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Peter Zijlstrae360adb2010-10-14 14:01:34 +08001/*
Peter Zijlstra90eec102015-11-16 11:08:45 +01002 * Copyright (C) 2010 Red Hat, Inc., Peter Zijlstra
Peter Zijlstrae360adb2010-10-14 14:01:34 +08003 *
4 * Provides a framework for enqueueing and running callbacks from hardirq
5 * context. The enqueueing is NMI-safe.
6 */
7
Paul Gortmaker83e3fa62012-04-01 16:38:37 -04008#include <linux/bug.h>
Peter Zijlstrae360adb2010-10-14 14:01:34 +08009#include <linux/kernel.h>
Paul Gortmaker9984de12011-05-23 14:51:41 -040010#include <linux/export.h>
Peter Zijlstrae360adb2010-10-14 14:01:34 +080011#include <linux/irq_work.h>
Paul Gortmaker967d1f92011-07-18 13:03:04 -040012#include <linux/percpu.h>
Peter Zijlstrae360adb2010-10-14 14:01:34 +080013#include <linux/hardirq.h>
Chris Metcalfef1f0982012-04-11 12:21:39 -040014#include <linux/irqflags.h>
Frederic Weisbeckerbc6679a2012-10-19 16:43:41 -040015#include <linux/sched.h>
16#include <linux/tick.h>
Steven Rostedtc0e980a2012-11-15 11:34:21 -050017#include <linux/cpu.h>
18#include <linux/notifier.h>
Frederic Weisbecker47885012014-05-08 01:37:48 +020019#include <linux/smp.h>
Paul Gortmaker967d1f92011-07-18 13:03:04 -040020#include <asm/processor.h>
Peter Zijlstrae360adb2010-10-14 14:01:34 +080021
Peter Zijlstrae360adb2010-10-14 14:01:34 +080022
Frederic Weisbeckerb93e0b82014-05-23 18:10:21 +020023static DEFINE_PER_CPU(struct llist_head, raised_list);
24static DEFINE_PER_CPU(struct llist_head, lazy_list);
Peter Zijlstrae360adb2010-10-14 14:01:34 +080025
26/*
27 * Claim the entry so that no one else will poke at it.
28 */
Huang Ying38aaf802011-09-08 14:00:46 +080029static bool irq_work_claim(struct irq_work *work)
Peter Zijlstrae360adb2010-10-14 14:01:34 +080030{
Frederic Weisbeckere0bbe2d2012-10-27 15:21:36 +020031 unsigned long flags, oflags, nflags;
Peter Zijlstrae360adb2010-10-14 14:01:34 +080032
Frederic Weisbeckere0bbe2d2012-10-27 15:21:36 +020033 /*
34 * Start with our best wish as a premise but only trust any
35 * flag value after cmpxchg() result.
36 */
37 flags = work->flags & ~IRQ_WORK_PENDING;
Huang Ying38aaf802011-09-08 14:00:46 +080038 for (;;) {
Huang Ying38aaf802011-09-08 14:00:46 +080039 nflags = flags | IRQ_WORK_FLAGS;
Frederic Weisbeckere0bbe2d2012-10-27 15:21:36 +020040 oflags = cmpxchg(&work->flags, flags, nflags);
41 if (oflags == flags)
Huang Ying38aaf802011-09-08 14:00:46 +080042 break;
Frederic Weisbeckere0bbe2d2012-10-27 15:21:36 +020043 if (oflags & IRQ_WORK_PENDING)
44 return false;
45 flags = oflags;
Huang Ying38aaf802011-09-08 14:00:46 +080046 cpu_relax();
47 }
Peter Zijlstrae360adb2010-10-14 14:01:34 +080048
49 return true;
50}
51
Peter Zijlstrae360adb2010-10-14 14:01:34 +080052void __weak arch_irq_work_raise(void)
53{
54 /*
55 * Lame architectures will get the timer tick callback
56 */
57}
58
59/*
Frederic Weisbecker47885012014-05-08 01:37:48 +020060 * Enqueue the irq_work @work on @cpu unless it's already pending
anish kumarc02cf5f2013-02-03 22:08:23 +010061 * somewhere.
