blob: 5a910f21dcf8e40b95747717c304d29a8be65d0f [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>
Tim Zimmermann6a834b72020-09-03 09:11:59 +020029#include <linux/debug-snapshot.h>
30#include <linux/sched/clock.h>
31#include <linux/nmi.h>
Heiko Carstensa0e39ed2009-04-29 13:51:39 +020032
33#define CREATE_TRACE_POINTS
Steven Rostedtad8d75f2009-04-14 19:39:12 -040034#include <trace/events/irq.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035
Linus Torvalds1da177e2005-04-16 15:20:36 -070036/*
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
55irq_cpustat_t irq_stat[NR_CPUS] ____cacheline_aligned;
56EXPORT_SYMBOL(irq_stat);
57#endif
58
Alexey Dobriyan978b0112008-09-06 20:04:36 +020059static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp;
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
Venkatesh Pallipadi4dd53d82010-12-21 17:09:00 -080061DEFINE_PER_CPU(struct task_struct *, ksoftirqd);
Linus Torvalds1da177e2005-04-16 15:20:36 -070062
Joe Perchesce85b4f2014-01-27 17:07:16 -080063const char * const softirq_to_name[NR_SOFTIRQS] = {
Sagi Grimbergf660f602016-10-10 15:10:51 +030064 "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "IRQ_POLL",
Shaohua Li09223372011-06-14 13:26:25 +080065 "TASKLET", "SCHED", "HRTIMER", "RCU"
Jason Baron5d592b42009-03-12 14:33:36 -040066};
67
Linus Torvalds1da177e2005-04-16 15:20:36 -070068/*
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 */
Thomas Gleixner676cb022009-07-20 23:33:49 +020074static void wakeup_softirqd(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -070075{
76 /* Interrupts are disabled: no need to stop preemption */
Christoph Lameter909ea962010-12-08 16:22:55 +010077 struct task_struct *tsk = __this_cpu_read(ksoftirqd);
Linus Torvalds1da177e2005-04-16 15:20:36 -070078
79 if (tsk && tsk->state != TASK_RUNNING)
80 wake_up_process(tsk);
81}
82
83/*
Eric Dumazet4cd13c22016-08-31 10:42:29 -070084 * If ksoftirqd is scheduled, we do not want to process pending softirqs
Linus Torvalds3eb86ff2018-01-08 11:51:04 -080085 * right now. Let ksoftirqd handle this at its own rate, to get fairness,
86 * unless we're doing some of the synchronous softirqs.
Eric Dumazet4cd13c22016-08-31 10:42:29 -070087 */
Linus Torvalds3eb86ff2018-01-08 11:51:04 -080088#define SOFTIRQ_NOW_MASK ((1 << HI_SOFTIRQ) | (1 << TASKLET_SOFTIRQ))
89static bool ksoftirqd_running(unsigned long pending)
Eric Dumazet4cd13c22016-08-31 10:42:29 -070090{
91 struct task_struct *tsk = __this_cpu_read(ksoftirqd);
92
Linus Torvalds3eb86ff2018-01-08 11:51:04 -080093 if (pending & SOFTIRQ_NOW_MASK)
94 return false;
Eric Dumazet4cd13c22016-08-31 10:42:29 -070095 return tsk && (tsk->state == TASK_RUNNING);
96}
97
98/*
Venkatesh Pallipadi75e10562010-10-04 17:03:16 -070099 * preempt_count and SOFTIRQ_OFFSET usage:
100 * - preempt_count is changed by SOFTIRQ_OFFSET on entering or leaving
101 * softirq processing.
102 * - preempt_count is changed by SOFTIRQ_DISABLE_OFFSET (= 2 * SOFTIRQ_OFFSET)
103 * on local_bh_disable or local_bh_enable.
104 * This lets us distinguish between whether we are currently processing
105 * softirq and whether we just have bh disabled.
106 */
107
108/*
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700109 * This one is for softirq.c-internal use,
110 * where hardirqs are disabled legitimately:
111 */
Tim Chen3c829c32006-07-30 03:04:02 -0700112#ifdef CONFIG_TRACE_IRQFLAGS
Peter Zijlstra0bd3a172013-11-19 16:13:38 +0100113void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700114{
115 unsigned long flags;
116
117 WARN_ON_ONCE(in_irq());
118
119 raw_local_irq_save(flags);
Steven Rostedt7e49fcc2009-01-22 19:01:40 -0500120 /*
Peter Zijlstrabdb43802013-09-10 12:15:23 +0200121 * The preempt tracer hooks into preempt_count_add and will break
Steven Rostedt7e49fcc2009-01-22 19:01:40 -0500122 * lockdep because it calls back into lockdep after SOFTIRQ_OFFSET
123 * is set and before current->softirq_enabled is cleared.
124 * We must manually increment preempt_count here and manually
125 * call the trace_preempt_off later.
