watchdog: Avoid kernel crash when disabling watchdog

watchdog: Avoid kernel crash when disabling watchdog

In case you boot with the watchdog disabled, i.e., nowatchdog, then,
if you try to disable it via /proc/sys/kernel/watchdog, you get
a kernel crash. The reason is that you are trying to cancel a hrtimer
which has never been initialized.

This patch fixes this by skipping execution of
watchdog_disable_all_cpus() when the watchdog is marked
disabled from boot.

Signed-off-by: Stephane Eranian <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
LKML-Reference: <4c8f7a23.cae9d80a[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>