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-maria@linutronix.de> --- 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
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-maria@linutronix.de> Reviewed-by: Paul E. McKenney <paulmck@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 >
On 07/31/2018 06:13 PM, 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. Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Thanks! -- Daniel > Fixes: 5d62c183f9e9 ("nohz: Prevent a timer interrupt storm in tick_nohz_stop_sched_tick()") > Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> > --- > 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) >
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-maria@linutronix.de>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Thanks!
Commit-ID: 80d20d35af1edd632a5e7a3b9c0ab7ceff92769e Gitweb: https://git.kernel.org/tip/80d20d35af1edd632a5e7a3b9c0ab7ceff92769e Author: Anna-Maria Gleixner <anna-maria@linutronix.de> AuthorDate: Tue, 31 Jul 2018 18:13:58 +0200 Committer: Thomas Gleixner <tglx@linutronix.de> CommitDate: Tue, 31 Jul 2018 22:08:44 +0200 nohz: Fix local_timer_softirq_pending() 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-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Acked-by: Frederic Weisbecker <frederic@kernel.org> Cc: bigeasy@linutronix.de Cc: peterz@infradead.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180731161358.29472-1-anna-maria@linutronix.de --- 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)