blob: 479e4436f787646c92c42e0dbe2d940b366fbf60 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/kernel/softirq.c
3 *
4 * Copyright (C) 1992 Linus Torvalds
5 *
Pavel Machekb10db7f2008-01-30 13:30:00 +01006 * Distribute under GPLv2.
7 *
8 * Rewritten. Old one was good in 2.2, but in 2.3 it was immoral. --ANK (990903)
Linus Torvalds1da177e2005-04-16 15:20:36 -07009 */
10
Joe Perches40322762014-01-27 17:07:15 -080011#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
Paul Gortmaker9984de12011-05-23 14:51:41 -040013#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/kernel_stat.h>
15#include <linux/interrupt.h>
16#include <linux/init.h>
17#include <linux/mm.h>
18#include <linux/notifier.h>
19#include <linux/percpu.h>
20#include <linux/cpu.h>
Rafael J. Wysocki83144182007-07-17 04:03:35 -070021#include <linux/freezer.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/kthread.h>
23#include <linux/rcupdate.h>
Steven Rostedt7e49fcc2009-01-22 19:01:40 -050024#include <linux/ftrace.h>
Andrew Morton78eef012006-03-22 00:08:16 -080025#include <linux/smp.h>
Thomas Gleixner3e339b52012-07-16 10:42:37 +000026#include <linux/smpboot.h>
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -080027#include <linux/tick.h>
Thomas Gleixnerd5326762014-03-19 11:19:52 +010028#include <linux/irq.h>
Heiko Carstensa0e39ed2009-04-29 13:51:39 +020029
30#define CREATE_TRACE_POINTS
Steven Rostedtad8d75f2009-04-14 19:39:12 -040031#include <trace/events/irq.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070032
Linus Torvalds1da177e2005-04-16 15:20:36 -070033/*
34 - No shared variables, all the data are CPU local.
35 - If a softirq needs serialization, let it serialize itself
36 by its own spinlocks.
37 - Even if softirq is serialized, only local cpu is marked for
38 execution. Hence, we get something sort of weak cpu binding.
39 Though it is still not clear, will it result in better locality
40 or will not.
41
42 Examples:
43 - NET RX softirq. It is multithreaded and does not require
44 any global serialization.
45 - NET TX softirq. It kicks software netdevice queues, hence
46 it is logically serialized per device, but this serialization
47 is invisible to common code.
48 - Tasklets: serialized wrt itself.
49 */
50
51#ifndef __ARCH_IRQ_STAT
52irq_cpustat_t irq_stat[NR_CPUS] ____cacheline_aligned;
53EXPORT_SYMBOL(irq_stat);
54#endif
55
Alexey Dobriyan978b0112008-09-06 20:04:36 +020056static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp;
Linus Torvalds1da177e2005-04-16 15:20:36 -070057
Venkatesh Pallipadi4dd53d82010-12-21 17:09:00 -080058DEFINE_PER_CPU(struct task_struct *, ksoftirqd);
Linus Torvalds1da177e2005-04-16 15:20:36 -070059
Joe Perchesce85b4f2014-01-27 17:07:16 -080060const char * const softirq_to_name[NR_SOFTIRQS] = {
Li Zefan5dd4de52009-09-17 17:38:32 +080061 "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "BLOCK_IOPOLL",
Shaohua Li09223372011-06-14 13:26:25 +080062 "TASKLET", "SCHED", "HRTIMER", "RCU"
Jason Baron5d592b42009-03-12 14:33:36 -040063};
64
Linus Torvalds1da177e2005-04-16 15:20:36 -070065/*
66 * we cannot loop indefinitely here to avoid userspace starvation,
67 * but we also don't want to introduce a worst case 1/HZ latency
68 * to the pending events, so lets the scheduler to balance
69 * the softirq load for us.
70 */
Thomas Gleixner676cb022009-07-20 23:33:49 +020071static void wakeup_softirqd(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -070072{
73 /* Interrupts are disabled: no need to stop preemption */
Christoph Lameter909ea962010-12-08 16:22:55 +010074 struct task_struct *tsk = __this_cpu_read(ksoftirqd);
Linus Torvalds1da177e2005-04-16 15:20:36 -070075
76 if (tsk && tsk->state != TASK_RUNNING)
77 wake_up_process(tsk);
78}
79
80/*
Venkatesh Pallipadi75e10562010-10-04 17:03:16 -070081 * preempt_count and SOFTIRQ_OFFSET usage:
82 * - preempt_count is changed by SOFTIRQ_OFFSET on entering or leaving
83 * softirq processing.
