read(ksoftirqd)) { |
ae9ef589 TG |
439 | #ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK |
440 | /* | |
441 | * We can safely execute softirq on the current stack if | |
442 | * it is the irq stack, because it should be near empty | |
443 | * at this stage. | |
444 | */ | |
445 | __do_softirq(); | |
446 | #else | |
447 | /* | |
448 | * Otherwise, irq_exit() is called on the task stack that can | |
449 | * be potentially deep already. So call softirq in its own stack | |
450 | * to prevent from any overrun. | |
451 | */ | |
452 | do_softirq_own_stack(); | |
453 | #endif | |
454 | } else { | |
455 | wakeup_softirqd(); | |
456 | } | |
457 | } | |
458 | ||
459 | asmlinkage __visible void do_softirq(void) | |
460 | { | |
461 | __u32 pending; | |
462 | unsigned long flags; | |
463 | ||
464 | if (in_interrupt()) | |
465 | return; | |
466 | ||
467 | local_irq_save(flags); | |
468 | ||
469 | pending = local_softirq_pending(); | |
470 | ||
471 | if (pending && !ksoftirqd_running(pending)) | |
472 | do_softirq_own_stack(); | |
473 | ||
474 | local_irq_restore(flags); | |
475 | } | |
476 | ||
8b1c04ac TG |
477 | #endif /* !CONFIG_PREEMPT_RT */ |
478 | ||
1da177e4 | 479 | /* |
34376a50 BG |
480 | * We restart softirq processing for at most MAX_SOFTIRQ_RESTART times, |
481 | * but break the loop if need_resched() is set or after 2 ms. | |
482 | * The MAX_SOFTIRQ_TIME provides a nice upper bound in most cases, but in | |
483 | * certain cases, such as stop_machine(), jiffies may cease to | |
484 | * increment and so we need the MAX_SOFTIRQ_RESTART limit as | |
485 | * well to make sure we eventually return from this method. | |
1da177e4 | 486 | * |
c10d7367 | 487 | * These limits have been established via experimentation. |
1da177e4 LT |
488 | * The two things to balance is latency against fairness - |
489 | * we want to handle softirqs as soon as possible, but they | |
490 | * should not be able to lock up the box. | |
491 | */ | |
c10d7367 | 492 | #define MAX_SOFTIRQ_TIME msecs_to_jiffies(2) |
34376a50 | 493 | #define MAX_SOFTIRQ_RESTART 10 |
1da177e4 | 494 | |
f1a83e65 PZ |
495 | #ifdef CONFIG_TRACE_IRQFLAGS |
496 | /* | |
f1a83e65 PZ |
497 | * When we run softirqs from irq_exit() and thus on the hardirq stack we need |
498 | * to keep the lockdep irq context tracking as tight as possible in order to | |
499 | * not miss-qualify lock contexts and miss possible deadlocks. | |
500 | */ | |
f1a83e65 | 501 | |
5c4853b6 | 502 | static inline bool lockdep_softirq_start(void) |
f1a83e65 | 503 | { |
5c4853b6 | 504 | bool in_hardirq = false; |
f1a83e65 | 505 | |
f9ad4a5f | 506 | if (lockdep_hardirq_context()) { |
5c4853b6 | 507 | in_hardirq = true; |
2502ec37 | 508 | lockdep_hardirq_exit(); |
5c4853b6 FW |
509 | } |
510 | ||
f1a83e65 | 511 | lockdep_softirq_enter(); |
5c4853b6 FW |
512 | |
513 | return in_hardirq; | |
f1a83e65 PZ |
514 | } |
515 | ||
5c4853b6 | 516 | static inline void lockdep_softirq_end(bool in_hardirq) |
