Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 1 | /* |
| 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 Gortmaker | 83e3fa6 | 2012-04-01 16:38:37 -0400 | [diff] [blame] | 8 | #include <linux/bug.h> |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 9 | #include <linux/kernel.h> |
Paul Gortmaker | 9984de1 | 2011-05-23 14:51:41 -0400 | [diff] [blame] | 10 | #include <linux/export.h> |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 11 | #include <linux/irq_work.h> |
Paul Gortmaker | 967d1f9 | 2011-07-18 13:03:04 -0400 | [diff] [blame] | 12 | #include <linux/percpu.h> |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 13 | #include <linux/hardirq.h> |
Chris Metcalf | ef1f098 | 2012-04-11 12:21:39 -0400 | [diff] [blame] | 14 | #include <linux/irqflags.h> |
Frederic Weisbecker | bc6679a | 2012-10-19 16:43:41 -0400 | [diff] [blame] | 15 | #include <linux/sched.h> |
| 16 | #include <linux/tick.h> |
Steven Rostedt | c0e980a | 2012-11-15 11:34:21 -0500 | [diff] [blame] | 17 | #include <linux/cpu.h> |
| 18 | #include <linux/notifier.h> |
Frederic Weisbecker | 4788501 | 2014-05-08 01:37:48 +0200 | [diff] [blame] | 19 | #include <linux/smp.h> |
Paul Gortmaker | 967d1f9 | 2011-07-18 13:03:04 -0400 | [diff] [blame] | 20 | #include <asm/processor.h> |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 21 | |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 22 | |
Frederic Weisbecker | b93e0b8 | 2014-05-23 18:10:21 +0200 | [diff] [blame] | 23 | static DEFINE_PER_CPU(struct llist_head, raised_list); |
| 24 | static DEFINE_PER_CPU(struct llist_head, lazy_list); |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 25 | |
| 26 | /* |
| 27 | * Claim the entry so that no one else will poke at it. |
| 28 | */ |
Huang Ying | 38aaf80 | 2011-09-08 14:00:46 +0800 | [diff] [blame] | 29 | static bool irq_work_claim(struct irq_work *work) |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 30 | { |
Frederic Weisbecker | e0bbe2d | 2012-10-27 15:21:36 +0200 | [diff] [blame] | 31 | unsigned long flags, oflags, nflags; |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 32 | |
Frederic Weisbecker | e0bbe2d | 2012-10-27 15:21:36 +0200 | [diff] [blame] | 33 | /* |
| 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 Ying | 38aaf80 | 2011-09-08 14:00:46 +0800 | [diff] [blame] | 38 | for (;;) { |
Huang Ying | 38aaf80 | 2011-09-08 14:00:46 +0800 | [diff] [blame] | 39 | nflags = flags | IRQ_WORK_FLAGS; |
Frederic Weisbecker | e0bbe2d | 2012-10-27 15:21:36 +0200 | [diff] [blame] | 40 | oflags = cmpxchg(&work->flags, flags, nflags); |
| 41 | if (oflags == flags) |
Huang Ying | 38aaf80 | 2011-09-08 14:00:46 +0800 | [diff] [blame] | 42 | break; |
Frederic Weisbecker | e0bbe2d | 2012-10-27 15:21:36 +0200 | [diff] [blame] | 43 | if (oflags & IRQ_WORK_PENDING) |
| 44 | return false; |
| 45 | flags = oflags; |
Huang Ying | 38aaf80 | 2011-09-08 14:00:46 +0800 | [diff] [blame] | 46 | cpu_relax(); |
| 47 | } |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 48 | |
| 49 | return true; |
| 50 | } |
| 51 | |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 52 | void __weak arch_irq_work_raise(void) |
| 53 | { |
| 54 | /* |
| 55 | * Lame architectures will get the timer tick callback |
| 56 | */ |
| 57 | } |
| 58 | |
Frederic Weisbecker | 4788501 | 2014-05-08 01:37:48 +0200 | [diff] [blame] | 59 | #ifdef CONFIG_SMP |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 60 | /* |
Frederic Weisbecker | 4788501 | 2014-05-08 01:37:48 +0200 | [diff] [blame] | 61 | * Enqueue the irq_work @work on @cpu unless it's already pending |
anish kumar | c02cf5f | 2013-02-03 22:08:23 +0100 | [diff] [blame] | 62 | * somewhere. |
| 63 | * |
| 64 | * Can be re-enqueued while the callback is still in progress. |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 65 | */ |