84 * - preempt_count is changed by SOFTIRQ_DISABLE_OFFSET (= 2 * SOFTIRQ_OFFSET)
85 * on local_bh_disable or local_bh_enable.
86 * This lets us distinguish between whether we are currently processing
87 * softirq and whether we just have bh disabled.
88 */
89
90/*
Ingo Molnarde30a2b2006-07-03 00:24:42 -070091 * This one is for softirq.c-internal use,
92 * where hardirqs are disabled legitimately:
93 */
Tim Chen3c829c32006-07-30 03:04:02 -070094#ifdef CONFIG_TRACE_IRQFLAGS
Peter Zijlstra0bd3a172013-11-19 16:13:38 +010095void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
Ingo Molnarde30a2b2006-07-03 00:24:42 -070096{
97 unsigned long flags;
98
99 WARN_ON_ONCE(in_irq());
100
101 raw_local_irq_save(flags);
Steven Rostedt7e49fcc2009-01-22 19:01:40 -0500102 /*
Peter Zijlstrabdb43802013-09-10 12:15:23 +0200103 * The preempt tracer hooks into preempt_count_add and will break
Steven Rostedt7e49fcc2009-01-22 19:01:40 -0500104 * lockdep because it calls back into lockdep after SOFTIRQ_OFFSET
105 * is set and before current->softirq_enabled is cleared.
106 * We must manually increment preempt_count here and manually
107 * call the trace_preempt_off later.
108 */
Peter Zijlstrabdb43802013-09-10 12:15:23 +0200109 __preempt_count_add(cnt);
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700110 /*
111 * Were softirqs turned off above:
112 */
Peter Zijlstra9ea4c382013-11-19 16:13:38 +0100113 if (softirq_count() == (cnt & SOFTIRQ_MASK))
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700114 trace_softirqs_off(ip);
115 raw_local_irq_restore(flags);
Steven Rostedt7e49fcc2009-01-22 19:01:40 -0500116
Heiko Carstens0f1ba9a2015-01-07 10:04:41 +0100117 if (preempt_count() == cnt) {
118#ifdef CONFIG_DEBUG_PREEMPT
119 current->preempt_disable_ip = get_parent_ip(CALLER_ADDR1);
120#endif
Steven Rostedt7e49fcc2009-01-22 19:01:40 -0500121 trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
Heiko Carstens0f1ba9a2015-01-07 10:04:41 +0100122 }
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700123}
Peter Zijlstra0bd3a172013-11-19 16:13:38 +0100124EXPORT_SYMBOL(__local_bh_disable_ip);
Tim Chen3c829c32006-07-30 03:04:02 -0700125#endif /* CONFIG_TRACE_IRQFLAGS */
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700126
Venkatesh Pallipadi75e10562010-10-04 17:03:16 -0700127static void __local_bh_enable(unsigned int cnt)
128{
Venkatesh Pallipadi75e10562010-10-04 17:03:16 -0700129 WARN_ON_ONCE(!irqs_disabled());
130
Peter Zijlstra9ea4c382013-11-19 16:13:38 +0100131 if (softirq_count() == (cnt & SOFTIRQ_MASK))
Davidlohr Buesod2e08472013-04-30 11:46:09 -0700132 trace_softirqs_on(_RET_IP_);
Peter Zijlstrabdb43802013-09-10 12:15:23 +0200133 preempt_count_sub(cnt);
Venkatesh Pallipadi75e10562010-10-04 17:03:16 -0700134}
135
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700136/*
137 * Special-case - softirqs can safely be enabled in
138 * cond_resched_softirq(), or by __do_softirq(),
139 * without processing still-pending softirqs:
140 */
141void _local_bh_enable(void)
142{
Frederic Weisbecker5d60d3e2013-09-24 04:11:35 +0200143 WARN_ON_ONCE(in_irq());
Venkatesh Pallipadi75e10562010-10-04 17:03:16 -0700144 __local_bh_enable(SOFTIRQ_DISABLE_OFFSET);
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700145}
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700146EXPORT_SYMBOL(_local_bh_enable);
147
Peter Zijlstra0bd3a172013-11-19 16:13:38 +0100148void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700149{
Johannes Berg0f476b6d2008-06-18 09:29:37 +0200150 WARN_ON_ONCE(in_irq() || irqs_disabled());
Tim Chen3c829c32006-07-30 03:04:02 -0700151#ifdef CONFIG_TRACE_IRQFLAGS
Johannes Berg0f476b6d2008-06-18 09:29:37 +0200152 local_irq_disable();
Tim Chen3c829c32006-07-30 03:04:02 -0700153#endif
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700154 /*
155 * Are softirqs going to be turned on now:
156 */
Venkatesh Pallipadi75e10562010-10-04 17:03:16 -0700157 if (softirq_count() == SOFTIRQ_DISABLE_OFFSET)
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700158 trace_softirqs_on(ip);
159 /*
160 * Keep preemption disabled until we are done with
161 * softirq processing:
Joe Perchesce85b4f2014-01-27 17:07:16 -0800162 */
Peter Zijlstra0bd3a172013-11-19 16:13:38 +0100163 preempt_count_sub(cnt - 1);
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700164
Frederic Weisbecker0bed6982013-09-05 16:14:00 +0200165 if (unlikely(!in_interrupt() && local_softirq_pending())) {
166 /*
167 * Run softirq if any pending. And do it in its own stack
168 * as we may be calling this deep in a task call stack already.
