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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335// SPDX-License-Identifier: GPL-2.0-only/* * Copyright (C) 2010 Red Hat, Inc., Peter Zijlstra * * Provides a framework for enqueueing and running callbacks from hardirq * context. The enqueueing is NMI-safe. */
#include <linux/bug.h>#include <linux/kernel.h>#include <linux/export.h>#include <linux/irq_work.h>#include <linux/percpu.h>#include <linux/hardirq.h>#include <linux/irqflags.h>#include <linux/sched.h>#include <linux/tick.h>#include <linux/cpu.h>#include <linux/notifier.h>#include <linux/smp.h>#include <linux/smpboot.h>#include <asm/processor.h>#include <linux/kasan.h>
#include <trace/events/ipi.h>
static DEFINE_PER_CPU(struct llist_head, raised_list);static DEFINE_PER_CPU(struct llist_head, lazy_list);static DEFINE_PER_CPU(struct task_struct *, irq_workd);
static void wake_irq_workd(void){ struct task_struct *tsk = __this_cpu_read(irq_workd);
if (!llist_empty(this_cpu_ptr(&lazy_list)) && tsk) wake_up_process(tsk);}
#ifdef CONFIG_SMPstatic void irq_work_wake(struct irq_work *entry){ wake_irq_workd();}
static DEFINE_PER_CPU(struct irq_work, irq_work_wakeup) = IRQ_WORK_INIT_HARD(irq_work_wake);#endif
static int irq_workd_should_run(unsigned int cpu){ return !llist_empty(this_cpu_ptr(&lazy_list));}
/* * Claim the entry so that no one else will poke at it. */static bool irq_work_claim(struct irq_work *work){ int oflags;
oflags = atomic_fetch_or(IRQ_WORK_CLAIMED | CSD_TYPE_IRQ_WORK, &work->node.a_flags); /* * If the work is already pending, no need to raise the IPI. * The pairing smp_mb() in irq_work_single() makes sure * everything we did before is visible. */ if (oflags & IRQ_WORK_PENDING) return false; return true;}
void __weak arch_irq_work_raise(void){ /* * Lame architectures will get the timer tick callback */}
static __always_inline void irq_work_raise(struct irq_work *work){ if (trace_ipi_send_cpu_enabled() && arch_irq_work_has_interrupt()) trace_call__ipi_send_cpu(smp_processor_id(), _RET_IP_, work->func);
arch_irq_work_raise();}
/* Enqueue on current CPU, work must already be claimed and preempt disabled */static void __irq_work_queue_local(struct irq_work *work){ struct llist_head *list; bool rt_lazy_work = false; bool lazy_work = false; int work_flags;
work_flags = atomic_read(&work->node.a_flags); if (work_flags & IRQ_WORK_LAZY) lazy_work = true; else if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(work_flags & IRQ_WORK_HARD_IRQ)) rt_lazy_work = true;
if (lazy_work || rt_lazy_work) list = this_cpu_ptr(&lazy_list); else list = this_cpu_ptr(&raised_list);
if (!llist_add(&work->node.llist, list)) return;
/* If the work is "lazy", handle it from next tick if any */ if (!lazy_work || tick_nohz_tick_stopped()) irq_work_raise(work);}
/* Enqueue the irq work @work on the current CPU */bool irq_work_queue(struct irq_work *work){ /* Only queue if not already pending */ if (!irq_work_claim(work)) return false;
/* Queue the entry and raise the IPI if needed. */ preempt_disable(); __irq_work_queue_local(work); preempt_enable();
return true;}EXPORT_SYMBOL_GPL(irq_work_queue);
/* * Enqueue the irq_work @work on @cpu unless it's already pending * somewhere. * * Can be re-enqueued while the callback is still in progress. */bool irq_work_queue_on(struct irq_work *work, int cpu){#ifndef CONFIG_SMP return irq_work_queue(work);
#else /* CONFIG_SMP: */ /* All work should have been flushed before going offline */ WARN_ON_ONCE(cpu_is_offline(cpu));
/* Only queue if not already pending */ if (!irq_work_claim(work)) return false;
kasan_record_aux_stack(work);
preempt_disable(); if (cpu != smp_processor_id()) { /* Arch remote IPI send/receive backend aren't NMI safe */ WARN_ON_ONCE(in_nmi());