62 *
63 * Can be re-enqueued while the callback is still in progress.
Peter Zijlstrae360adb2010-10-14 14:01:34 +080064 */
Frederic Weisbecker47885012014-05-08 01:37:48 +020065bool irq_work_queue_on(struct irq_work *work, int cpu)
66{
67 /* All work should have been flushed before going offline */
68 WARN_ON_ONCE(cpu_is_offline(cpu));
69
Paul E. McKenney6733bab2017-08-18 10:59:16 -070070#ifdef CONFIG_SMP
71
Frederic Weisbecker47885012014-05-08 01:37:48 +020072 /* Arch remote IPI send/receive backend aren't NMI safe */
73 WARN_ON_ONCE(in_nmi());
74
75 /* Only queue if not already pending */
76 if (!irq_work_claim(work))
77 return false;
78
79 if (llist_add(&work->llnode, &per_cpu(raised_list, cpu)))
80 arch_send_call_function_single_ipi(cpu);
81
Paul E. McKenney6733bab2017-08-18 10:59:16 -070082#else /* #ifdef CONFIG_SMP */
83 irq_work_queue(work);
84#endif /* #else #ifdef CONFIG_SMP */
85
Frederic Weisbecker47885012014-05-08 01:37:48 +020086 return true;
87}
Frederic Weisbecker47885012014-05-08 01:37:48 +020088
89/* Enqueue the irq work @work on the current CPU */
Peter Zijlstracd578ab2014-02-11 16:01:16 +010090bool irq_work_queue(struct irq_work *work)
Peter Zijlstrae360adb2010-10-14 14:01:34 +080091{
anish kumarc02cf5f2013-02-03 22:08:23 +010092 /* Only queue if not already pending */
93 if (!irq_work_claim(work))
Peter Zijlstracd578ab2014-02-11 16:01:16 +010094 return false;
anish kumarc02cf5f2013-02-03 22:08:23 +010095
96 /* Queue the entry and raise the IPI if needed. */
Christoph Lameter20b87692010-12-14 10:28:45 -060097 preempt_disable();
Peter Zijlstrae360adb2010-10-14 14:01:34 +080098
Frederic Weisbeckerb93e0b82014-05-23 18:10:21 +020099 /* If the work is "lazy", handle it from next tick if any */
100 if (work->flags & IRQ_WORK_LAZY) {
Christoph Lameter22127e92014-08-17 12:30:25 -0500101 if (llist_add(&work->llnode, this_cpu_ptr(&lazy_list)) &&
Frederic Weisbeckerb93e0b82014-05-23 18:10:21 +0200102 tick_nohz_tick_stopped())
103 arch_irq_work_raise();
104 } else {
Christoph Lameter22127e92014-08-17 12:30:25 -0500105 if (llist_add(&work->llnode, this_cpu_ptr(&raised_list)))
Frederic Weisbeckerbc6679a2012-10-19 16:43:41 -0400106 arch_irq_work_raise();
107 }
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800108
Christoph Lameter20b87692010-12-14 10:28:45 -0600109 preempt_enable();
Peter Zijlstracd578ab2014-02-11 16:01:16 +0100110
111 return true;
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800112}
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800113EXPORT_SYMBOL_GPL(irq_work_queue);
114
Frederic Weisbecker00b42952012-11-07 21:03:07 +0100115bool irq_work_needs_cpu(void)
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800116{
Frederic Weisbeckerb93e0b82014-05-23 18:10:21 +0200117 struct llist_head *raised, *lazy;
Frederic Weisbecker00b42952012-11-07 21:03:07 +0100118
Christoph Lameter22127e92014-08-17 12:30:25 -0500119 raised = this_cpu_ptr(&raised_list);
120 lazy = this_cpu_ptr(&lazy_list);
Frederic Weisbecker76a33062014-08-16 18:37:19 +0200121
122 if (llist_empty(raised) || arch_irq_work_has_interrupt())
123 if (llist_empty(lazy))
124 return false;
Frederic Weisbecker00b42952012-11-07 21:03:07 +0100125
Steven Rostedt8aa2acc2012-11-15 12:52:44 -0500126 /* All work should have been flushed before going offline */
127 WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
128
Frederic Weisbecker00b42952012-11-07 21:03:07 +0100129 return true;
130}
131
Frederic Weisbeckerb93e0b82014-05-23 18:10:21 +0200132static void irq_work_run_list(struct llist_head *list)
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800133{
Thomas Gleixnerd00a08c2017-11-12 13:02:51 +0100134 struct irq_work *work, *tmp;
Huang Ying38aaf802011-09-08 14:00:46 +0800135 struct llist_node *llnode;
Thomas Gleixnerd00a08c2017-11-12 13:02:51 +0100136 unsigned long flags;
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800137
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800138 BUG_ON(!irqs_disabled());
139
Frederic Weisbeckerb93e0b82014-05-23 18:10:21 +0200140 if (llist_empty(list))
141 return;
142
143 llnode = llist_del_all(list);
Thomas Gleixnerd00a08c2017-11-12 13:02:51 +0100144 llist_for_each_entry_safe(work, tmp, llnode, llnode) {
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800145 /*
Huang Ying38aaf802011-09-08 14:00:46 +0800146 * Clear the PENDING bit, after this point the @work
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800147 * can be re-used.