169 */
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700170 do_softirq();
Frederic Weisbecker0bed6982013-09-05 16:14:00 +0200171 }
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700172
Peter Zijlstrabdb43802013-09-10 12:15:23 +0200173 preempt_count_dec();
Tim Chen3c829c32006-07-30 03:04:02 -0700174#ifdef CONFIG_TRACE_IRQFLAGS
Johannes Berg0f476b6d2008-06-18 09:29:37 +0200175 local_irq_enable();
Tim Chen3c829c32006-07-30 03:04:02 -0700176#endif
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700177 preempt_check_resched();
178}
Peter Zijlstra0bd3a172013-11-19 16:13:38 +0100179EXPORT_SYMBOL(__local_bh_enable_ip);
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700180
181/*
Ben Greear34376a52013-06-06 14:29:49 -0700182 * We restart softirq processing for at most MAX_SOFTIRQ_RESTART times,
183 * but break the loop if need_resched() is set or after 2 ms.
184 * The MAX_SOFTIRQ_TIME provides a nice upper bound in most cases, but in
185 * certain cases, such as stop_machine(), jiffies may cease to
186 * increment and so we need the MAX_SOFTIRQ_RESTART limit as
187 * well to make sure we eventually return from this method.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188 *
Eric Dumazetc10d7362013-01-10 15:26:34 -0800189 * These limits have been established via experimentation.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190 * The two things to balance is latency against fairness -
191 * we want to handle softirqs as soon as possible, but they
192 * should not be able to lock up the box.
193 */
Eric Dumazetc10d7362013-01-10 15:26:34 -0800194#define MAX_SOFTIRQ_TIME msecs_to_jiffies(2)
Ben Greear34376a52013-06-06 14:29:49 -0700195#define MAX_SOFTIRQ_RESTART 10
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100197#ifdef CONFIG_TRACE_IRQFLAGS
198/*
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100199 * When we run softirqs from irq_exit() and thus on the hardirq stack we need
200 * to keep the lockdep irq context tracking as tight as possible in order to
201 * not miss-qualify lock contexts and miss possible deadlocks.
202 */
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100203
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100204static inline bool lockdep_softirq_start(void)
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100205{
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100206 bool in_hardirq = false;
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100207
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100208 if (trace_hardirq_context(current)) {
209 in_hardirq = true;
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100210 trace_hardirq_exit();
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100211 }
212
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100213 lockdep_softirq_enter();
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100214
215 return in_hardirq;
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100216}
217
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100218static inline void lockdep_softirq_end(bool in_hardirq)
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100219{
220 lockdep_softirq_exit();
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100221
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100222 if (in_hardirq)
223 trace_hardirq_enter();
224}
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100225#else
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100226static inline bool lockdep_softirq_start(void) { return false; }
227static inline void lockdep_softirq_end(bool in_hardirq) { }
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100228#endif
229
Andi Kleen722a9f92014-05-02 00:44:38 +0200230asmlinkage __visible void __do_softirq(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231{
Eric Dumazetc10d7362013-01-10 15:26:34 -0800232 unsigned long end = jiffies + MAX_SOFTIRQ_TIME;
Mel Gorman907aed42012-07-31 16:44:07 -0700233 unsigned long old_flags = current->flags;
Ben Greear34376a52013-06-06 14:29:49 -0700234 int max_restart = MAX_SOFTIRQ_RESTART;
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100235 struct softirq_action *h;
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100236 bool in_hardirq;
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100237 __u32 pending;
Joe Perches2e702b92014-01-27 17:07:14 -0800238 int softirq_bit;
