Re: Race in vt_event_wait() during suspend/resume

Alan Cox
2012-05-18T11:38:07Z

On Fri, 18 May 2012 16:34:53 +0530
Rabin Vincent <rabin@rab.in> wrote:

> pm_restore_console() is called from the suspend/resume path,
> this calls vt_move_to_console(), which calls vt_event_wait().
>
> There's a race in this path which causes the process
> which requests the suspend to sleep indefinitely waiting
> for an event which already happened:
>
> P1 P2
> vt_move_to_console()
> set_console()
> schedule_console_callback()
> vt_waitactive()
> check n == fg_console +1
> console_callback()
> switch_screen()
> vt_event_post() // no waiters
>
> vt_event_wait() // forever
>
> I think the following should fix it. Comments?
>

Looks right to me.

Alan