Messages in this thread | | | Date | Mon, 23 Nov 2015 17:58:23 -0500 | From | Tejun Heo <> | Subject | Re: [PATCH v3 09/22] kthread: Allow to cancel kthread work |
| |
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
| |