Mel Gorman907aed42012-07-31 16:44:07 -0700239
240 /*
241 * Mask out PF_MEMALLOC s current task context is borrowed for the
242 * softirq. A softirq handled such as network RX might set PF_MEMALLOC
243 * again if the socket is related to swap
244 */
245 current->flags &= ~PF_MEMALLOC;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246
247 pending = local_softirq_pending();
Frederic Weisbecker6a616712012-12-16 20:00:34 +0100248 account_irq_enter_time(current);
Paul Mackerras829035fd2006-07-03 00:25:40 -0700249
Peter Zijlstra0bd3a172013-11-19 16:13:38 +0100250 __local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET);
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100251 in_hardirq = lockdep_softirq_start();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253restart:
254 /* Reset the pending bitmask before enabling irqs */
Andi Kleen3f744782005-09-12 18:49:24 +0200255 set_softirq_pending(0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256
Andrew Mortonc70f5d62005-07-30 10:22:49 -0700257 local_irq_enable();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258
259 h = softirq_vec;
260
Joe Perches2e702b92014-01-27 17:07:14 -0800261 while ((softirq_bit = ffs(pending))) {
262 unsigned int vec_nr;
263 int prev_count;
Thomas Gleixner8e85b4b2008-10-02 10:50:53 +0200264
Joe Perches2e702b92014-01-27 17:07:14 -0800265 h += softirq_bit - 1;
Thomas Gleixnerf4bc6bb2010-10-19 15:00:13 +0200266
Joe Perches2e702b92014-01-27 17:07:14 -0800267 vec_nr = h - softirq_vec;
268 prev_count = preempt_count();
Thomas Gleixner8e85b4b2008-10-02 10:50:53 +0200269
Joe Perches2e702b92014-01-27 17:07:14 -0800270 kstat_incr_softirqs_this_cpu(vec_nr);
271
272 trace_softirq_entry(vec_nr);
273 h->action(h);
274 trace_softirq_exit(vec_nr);
275 if (unlikely(prev_count != preempt_count())) {
Joe Perches40322762014-01-27 17:07:15 -0800276 pr_err("huh, entered softirq %u %s %p with preempt_count %08x, exited with %08x?\n",
Joe Perches2e702b92014-01-27 17:07:14 -0800277 vec_nr, softirq_to_name[vec_nr], h->action,
278 prev_count, preempt_count());
279 preempt_count_set(prev_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280 }
281 h++;
Joe Perches2e702b92014-01-27 17:07:14 -0800282 pending >>= softirq_bit;
283 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284
Paul E. McKenney284a8c92014-08-14 16:38:46 -0700285 rcu_bh_qs();
Andrew Mortonc70f5d62005-07-30 10:22:49 -0700286 local_irq_disable();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287
288 pending = local_softirq_pending();
Eric Dumazetc10d7362013-01-10 15:26:34 -0800289 if (pending) {
Ben Greear34376a52013-06-06 14:29:49 -0700290 if (time_before(jiffies, end) && !need_resched() &&
291 --max_restart)
Eric Dumazetc10d7362013-01-10 15:26:34 -0800292 goto restart;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294 wakeup_softirqd();
Eric Dumazetc10d7362013-01-10 15:26:34 -0800295 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100297 lockdep_softirq_end(in_hardirq);
Frederic Weisbecker6a616712012-12-16 20:00:34 +0100298 account_irq_exit_time(current);
Venkatesh Pallipadi75e10562010-10-04 17:03:16 -0700299 __local_bh_enable(SOFTIRQ_OFFSET);
Frederic Weisbecker5d60d3e2013-09-24 04:11:35 +0200300 WARN_ON_ONCE(in_interrupt());
Mel Gorman907aed42012-07-31 16:44:07 -0700301 tsk_restore_flags(current, old_flags, PF_MEMALLOC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302}
303
Andi Kleen722a9f92014-05-02 00:44:38 +0200304asmlinkage __visible void do_softirq(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305{
306 __u32 pending;
307 unsigned long flags;
308
309 if (in_interrupt())
310 return;
311
312 local_irq_save(flags);
313
314 pending = local_softirq_pending();
315
316 if (pending)
Frederic Weisbecker7d65f4a2013-09-05 15:49:45 +0200317 do_softirq_own_stack();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318
319 local_irq_restore(flags);
320}
321
Ingo Molnardde4b2b2007-02-16 01:27:45 -0800322/*
323 * Enter an interrupt context.
324 */
325void irq_enter(void)
326{
Paul E. McKenney64db4cf2008-12-18 21:55:32 +0100327 rcu_irq_enter();
Frederic Weisbecker0a8a2e72012-01-24 18:59:44 +0100328 if (is_idle_task(current) && !in_interrupt()) {
Venkatesh Pallipadid267f872010-10-04 17:03:23 -0700329 /*
330 * Prevent raise_softirq from needlessly waking up ksoftirqd
331 * here, as softirq will be serviced on return from interrupt.