126 */
Peter Zijlstrabdb43802013-09-10 12:15:23 +0200127 __preempt_count_add(cnt);
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700128 /*
129 * Were softirqs turned off above:
130 */
Peter Zijlstra9ea4c382013-11-19 16:13:38 +0100131 if (softirq_count() == (cnt & SOFTIRQ_MASK))
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700132 trace_softirqs_off(ip);
133 raw_local_irq_restore(flags);
Steven Rostedt7e49fcc2009-01-22 19:01:40 -0500134
Heiko Carstens0f1ba9a2015-01-07 10:04:41 +0100135 if (preempt_count() == cnt) {
136#ifdef CONFIG_DEBUG_PREEMPT
Sebastian Andrzej Siewiorf904f582016-02-26 14:54:56 +0100137 current->preempt_disable_ip = get_lock_parent_ip();
Heiko Carstens0f1ba9a2015-01-07 10:04:41 +0100138#endif
Sebastian Andrzej Siewiorf904f582016-02-26 14:54:56 +0100139 trace_preempt_off(CALLER_ADDR0, get_lock_parent_ip());
Heiko Carstens0f1ba9a2015-01-07 10:04:41 +0100140 }
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700141}
Peter Zijlstra0bd3a172013-11-19 16:13:38 +0100142EXPORT_SYMBOL(__local_bh_disable_ip);
Tim Chen3c829c32006-07-30 03:04:02 -0700143#endif /* CONFIG_TRACE_IRQFLAGS */
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700144
Venkatesh Pallipadi75e10562010-10-04 17:03:16 -0700145static void __local_bh_enable(unsigned int cnt)
146{
Venkatesh Pallipadi75e10562010-10-04 17:03:16 -0700147 WARN_ON_ONCE(!irqs_disabled());
148
Peter Zijlstra9ea4c382013-11-19 16:13:38 +0100149 if (softirq_count() == (cnt & SOFTIRQ_MASK))
Davidlohr Buesod2e08472013-04-30 11:46:09 -0700150 trace_softirqs_on(_RET_IP_);
Peter Zijlstrabdb43802013-09-10 12:15:23 +0200151 preempt_count_sub(cnt);
Venkatesh Pallipadi75e10562010-10-04 17:03:16 -0700152}
153
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700154/*
155 * Special-case - softirqs can safely be enabled in
156 * cond_resched_softirq(), or by __do_softirq(),
157 * without processing still-pending softirqs:
158 */
159void _local_bh_enable(void)
160{
Frederic Weisbecker5d60d3e2013-09-24 04:11:35 +0200161 WARN_ON_ONCE(in_irq());
Venkatesh Pallipadi75e10562010-10-04 17:03:16 -0700162 __local_bh_enable(SOFTIRQ_DISABLE_OFFSET);
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700163}
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700164EXPORT_SYMBOL(_local_bh_enable);
165
Peter Zijlstra0bd3a172013-11-19 16:13:38 +0100166void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700167{
Johannes Berg0f476b6d2008-06-18 09:29:37 +0200168 WARN_ON_ONCE(in_irq() || irqs_disabled());
Tim Chen3c829c32006-07-30 03:04:02 -0700169#ifdef CONFIG_TRACE_IRQFLAGS
Johannes Berg0f476b6d2008-06-18 09:29:37 +0200170 local_irq_disable();
Tim Chen3c829c32006-07-30 03:04:02 -0700171#endif
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700172 /*
173 * Are softirqs going to be turned on now:
174 */
Venkatesh Pallipadi75e10562010-10-04 17:03:16 -0700175 if (softirq_count() == SOFTIRQ_DISABLE_OFFSET)
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700176 trace_softirqs_on(ip);
177 /*
178 * Keep preemption disabled until we are done with
179 * softirq processing:
Joe Perchesce85b4f2014-01-27 17:07:16 -0800180 */
Peter Zijlstra0bd3a172013-11-19 16:13:38 +0100181 preempt_count_sub(cnt - 1);
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700182
Frederic Weisbecker0bed6982013-09-05 16:14:00 +0200183 if (unlikely(!in_interrupt() && local_softirq_pending())) {
184 /*
185 * Run softirq if any pending. And do it in its own stack
186 * as we may be calling this deep in a task call stack already.
187 */
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700188 do_softirq();
Frederic Weisbecker0bed6982013-09-05 16:14:00 +0200189 }
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700190
Peter Zijlstrabdb43802013-09-10 12:15:23 +0200191 preempt_count_dec();
Tim Chen3c829c32006-07-30 03:04:02 -0700192#ifdef CONFIG_TRACE_IRQFLAGS
Johannes Berg0f476b6d2008-06-18 09:29:37 +0200193 local_irq_enable();
Tim Chen3c829c32006-07-30 03:04:02 -0700194#endif
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700195 preempt_check_resched();
196}
Peter Zijlstra0bd3a172013-11-19 16:13:38 +0100197EXPORT_SYMBOL(__local_bh_enable_ip);
Ingo Molnarde30a2b2006-07-03 00:24:42 -0700198
199/*
Ben Greear34376a52013-06-06 14:29:49 -0700200 * We restart softirq processing for at most MAX_SOFTIRQ_RESTART times,
201 * but break the loop if need_resched() is set or after 2 ms.
