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

[Oleg Nesterov]

On 11/01, Tejun Heo wrote:
>
> diddling with
> sigmask in kernel generally isn't a good idea.

Agreed.

> If there are only a handful sites which need this type of behavior,
> wouldn't something like the following work?
>
> #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.

Oleg.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/