332 */
333 local_bh_disable();
Frederic Weisbecker5acac1b2013-12-04 18:28:20 +0100334 tick_irq_enter();
Venkatesh Pallipadid267f872010-10-04 17:03:23 -0700335 _local_bh_enable();
336 }
337
338 __irq_enter();
Ingo Molnardde4b2b2007-02-16 01:27:45 -0800339}
340
Heiko Carstensb2a00172012-03-05 15:07:25 -0800341static inline void invoke_softirq(void)
342{
Frederic Weisbeckerded79752013-09-24 00:50:25 +0200343 if (!force_irqthreads) {
Frederic Weisbeckercc1f0272013-09-24 17:17:47 +0200344#ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
Frederic Weisbeckerded79752013-09-24 00:50:25 +0200345 /*
346 * We can safely execute softirq on the current stack if
347 * it is the irq stack, because it should be near empty
Frederic Weisbeckercc1f0272013-09-24 17:17:47 +0200348 * at this stage.
349 */
350 __do_softirq();
351#else
352 /*
353 * Otherwise, irq_exit() is called on the task stack that can
354 * be potentially deep already. So call softirq in its own stack
355 * to prevent from any overrun.
Frederic Weisbeckerded79752013-09-24 00:50:25 +0200356 */
Frederic Weisbeckerbe6e1012013-09-24 16:39:41 +0200357 do_softirq_own_stack();
Frederic Weisbeckercc1f0272013-09-24 17:17:47 +0200358#endif
Frederic Weisbeckerded79752013-09-24 00:50:25 +0200359 } else {
Thomas Gleixner8d32a302011-02-23 23:52:23 +0000360 wakeup_softirqd();
Frederic Weisbeckerded79752013-09-24 00:50:25 +0200361 }
Thomas Gleixner8d32a302011-02-23 23:52:23 +0000362}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363
Frederic Weisbecker67826ea2013-04-20 17:43:13 +0200364static inline void tick_irq_exit(void)
365{
366#ifdef CONFIG_NO_HZ_COMMON
367 int cpu = smp_processor_id();
368
369 /* Make sure that timer wheel updates are propagated */
370 if ((idle_cpu(cpu) && !need_resched()) || tick_nohz_full_cpu(cpu)) {
371 if (!in_interrupt())
372 tick_nohz_irq_exit();
373 }
374#endif
375}
376
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377/*
378 * Exit an interrupt context. Process softirqs if needed and possible:
379 */
380void irq_exit(void)
381{
Thomas Gleixner74eed012013-02-20 22:00:48 +0100382#ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED
Frederic Weisbecker4cd5d112013-02-28 20:00:43 +0100383 local_irq_disable();
Thomas Gleixner74eed012013-02-20 22:00:48 +0100384#else
385 WARN_ON_ONCE(!irqs_disabled());
386#endif
387
Frederic Weisbecker6a616712012-12-16 20:00:34 +0100388 account_irq_exit_time(current);
Peter Zijlstrabdb43802013-09-10 12:15:23 +0200389 preempt_count_sub(HARDIRQ_OFFSET);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390 if (!in_interrupt() && local_softirq_pending())
391 invoke_softirq();
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -0800392
Frederic Weisbecker67826ea2013-04-20 17:43:13 +0200393 tick_irq_exit();
Frederic Weisbecker416eb332011-10-07 16:31:02 -0700394 rcu_irq_exit();
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100395 trace_hardirq_exit(); /* must be last! */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396}
397
398/*
399 * This function must run with irqs disabled!
400 */
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800401inline void raise_softirq_irqoff(unsigned int nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402{
403 __raise_softirq_irqoff(nr);
404
405 /*
406 * If we're in an interrupt or softirq, we're done
407 * (this also catches softirq-disabled code). We will
408 * actually run the softirq once we return from
409 * the irq or softirq.
410 *
411 * Otherwise we wake up ksoftirqd to make sure we
412 * schedule the softirq soon.
