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watchdog: unregister PM notifier on watchdog unregister

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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>
This commit is contained in:
Yuho Choi 2026-06-01 15:20:05 -04:00 committed by Guenter Roeck
parent 942d413e9c
commit a298c7302e
1 changed files with 3 additions and 0 deletions
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3
drivers/watchdog/watchdog_core.c
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@ -391,6 +391,9 @@ static void __watchdog_unregister_device(struct watchdog_device *wdd)
if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status))
unregister_reboot_notifier(&wdd->reboot_nb);
if (test_bit(WDOG_NO_PING_ON_SUSPEND, &wdd->status))
unregister_pm_notifier(&wdd->pm_nb);
watchdog_dev_unregister(wdd);
ida_free(&watchdog_ida, wdd->id);
}