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watchdog: mei: avoid oops in watchdog unregister code path

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With commit c7d3df3 "mei: use internal watchdog device registration
tracking" will crash the kernel on shutdown path on systems
where ME watchdog is not present.
Since the watchdog was never initialized in such case
the WDOG_UNREGISTERED bit is never set and the system
crashes on access to uninitialized variables down the path.

To solve the issue we query for NULL on watchdog driver driver_data
to check whether the device is registered. This is handled in the
driver and doesn't depend on watchdog core internals.

Cc: Borislav Petkov <bp@alien8.de>
Cc: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Signed-off-by: Jerry Snitselaar <jerry.snitselaar@oracle.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
This commit is contained in:
Tomas Winkler 2012-12-16 13:23:17 +02:00 committed by Wim Van Sebroeck
parent 8c4c419ca3
commit d692170037
1 changed files with 1 additions and 1 deletions
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2
drivers/misc/mei/wd.c
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@ -370,7 +370,7 @@ void mei_watchdog_register(struct mei_device *dev)
void mei_watchdog_unregister(struct mei_device *dev)
{
if (test_bit(WDOG_UNREGISTERED, &amt_wd_dev.status))
if (watchdog_get_drvdata(&amt_wd_dev) == NULL)
return;
watchdog_set_drvdata(&amt_wd_dev, NULL);