413 */
414 if (!in_interrupt())
415 wakeup_softirqd();
416}
417
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800418void raise_softirq(unsigned int nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419{
420 unsigned long flags;
421
422 local_irq_save(flags);
423 raise_softirq_irqoff(nr);
424 local_irq_restore(flags);
425}
426
Steven Rostedtf0696862012-01-25 20:18:55 -0500427void __raise_softirq_irqoff(unsigned int nr)
428{
429 trace_softirq_raise(nr);
430 or_softirq_pending(1UL << nr);
431}
432
Carlos R. Mafra962cf362008-05-15 11:15:37 -0300433void open_softirq(int nr, void (*action)(struct softirq_action *))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435 softirq_vec[nr].action = action;
436}
437
Peter Zijlstra9ba5f002009-07-22 14:18:35 +0200438/*
439 * Tasklets
440 */
Joe Perchesce85b4f2014-01-27 17:07:16 -0800441struct tasklet_head {
Olof Johansson48f20a92008-03-04 15:23:25 -0800442 struct tasklet_struct *head;
443 struct tasklet_struct **tail;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444};
445
Vegard Nossum4620b492008-06-12 23:21:53 +0200446static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec);
447static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800449void __tasklet_schedule(struct tasklet_struct *t)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450{
451 unsigned long flags;
452
453 local_irq_save(flags);
Olof Johansson48f20a92008-03-04 15:23:25 -0800454 t->next = NULL;
Christoph Lameter909ea962010-12-08 16:22:55 +0100455 *__this_cpu_read(tasklet_vec.tail) = t;
456 __this_cpu_write(tasklet_vec.tail, &(t->next));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457 raise_softirq_irqoff(TASKLET_SOFTIRQ);
458 local_irq_restore(flags);
459}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460EXPORT_SYMBOL(__tasklet_schedule);
461
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800462void __tasklet_hi_schedule(struct tasklet_struct *t)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463{
464 unsigned long flags;
465
466 local_irq_save(flags);
Olof Johansson48f20a92008-03-04 15:23:25 -0800467 t->next = NULL;
Christoph Lameter909ea962010-12-08 16:22:55 +0100468 *__this_cpu_read(tasklet_hi_vec.tail) = t;
469 __this_cpu_write(tasklet_hi_vec.tail, &(t->next));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470 raise_softirq_irqoff(HI_SOFTIRQ);
471 local_irq_restore(flags);
472}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473EXPORT_SYMBOL(__tasklet_hi_schedule);
474
Vegard Nossum7c692cb2008-05-21 22:53:13 +0200475void __tasklet_hi_schedule_first(struct tasklet_struct *t)
476{
477 BUG_ON(!irqs_disabled());
478
Christoph Lameter909ea962010-12-08 16:22:55 +0100479 t->next = __this_cpu_read(tasklet_hi_vec.head);
480 __this_cpu_write(tasklet_hi_vec.head, t);
Vegard Nossum7c692cb2008-05-21 22:53:13 +0200481 __raise_softirq_irqoff(HI_SOFTIRQ);
482}
Vegard Nossum7c692cb2008-05-21 22:53:13 +0200483EXPORT_SYMBOL(__tasklet_hi_schedule_first);
484
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485static void tasklet_action(struct softirq_action *a)
486{
487 struct tasklet_struct *list;
488
489 local_irq_disable();
Christoph Lameter909ea962010-12-08 16:22:55 +0100490 list = __this_cpu_read(tasklet_vec.head);
491 __this_cpu_write(tasklet_vec.head, NULL);
Christoph Lameter22127e92014-08-17 12:30:25 -0500492 __this_cpu_write(tasklet_vec.tail, this_cpu_ptr(&tasklet_vec.head));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 local_irq_enable();
494
495 while (list) {
496 struct tasklet_struct *t = list;
497
498 list = list->next;
499
500 if (tasklet_trylock(t)) {
501 if (!atomic_read(&t->count)) {
Joe Perchesce85b4f2014-01-27 17:07:16 -0800502 if (!test_and_clear_bit(TASKLET_STATE_SCHED,
503 &t->state))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504 BUG();
505 t->func(t->data);
506 tasklet_unlock(t);
507 continue;
508 }
509 tasklet_unlock(t);
510 }
511
512 local_irq_disable();
Olof Johansson48f20a92008-03-04 15:23:25 -0800513 t->next = NULL;
Christoph Lameter909ea962010-12-08 16:22:55 +0100514 *__this_cpu_read(tasklet_vec.tail) = t;
515 __this_cpu_write(tasklet_vec.tail, &(t->next));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 __raise_softirq_irqoff(TASKLET_SOFTIRQ);
517 local_irq_enable();
518 }
519}
520
521static void tasklet_hi_action(struct softirq_action *a)
522{
523 struct tasklet_struct *list;
524
525 local_irq_disable();
Christoph Lameter909ea962010-12-08 16:22:55 +0100526 list = __this_cpu_read(tasklet_hi_vec.head);
527 __this_cpu_write(tasklet_hi_vec.head, NULL);
Christoph Lameter22127e92014-08-17 12:30:25 -0500528 __this_cpu_write(tasklet_hi_vec.tail, this_cpu_ptr(&tasklet_hi_vec.head));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 local_irq_enable();
530
531 while (list) {
532 struct tasklet_struct *t = list;
533
534 list = list->next;
535