202 * The MAX_SOFTIRQ_TIME provides a nice upper bound in most cases, but in
203 * certain cases, such as stop_machine(), jiffies may cease to
204 * increment and so we need the MAX_SOFTIRQ_RESTART limit as
205 * well to make sure we eventually return from this method.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206 *
Eric Dumazetc10d7362013-01-10 15:26:34 -0800207 * These limits have been established via experimentation.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208 * The two things to balance is latency against fairness -
209 * we want to handle softirqs as soon as possible, but they
210 * should not be able to lock up the box.
211 */
Eric Dumazetc10d7362013-01-10 15:26:34 -0800212#define MAX_SOFTIRQ_TIME msecs_to_jiffies(2)
Ben Greear34376a52013-06-06 14:29:49 -0700213#define MAX_SOFTIRQ_RESTART 10
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100215#ifdef CONFIG_TRACE_IRQFLAGS
216/*
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100217 * When we run softirqs from irq_exit() and thus on the hardirq stack we need
218 * to keep the lockdep irq context tracking as tight as possible in order to
219 * not miss-qualify lock contexts and miss possible deadlocks.
220 */
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100221
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100222static inline bool lockdep_softirq_start(void)
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100223{
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100224 bool in_hardirq = false;
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100225
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100226 if (trace_hardirq_context(current)) {
227 in_hardirq = true;
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100228 trace_hardirq_exit();
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100229 }
230
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100231 lockdep_softirq_enter();
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100232
233 return in_hardirq;
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100234}
235
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100236static inline void lockdep_softirq_end(bool in_hardirq)
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100237{
238 lockdep_softirq_exit();
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100239
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100240 if (in_hardirq)
241 trace_hardirq_enter();
242}
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100243#else
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100244static inline bool lockdep_softirq_start(void) { return false; }
245static inline void lockdep_softirq_end(bool in_hardirq) { }
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100246#endif
247
Alexander Potapenkobe7635e2016-03-25 14:22:05 -0700248asmlinkage __visible void __softirq_entry __do_softirq(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249{
Eric Dumazetc10d7362013-01-10 15:26:34 -0800250 unsigned long end = jiffies + MAX_SOFTIRQ_TIME;
Mel Gorman907aed42012-07-31 16:44:07 -0700251 unsigned long old_flags = current->flags;
Tim Zimmermann6a834b72020-09-03 09:11:59 +0200252 unsigned long long start_time;
Ben Greear34376a52013-06-06 14:29:49 -0700253 int max_restart = MAX_SOFTIRQ_RESTART;
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100254 struct softirq_action *h;
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100255 bool in_hardirq;
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100256 __u32 pending;
Joe Perches2e702b92014-01-27 17:07:14 -0800257 int softirq_bit;
Mel Gorman907aed42012-07-31 16:44:07 -0700258
259 /*
260 * Mask out PF_MEMALLOC s current task context is borrowed for the
261 * softirq. A softirq handled such as network RX might set PF_MEMALLOC
262 * again if the socket is related to swap
263 */
264 current->flags &= ~PF_MEMALLOC;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265
266 pending = local_softirq_pending();
Frederic Weisbecker6a616712012-12-16 20:00:34 +0100267 account_irq_enter_time(current);
Paul Mackerras829035fd2006-07-03 00:25:40 -0700268
Peter Zijlstra0bd3a172013-11-19 16:13:38 +0100269 __local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET);
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100270 in_hardirq = lockdep_softirq_start();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272restart:
273 /* Reset the pending bitmask before enabling irqs */
Andi Kleen3f744782005-09-12 18:49:24 +0200274 set_softirq_pending(0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275
Andrew Mortonc70f5d62005-07-30 10:22:49 -0700276 local_irq_enable();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277
278 h = softirq_vec;
279