Frederic Weisbecker | 4788501 | 2014-05-08 01:37:48 +0200 | [diff] [blame] | 66 | bool 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 | } |
| 83 | EXPORT_SYMBOL_GPL(irq_work_queue_on); |
| 84 | #endif |
| 85 | |
| 86 | /* Enqueue the irq work @work on the current CPU */ |
Peter Zijlstra | cd578ab | 2014-02-11 16:01:16 +0100 | [diff] [blame] | 87 | bool irq_work_queue(struct irq_work *work) |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 88 | { |
anish kumar | c02cf5f | 2013-02-03 22:08:23 +0100 | [diff] [blame] | 89 | /* Only queue if not already pending */ |
| 90 | if (!irq_work_claim(work)) |
Peter Zijlstra | cd578ab | 2014-02-11 16:01:16 +0100 | [diff] [blame] | 91 | return false; |
anish kumar | c02cf5f | 2013-02-03 22:08:23 +0100 | [diff] [blame] | 92 | |
| 93 | /* Queue the entry and raise the IPI if needed. */ |
Christoph Lameter | 20b8769 | 2010-12-14 10:28:45 -0600 | [diff] [blame] | 94 | preempt_disable(); |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 95 | |
Frederic Weisbecker | b93e0b8 | 2014-05-23 18:10:21 +0200 | [diff] [blame] | 96 | /* If the work is "lazy", handle it from next tick if any */ |
| 97 | if (work->flags & IRQ_WORK_LAZY) { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 98 | if (llist_add(&work->llnode, this_cpu_ptr(&lazy_list)) && |
Frederic Weisbecker | b93e0b8 | 2014-05-23 18:10:21 +0200 | [diff] [blame] | 99 | tick_nohz_tick_stopped()) |
| 100 | arch_irq_work_raise(); |
| 101 | } else { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 102 | if (llist_add(&work->llnode, this_cpu_ptr(&raised_list))) |
Frederic Weisbecker | bc6679a | 2012-10-19 16:43:41 -0400 | [diff] [blame] | 103 | arch_irq_work_raise(); |
| 104 | } |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 105 | |
Christoph Lameter | 20b8769 | 2010-12-14 10:28:45 -0600 | [diff] [blame] | 106 | preempt_enable(); |
Peter Zijlstra | cd578ab | 2014-02-11 16:01:16 +0100 | [diff] [blame] | 107 | |
| 108 | return true; |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 109 | } |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 110 | EXPORT_SYMBOL_GPL(irq_work_queue); |
| 111 | |
Frederic Weisbecker | 00b4295 | 2012-11-07 21:03:07 +0100 | [diff] [blame] | 112 | bool irq_work_needs_cpu(void) |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 113 | { |
Frederic Weisbecker | b93e0b8 | 2014-05-23 18:10:21 +0200 | [diff] [blame] | 114 | struct llist_head *raised, *lazy; |
Frederic Weisbecker | 00b4295 | 2012-11-07 21:03:07 +0100 | [diff] [blame] | 115 | |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 116 | raised = this_cpu_ptr(&raised_list); |
| 117 | lazy = this_cpu_ptr(&lazy_list); |
Frederic Weisbecker | 76a3306 | 2014-08-16 18:37:19 +0200 | [diff] [blame] | 118 | |
| 119 | if (llist_empty(raised) || arch_irq_work_has_interrupt()) |
| 120 | if (llist_empty(lazy)) |
| 121 | return false; |
Frederic Weisbecker | 00b4295 | 2012-11-07 21:03:07 +0100 | [diff] [blame] | 122 | |
Steven Rostedt | 8aa2acc | 2012-11-15 12:52:44 -0500 | [diff] [blame] | 123 | /* All work should have been flushed before going offline */ |
| 124 | WARN_ON_ONCE(cpu_is_offline(smp_processor_id())); |
| 125 | |
Frederic Weisbecker | 00b4295 | 2012-11-07 21:03:07 +0100 | [diff] [blame] | 126 | return true; |
| 127 | } |
| 128 | |
Frederic Weisbecker | b93e0b8 | 2014-05-23 18:10:21 +0200 | [diff] [blame] | 129 | static void irq_work_run_list(struct llist_head *list) |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 130 | { |
Frederic Weisbecker | bc6679a | 2012-10-19 16:43:41 -0400 | [diff] [blame] | 131 | unsigned long flags; |
Huang Ying | 38aaf80 | 2011-09-08 14:00:46 +0800 | [diff] [blame] | 132 | struct irq_work *work; |
Huang Ying | 38aaf80 | 2011-09-08 14:00:46 +0800 | [diff] [blame] | 133 | struct llist_node *llnode; |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 134 | |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 135 | BUG_ON(!irqs_disabled()); |