f1a83e65 PZ |
517 | { |
518 | lockdep_softirq_exit(); | |
5c4853b6 FW |
519 | |
520 | if (in_hardirq) | |
2502ec37 | 521 | lockdep_hardirq_enter(); |
f1a83e65 | 522 | } |
f1a83e65 | 523 | #else |
5c4853b6 FW |
524 | static inline bool lockdep_softirq_start(void) { return false; } |
525 | static inline void lockdep_softirq_end(bool in_hardirq) { } | |
f1a83e65 PZ |
526 | #endif |
527 | ||
be7635e7 | 528 | asmlinkage __visible void __softirq_entry __do_softirq(void) |
1da177e4 | 529 | { |
c10d7367 | 530 | unsigned long end = jiffies + MAX_SOFTIRQ_TIME; |
907aed48 | 531 | unsigned long old_flags = current->flags; |
34376a50 | 532 | int max_restart = MAX_SOFTIRQ_RESTART; |
f1a83e65 | 533 | struct softirq_action *h; |
5c4853b6 | 534 | bool in_hardirq; |
f1a83e65 | 535 | __u32 pending; |
2e702b9f | 536 | int softirq_bit; |
907aed48 MG |
537 | |
538 | /* | |
e45506ac YL |
539 | * Mask out PF_MEMALLOC as the current task context is borrowed for the |
540 | * softirq. A softirq handled, such as network RX, might set PF_MEMALLOC | |
541 | * again if the socket is related to swapping. | |
907aed48 MG |
542 | */ |
543 | current->flags &= ~PF_MEMALLOC; | |
1da177e4 LT |
544 | |
545 | pending = local_softirq_pending(); | |
829035fd | 546 | |
f02fc963 | 547 | softirq_handle_begin(); |
5c4853b6 | 548 | in_hardirq = lockdep_softirq_start(); |
d3759e71 | 549 | account_softirq_enter(current); |
1da177e4 | 550 | |
1da177e4 LT |
551 | restart: |
552 | /* Reset the pending bitmask before enabling irqs */ | |
3f74478b | 553 | set_softirq_pending(0); |
1da177e4 | 554 | |
c70f5d66 | 555 | local_irq_enable(); |
1da177e4 LT |
556 | |
557 | h = softirq_vec; | |
558 | ||
2e702b9f JP |
559 | while ((softirq_bit = ffs(pending))) { |
560 | unsigned int vec_nr; | |
561 | int prev_count; | |
562 | ||
563 | h += softirq_bit - 1; | |
564 | ||
565 | vec_nr = h - softirq_vec; | |
566 | prev_count = preempt_count(); | |
567 | ||
568 | kstat_incr_softirqs_this_cpu(vec_nr); | |
569 | ||
570 | trace_softirq_entry(vec_nr); | |
571 | h->action(h); | |
572 | trace_softirq_exit(vec_nr); | |
573 | if (unlikely(prev_count != preempt_count())) { | |
40322764 | 574 | pr_err("huh, entered softirq %u %s %p with preempt_count %08x, exited with %08x?\n", |
2e702b9f JP |
575 | vec_nr, softirq_to_name[vec_nr], h->action, |
576 | prev_count, preempt_count()); | |
577 | preempt_count_set(prev_count); | |
1da177e4 LT |
578 | } |
579 | h++; | |
2e702b9f JP |
580 | pending >>= softirq_bit; |
581 | } | |
1da177e4 | 582 | |
8b1c04ac TG |
583 | if (!IS_ENABLED(CONFIG_PREEMPT_RT) && |
584 | __this_cpu_read(ksoftirqd) == current) | |
d28139c4 | 585 | rcu_softirq_qs(); |
8b1c04ac | 586 | |
c70f5d66 | 587 | local_irq_disable(); |
1da177e4 LT |
588 | |
589 | pending = local_softirq_pending(); | |
c10d7367 | 590 | if (pending) { |
34376a50 BG |
591 | if (time_before(jiffies, end) && !need_resched() && |
592 | --max_restart) | |
c10d7367 | 593 | goto restart; |
