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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2014-01-14 17:11:39 +1100
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2014-01-15 13:59:03 +1100
commit0215f7d8c53fb192cd4491ede0ece5cca6b5db57 (patch)
tree3c72b3f85caf97ec9a2d42367a32a06df5623e1a /arch/powerpc/kernel/time.c
parent30c826358d10c1d6f8147de3310b97488daec830 (diff)
downloadop-kernel-dev-0215f7d8c53fb192cd4491ede0ece5cca6b5db57.zip
op-kernel-dev-0215f7d8c53fb192cd4491ede0ece5cca6b5db57.tar.gz
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: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel/time.c')
-rw-r--r--arch/powerpc/kernel/time.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index afb1b56..b3dab20 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -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;
}
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