| 136 | |
Frederic Weisbecker | b93e0b8 | 2014-05-23 18:10:21 +0200 | [diff] [blame] | 137 | if (llist_empty(list)) |
| 138 | return; |
| 139 | |
| 140 | llnode = llist_del_all(list); |
Huang Ying | 38aaf80 | 2011-09-08 14:00:46 +0800 | [diff] [blame] | 141 | while (llnode != NULL) { |
| 142 | work = llist_entry(llnode, struct irq_work, llnode); |
Christoph Lameter | 20b8769 | 2010-12-14 10:28:45 -0600 | [diff] [blame] | 143 | |
Peter Zijlstra | 924f8f5 | 2011-09-12 13:12:28 +0200 | [diff] [blame] | 144 | llnode = llist_next(llnode); |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 145 | |
| 146 | /* |
Huang Ying | 38aaf80 | 2011-09-08 14:00:46 +0800 | [diff] [blame] | 147 | * Clear the PENDING bit, after this point the @work |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 148 | * can be re-used. |
Frederic Weisbecker | c8446b7 | 2012-10-30 13:33:54 +0100 | [diff] [blame] | 149 | * 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 Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 152 | */ |
Frederic Weisbecker | bc6679a | 2012-10-19 16:43:41 -0400 | [diff] [blame] | 153 | flags = work->flags & ~IRQ_WORK_PENDING; |
| 154 | xchg(&work->flags, flags); |
| 155 | |
Huang Ying | 38aaf80 | 2011-09-08 14:00:46 +0800 | [diff] [blame] | 156 | work->func(work); |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 157 | /* |
| 158 | * Clear the BUSY bit and return to the free state if |
| 159 | * no-one else claimed it meanwhile. |
| 160 | */ |
Frederic Weisbecker | bc6679a | 2012-10-19 16:43:41 -0400 | [diff] [blame] | 161 | (void)cmpxchg(&work->flags, flags, flags & ~IRQ_WORK_BUSY); |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 162 | } |
| 163 | } |
Steven Rostedt | c0e980a | 2012-11-15 11:34:21 -0500 | [diff] [blame] | 164 | |
| 165 | /* |
Peter Zijlstra | a77353e | 2014-06-25 07:13:07 +0200 | [diff] [blame] | 166 | * hotplug calls this through: |
| 167 | * hotplug_cfd() -> flush_smp_call_function_queue() |
Steven Rostedt | c0e980a | 2012-11-15 11:34:21 -0500 | [diff] [blame] | 168 | */ |
| 169 | void irq_work_run(void) |
| 170 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 171 | irq_work_run_list(this_cpu_ptr(&raised_list)); |
| 172 | irq_work_run_list(this_cpu_ptr(&lazy_list)); |
Steven Rostedt | c0e980a | 2012-11-15 11:34:21 -0500 | [diff] [blame] | 173 | } |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 174 | EXPORT_SYMBOL_GPL(irq_work_run); |
| 175 | |
Frederic Weisbecker | 76a3306 | 2014-08-16 18:37:19 +0200 | [diff] [blame] | 176 | void irq_work_tick(void) |
| 177 | { |
Christoph Lameter | 56e4dea | 2014-10-27 10:49:45 -0500 | [diff] [blame] | 178 | struct llist_head *raised = this_cpu_ptr(&raised_list); |
Frederic Weisbecker | 76a3306 | 2014-08-16 18:37:19 +0200 | [diff] [blame] | 179 | |
| 180 | if (!llist_empty(raised) && !arch_irq_work_has_interrupt()) |
| 181 | irq_work_run_list(raised); |
Christoph Lameter | 56e4dea | 2014-10-27 10:49:45 -0500 | [diff] [blame] | 182 | irq_work_run_list(this_cpu_ptr(&lazy_list)); |
Frederic Weisbecker | 76a3306 | 2014-08-16 18:37:19 +0200 | [diff] [blame] | 183 | } |
| 184 | |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 185 | /* |
| 186 | * Synchronize against the irq_work @entry, ensures the entry is not |
| 187 | * currently in use. |
| 188 | */ |
Huang Ying | 38aaf80 | 2011-09-08 14:00:46 +0800 | [diff] [blame] | 189 | void irq_work_sync(struct irq_work *work) |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 190 | { |
| 191 | WARN_ON_ONCE(irqs_disabled()); |
| 192 | |
Huang Ying | 38aaf80 | 2011-09-08 14:00:46 +0800 | [diff] [blame] | 193 | while (work->flags & IRQ_WORK_BUSY) |
Peter Zijlstra | e360adb | 2010-10-14 14:01:34 +0800 | [diff] [blame] | 194 | cpu_relax(); |
| 195 | } |
| 196 | EXPORT_SYMBOL_GPL(irq_work_sync); |