Joe Perches2e702b92014-01-27 17:07:14 -0800280 while ((softirq_bit = ffs(pending))) {
281 unsigned int vec_nr;
282 int prev_count;
Thomas Gleixner8e85b4b2008-10-02 10:50:53 +0200283
Joe Perches2e702b92014-01-27 17:07:14 -0800284 h += softirq_bit - 1;
Thomas Gleixnerf4bc6bb2010-10-19 15:00:13 +0200285
Joe Perches2e702b92014-01-27 17:07:14 -0800286 vec_nr = h - softirq_vec;
287 prev_count = preempt_count();
Thomas Gleixner8e85b4b2008-10-02 10:50:53 +0200288
Joe Perches2e702b92014-01-27 17:07:14 -0800289 kstat_incr_softirqs_this_cpu(vec_nr);
290
291 trace_softirq_entry(vec_nr);
Tim Zimmermann6a834b72020-09-03 09:11:59 +0200292 dbg_snapshot_irq_var(start_time);
293 dbg_snapshot_irq(DSS_FLAG_SOFTIRQ, h->action, NULL, 0, DSS_FLAG_IN);
294 sl_softirq_entry(softirq_to_name[vec_nr], h->action);
Joe Perches2e702b92014-01-27 17:07:14 -0800295 h->action(h);
Tim Zimmermann6a834b72020-09-03 09:11:59 +0200296 sl_softirq_exit();
297 dbg_snapshot_irq(DSS_FLAG_SOFTIRQ, h->action, NULL, start_time, DSS_FLAG_OUT);
Joe Perches2e702b92014-01-27 17:07:14 -0800298 trace_softirq_exit(vec_nr);
299 if (unlikely(prev_count != preempt_count())) {
Joe Perches40322762014-01-27 17:07:15 -0800300 pr_err("huh, entered softirq %u %s %p with preempt_count %08x, exited with %08x?\n",
Joe Perches2e702b92014-01-27 17:07:14 -0800301 vec_nr, softirq_to_name[vec_nr], h->action,
302 prev_count, preempt_count());
303 preempt_count_set(prev_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304 }
305 h++;
Joe Perches2e702b92014-01-27 17:07:14 -0800306 pending >>= softirq_bit;
307 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308
Paul E. McKenney284a8c92014-08-14 16:38:46 -0700309 rcu_bh_qs();
Andrew Mortonc70f5d62005-07-30 10:22:49 -0700310 local_irq_disable();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311
312 pending = local_softirq_pending();
Eric Dumazetc10d7362013-01-10 15:26:34 -0800313 if (pending) {
Ben Greear34376a52013-06-06 14:29:49 -0700314 if (time_before(jiffies, end) && !need_resched() &&
315 --max_restart)
Eric Dumazetc10d7362013-01-10 15:26:34 -0800316 goto restart;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 wakeup_softirqd();
Eric Dumazetc10d7362013-01-10 15:26:34 -0800319 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320
Frederic Weisbecker5c4853b2013-11-20 01:07:34 +0100321 lockdep_softirq_end(in_hardirq);
Frederic Weisbecker6a616712012-12-16 20:00:34 +0100322 account_irq_exit_time(current);
Venkatesh Pallipadi75e10562010-10-04 17:03:16 -0700323 __local_bh_enable(SOFTIRQ_OFFSET);
Frederic Weisbecker5d60d3e2013-09-24 04:11:35 +0200324 WARN_ON_ONCE(in_interrupt());
NeilBrown717a94b2017-04-07 10:03:26 +1000325 current_restore_flags(old_flags, PF_MEMALLOC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326}
327
Andi Kleen722a9f92014-05-02 00:44:38 +0200328asmlinkage __visible void do_softirq(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329{
330 __u32 pending;
331 unsigned long flags;
332
333 if (in_interrupt())
334 return;
335
336 local_irq_save(flags);
337
338 pending = local_softirq_pending();
339
Linus Torvalds3eb86ff2018-01-08 11:51:04 -0800340 if (pending && !ksoftirqd_running(pending))
Frederic Weisbecker7d65f4a2013-09-05 15:49:45 +0200341 do_softirq_own_stack();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342
343 local_irq_restore(flags);
344}
345
Ingo Molnardde4b2b2007-02-16 01:27:45 -0800346/*
347 * Enter an interrupt context.
348 */
349void irq_enter(void)
350{
Paul E. McKenney64db4cf2008-12-18 21:55:32 +0100351 rcu_irq_enter();
Frederic Weisbecker0a8a2e72012-01-24 18:59:44 +0100352 if (is_idle_task(current) && !in_interrupt()) {
Venkatesh Pallipadid267f872010-10-04 17:03:23 -0700353 /*
354 * Prevent raise_softirq from needlessly waking up ksoftirqd
355 * here, as softirq will be serviced on return from interrupt.
356 */
357 local_bh_disable();
Frederic Weisbecker5acac1b2013-12-04 18:28:20 +0100358 tick_irq_enter();
Venkatesh Pallipadid267f872010-10-04 17:03:23 -0700359 _local_bh_enable();
360 }
361
362 __irq_enter();
Ingo Molnardde4b2b2007-02-16 01:27:45 -0800363}
364
Heiko Carstensb2a00172012-03-05 15:07:25 -0800365static inline void invoke_softirq(void)
366{
Linus Torvalds3eb86ff2018-01-08 11:51:04 -0800367 if (ksoftirqd_running(local_softirq_pending()))
Eric Dumazet4cd13c22016-08-31 10:42:29 -0700368 return;
369
Frederic Weisbeckerded79752013-09-24 00:50:25 +0200370 if (!force_irqthreads) {
Frederic Weisbeckercc1f0272013-09-24 17:17:47 +0200371#ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
Frederic Weisbeckerded79752013-09-24 00:50:25 +0200372 /*
373 * We can safely execute softirq on the current stack if
374 * it is the irq stack, because it should be near empty
Frederic Weisbeckercc1f0272013-09-24 17:17:47 +0200375 * at this stage.