Frederic Weisbeckerc8446b72012-10-30 13:33:54 +0100148 * Make it immediately visible so that other CPUs trying
149 * to claim that work don't rely on us to handle their data
150 * while we are in the middle of the func.
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800151 */
Frederic Weisbeckerbc6679a2012-10-19 16:43:41 -0400152 flags = work->flags & ~IRQ_WORK_PENDING;
153 xchg(&work->flags, flags);
154
Huang Ying38aaf802011-09-08 14:00:46 +0800155 work->func(work);
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800156 /*
157 * Clear the BUSY bit and return to the free state if
158 * no-one else claimed it meanwhile.
159 */
Frederic Weisbeckerbc6679a2012-10-19 16:43:41 -0400160 (void)cmpxchg(&work->flags, flags, flags & ~IRQ_WORK_BUSY);
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800161 }
162}
Steven Rostedtc0e980a2012-11-15 11:34:21 -0500163
164/*
Peter Zijlstraa77353e2014-06-25 07:13:07 +0200165 * hotplug calls this through:
166 * hotplug_cfd() -> flush_smp_call_function_queue()
Steven Rostedtc0e980a2012-11-15 11:34:21 -0500167 */
168void irq_work_run(void)
169{
Christoph Lameter22127e92014-08-17 12:30:25 -0500170 irq_work_run_list(this_cpu_ptr(&raised_list));
171 irq_work_run_list(this_cpu_ptr(&lazy_list));
Steven Rostedtc0e980a2012-11-15 11:34:21 -0500172}
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800173EXPORT_SYMBOL_GPL(irq_work_run);
174
Frederic Weisbecker76a33062014-08-16 18:37:19 +0200175void irq_work_tick(void)
176{
Christoph Lameter56e4dea2014-10-27 10:49:45 -0500177 struct llist_head *raised = this_cpu_ptr(&raised_list);
Frederic Weisbecker76a33062014-08-16 18:37:19 +0200178
179 if (!llist_empty(raised) && !arch_irq_work_has_interrupt())
180 irq_work_run_list(raised);
Christoph Lameter56e4dea2014-10-27 10:49:45 -0500181 irq_work_run_list(this_cpu_ptr(&lazy_list));
Frederic Weisbecker76a33062014-08-16 18:37:19 +0200182}
183
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800184/*
185 * Synchronize against the irq_work @entry, ensures the entry is not
186 * currently in use.
187 */
Huang Ying38aaf802011-09-08 14:00:46 +0800188void irq_work_sync(struct irq_work *work)
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800189{
Frederic Weisbecker3c7169a2017-11-06 16:01:26 +0100190 lockdep_assert_irqs_enabled();
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800191
Huang Ying38aaf802011-09-08 14:00:46 +0800192 while (work->flags & IRQ_WORK_BUSY)
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800193 cpu_relax();
194}
195EXPORT_SYMBOL_GPL(irq_work_sync);