536 if (tasklet_trylock(t)) {
537 if (!atomic_read(&t->count)) {
Joe Perchesce85b4f2014-01-27 17:07:16 -0800538 if (!test_and_clear_bit(TASKLET_STATE_SCHED,
539 &t->state))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540 BUG();
541 t->func(t->data);
542 tasklet_unlock(t);
543 continue;
544 }
545 tasklet_unlock(t);
546 }
547
548 local_irq_disable();
Olof Johansson48f20a92008-03-04 15:23:25 -0800549 t->next = NULL;
Christoph Lameter909ea962010-12-08 16:22:55 +0100550 *__this_cpu_read(tasklet_hi_vec.tail) = t;
551 __this_cpu_write(tasklet_hi_vec.tail, &(t->next));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552 __raise_softirq_irqoff(HI_SOFTIRQ);
553 local_irq_enable();
554 }
555}
556
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557void tasklet_init(struct tasklet_struct *t,
558 void (*func)(unsigned long), unsigned long data)
559{
560 t->next = NULL;
561 t->state = 0;
562 atomic_set(&t->count, 0);
563 t->func = func;
564 t->data = data;
565}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566EXPORT_SYMBOL(tasklet_init);
567
568void tasklet_kill(struct tasklet_struct *t)
569{
570 if (in_interrupt())
Joe Perches40322762014-01-27 17:07:15 -0800571 pr_notice("Attempt to kill tasklet from interrupt\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572
573 while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) {
H Hartley Sweeten79d381c2009-04-16 19:30:18 -0400574 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575 yield();
H Hartley Sweeten79d381c2009-04-16 19:30:18 -0400576 } while (test_bit(TASKLET_STATE_SCHED, &t->state));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700577 }
578 tasklet_unlock_wait(t);
579 clear_bit(TASKLET_STATE_SCHED, &t->state);
580}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581EXPORT_SYMBOL(tasklet_kill);
582
Peter Zijlstra9ba5f002009-07-22 14:18:35 +0200583/*
584 * tasklet_hrtimer
585 */
586
587/*
Peter Zijlstrab9c30322010-02-03 18:08:52 +0100588 * 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.
Peter Zijlstra9ba5f002009-07-22 14:18:35 +0200591 */
592static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer)
593{
594 struct tasklet_hrtimer *ttimer =
595 container_of(timer, struct tasklet_hrtimer, timer);
596
Peter Zijlstrab9c30322010-02-03 18:08:52 +0100597 tasklet_hi_schedule(&ttimer->tasklet);
598 return HRTIMER_NORESTART;
Peter Zijlstra9ba5f002009-07-22 14:18:35 +0200599}
600
601/*
602 * Helper function which calls the hrtimer callback from
603 * tasklet/softirq context
604 */
605static 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
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300618 * @function: hrtimer callback function which gets called from softirq context
Peter Zijlstra9ba5f002009-07-22 14:18:35 +0200619 * @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME)
620 * @mode: hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL)
621 */
622void 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}
632EXPORT_SYMBOL_GPL(tasklet_hrtimer_init);
633
Linus Torvalds1da177e2005-04-16 15:20:36 -0700634void __init softirq_init(void)
635{
Olof Johansson48f20a92008-03-04 15:23:25 -0800636 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
Carlos R. Mafra962cf362008-05-15 11:15:37 -0300645 open_softirq(TASKLET_SOFTIRQ, tasklet_action);
646 open_softirq(HI_SOFTIRQ, tasklet_hi_action);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647}
648
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000649static int ksoftirqd_should_run(unsigned int cpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650{
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000651 return local_softirq_pending();
652}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000654static void run_ksoftirqd(unsigned int cpu)
655{
656 local_irq_disable();
657 if (local_softirq_pending()) {
Frederic Weisbecker0bed6982013-09-05 16:14:00 +0200658 /*
659 * We can safely run softirq on inline stack, as we are not deep
660 * in the task stack here.
661 */
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000662 __do_softirq();
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000663 local_irq_enable();
Paul E. McKenney60479672015-01-14 13:20:26 -0800664 cond_resched_rcu_qs();
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000665 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666 }
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000667 local_irq_enable();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668}
669
670#ifdef CONFIG_HOTPLUG_CPU
671/*
672 * tasklet_kill_immediate is called to remove a tasklet which can already be
673 * scheduled for execution on @cpu.
674 *
675 * Unlike tasklet_kill, this function removes the tasklet
676 * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state.
677 *
678 * When this function is called, @cpu must be in the CPU_DEAD state.
