Re: [PATCH v3 09/22] kthread: Allow to cancel kthread work
flat view
From: Tejun Heo <hidden>
Date: 2015-11-23 22:58:29
Also in:
linux-mm, lkml
Hello, On Wed, Nov 18, 2015 at 02:25:14PM +0100, Petr Mladek wrote:
quoted hunk ↗ jump to hunk
+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