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Thomas Gleixner457c8992019-05-19 13:08:55 +01001// SPDX-License-Identifier: GPL-2.0-only
Peter Zijlstrae360adb2010-10-14 14:01:34 +08002/*
Peter Zijlstra90eec102015-11-16 11:08:45 +01003 * Copyright (C) 2010 Red Hat, Inc., Peter Zijlstra
Peter Zijlstrae360adb2010-10-14 14:01:34 +08004 *
5 * Provides a framework for enqueueing and running callbacks from hardirq
6 * context. The enqueueing is NMI-safe.
7 */
8
Paul Gortmaker83e3fa62012-04-01 16:38:37 -04009#include <linux/bug.h>
Peter Zijlstrae360adb2010-10-14 14:01:34 +080010#include <linux/kernel.h>
Paul Gortmaker9984de12011-05-23 14:51:41 -040011#include <linux/export.h>
Peter Zijlstrae360adb2010-10-14 14:01:34 +080012#include <linux/irq_work.h>
Paul Gortmaker967d1f92011-07-18 13:03:04 -040013#include <linux/percpu.h>
Peter Zijlstrae360adb2010-10-14 14:01:34 +080014#include <linux/hardirq.h>
Chris Metcalfef1f0982012-04-11 12:21:39 -040015#include <linux/irqflags.h>
Frederic Weisbeckerbc6679a2012-10-19 16:43:41 -040016#include <linux/sched.h>
17#include <linux/tick.h>
Steven Rostedtc0e980a2012-11-15 11:34:21 -050018#include <linux/cpu.h>
19#include <linux/notifier.h>
Frederic Weisbecker47885012014-05-08 01:37:48 +020020#include <linux/smp.h>
Paul Gortmaker967d1f92011-07-18 13:03:04 -040021#include <asm/processor.h>
Peter Zijlstrae360adb2010-10-14 14:01:34 +080022
Peter Zijlstrae360adb2010-10-14 14:01:34 +080023
Frederic Weisbeckerb93e0b82014-05-23 18:10:21 +020024static DEFINE_PER_CPU(struct llist_head, raised_list);
25static DEFINE_PER_CPU(struct llist_head, lazy_list);
Peter Zijlstrae360adb2010-10-14 14:01:34 +080026
27/*
28 * Claim the entry so that no one else will poke at it.
29 */
Huang Ying38aaf802011-09-08 14:00:46 +080030static bool irq_work_claim(struct irq_work *work)
Peter Zijlstrae360adb2010-10-14 14:01:34 +080031{
Frederic Weisbecker25269872019-11-08 17:08:56 +010032 int oflags;
Peter Zijlstrae360adb2010-10-14 14:01:34 +080033
Peter Zijlstra4b44a212020-05-26 18:11:02 +020034 oflags = atomic_fetch_or(IRQ_WORK_CLAIMED | CSD_TYPE_IRQ_WORK, &work->flags);
Frederic Weisbeckere0bbe2d2012-10-27 15:21:36 +020035 /*
Frederic Weisbecker25269872019-11-08 17:08:56 +010036 * If the work is already pending, no need to raise the IPI.
Frederic Weisbeckerfeb4a512019-11-08 17:08:57 +010037 * The pairing atomic_fetch_andnot() in irq_work_run() makes sure
Frederic Weisbecker25269872019-11-08 17:08:56 +010038 * everything we did before is visible.