1da177e4 | 594 | |
1da177e4 | 595 | wakeup_softirqd(); |
c10d7367 | 596 | } |
1da177e4 | 597 | |
d3759e71 | 598 | account_softirq_exit(current); |
5c4853b6 | 599 | lockdep_softirq_end(in_hardirq); |
f02fc963 | 600 | softirq_handle_end(); |
717a94b5 | 601 | current_restore_flags(old_flags, PF_MEMALLOC); |
1da177e4 LT |
602 | } |
603 | ||
8a6bc478 TG |
604 | /** |
605 | * irq_enter_rcu - Enter an interrupt context with RCU watching | |
dde4b2b5 | 606 | */ |
8a6bc478 | 607 | void irq_enter_rcu(void) |
dde4b2b5 | 608 | { |
d14ce74f FW |
609 | __irq_enter_raw(); |
610 | ||
53e87e3c FW |
611 | if (tick_nohz_full_cpu(smp_processor_id()) || |
612 | (is_idle_task(current) && (irq_count() == HARDIRQ_OFFSET))) | |
5acac1be | 613 | tick_irq_enter(); |
d14ce74f FW |
614 | |
615 | account_hardirq_enter(current); | |
dde4b2b5 IM |
616 | } |
617 | ||
8a6bc478 TG |
618 | /** |
619 | * irq_enter - Enter an interrupt context including RCU update | |
620 | */ | |
621 | void irq_enter(void) | |
622 | { | |
6f0e6c15 | 623 | ct_irq_enter(); |
8a6bc478 TG |
624 | irq_enter_rcu(); |
625 | } | |
626 | ||
67826eae FW |
627 | static inline void tick_irq_exit(void) |
628 | { | |
629 | #ifdef CONFIG_NO_HZ_COMMON | |
630 | int cpu = smp_processor_id(); | |
631 | ||
632 | /* Make sure that timer wheel updates are propagated */ | |
633 | if ((idle_cpu(cpu) && !need_resched()) || tick_nohz_full_cpu(cpu)) { | |
fe13889c | 634 | if (!in_hardirq()) |
67826eae FW |
635 | tick_nohz_irq_exit(); |
636 | } | |
637 | #endif | |
638 | } | |
639 | ||
59bc300b | 640 | static inline void __irq_exit_rcu(void) |
1da177e4 | 641 | { |
74eed016 | 642 | #ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED |
4cd5d111 | 643 | local_irq_disable(); |
74eed016 | 644 | #else |
f71b74bc | 645 | lockdep_assert_irqs_disabled(); |
74eed016 | 646 | #endif |
d3759e71 | 647 | account_hardirq_exit(current); |
bdb43806 | 648 | preempt_count_sub(HARDIRQ_OFFSET); |
1da177e4 LT |
649 | if (!in_interrupt() && local_softirq_pending()) |
650 | invoke_softirq(); | |
79bf2bb3 | 651 | |
67826eae | 652 | tick_irq_exit(); |
8a6bc478 TG |
653 | } |
654 | ||
59bc300b PZ |
655 | /** |
656 | * irq_exit_rcu() - Exit an interrupt context without updating RCU | |
657 | * | |
658 | * Also processes softirqs if needed and possible. | |
659 | */ | |
660 | void irq_exit_rcu(void) | |
661 | { | |
662 | __irq_exit_rcu(); | |
663 | /* must be last! */ | |
664 | lockdep_hardirq_exit(); | |
665 | } | |
666 | ||
8a6bc478 TG |
667 | /** |
668 | * irq_exit - Exit an interrupt context, update RCU and lockdep | |
669 | * | |
670 | * Also processes softirqs if needed and possible. | |
671 | */ | |
672 | void irq_exit(void) | |
673 | { | |
59bc300b | 674 | __irq_exit_rcu(); |
6f0e6c15 | 675 | ct_irq_exit(); |
2502ec37 TG |
676 | /* must be last! */ |
677 | lockdep_hardirq_exit(); | |
1da177e4 LT |
678 | } |
679 | ||
680 | /* | |
681 | * This function must run with irqs disabled! | |
682 | */ | |
