watchdog: unregister PM notifier on watchdog unregister

[ Upstream commit a298c7302e ]

watchdog_register_device() registers wdd->pm_nb when
WDOG_NO_PING_ON_SUSPEND is set, but watchdog_unregister_device() does not
remove it. This leaves an embedded notifier block on the PM notifier chain
after the watchdog device has been unregistered.

A later suspend/resume notification can then call watchdog_pm_notifier()
with a stale watchdog_device pointer, or at minimum after wdd->wd_data has
been cleared by watchdog_dev_unregister().

Unregister the PM notifier before tearing down the watchdog device.

Fixes: 60bcd91aaf ("watchdog: introduce watchdog_dev_suspend/resume")
Signed-off-by: Yuho Choi <dbgh9129@gmail.com>
Link: https://lore.kernel.org/r/20260601192005.1970805-1-dbgh9129@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Yuho Choi 2026-06-01 15:20:05 -04:00 • committed by Greg Kroah-Hartman
commit cd2d1b1f99