Messages in this thread | | | Date | Tue, 28 Mar 2006 02:03:28 +0200 (CEST) | From | Roman Zippel <> | Subject | Re: [patch 2/2] hrtimer |
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Hi,
On Tue, 28 Mar 2006, Oleg Nesterov wrote:
> I also think this is racy. > > CPU_0 CPU_1 > > hrtimer_wakeup: > > task = t->task; > t->task = NULL; > > <--- INTERRUPT ---> > > task is woken by signal, > do_nanosleep() sees t->task == NULL, > returns without hrtimer_cancel(), > and __exits__. > > <--- RESUME ---> > > wake_up_process(task); > > Instead of exit(), 'task' can go to TASK_STOPPED or TASK_UNINTERRUPTIBLE > after return from do_nanosleep(), it will be awakened by hrtimer_wakeup() > unexpectedly.
Indeed and my original patch did call hrtimer_cancel() unconditionally to synchronize with a possibly running timer. Thomas, could you please document it a bit better, when you modify my patches?
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