7ad5b3a5 | 683 | inline void raise_softirq_irqoff(unsigned int nr) |
1da177e4 LT |
684 | { |
685 | __raise_softirq_irqoff(nr); | |
686 | ||
687 | /* | |
688 | * If we're in an interrupt or softirq, we're done | |
689 | * (this also catches softirq-disabled code). We will | |
690 | * actually run the softirq once we return from | |
691 | * the irq or softirq. | |
692 | * | |
693 | * Otherwise we wake up ksoftirqd to make sure we | |
694 | * schedule the softirq soon. | |
695 | */ | |
f02fc963 | 696 | if (!in_interrupt() && should_wake_ksoftirqd()) |
1da177e4 LT |
697 | wakeup_softirqd(); |
698 | } | |
699 | ||
7ad5b3a5 | 700 | void raise_softirq(unsigned int nr) |
1da177e4 LT |
701 | { |
702 | unsigned long flags; | |
703 | ||
704 | local_irq_save(flags); | |
705 | raise_softirq_irqoff(nr); | |
706 | local_irq_restore(flags); | |
707 | } | |
708 | ||
f069686e SR |
709 | void __raise_softirq_irqoff(unsigned int nr) |
710 | { | |
cdabce2e | 711 | lockdep_assert_irqs_disabled(); |
f069686e SR |
712 | trace_softirq_raise(nr); |
713 | or_softirq_pending(1UL << nr); | |
714 | } | |
715 | ||
962cf36c | 716 | void open_softirq(int nr, void (*action)(struct softirq_action *)) |
1da177e4 | 717 | { |
1da177e4 LT |
718 | softirq_vec[nr].action = action; |
719 | } | |
720 | ||
9ba5f005 PZ |
721 | /* |
722 | * Tasklets | |
723 | */ | |
ce85b4f2 | 724 | struct tasklet_head { |
48f20a9a OJ |
725 | struct tasklet_struct *head; |
726 | struct tasklet_struct **tail; | |
1da177e4 LT |
727 | }; |
728 | ||
4620b49f VN |
729 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec); |
730 | static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec); | |
1da177e4 | 731 | |
6498ddad IM |
732 | static void __tasklet_schedule_common(struct tasklet_struct *t, |
733 | struct tasklet_head __percpu *headp, | |
734 | unsigned int softirq_nr) | |
1da177e4 | 735 | { |
6498ddad | 736 | struct tasklet_head *head; |
1da177e4 LT |
737 | unsigned long flags; |
738 | ||
739 | local_irq_save(flags); | |
6498ddad | 740 | head = this_cpu_ptr(headp); |
48f20a9a | 741 | t->next = NULL; |
6498ddad IM |
742 | *head->tail = t; |
743 | head->tail = &(t->next); | |
744 | raise_softirq_irqoff(softirq_nr); | |
1da177e4 LT |
745 | local_irq_restore(flags); |
746 | } | |
6498ddad IM |
747 | |
748 | void __tasklet_schedule(struct tasklet_struct *t) | |
749 | { | |
750 | __tasklet_schedule_common(t, &tasklet_vec, | |
751 | TASKLET_SOFTIRQ); | |
752 | } | |
1da177e4 LT |
753 | EXPORT_SYMBOL(__tasklet_schedule); |
754 | ||
7ad5b3a5 | 755 | void __tasklet_hi_schedule(struct tasklet_struct *t) |
1da177e4 | 756 | { |
6498ddad IM |
757 | __tasklet_schedule_common(t, &tasklet_hi_vec, |
758 | HI_SOFTIRQ); | |
1da177e4 | 759 | } |
1da177e4 LT |
760 | EXPORT_SYMBOL(__tasklet_hi_schedule); |
761 | ||
697d8c63 | 762 | static bool tasklet_clear_sched(struct tasklet_struct *t) |
6b2c339d | 763 | { |
697d8c63 PZ |
764 | if (test_and_clear_bit(TASKLET_STATE_SCHED, &t->state)) { |
