Messages in this thread | | | Date | Thu, 14 Jun 2012 10:20:45 -0700 | From | Greg KH <> | Subject | Re: [PATCH] vt: fix race in vt_waitactive() |
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On Thu, Jun 14, 2012 at 10:48:02AM +0100, Alan Cox wrote: > On Wed, 13 Jun 2012 16:44:52 -0700 > Greg KH <gregkh@linuxfoundation.org> wrote: > > > On Mon, May 21, 2012 at 01:38:42PM +0530, Rabin Vincent wrote: > > > pm_restore_console() is called from the suspend/resume path, and this > > > calls vt_move_to_console(), which calls vt_waitactive(). > > > > > > 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 > > > > > > Fix the race by ensuring we're registered for the event before we check > > > if it's already completed. > > > > > > Cc: Alan Cox <alan@linux.intel.com> > > > Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com> > > > --- > > > drivers/tty/vt/vt_ioctl.c | 47 ++++++++++++++++++++++++++++++++------------ > > > 1 files changed, 34 insertions(+), 13 deletions(-) > > > > Alan, any thoughts on this patch? > > I acked it when first posted - I believe its correct.
Ah, sorry, I missed that somehow. I'll go queue it up now.
greg k-h
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