376 */
377 __do_softirq();
378#else
379 /*
380 * Otherwise, irq_exit() is called on the task stack that can
381 * be potentially deep already. So call softirq in its own stack
382 * to prevent from any overrun.
Frederic Weisbeckerded79752013-09-24 00:50:25 +0200383 */
Frederic Weisbeckerbe6e1012013-09-24 16:39:41 +0200384 do_softirq_own_stack();
Frederic Weisbeckercc1f0272013-09-24 17:17:47 +0200385#endif
Frederic Weisbeckerded79752013-09-24 00:50:25 +0200386 } else {
Thomas Gleixner8d32a302011-02-23 23:52:23 +0000387 wakeup_softirqd();
Frederic Weisbeckerded79752013-09-24 00:50:25 +0200388 }
Thomas Gleixner8d32a302011-02-23 23:52:23 +0000389}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390
Frederic Weisbecker67826ea2013-04-20 17:43:13 +0200391static inline void tick_irq_exit(void)
392{
393#ifdef CONFIG_NO_HZ_COMMON
394 int cpu = smp_processor_id();
395
396 /* Make sure that timer wheel updates are propagated */
397 if ((idle_cpu(cpu) && !need_resched()) || tick_nohz_full_cpu(cpu)) {
Frederic Weisbecker2d898912018-08-03 15:31:34 +0200398 if (!in_irq())
Frederic Weisbecker67826ea2013-04-20 17:43:13 +0200399 tick_nohz_irq_exit();
400 }
401#endif
402}
403
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404/*
405 * Exit an interrupt context. Process softirqs if needed and possible:
406 */
407void irq_exit(void)
408{
Thomas Gleixner74eed012013-02-20 22:00:48 +0100409#ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED
Frederic Weisbecker4cd5d112013-02-28 20:00:43 +0100410 local_irq_disable();
Thomas Gleixner74eed012013-02-20 22:00:48 +0100411#else
412 WARN_ON_ONCE(!irqs_disabled());
413#endif
414
Frederic Weisbecker6a616712012-12-16 20:00:34 +0100415 account_irq_exit_time(current);
Peter Zijlstrabdb43802013-09-10 12:15:23 +0200416 preempt_count_sub(HARDIRQ_OFFSET);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 if (!in_interrupt() && local_softirq_pending())
418 invoke_softirq();
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -0800419
Frederic Weisbecker67826ea2013-04-20 17:43:13 +0200420 tick_irq_exit();
Frederic Weisbecker416eb332011-10-07 16:31:02 -0700421 rcu_irq_exit();
Peter Zijlstraf1a83e62013-11-19 16:42:47 +0100422 trace_hardirq_exit(); /* must be last! */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423}
424
425/*
426 * This function must run with irqs disabled!
427 */
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800428inline void raise_softirq_irqoff(unsigned int nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429{
430 __raise_softirq_irqoff(nr);
431
432 /*
433 * If we're in an interrupt or softirq, we're done
434 * (this also catches softirq-disabled code). We will
435 * actually run the softirq once we return from
436 * the irq or softirq.
437 *
438 * Otherwise we wake up ksoftirqd to make sure we
439 * schedule the softirq soon.
440 */
441 if (!in_interrupt())
442 wakeup_softirqd();
443}
444
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800445void raise_softirq(unsigned int nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700446{
447 unsigned long flags;
448
449 local_irq_save(flags);
450 raise_softirq_irqoff(nr);
451 local_irq_restore(flags);
452}
453
Steven Rostedtf0696862012-01-25 20:18:55 -0500454void __raise_softirq_irqoff(unsigned int nr)
455{
456 trace_softirq_raise(nr);
457 or_softirq_pending(1UL << nr);
458}
459
Carlos R. Mafra962cf362008-05-15 11:15:37 -0300460void open_softirq(int nr, void (*action)(struct softirq_action *))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462 softirq_vec[nr].action = action;
463}
464
Peter Zijlstra9ba5f002009-07-22 14:18:35 +0200465/*
466 * Tasklets
467 */
Joe Perchesce85b4f2014-01-27 17:07:16 -0800468struct tasklet_head {
Olof Johansson48f20a92008-03-04 15:23:25 -0800469 struct tasklet_struct *head;
470 struct tasklet_struct **tail;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471};
472
Vegard Nossum4620b492008-06-12 23:21:53 +0200473static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec);
474static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800476void __tasklet_schedule(struct tasklet_struct *t)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477{
478 unsigned long flags;
479
480 local_irq_save(flags);
Olof Johansson48f20a92008-03-04 15:23:25 -0800481 t->next = NULL;
Christoph Lameter909ea962010-12-08 16:22:55 +0100482 *__this_cpu_read(tasklet_vec.tail) = t;
483 __this_cpu_write(tasklet_vec.tail, &(t->next));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484 raise_softirq_irqoff(TASKLET_SOFTIRQ);
485 local_irq_restore(flags);
486}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487EXPORT_SYMBOL(__tasklet_schedule);
488
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800489void __tasklet_hi_schedule(struct tasklet_struct *t)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490{