765 | wake_up_var(&t->state); | |
6b2c339d | 766 | return true; |
697d8c63 | 767 | } |
6b2c339d DB |
768 | |
769 | WARN_ONCE(1, "tasklet SCHED state not set: %s %pS\n", | |
770 | t->use_callback ? "callback" : "func", | |
771 | t->use_callback ? (void *)t->callback : (void *)t->func); | |
772 | ||
773 | return false; | |
774 | } | |
775 | ||
82b691be IM |
776 | static void tasklet_action_common(struct softirq_action *a, |
777 | struct tasklet_head *tl_head, | |
778 | unsigned int softirq_nr) | |
1da177e4 LT |
779 | { |
780 | struct tasklet_struct *list; | |
781 | ||
782 | local_irq_disable(); | |
82b691be IM |
783 | list = tl_head->head; |
784 | tl_head->head = NULL; | |
785 | tl_head->tail = &tl_head->head; | |
1da177e4 LT |
786 | local_irq_enable(); |
787 | ||
788 | while (list) { | |
789 | struct tasklet_struct *t = list; | |
790 | ||
791 | list = list->next; | |
792 | ||
793 | if (tasklet_trylock(t)) { | |
794 | if (!atomic_read(&t->count)) { | |
697d8c63 | 795 | if (tasklet_clear_sched(t)) { |
6b2c339d DB |
796 | if (t->use_callback) |
797 | t->callback(t); | |
798 | else | |
799 | t->func(t->data); | |
800 | } | |
1da177e4 LT |
801 | tasklet_unlock(t); |
802 | continue; | |
803 | } | |
804 | tasklet_unlock(t); | |
805 | } | |
806 | ||
807 | local_irq_disable(); | |
48f20a9a | 808 | t->next = NULL; |
82b691be IM |
809 | *tl_head->tail = t; |
810 | tl_head->tail = &t->next; | |
811 | __raise_softirq_irqoff(softirq_nr); | |
1da177e4 LT |
812 | local_irq_enable(); |
813 | } | |
814 | } | |
815 | ||
82b691be | 816 | static __latent_entropy void tasklet_action(struct softirq_action *a) |
1da177e4 | 817 | { |
82b691be IM |
818 | tasklet_action_common(a, this_cpu_ptr(&tasklet_vec), TASKLET_SOFTIRQ); |
819 | } | |
1da177e4 | 820 | |
82b691be IM |
821 | static __latent_entropy void tasklet_hi_action(struct softirq_action *a) |
822 | { | |
823 | tasklet_action_common(a, this_cpu_ptr(&tasklet_hi_vec), HI_SOFTIRQ); | |
1da177e4 LT |
824 | } |
825 | ||
12cc923f RP |
826 | void tasklet_setup(struct tasklet_struct *t, |
827 | void (*callback)(struct tasklet_struct *)) | |
828 | { | |
829 | t->next = NULL; | |
830 | t->state = 0; | |
831 | atomic_set(&t->count, 0); | |
832 | t->callback = callback; | |
833 | t->use_callback = true; | |
834 | t->data = 0; | |
835 | } | |
836 | EXPORT_SYMBOL(tasklet_setup); | |
837 | ||
1da177e4 LT |
838 | void tasklet_init(struct tasklet_struct *t, |
839 | void (*func)(unsigned long), unsigned long data) | |
840 | { | |
841 | t->next = NULL; | |
842 | t->state = 0; | |
843 | atomic_set(&t->count, 0); | |
844 | t->func = func; | |
12cc923f | 845 | t->use_callback = false; |
1da177e4 LT |
846 | t->data = data; |
847 | } | |
1da177e4 LT |
848 | EXPORT_SYMBOL(tasklet_init); |
849 | ||
eb2dafbb TG |
850 | #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT) |
851 | /* | |
852 | * Do not use in new code. Waiting for tasklets from atomic contexts is | |
