Re: [RFC PATCH] freezer: revert 27920651fe "PM / Freezer: Makefake_signal_wake_up() wake TASK_KILLABLE tasks too"

[Tejun Heo]

On Tue, Nov 01, 2011 at 06:59:53PM +0100, Oleg Nesterov wrote:
> > #define wait_event_freezekillable(wq, condition)			\
> > do {									\
> > 	DEFINE_WAIT(__wait);						\
> > 	for (;;) {							\
> > 		prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);	\
> > 		if (condition || fatal_signal_pending(current))		\
> > 			break;						\
> > 		schedule();						\
> 
> No, this can't work, afaics.
> 
> Once the caller recieves a non-fatal signal (gets TIF_SIGPENDING),
> schedule() won't block in TASK_INTERRUPTIBLE state.
> 
> IOW, wait_event_freezekillable() becomes a busy-wait loop.

Yeah yeah, Trond already pointed it out.  I forgot about the
sigpending special case in schedule(), which I think is rather odd, oh
well.  Any better ideas?

-- 
tejun
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