491 unsigned long flags;
492
493 local_irq_save(flags);
Olof Johansson48f20a92008-03-04 15:23:25 -0800494 t->next = NULL;
Christoph Lameter909ea962010-12-08 16:22:55 +0100495 *__this_cpu_read(tasklet_hi_vec.tail) = t;
496 __this_cpu_write(tasklet_hi_vec.tail, &(t->next));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497 raise_softirq_irqoff(HI_SOFTIRQ);
498 local_irq_restore(flags);
499}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500EXPORT_SYMBOL(__tasklet_hi_schedule);
501
Emese Revfy0766f782016-06-20 20:42:34 +0200502static __latent_entropy void tasklet_action(struct softirq_action *a)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503{
504 struct tasklet_struct *list;
Tim Zimmermann6a834b72020-09-03 09:11:59 +0200505 unsigned long long start_time;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506
507 local_irq_disable();
Christoph Lameter909ea962010-12-08 16:22:55 +0100508 list = __this_cpu_read(tasklet_vec.head);
509 __this_cpu_write(tasklet_vec.head, NULL);
Christoph Lameter22127e92014-08-17 12:30:25 -0500510 __this_cpu_write(tasklet_vec.tail, this_cpu_ptr(&tasklet_vec.head));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511 local_irq_enable();
512
513 while (list) {
514 struct tasklet_struct *t = list;
515
516 list = list->next;
517
518 if (tasklet_trylock(t)) {
519 if (!atomic_read(&t->count)) {
Joe Perchesce85b4f2014-01-27 17:07:16 -0800520 if (!test_and_clear_bit(TASKLET_STATE_SCHED,
521 &t->state))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522 BUG();
Tim Zimmermann6a834b72020-09-03 09:11:59 +0200523 dbg_snapshot_irq_var(start_time);
524 dbg_snapshot_irq(DSS_FLAG_SOFTIRQ_TASKLET,
525 t->func, NULL, 0, DSS_FLAG_IN);
526 sl_softirq_entry(softirq_to_name[TASKLET_SOFTIRQ], t->func);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527 t->func(t->data);
Tim Zimmermann6a834b72020-09-03 09:11:59 +0200528 sl_softirq_exit();
529 dbg_snapshot_irq(DSS_FLAG_SOFTIRQ_TASKLET,
530 t->func, NULL, start_time, DSS_FLAG_OUT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531 tasklet_unlock(t);
532 continue;
533 }
534 tasklet_unlock(t);
535 }
536
537 local_irq_disable();
Olof Johansson48f20a92008-03-04 15:23:25 -0800538 t->next = NULL;
Christoph Lameter909ea962010-12-08 16:22:55 +0100539 *__this_cpu_read(tasklet_vec.tail) = t;
540 __this_cpu_write(tasklet_vec.tail, &(t->next));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541 __raise_softirq_irqoff(TASKLET_SOFTIRQ);
542 local_irq_enable();
543 }
544}
545
Emese Revfy0766f782016-06-20 20:42:34 +0200546static __latent_entropy void tasklet_hi_action(struct softirq_action *a)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547{
548 struct tasklet_struct *list;
Tim Zimmermann6a834b72020-09-03 09:11:59 +0200549 unsigned long long start_time;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550
551 local_irq_disable();
Christoph Lameter909ea962010-12-08 16:22:55 +0100552 list = __this_cpu_read(tasklet_hi_vec.head);
553 __this_cpu_write(tasklet_hi_vec.head, NULL);
Christoph Lameter22127e92014-08-17 12:30:25 -0500554 __this_cpu_write(tasklet_hi_vec.tail, this_cpu_ptr(&tasklet_hi_vec.head));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555 local_irq_enable();
556
557 while (list) {
558 struct tasklet_struct *t = list;
559
560 list = list->next;
561
562 if (tasklet_trylock(t)) {
563 if (!atomic_read(&t->count)) {
Joe Perchesce85b4f2014-01-27 17:07:16 -0800564 if (!test_and_clear_bit(TASKLET_STATE_SCHED,
565 &t->state))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566 BUG();
Tim Zimmermann6a834b72020-09-03 09:11:59 +0200567 dbg_snapshot_irq_var(start_time);
568 dbg_snapshot_irq(DSS_FLAG_SOFTIRQ_HI_TASKLET,
569 t->func, NULL, 0, DSS_FLAG_IN);
570 sl_softirq_entry(softirq_to_name[HI_SOFTIRQ], t->func);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571 t->func(t->data);
Tim Zimmermann6a834b72020-09-03 09:11:59 +0200572 sl_softirq_exit();
573 dbg_snapshot_irq(DSS_FLAG_SOFTIRQ_HI_TASKLET,
574 t->func, NULL, start_time, DSS_FLAG_OUT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575 tasklet_unlock(t);
576 continue;
577 }
578 tasklet_unlock(t);
579 }
580
581 local_irq_disable();
Olof Johansson48f20a92008-03-04 15:23:25 -0800582 t->next = NULL;
Christoph Lameter909ea962010-12-08 16:22:55 +0100583 *__this_cpu_read(tasklet_hi_vec.tail) = t;
584 __this_cpu_write(tasklet_hi_vec.tail, &(t->next));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585 __raise_softirq_irqoff(HI_SOFTIRQ);
586 local_irq_enable();
587 }
588}
589
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590void tasklet_init(struct tasklet_struct *t,
591 void (*func)(unsigned long), unsigned long data)
592{
593 t->next = NULL;
594 t->state = 0;
