Hello,
On Wed, Nov 18, 2015 at 02:25:14PM +0100, Petr Mladek wrote:
> +static int
> +try_to_cancel_kthread_work(struct kthread_work *work,
> + spinlock_t *lock,
> + unsigned long *flags)
> +{
> + int ret = 0;
> +
> + if (work->timer) {
> + /* Try to cancel the timer if pending. */
> + if (del_timer(work->timer)) {
> + ret = 1;
> + goto out;
> + }
> +
> + /* Are we racing with the timer callback? */
> + if (timer_active(work->timer)) {
> + /* Bad luck, need to avoid a deadlock. */
> + spin_unlock_irqrestore(lock, *flags);
> + del_timer_sync(work->timer);
> + ret = -EAGAIN;
> + goto out;
> + }
As the timer side is already kinda trylocking anyway, can't the cancel
path be made simpler? Sth like
lock(worker);
work->canceling = true;
del_timer_sync(work->timer);
unlock(worker);
And the timer can do (ignoring the multiple worker support, do we even
need that?)
while (!trylock(worker)) {
if (work->canceling)
return;
cpu_relax();
}
queue;
unlock(worker);
Thanks.
--
tejun
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