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SubjectRe: [PATCH 1/2] timer: Avoid waking up an idle-core by migrate running timer
On Tue, 31 Mar 2015, Viresh Kumar wrote:
> @@ -1213,6 +1249,25 @@ static inline void __run_timers(struct tvec_base *base)
> call_timer_fn(timer, fn, data);
> spin_lock_irq(&base->lock);
> }
> +
> + /*
> + * Handler running on this base, re-queued itself on
> + * another base ?
> + */
> + if (unlikely(timer->base != base)) {
> + unsigned long flags;
> + struct tvec_base *tbase;
> +
> + spin_unlock(&base->lock);
> +
> + tbase = lock_timer_base(timer, &flags);
> + timer_clear_running(timer);
> + spin_unlock(&tbase->lock);
> +
> + spin_lock(&base->lock);
> + } else {
> + timer_clear_running(timer);
> + }

And just for the record:

Dereferencing timer _AFTER_ the callback function is a big NONO. The
callback function is allowed to free the timer. See the comment in
call_timer_fn()

Oh well,

tglx


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