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| author | NeilBrown <neilb@suse.de> | 2012-04-01 20:19:30 +1000 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2012-04-03 03:42:36 +0200 |
| commit | f283d22713b0bdc147097c92c9b45855339cf1c8 (patch) | |
| tree | fee788fb13479ebe013eae8c9a4b621d6ccd3057 | |
| parent | b4a133da2eaccb844a7beaef16ffd9c76a0d21d3 (diff) | |
| download | linux-f283d22713b0bdc147097c92c9b45855339cf1c8.tar.gz linux-f283d22713b0bdc147097c92c9b45855339cf1c8.tar.bz2 linux-f283d22713b0bdc147097c92c9b45855339cf1c8.zip | |
APM: fix deadlock in APM_IOC_SUSPEND ioctl
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>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
| -rw-r--r-- | drivers/char/apm-emulation.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/char/apm-emulation.c b/drivers/char/apm-emulation.c index f4837a893dfa..6005c5c03f2a 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: |