On 04/23, Gautham R Shenoy wrote: > > On Sun, Apr 22, 2007 at 09:40:59PM +0200, Rafael J. Wysocki wrote: > > /* > > @@ -232,6 +233,14 @@ int kthread_stop(struct task_struct *k) > > > > /* Now set kthread_should_stop() to true, and wake it up. */ > > kthread_stop_info.k = k; > > + if (!freezer_should_exempt(current)) { > > + /* We are freezable, so we must make sure that the thread being > > + * stopped is not frozen and will not be frozen until it dies > > + */ > > + freezer_exempt(k); > > + if (frozen(k)) > > + clear_frozen_flag(k); > > + } > > I'm trying hard to convince myself that this will work. May be I am > missing something here, but I find a potential race window (very small > though) > when k is entering the refrigerator. > > [... snip ... ] > > IMO, we need the to take the task_lock for k here. Something like > > > + if (!freezer_should_exempt(current)) { > task_lock(k); > > + /* We are freezable, so we must make sure that the thread being > > + * stopped is not frozen and will not be frozen until it dies > > + */ > > + freezer_exempt(k); > > + if (frozen(k)) > > + clear_frozen_flag(k); > task_unlock(k); > > + }
Well, probably I missed something, but why can't we do if (!freezer_should_exempt(current)) { freezer_exempt(k); thaw_process(k); } ? thaw_process(k) is properly serialized with refrigerator(), and it checks frozen(k). We can make an extra wake_up, but this should not matter. Rafael, please check the recent changes in kthread.c, kthread_stop() was reworked, we don't have kthread_stop_info any longer. Oleg. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/