/* * On PREEMPT_RT the items which are not marked as * IRQ_WORK_HARD_IRQ are added to the lazy list and a HARD work * item is used on the remote CPU to wake the thread. */ if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(atomic_read(&work->node.a_flags) & IRQ_WORK_HARD_IRQ)) {
if (!llist_add(&work->node.llist, &per_cpu(lazy_list, cpu))) goto out;
work = &per_cpu(irq_work_wakeup, cpu); if (!irq_work_claim(work)) goto out; }
__smp_call_single_queue(cpu, &work->node.llist); } else { __irq_work_queue_local(work); }out: preempt_enable();
return true;#endif /* CONFIG_SMP */}
bool irq_work_needs_cpu(void){ struct llist_head *raised, *lazy;
raised = this_cpu_ptr(&raised_list); lazy = this_cpu_ptr(&lazy_list);
if (llist_empty(raised) || arch_irq_work_has_interrupt()) if (llist_empty(lazy)) return false;
/* All work should have been flushed before going offline */ WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
return true;}
void irq_work_single(void *arg){ struct irq_work *work = arg; int flags;
/* * Clear the PENDING bit, after this point the @work can be re-used. * The PENDING bit acts as a lock, and we own it, so we can clear it * without atomic ops. */ flags = atomic_read(&work->node.a_flags); flags &= ~IRQ_WORK_PENDING; atomic_set(&work->node.a_flags, flags);
/* * See irq_work_claim(). */ smp_mb();
lockdep_irq_work_enter(flags); work->func(work); lockdep_irq_work_exit(flags);
/* * Clear the BUSY bit, if set, and return to the free state if no-one * else claimed it meanwhile. */ (void)atomic_cmpxchg(&work->node.a_flags, flags, flags & ~IRQ_WORK_BUSY);
if ((IS_ENABLED(CONFIG_PREEMPT_RT) && !irq_work_is_hard(work)) || !arch_irq_work_has_interrupt()) rcuwait_wake_up(&work->irqwait);}
static void irq_work_run_list(struct llist_head *list){ struct irq_work *work, *tmp; struct llist_node *llnode;
/* * On PREEMPT_RT IRQ-work which is not marked as HARD will be processed * in a per-CPU thread in preemptible context. Only the items which are * marked as IRQ_WORK_HARD_IRQ will be processed in hardirq context. */ BUG_ON(!irqs_disabled() && !IS_ENABLED(CONFIG_PREEMPT_RT));
if (llist_empty(list)) return;
llnode = llist_del_all(list); llist_for_each_entry_safe(work, tmp, llnode, node.llist) irq_work_single(work);}
/* * hotplug calls this through: * hotplug_cfd() -> flush_smp_call_function_queue() */void irq_work_run(void){ irq_work_run_list(this_cpu_ptr(&raised_list)); if (!IS_ENABLED(CONFIG_PREEMPT_RT)) irq_work_run_list(this_cpu_ptr(&lazy_list)); else wake_irq_workd();}EXPORT_SYMBOL_GPL(irq_work_run);
void irq_work_tick(void){ struct llist_head *raised = this_cpu_ptr(&raised_list);
if (!llist_empty(raised) && !arch_irq_work_has_interrupt()) irq_work_run_list(raised);
if (!IS_ENABLED(CONFIG_PREEMPT_RT)) irq_work_run_list(this_cpu_ptr(&lazy_list)); else wake_irq_workd();}
/* * Synchronize against the irq_work @entry, ensures the entry is not * currently in use. */void irq_work_sync(struct irq_work *work){ lockdep_assert_irqs_enabled(); might_sleep();
if ((IS_ENABLED(CONFIG_PREEMPT_RT) && !irq_work_is_hard(work)) || !arch_irq_work_has_interrupt()) { rcuwait_wait_event(&work->irqwait, !irq_work_is_busy(work), TASK_UNINTERRUPTIBLE); /* * Ensure irq_work_single() does not access @work * after removing IRQ_WORK_BUSY. It is always * accessed within a RCU-read section. */ synchronize_rcu(); return; }
while (irq_work_is_busy(work)) cpu_relax();}EXPORT_SYMBOL_GPL(irq_work_sync);
static void run_irq_workd(unsigned int cpu){ guard(rcu)(); irq_work_run_list(this_cpu_ptr(&lazy_list));}
static void irq_workd_setup(unsigned int cpu){ sched_set_fifo_low(current);}
static struct smp_hotplug_thread irqwork_threads = { .store = &irq_workd, .setup = irq_workd_setup, .thread_should_run = irq_workd_should_run, .thread_fn = run_irq_workd, .thread_comm = "irq_work/%u",};
static __init int irq_work_init_threads(void){ if (IS_ENABLED(CONFIG_PREEMPT_RT)) BUG_ON(smpboot_register_percpu_thread(&irqwork_threads)); return 0;}early_initcall(irq_work_init_threads);