Messages in this thread Patch in this message | | | Date | Sun, 1 Apr 2012 20:19:30 +1000 | From | NeilBrown <> | Subject | Subject: [PATCH] APM: fix deadlock in APM_IOC_SUSPEND ioctl |
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I found the Xorg server on my ARM device stuck in the 'msleep()' loop in apm_ioctl.
I suspect it had attempted suspend immediately after resuming and lost a race. During that msleep(10);, a new suspend cycle must have started and changed ->suspend_state to SUSPEND_PENDING, so it was never seen to be SUSPEND_DONE and the loop could never exited. It would have moved on to SUSPEND_ACKTO but never been able to reach SUSPEND_DONE.
So change the loop to only run while SUSPEND_ACKED rather than until SUSPEND_DONE. This is much safer.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/char/apm-emulation.c b/drivers/char/apm-emulation.c index f4837a8..6005c5c 100644 --- a/drivers/char/apm-emulation.c +++ b/drivers/char/apm-emulation.c @@ -302,7 +302,7 @@ apm_ioctl(struct file *filp, u_int cmd, u_long arg) * anything critical, chill a bit on each iteration. */ while (wait_event_freezable(apm_suspend_waitqueue, - as->suspend_state == SUSPEND_DONE)) + as->suspend_state != SUSPEND_ACKED)) msleep(10); break; case SUSPEND_ACKTO:[unhandled content-type:application/pgp-signature]
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