Sorry, for double/wrong posting. Please ignore this one, I've resent
it in reply to 0/3.
On 06/08, Oleg Nesterov wrote:
>
> migrate_hrtimer_list() sets HRTIMER_STATE_MIGRATE to avoid the
> race with hrtimer_active(), but this can't avoid the same race
> with hrtimer_is_queued().
>
> Kill HRTIMER_STATE_MIGRATE, we can simply use STATE_ENQUEUED.
> ---
> include/linux/hrtimer.h | 6 +-----
> kernel/time/hrtimer.c | 7 ++-----
> 2 files changed, 3 insertions(+), 10 deletions(-)
>
> diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
> index 05f6df1..44810bc 100644
> --- a/include/linux/hrtimer.h
> +++ b/include/linux/hrtimer.h
> @@ -70,17 +70,13 @@ enum hrtimer_restart {
> * the handling of the timer.
> *
> * The HRTIMER_STATE_ENQUEUED bit is always or'ed to the current state
> - * to preserve the HRTIMER_STATE_CALLBACK in the above scenario. This
> - * also affects HRTIMER_STATE_MIGRATE where the preservation is not
> - * necessary. HRTIMER_STATE_MIGRATE is cleared after the timer is
> - * enqueued on the new cpu.
> + * to preserve the HRTIMER_STATE_CALLBACK in the above scenario.
> *
> * All state transitions are protected by cpu_base->lock.
> */
> #define HRTIMER_STATE_INACTIVE 0x00
> #define HRTIMER_STATE_ENQUEUED 0x01
> #define HRTIMER_STATE_CALLBACK 0x02
> -#define HRTIMER_STATE_MIGRATE 0x04
>
> /**
> * struct hrtimer - the basic hrtimer structure
> diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
> index 76d4bd9..005fd44 100644
> --- a/kernel/time/hrtimer.c
> +++ b/kernel/time/hrtimer.c
> @@ -1640,11 +1640,11 @@ static void migrate_hrtimer_list(struct
> hrtimer_clock_base *old_base,
> debug_deactivate(timer);
>
> /*
> - * Mark it as STATE_MIGRATE not INACTIVE otherwise the
> + * Mark it as ENQUEUED not INACTIVE otherwise the
> * timer could be seen as !active and just vanish away
> * under us on another CPU
> */
> - __remove_hrtimer(timer, old_base, HRTIMER_STATE_MIGRATE, 0);
> + __remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
> timer->base = new_base;
> /*
> * Enqueue the timers on the new cpu. This does not
> @@ -1655,9 +1655,6 @@ static void migrate_hrtimer_list(struct
> hrtimer_clock_base *old_base,
> * event device.
> */
> enqueue_hrtimer(timer, new_base);
> -
> - /* Clear the migration state bit */
> - timer->state &= ~HRTIMER_STATE_MIGRATE;
> }
> }
>
> --
> 1.5.5.1
>
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