853 | * error prone and should be avoided. | |
854 | */ | |
855 | void tasklet_unlock_spin_wait(struct tasklet_struct *t) | |
856 | { | |
857 | while (test_bit(TASKLET_STATE_RUN, &(t)->state)) { | |
858 | if (IS_ENABLED(CONFIG_PREEMPT_RT)) { | |
859 | /* | |
860 | * Prevent a live lock when current preempted soft | |
861 | * interrupt processing or prevents ksoftirqd from | |
862 | * running. If the tasklet runs on a different CPU | |
863 | * then this has no effect other than doing the BH | |
864 | * disable/enable dance for nothing. | |
865 | */ | |
866 | local_bh_disable(); | |
867 | local_bh_enable(); | |
868 | } else { | |
869 | cpu_relax(); | |
870 | } | |
871 | } | |
872 | } | |
873 | EXPORT_SYMBOL(tasklet_unlock_spin_wait); | |
874 | #endif | |
875 | ||
1da177e4 LT |
876 | void tasklet_kill(struct tasklet_struct *t) |
877 | { | |
878 | if (in_interrupt()) | |
40322764 | 879 | pr_notice("Attempt to kill tasklet from interrupt\n"); |
1da177e4 | 880 | |
697d8c63 PZ |
881 | while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) |
882 | wait_var_event(&t->state, !test_bit(TASKLET_STATE_SCHED, &t->state)); | |
883 | ||
1da177e4 | 884 | tasklet_unlock_wait(t); |
697d8c63 | 885 | tasklet_clear_sched(t); |
1da177e4 | 886 | } |
1da177e4 LT |
887 | EXPORT_SYMBOL(tasklet_kill); |
888 | ||
eb2dafbb | 889 | #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT) |
da044747 PZ |
890 | void tasklet_unlock(struct tasklet_struct *t) |
891 | { | |
892 | smp_mb__before_atomic(); | |
893 | clear_bit(TASKLET_STATE_RUN, &t->state); | |
894 | smp_mb__after_atomic(); | |
895 | wake_up_var(&t->state); | |
896 | } | |
897 | EXPORT_SYMBOL_GPL(tasklet_unlock); | |
898 | ||
899 | void tasklet_unlock_wait(struct tasklet_struct *t) | |
900 | { | |
901 | wait_var_event(&t->state, !test_bit(TASKLET_STATE_RUN, &t->state)); | |
902 | } | |
903 | EXPORT_SYMBOL_GPL(tasklet_unlock_wait); | |
904 | #endif | |
905 | ||
1da177e4 LT |
906 | void __init softirq_init(void) |
907 | { | |
48f20a9a OJ |
908 | int cpu; |
909 | ||
910 | for_each_possible_cpu(cpu) { | |
911 | per_cpu(tasklet_vec, cpu).tail = | |
912 | &per_cpu(tasklet_vec, cpu).head; | |
913 | per_cpu(tasklet_hi_vec, cpu).tail = | |
914 | &per_cpu(tasklet_hi_vec, cpu).head; | |
915 | } | |
916 | ||
962cf36c CM |
917 | open_softirq(TASKLET_SOFTIRQ, tasklet_action); |
918 | open_softirq(HI_SOFTIRQ, tasklet_hi_action); | |
1da177e4 LT |
919 | } |
920 | ||
3e339b5d | 921 | static int ksoftirqd_should_run(unsigned int cpu) |
1da177e4 | 922 | { |
3e339b5d TG |
923 | return local_softirq_pending(); |
924 | } | |
1da177e4 | 925 | |
3e339b5d TG |
926 | static void run_ksoftirqd(unsigned int cpu) |
927 | { | |
f02fc963 | 928 | ksoftirqd_run_begin(); |
3e339b5d | 929 | if (local_softirq_pending()) { |
0bed698a FW |
930 | /* |
931 | * We can safely run softirq on inline stack, as we are not deep | |
932 | * in the task stack here. | |
933 | */ | |
3e339b5d | 934 | __do_softirq(); |
f02fc963 | 935 | ksoftirqd_run_end(); |