679 */
680void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu)
681{
682 struct tasklet_struct **i;
683
684 BUG_ON(cpu_online(cpu));
685 BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state));
686
687 if (!test_bit(TASKLET_STATE_SCHED, &t->state))
688 return;
689
690 /* CPU is dead, so no lock needed. */
Olof Johansson48f20a92008-03-04 15:23:25 -0800691 for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 if (*i == t) {
693 *i = t->next;
Olof Johansson48f20a92008-03-04 15:23:25 -0800694 /* If this was the tail element, move the tail ptr */
695 if (*i == NULL)
696 per_cpu(tasklet_vec, cpu).tail = i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697 return;
698 }
699 }
700 BUG();
701}
702
703static void takeover_tasklets(unsigned int cpu)
704{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 /* CPU is dead, so no lock needed. */
706 local_irq_disable();
707
708 /* Find end, append list for that CPU. */
Christian Borntraegere5e41722008-05-01 04:34:23 -0700709 if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) {
Christoph Lameter909ea962010-12-08 16:22:55 +0100710 *__this_cpu_read(tasklet_vec.tail) = per_cpu(tasklet_vec, cpu).head;
711 this_cpu_write(tasklet_vec.tail, per_cpu(tasklet_vec, cpu).tail);
Christian Borntraegere5e41722008-05-01 04:34:23 -0700712 per_cpu(tasklet_vec, cpu).head = NULL;
713 per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head;
714 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715 raise_softirq_irqoff(TASKLET_SOFTIRQ);
716
Christian Borntraegere5e41722008-05-01 04:34:23 -0700717 if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) {
Christoph Lameter909ea962010-12-08 16:22:55 +0100718 *__this_cpu_read(tasklet_hi_vec.tail) = per_cpu(tasklet_hi_vec, cpu).head;
719 __this_cpu_write(tasklet_hi_vec.tail, per_cpu(tasklet_hi_vec, cpu).tail);
Christian Borntraegere5e41722008-05-01 04:34:23 -0700720 per_cpu(tasklet_hi_vec, cpu).head = NULL;
721 per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head;
722 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723 raise_softirq_irqoff(HI_SOFTIRQ);
724
725 local_irq_enable();
726}
727#endif /* CONFIG_HOTPLUG_CPU */
728
Joe Perchesce85b4f2014-01-27 17:07:16 -0800729static int cpu_callback(struct notifier_block *nfb, unsigned long action,
730 void *hcpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700732 switch (action) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733#ifdef CONFIG_HOTPLUG_CPU
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734 case CPU_DEAD:
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000735 case CPU_DEAD_FROZEN:
736 takeover_tasklets((unsigned long)hcpu);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737 break;
738#endif /* CONFIG_HOTPLUG_CPU */
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000739 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 return NOTIFY_OK;
741}
742
Paul Gortmaker0db06282013-06-19 14:53:51 -0400743static struct notifier_block cpu_nfb = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744 .notifier_call = cpu_callback
745};
746
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000747static struct smp_hotplug_thread softirq_threads = {
748 .store = &ksoftirqd,
749 .thread_should_run = ksoftirqd_should_run,
750 .thread_fn = run_ksoftirqd,
751 .thread_comm = "ksoftirqd/%u",
752};
753
Eduard - Gabriel Munteanu7babe8d2008-07-25 19:45:11 -0700754static __init int spawn_ksoftirqd(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700756 register_cpu_notifier(&cpu_nfb);
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000757
758 BUG_ON(smpboot_register_percpu_thread(&softirq_threads));
759
Linus Torvalds1da177e2005-04-16 15:20:36 -0700760 return 0;
761}
Eduard - Gabriel Munteanu7babe8d2008-07-25 19:45:11 -0700762early_initcall(spawn_ksoftirqd);
Andrew Morton78eef012006-03-22 00:08:16 -0800763
Yinghai Lu43a25632008-12-28 16:01:13 -0800764/*
765 * [ These __weak aliases are kept in a separate compilation unit, so that
766 * GCC does not inline them incorrectly. ]
767 */
768
769int __init __weak early_irq_init(void)
770{
771 return 0;
772}
773
Yinghai Lu4a046d12009-01-12 17:39:24 -0800774int __init __weak arch_probe_nr_irqs(void)
775{
Thomas Gleixnerb683de22010-09-27 20:55:03 +0200776 return NR_IRQS_LEGACY;
Yinghai Lu4a046d12009-01-12 17:39:24 -0800777}
778
Yinghai Lu43a25632008-12-28 16:01:13 -0800779int __init __weak arch_early_irq_init(void)
780{
781 return 0;
782}
Thomas Gleixner62a08ae2014-04-24 09:50:53 +0200783
784unsigned int __weak arch_dynirq_lower_bound(unsigned int from)
785{
786 return from;
787}