Re: Race in vt_event_wait() during suspend/resume

[Alan Cox]

On Fri, 18 May 2012 16:34:53 +0530
Rabin Vincent <rabin@xxxxxx> 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
--
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/