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Peter Zijlstrae360adb2010-10-14 14:01:34 +08001/*
2 * Copyright (C) 2010 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
3 *
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
Frederic Weisbecker47885012014-05-08 01:37:48 +020059#ifdef CONFIG_SMP
Peter Zijlstrae360adb2010-10-14 14:01:34 +080060/*
Frederic Weisbecker47885012014-05-08 01:37:48 +020061 * Enqueue the irq_work @work on @cpu unless it's already pending
anish kumarc02cf5f2013-02-03 22:08:23 +010062 * somewhere.
63 *
64 * Can be re-enqueued while the callback is still in progress.
Peter Zijlstrae360adb2010-10-14 14:01:34 +080065 */
Frederic Weisbecker47885012014-05-08 01:37:48 +020066bool irq_work_queue_on(struct irq_work *work, int cpu)
67{
68 /* All work should have been flushed before going offline */
69 WARN_ON_ONCE(cpu_is_offline(cpu));
70
71 /* Arch remote IPI send/receive backend aren't NMI safe */
72 WARN_ON_ONCE(in_nmi());
73
74 /* Only queue if not already pending */
75 if (!irq_work_claim(work))
76 return false;
77
78 if (llist_add(&work->llnode, &per_cpu(raised_list, cpu)))
79 arch_send_call_function_single_ipi(cpu);
80
81 return true;
82}
83EXPORT_SYMBOL_GPL(irq_work_queue_on);
84#endif
85
86/* Enqueue the irq work @work on the current CPU */
Peter Zijlstracd578ab2014-02-11 16:01:16 +010087bool irq_work_queue(struct irq_work *work)
Peter Zijlstrae360adb2010-10-14 14:01:34 +080088{
anish kumarc02cf5f2013-02-03 22:08:23 +010089 /* Only queue if not already pending */
90 if (!irq_work_claim(work))
Peter Zijlstracd578ab2014-02-11 16:01:16 +010091 return false;
anish kumarc02cf5f2013-02-03 22:08:23 +010092
93 /* Queue the entry and raise the IPI if needed. */
Christoph Lameter20b87692010-12-14 10:28:45 -060094 preempt_disable();
Peter Zijlstrae360adb2010-10-14 14:01:34 +080095
Frederic Weisbeckerb93e0b82014-05-23 18:10:21 +020096 /* If the work is "lazy", handle it from next tick if any */
97 if (work->flags & IRQ_WORK_LAZY) {
Christoph Lameter22127e92014-08-17 12:30:25 -050098 if (llist_add(&work->llnode, this_cpu_ptr(&lazy_list)) &&
Frederic Weisbeckerb93e0b82014-05-23 18:10:21 +020099 tick_nohz_tick_stopped())
100 arch_irq_work_raise();
101 } else {
Christoph Lameter22127e92014-08-17 12:30:25 -0500102 if (llist_add(&work->llnode, this_cpu_ptr(&raised_list)))
Frederic Weisbeckerbc6679a2012-10-19 16:43:41 -0400103 arch_irq_work_raise();
104 }
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800105
Christoph Lameter20b87692010-12-14 10:28:45 -0600106 preempt_enable();
Peter Zijlstracd578ab2014-02-11 16:01:16 +0100107
108 return true;
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800109}
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800110EXPORT_SYMBOL_GPL(irq_work_queue);
111
Frederic Weisbecker00b42952012-11-07 21:03:07 +0100112bool irq_work_needs_cpu(void)
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800113{
Frederic Weisbeckerb93e0b82014-05-23 18:10:21 +0200114 struct llist_head *raised, *lazy;
Frederic Weisbecker00b42952012-11-07 21:03:07 +0100115
Christoph Lameter22127e92014-08-17 12:30:25 -0500116 raised = this_cpu_ptr(&raised_list);
117 lazy = this_cpu_ptr(&lazy_list);
Frederic Weisbecker76a33062014-08-16 18:37:19 +0200118
119 if (llist_empty(raised) || arch_irq_work_has_interrupt())
120 if (llist_empty(lazy))
121 return false;
Frederic Weisbecker00b42952012-11-07 21:03:07 +0100122
Steven Rostedt8aa2acc2012-11-15 12:52:44 -0500123 /* All work should have been flushed before going offline */
124 WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
125
Frederic Weisbecker00b42952012-11-07 21:03:07 +0100126 return true;