Frederic Weisbeckere0bbe2d2012-10-27 15:21:36 +020039 */
Frederic Weisbecker25269872019-11-08 17:08:56 +010040 if (oflags & IRQ_WORK_PENDING)
41 return false;
Peter Zijlstrae360adb2010-10-14 14:01:34 +080042 return true;
43}
44
Peter Zijlstrae360adb2010-10-14 14:01:34 +080045void __weak arch_irq_work_raise(void)
46{
47 /*
48 * Lame architectures will get the timer tick callback
49 */
50}
51
Nicholas Piggin471ba0e2019-04-09 19:34:03 +100052/* Enqueue on current CPU, work must already be claimed and preempt disabled */
53static void __irq_work_queue_local(struct irq_work *work)
Frederic Weisbecker47885012014-05-08 01:37:48 +020054{
Nicholas Piggin471ba0e2019-04-09 19:34:03 +100055 /* If the work is "lazy", handle it from next tick if any */
Frederic Weisbecker153bedb2019-11-08 17:08:55 +010056 if (atomic_read(&work->flags) & IRQ_WORK_LAZY) {
Nicholas Piggin471ba0e2019-04-09 19:34:03 +100057 if (llist_add(&work->llnode, this_cpu_ptr(&lazy_list)) &&
58 tick_nohz_tick_stopped())
59 arch_irq_work_raise();
60 } else {
61 if (llist_add(&work->llnode, this_cpu_ptr(&raised_list)))
62 arch_irq_work_raise();
63 }
Frederic Weisbecker47885012014-05-08 01:37:48 +020064}
Frederic Weisbecker47885012014-05-08 01:37:48 +020065
66/* Enqueue the irq work @work on the current CPU */
Peter Zijlstracd578ab2014-02-11 16:01:16 +010067bool irq_work_queue(struct irq_work *work)
Peter Zijlstrae360adb2010-10-14 14:01:34 +080068{
anish kumarc02cf5f2013-02-03 22:08:23 +010069 /* Only queue if not already pending */
70 if (!irq_work_claim(work))
Peter Zijlstracd578ab2014-02-11 16:01:16 +010071 return false;
anish kumarc02cf5f2013-02-03 22:08:23 +010072
73 /* Queue the entry and raise the IPI if needed. */
Christoph Lameter20b87692010-12-14 10:28:45 -060074 preempt_disable();
Nicholas Piggin471ba0e2019-04-09 19:34:03 +100075 __irq_work_queue_local(work);
Christoph Lameter20b87692010-12-14 10:28:45 -060076 preempt_enable();
Peter Zijlstracd578ab2014-02-11 16:01:16 +010077
78 return true;
Peter Zijlstrae360adb2010-10-14 14:01:34 +080079}
Peter Zijlstrae360adb2010-10-14 14:01:34 +080080EXPORT_SYMBOL_GPL(irq_work_queue);
81
Nicholas Piggin471ba0e2019-04-09 19:34:03 +100082/*
83 * Enqueue the irq_work @work on @cpu unless it's already pending
84 * somewhere.
85 *
86 * Can be re-enqueued while the callback is still in progress.
87 */
88bool irq_work_queue_on(struct irq_work *work, int cpu)
89{
90#ifndef CONFIG_SMP
91 return irq_work_queue(work);
92
93#else /* CONFIG_SMP: */
94 /* All work should have been flushed before going offline */
95 WARN_ON_ONCE(cpu_is_offline(cpu));
96
97 /* Only queue if not already pending */
98 if (!irq_work_claim(work))
99 return false;
100
101 preempt_disable();
102 if (cpu != smp_processor_id()) {
103 /* Arch remote IPI send/receive backend aren't NMI safe */
104 WARN_ON_ONCE(in_nmi());
Peter Zijlstra4b44a212020-05-26 18:11:02 +0200105 __smp_call_single_queue(cpu, &work->llnode);
Nicholas Piggin471ba0e2019-04-09 19:34:03 +1000106 } else {
107 __irq_work_queue_local(work);
108 }
109 preempt_enable();
110
111 return true;
112#endif /* CONFIG_SMP */
113}
114
115
Frederic Weisbecker00b42952012-11-07 21:03:07 +0100116bool irq_work_needs_cpu(void)
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800117{
Frederic Weisbeckerb93e0b82014-05-23 18:10:21 +0200118 struct llist_head *raised, *lazy;
Frederic Weisbecker00b42952012-11-07 21:03:07 +0100119
Christoph Lameter22127e92014-08-17 12:30:25 -0500120 raised = this_cpu_ptr(&raised_list);
121 lazy = this_cpu_ptr(&lazy_list);
Frederic Weisbecker76a33062014-08-16 18:37:19 +0200122
123 if (llist_empty(raised) || arch_irq_work_has_interrupt())
124 if (llist_empty(lazy))
125 return false;
Frederic Weisbecker00b42952012-11-07 21:03:07 +0100126
Steven Rostedt8aa2acc2012-11-15 12:52:44 -0500127 /* All work should have been flushed before going offline */
128 WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
129
Frederic Weisbecker00b42952012-11-07 21:03:07 +0100130 return true;
131}
132
Peter Zijlstra4b44a212020-05-26 18:11:02 +0200133void irq_work_single(void *arg)
134{
135 struct irq_work *work = arg;
136 int flags;
137
138 /*
139 * Clear the PENDING bit, after this point the @work
140 * can be re-used.
