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Commit c0e980a4 authored by Steven Rostedt's avatar Steven Rostedt Committed by Frederic Weisbecker
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irq_work: Flush work on CPU_DYING 



In order not to offline a CPU with pending irq works, flush the
queue from CPU_DYING. The notifier is called by stop_machine on
the CPU that is going down. The code will not be called from irq context
(so things like get_irq_regs() wont work) but I'm not sure what the
requirements are for irq_work in that regard (Peter?). But irqs are
disabled and the CPU is about to go offline. Might as well flush the work.

Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
parent 00b42959

kernel/irq_work.c

+45 −6
Original line number Diff line number Diff line
@@ -12,6 +12,8 @@ 
#include <linux/percpu.h>

#include <linux/hardirq.h>

#include <linux/irqflags.h>

#include <linux/cpu.h>

#include <linux/notifier.h>

#include <asm/processor.h>



/*
@@ -110,11 +112,7 @@ bool irq_work_needs_cpu(void) 
	return true;

}



/*

 * Run the irq_work entries on this cpu. Requires to be ran from hardirq

 * context with local IRQs disabled.

 */

void irq_work_run(void)

static void __irq_work_run(void)

{

	struct irq_work *work;

	struct llist_head *this_list;
@@ -124,7 +122,6 @@ void irq_work_run(void) 
	if (llist_empty(this_list))

		return;



	BUG_ON(!in_irq());

	BUG_ON(!irqs_disabled());



	llnode = llist_del_all(this_list);
@@ -149,6 +146,16 @@ void irq_work_run(void) 
		(void)cmpxchg(&work->flags, IRQ_WORK_BUSY, 0);

	}

}



/*

 * Run the irq_work entries on this cpu. Requires to be ran from hardirq

 * context with local IRQs disabled.

 */

void irq_work_run(void)

{

	BUG_ON(!in_irq());

	__irq_work_run();

}

EXPORT_SYMBOL_GPL(irq_work_run);



/*
@@ -163,3 +170,35 @@ void irq_work_sync(struct irq_work *work) 
		cpu_relax();

}

EXPORT_SYMBOL_GPL(irq_work_sync);



#ifdef CONFIG_HOTPLUG_CPU

static int irq_work_cpu_notify(struct notifier_block *self,

			       unsigned long action, void *hcpu)

{

	long cpu = (long)hcpu;



	switch (action) {

	case CPU_DYING:

		/* Called from stop_machine */

		if (WARN_ON_ONCE(cpu != smp_processor_id()))

			break;

		__irq_work_run();

		break;

	default:

		break;

	}

	return NOTIFY_OK;

}



static struct notifier_block cpu_notify;



static __init int irq_work_init_cpu_notifier(void)

{

	cpu_notify.notifier_call = irq_work_cpu_notify;

	cpu_notify.priority = 0;

	register_cpu_notifier(&cpu_notify);

	return 0;

}

device_initcall(irq_work_init_cpu_notifier);



#endif /* CONFIG_HOTPLUG_CPU */