edf22f4c | 936 | cond_resched(); |
3e339b5d | 937 | return; |
1da177e4 | 938 | } |
f02fc963 | 939 | ksoftirqd_run_end(); |
1da177e4 LT |
940 | } |
941 | ||
942 | #ifdef CONFIG_HOTPLUG_CPU | |
c4544dbc | 943 | static int takeover_tasklets(unsigned int cpu) |
1da177e4 | 944 | { |
1da177e4 LT |
945 | /* CPU is dead, so no lock needed. */ |
946 | local_irq_disable(); | |
947 | ||
948 | /* Find end, append list for that CPU. */ | |
e5e41723 | 949 | if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) { |
909ea964 | 950 | *__this_cpu_read(tasklet_vec.tail) = per_cpu(tasklet_vec, cpu).head; |
8afecaa6 | 951 | __this_cpu_write(tasklet_vec.tail, per_cpu(tasklet_vec, cpu).tail); |
e5e41723 CB |
952 | per_cpu(tasklet_vec, cpu).head = NULL; |
953 | per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; | |
954 | } | |
1da177e4 LT |
955 | raise_softirq_irqoff(TASKLET_SOFTIRQ); |
956 | ||
e5e41723 | 957 | if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) { |
909ea964 CL |
958 | *__this_cpu_read(tasklet_hi_vec.tail) = per_cpu(tasklet_hi_vec, cpu).head; |
959 | __this_cpu_write(tasklet_hi_vec.tail, per_cpu(tasklet_hi_vec, cpu).tail); | |
e5e41723 CB |
960 | per_cpu(tasklet_hi_vec, cpu).head = NULL; |
961 | per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; | |
962 | } | |
1da177e4 LT |
963 | raise_softirq_irqoff(HI_SOFTIRQ); |
964 | ||
965 | local_irq_enable(); | |
c4544dbc | 966 | return 0; |
1da177e4 | 967 | } |
c4544dbc SAS |
968 | #else |
969 | #define takeover_tasklets NULL | |
1da177e4 LT |
970 | #endif /* CONFIG_HOTPLUG_CPU */ |
971 | ||
3e339b5d TG |
972 | static struct smp_hotplug_thread softirq_threads = { |
973 | .store = &ksoftirqd, | |
974 | .thread_should_run = ksoftirqd_should_run, | |
975 | .thread_fn = run_ksoftirqd, | |
976 | .thread_comm = "ksoftirqd/%u", | |
977 | }; | |
978 | ||
7babe8db | 979 | static __init int spawn_ksoftirqd(void) |
1da177e4 | 980 | { |
c4544dbc SAS |
981 | cpuhp_setup_state_nocalls(CPUHP_SOFTIRQ_DEAD, "softirq:dead", NULL, |
982 | takeover_tasklets); | |
3e339b5d TG |
983 | BUG_ON(smpboot_register_percpu_thread(&softirq_threads)); |
984 | ||
1da177e4 LT |
985 | return 0; |
986 | } | |
7babe8db | 987 | early_initcall(spawn_ksoftirqd); |
78eef01b | 988 | |
43a25632 YL |
989 | /* |
990 | * [ These __weak aliases are kept in a separate compilation unit, so that | |
991 | * GCC does not inline them incorrectly. ] | |
992 | */ | |
993 | ||
994 | int __init __weak early_irq_init(void) | |
995 | { | |
996 | return 0; | |
997 | } | |
998 | ||
4a046d17 YL |
999 | int __init __weak arch_probe_nr_irqs(void) |
1000 | { | |
b683de2b | 1001 | return NR_IRQS_LEGACY; |
4a046d17 YL |
1002 | } |
1003 | ||
43a25632 YL |
1004 | int __init __weak arch_early_irq_init(void) |
1005 | { | |
1006 | return 0; | |
1007 | } | |
62a08ae2 TG |
1008 | |
1009 | unsigned int __weak arch_dynirq_lower_bound(unsigned int from) | |
1010 | { | |
1011 | return from; | |
1012 | } |