595 atomic_set(&t->count, 0);
596 t->func = func;
597 t->data = data;
598}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599EXPORT_SYMBOL(tasklet_init);
600
601void tasklet_kill(struct tasklet_struct *t)
602{
603 if (in_interrupt())
Joe Perches40322762014-01-27 17:07:15 -0800604 pr_notice("Attempt to kill tasklet from interrupt\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605
606 while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) {
H Hartley Sweeten79d381c2009-04-16 19:30:18 -0400607 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608 yield();
H Hartley Sweeten79d381c2009-04-16 19:30:18 -0400609 } while (test_bit(TASKLET_STATE_SCHED, &t->state));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610 }
611 tasklet_unlock_wait(t);
612 clear_bit(TASKLET_STATE_SCHED, &t->state);
613}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700614EXPORT_SYMBOL(tasklet_kill);
615
Peter Zijlstra9ba5f002009-07-22 14:18:35 +0200616/*
617 * tasklet_hrtimer
618 */
619
620/*
Peter Zijlstrab9c30322010-02-03 18:08:52 +0100621 * The trampoline is called when the hrtimer expires. It schedules a tasklet
622 * to run __tasklet_hrtimer_trampoline() which in turn will call the intended
623 * hrtimer callback, but from softirq context.
Peter Zijlstra9ba5f002009-07-22 14:18:35 +0200624 */
625static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer)
626{
627 struct tasklet_hrtimer *ttimer =
628 container_of(timer, struct tasklet_hrtimer, timer);
629
Peter Zijlstrab9c30322010-02-03 18:08:52 +0100630 tasklet_hi_schedule(&ttimer->tasklet);
631 return HRTIMER_NORESTART;
Peter Zijlstra9ba5f002009-07-22 14:18:35 +0200632}
633
634/*
635 * Helper function which calls the hrtimer callback from
636 * tasklet/softirq context
637 */
638static void __tasklet_hrtimer_trampoline(unsigned long data)
639{
640 struct tasklet_hrtimer *ttimer = (void *)data;
641 enum hrtimer_restart restart;
642
643 restart = ttimer->function(&ttimer->timer);
644 if (restart != HRTIMER_NORESTART)
645 hrtimer_restart(&ttimer->timer);
646}
647
648/**
649 * tasklet_hrtimer_init - Init a tasklet/hrtimer combo for softirq callbacks
650 * @ttimer: tasklet_hrtimer which is initialized
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300651 * @function: hrtimer callback function which gets called from softirq context
Peter Zijlstra9ba5f002009-07-22 14:18:35 +0200652 * @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME)
653 * @mode: hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL)
654 */
655void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer,
656 enum hrtimer_restart (*function)(struct hrtimer *),
657 clockid_t which_clock, enum hrtimer_mode mode)
658{
659 hrtimer_init(&ttimer->timer, which_clock, mode);
660 ttimer->timer.function = __hrtimer_tasklet_trampoline;
661 tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline,
662 (unsigned long)ttimer);
663 ttimer->function = function;
664}
665EXPORT_SYMBOL_GPL(tasklet_hrtimer_init);
666
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667void __init softirq_init(void)
668{
Olof Johansson48f20a92008-03-04 15:23:25 -0800669 int cpu;
670
671 for_each_possible_cpu(cpu) {
672 per_cpu(tasklet_vec, cpu).tail =
673 &per_cpu(tasklet_vec, cpu).head;
674 per_cpu(tasklet_hi_vec, cpu).tail =
675 &per_cpu(tasklet_hi_vec, cpu).head;
676 }
677
Carlos R. Mafra962cf362008-05-15 11:15:37 -0300678 open_softirq(TASKLET_SOFTIRQ, tasklet_action);
679 open_softirq(HI_SOFTIRQ, tasklet_hi_action);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680}
681
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000682static int ksoftirqd_should_run(unsigned int cpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683{
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000684 return local_softirq_pending();
685}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000687static void run_ksoftirqd(unsigned int cpu)
688{
689 local_irq_disable();
690 if (local_softirq_pending()) {
Frederic Weisbecker0bed6982013-09-05 16:14:00 +0200691 /*
692 * We can safely run softirq on inline stack, as we are not deep
693 * in the task stack here.
694 */
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000695 __do_softirq();
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000696 local_irq_enable();
Paul E. McKenney60479672015-01-14 13:20:26 -0800697 cond_resched_rcu_qs();
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000698 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699 }
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000700 local_irq_enable();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700701}
702
703#ifdef CONFIG_HOTPLUG_CPU
704/*
705 * tasklet_kill_immediate is called to remove a tasklet which can already be
706 * scheduled for execution on @cpu.
