On Tue, Jul 31, 2018 at 06:13:58PM +0200, Anna-Maria Gleixner wrote:
> local_timer_softirq_pending() checks whether the timer softirq is
> pending with: local_softirq_pending() & TIMER_SOFTIRQ.
>
> This is wrong because TIMER_SOFTIRQ is the softirq number and not a
> bitmask. So the test checks for the wrong bit.
>
> Use BIT(TIMER_SOFTIRQ) instead.
>
> Fixes: 5d62c183f9e9 ("nohz: Prevent a timer interrupt storm in
> tick_nohz_stop_sched_tick()")
> Signed-off-by: Anna-Maria Gleixner <anna-ma...@linutronix.de>
Reviewed-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
2729 opportunities to change "1UL << x" to "BIT(x)", including
__raise_softirq_irqoff(). I did the two in RCU. ;-)
Thanx, Paul
> ---
> kernel/time/tick-sched.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index da9455a6b42b..5b33e2f5c0ed 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -642,7 +642,7 @@ static void tick_nohz_restart(struct tick_sched *ts,
> ktime_t now)
>
> static inline bool local_timer_softirq_pending(void)
> {
> - return local_softirq_pending() & TIMER_SOFTIRQ;
> + return local_softirq_pending() & BIT(TIMER_SOFTIRQ);
> }
>
> static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu)
> --
> 2.18.0
>