141 * Make it immediately visible so that other CPUs trying
142 * to claim that work don't rely on us to handle their data
143 * while we are in the middle of the func.
144 */
145 flags = atomic_fetch_andnot(IRQ_WORK_PENDING, &work->flags);
146
147 lockdep_irq_work_enter(work);
148 work->func(work);
149 lockdep_irq_work_exit(work);
150 /*
151 * Clear the BUSY bit and return to the free state if
152 * no-one else claimed it meanwhile.
153 */
154 flags &= ~IRQ_WORK_PENDING;
155 (void)atomic_cmpxchg(&work->flags, flags, flags & ~IRQ_WORK_BUSY);
156}
157
Frederic Weisbeckerb93e0b82014-05-23 18:10:21 +0200158static void irq_work_run_list(struct llist_head *list)
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800159{
Thomas Gleixnerd00a08c2017-11-12 13:02:51 +0100160 struct irq_work *work, *tmp;
Huang Ying38aaf802011-09-08 14:00:46 +0800161 struct llist_node *llnode;
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800162
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800163 BUG_ON(!irqs_disabled());
164
Frederic Weisbeckerb93e0b82014-05-23 18:10:21 +0200165 if (llist_empty(list))
166 return;
167
168 llnode = llist_del_all(list);
Peter Zijlstra4b44a212020-05-26 18:11:02 +0200169 llist_for_each_entry_safe(work, tmp, llnode, llnode)
170 irq_work_single(work);
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800171}
Steven Rostedtc0e980a2012-11-15 11:34:21 -0500172
173/*
Peter Zijlstraa77353e2014-06-25 07:13:07 +0200174 * hotplug calls this through:
175 * hotplug_cfd() -> flush_smp_call_function_queue()
Steven Rostedtc0e980a2012-11-15 11:34:21 -0500176 */
177void irq_work_run(void)
178{
Christoph Lameter22127e92014-08-17 12:30:25 -0500179 irq_work_run_list(this_cpu_ptr(&raised_list));
180 irq_work_run_list(this_cpu_ptr(&lazy_list));
Steven Rostedtc0e980a2012-11-15 11:34:21 -0500181}
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800182EXPORT_SYMBOL_GPL(irq_work_run);
183
Frederic Weisbecker76a33062014-08-16 18:37:19 +0200184void irq_work_tick(void)
185{
Christoph Lameter56e4dea2014-10-27 10:49:45 -0500186 struct llist_head *raised = this_cpu_ptr(&raised_list);
Frederic Weisbecker76a33062014-08-16 18:37:19 +0200187
188 if (!llist_empty(raised) && !arch_irq_work_has_interrupt())
189 irq_work_run_list(raised);
Christoph Lameter56e4dea2014-10-27 10:49:45 -0500190 irq_work_run_list(this_cpu_ptr(&lazy_list));
Frederic Weisbecker76a33062014-08-16 18:37:19 +0200191}
192
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800193/*
194 * Synchronize against the irq_work @entry, ensures the entry is not
195 * currently in use.
196 */
Huang Ying38aaf802011-09-08 14:00:46 +0800197void irq_work_sync(struct irq_work *work)
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800198{
Frederic Weisbecker3c7169a2017-11-06 16:01:26 +0100199 lockdep_assert_irqs_enabled();
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800200
Frederic Weisbecker153bedb2019-11-08 17:08:55 +0100201 while (atomic_read(&work->flags) & IRQ_WORK_BUSY)
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800202 cpu_relax();
203}
204EXPORT_SYMBOL_GPL(irq_work_sync);