From 0215f7d8c53fb192cd4491ede0ece5cca6b5db57 Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Tue, 14 Jan 2014 17:11:39 +1100 Subject: [PATCH] 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 --- arch/powerpc/kernel/time.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index afb1b56ef4f..b3dab20acf3 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; } -- 2.41.0