127}
128
Frederic Weisbeckerb93e0b82014-05-23 18:10:21 +0200129static void irq_work_run_list(struct llist_head *list)
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800130{
Frederic Weisbeckerbc6679a2012-10-19 16:43:41 -0400131 unsigned long flags;
Huang Ying38aaf802011-09-08 14:00:46 +0800132 struct irq_work *work;
Huang Ying38aaf802011-09-08 14:00:46 +0800133 struct llist_node *llnode;
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800134
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800135 BUG_ON(!irqs_disabled());
136
Frederic Weisbeckerb93e0b82014-05-23 18:10:21 +0200137 if (llist_empty(list))
138 return;
139
140 llnode = llist_del_all(list);
Huang Ying38aaf802011-09-08 14:00:46 +0800141 while (llnode != NULL) {
142 work = llist_entry(llnode, struct irq_work, llnode);
Christoph Lameter20b87692010-12-14 10:28:45 -0600143
Peter Zijlstra924f8f52011-09-12 13:12:28 +0200144 llnode = llist_next(llnode);
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800145
146 /*
Huang Ying38aaf802011-09-08 14:00:46 +0800147 * Clear the PENDING bit, after this point the @work
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800148 * can be re-used.
Frederic Weisbeckerc8446b72012-10-30 13:33:54 +0100149 * Make it immediately visible so that other CPUs trying
150 * to claim that work don't rely on us to handle their data
151 * while we are in the middle of the func.
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800152 */
Frederic Weisbeckerbc6679a2012-10-19 16:43:41 -0400153 flags = work->flags & ~IRQ_WORK_PENDING;
154 xchg(&work->flags, flags);
155
Huang Ying38aaf802011-09-08 14:00:46 +0800156 work->func(work);
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800157 /*
158 * Clear the BUSY bit and return to the free state if
159 * no-one else claimed it meanwhile.
160 */
Frederic Weisbeckerbc6679a2012-10-19 16:43:41 -0400161 (void)cmpxchg(&work->flags, flags, flags & ~IRQ_WORK_BUSY);
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800162 }
163}
Steven Rostedtc0e980a2012-11-15 11:34:21 -0500164
165/*
Peter Zijlstraa77353e2014-06-25 07:13:07 +0200166 * hotplug calls this through:
167 * hotplug_cfd() -> flush_smp_call_function_queue()
Steven Rostedtc0e980a2012-11-15 11:34:21 -0500168 */
169void irq_work_run(void)
170{
Christoph Lameter22127e92014-08-17 12:30:25 -0500171 irq_work_run_list(this_cpu_ptr(&raised_list));
172 irq_work_run_list(this_cpu_ptr(&lazy_list));
Steven Rostedtc0e980a2012-11-15 11:34:21 -0500173}
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800174EXPORT_SYMBOL_GPL(irq_work_run);
175
Frederic Weisbecker76a33062014-08-16 18:37:19 +0200176void irq_work_tick(void)
177{
Christoph Lameter56e4dea2014-10-27 10:49:45 -0500178 struct llist_head *raised = this_cpu_ptr(&raised_list);
Frederic Weisbecker76a33062014-08-16 18:37:19 +0200179
180 if (!llist_empty(raised) && !arch_irq_work_has_interrupt())
181 irq_work_run_list(raised);
Christoph Lameter56e4dea2014-10-27 10:49:45 -0500182 irq_work_run_list(this_cpu_ptr(&lazy_list));
Frederic Weisbecker76a33062014-08-16 18:37:19 +0200183}
184
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800185/*
186 * Synchronize against the irq_work @entry, ensures the entry is not
187 * currently in use.
188 */
Huang Ying38aaf802011-09-08 14:00:46 +0800189void irq_work_sync(struct irq_work *work)
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800190{
191 WARN_ON_ONCE(irqs_disabled());
192
Huang Ying38aaf802011-09-08 14:00:46 +0800193 while (work->flags & IRQ_WORK_BUSY)
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800194 cpu_relax();
195}
196EXPORT_SYMBOL_GPL(irq_work_sync);