707 *
708 * Unlike tasklet_kill, this function removes the tasklet
709 * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state.
710 *
711 * When this function is called, @cpu must be in the CPU_DEAD state.
712 */
713void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu)
714{
715 struct tasklet_struct **i;
716
717 BUG_ON(cpu_online(cpu));
718 BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state));
719
720 if (!test_bit(TASKLET_STATE_SCHED, &t->state))
721 return;
722
723 /* CPU is dead, so no lock needed. */
Olof Johansson48f20a92008-03-04 15:23:25 -0800724 for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 if (*i == t) {
726 *i = t->next;
Olof Johansson48f20a92008-03-04 15:23:25 -0800727 /* If this was the tail element, move the tail ptr */
728 if (*i == NULL)
729 per_cpu(tasklet_vec, cpu).tail = i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730 return;
731 }
732 }
733 BUG();
734}
735
Sebastian Andrzej Siewiorc4544db2016-08-18 14:57:21 +0200736static int takeover_tasklets(unsigned int cpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738 /* CPU is dead, so no lock needed. */
739 local_irq_disable();
740
741 /* Find end, append list for that CPU. */
Christian Borntraegere5e41722008-05-01 04:34:23 -0700742 if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) {
Christoph Lameter909ea962010-12-08 16:22:55 +0100743 *__this_cpu_read(tasklet_vec.tail) = per_cpu(tasklet_vec, cpu).head;
744 this_cpu_write(tasklet_vec.tail, per_cpu(tasklet_vec, cpu).tail);
Christian Borntraegere5e41722008-05-01 04:34:23 -0700745 per_cpu(tasklet_vec, cpu).head = NULL;
746 per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head;
747 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748 raise_softirq_irqoff(TASKLET_SOFTIRQ);
749
Christian Borntraegere5e41722008-05-01 04:34:23 -0700750 if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) {
Christoph Lameter909ea962010-12-08 16:22:55 +0100751 *__this_cpu_read(tasklet_hi_vec.tail) = per_cpu(tasklet_hi_vec, cpu).head;
752 __this_cpu_write(tasklet_hi_vec.tail, per_cpu(tasklet_hi_vec, cpu).tail);
Christian Borntraegere5e41722008-05-01 04:34:23 -0700753 per_cpu(tasklet_hi_vec, cpu).head = NULL;
754 per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head;
755 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700756 raise_softirq_irqoff(HI_SOFTIRQ);
757
758 local_irq_enable();
Sebastian Andrzej Siewiorc4544db2016-08-18 14:57:21 +0200759 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700760}
Sebastian Andrzej Siewiorc4544db2016-08-18 14:57:21 +0200761#else
762#define takeover_tasklets NULL
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763#endif /* CONFIG_HOTPLUG_CPU */
764
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000765static struct smp_hotplug_thread softirq_threads = {
766 .store = &ksoftirqd,
767 .thread_should_run = ksoftirqd_should_run,
768 .thread_fn = run_ksoftirqd,
769 .thread_comm = "ksoftirqd/%u",
770};
771
Eduard - Gabriel Munteanu7babe8d2008-07-25 19:45:11 -0700772static __init int spawn_ksoftirqd(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773{
Sebastian Andrzej Siewiorc4544db2016-08-18 14:57:21 +0200774 cpuhp_setup_state_nocalls(CPUHP_SOFTIRQ_DEAD, "softirq:dead", NULL,
775 takeover_tasklets);
Thomas Gleixner3e339b52012-07-16 10:42:37 +0000776 BUG_ON(smpboot_register_percpu_thread(&softirq_threads));
777
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778 return 0;
779}
Eduard - Gabriel Munteanu7babe8d2008-07-25 19:45:11 -0700780early_initcall(spawn_ksoftirqd);
Andrew Morton78eef012006-03-22 00:08:16 -0800781
Yinghai Lu43a25632008-12-28 16:01:13 -0800782/*
783 * [ These __weak aliases are kept in a separate compilation unit, so that
784 * GCC does not inline them incorrectly. ]
785 */
786
787int __init __weak early_irq_init(void)
788{
789 return 0;
790}
791
Yinghai Lu4a046d12009-01-12 17:39:24 -0800792int __init __weak arch_probe_nr_irqs(void)
793{
Thomas Gleixnerb683de22010-09-27 20:55:03 +0200794 return NR_IRQS_LEGACY;
Yinghai Lu4a046d12009-01-12 17:39:24 -0800795}
796
Yinghai Lu43a25632008-12-28 16:01:13 -0800797int __init __weak arch_early_irq_init(void)
798{
799 return 0;
800}
Thomas Gleixner62a08ae2014-04-24 09:50:53 +0200801
802unsigned int __weak arch_dynirq_lower_bound(unsigned int from)
803{
804 return from;
805}