If we enqueue a work while in dyntick idle mode and the arch doesn't have self-IPI support, we may not find an opportunity to run the work before a while.
In this case, exit the idle loop to re-evaluate irq_work_needs_cpu() and restart the tick. Signed-off-by: Frederic Weisbecker <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Paul Gortmaker <[email protected]> --- kernel/irq_work.c | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-) diff --git a/kernel/irq_work.c b/kernel/irq_work.c index ce72b20..b500271 100644 --- a/kernel/irq_work.c +++ b/kernel/irq_work.c @@ -76,6 +76,17 @@ static void __irq_work_queue(struct irq_work *work) */ if (!arch_irq_work_has_ipi() || tick_nohz_tick_stopped()) arch_irq_work_raise(); + + /* + * If we rely on the timer tick or some obscure way to run the work + * while the CPU is in dyntick idle mode, we may not have an opportunity + * to do so before a while. Let's just exit the idle loop and hope we + * haven't yet reached the last need_resched() check before the CPU goes + * to low power mode. + */ + if (!arch_irq_work_has_ipi() && tick_nohz_tick_stopped() + && is_idle_task(current)) + set_need_resched(); } out: preempt_enable(); -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
