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Commit 0215f7d8 authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt
Browse files

powerpc: Fix races with irq_work 



If we set irq_work on a processor and immediately afterward, before the
irq work has a chance to be processed, we change the decrementer value,
we can seriously delay the handling of that irq_work.

Fix it by checking in a few places for pending irq work, first before
changing the decrementer in decrementer_set_next_event() and after
changing it in the same function and in timer_interrupt().

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 30c82635

arch/powerpc/kernel/time.c

+11 −0
Original line number Diff line number Diff line
@@ -536,6 +536,9 @@ void timer_interrupt(struct pt_regs * regs) 
		now = *next_tb - now;

		if (now <= DECREMENTER_MAX)

			set_dec((int)now);

		/* We may have raced with new irq work */

		if (test_irq_work_pending())

			set_dec(1);

		__get_cpu_var(irq_stat).timer_irqs_others++;

	}
@@ -802,8 +805,16 @@ static void __init clocksource_init(void) 
static int decrementer_set_next_event(unsigned long evt,

				      struct clock_event_device *dev)

{

	/* Don't adjust the decrementer if some irq work is pending */

	if (test_irq_work_pending())

		return 0;

	__get_cpu_var(decrementers_next_tb) = get_tb_or_rtc() + evt;

	set_dec(evt);



	/* We may have raced with new irq work */

	if (test_irq_work_pending())

		set_dec(1);



	return 0;

}