linux-kernel - [PATCH REVIEW 1/2] watchdog: extend the mutex-protected section in watchdog_cdev

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Message-Id: <20220818020624.2386475-1-aklimov@redhat.com>
Date:   Thu, 18 Aug 2022 03:06:23 +0100
From:   Alexey Klimov <aklimov@...hat.com>
To:     linux-watchdog@...r.kernel.org
Cc:     wim@...ux-watchdog.org, linux@...ck-us.net,
        linux-kernel@...r.kernel.org, klimov.linux@...il.com
Subject: [PATCH REVIEW 1/2] watchdog: extend the mutex-protected section in watchdog_cdev_unregister()

watchdog_stop() should be called with wd_data->lock mutex locked.
Updates to wdd->status also occur under this look throughout the
watchdog_dev.c as well as functions that deal with pretimeout hrtimer
like watchdog_hrtimer_pretimeout_stop() here.

Signed-off-by: Alexey Klimov <aklimov@...hat.com>
---
 drivers/watchdog/watchdog_dev.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 54903f3c851e..804236a094f6 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -1095,6 +1095,8 @@ static void watchdog_cdev_unregister(struct watchdog_device *wdd)
 		old_wd_data = NULL;
 	}
 
+	mutex_lock(&wd_data->lock);
+
 	if (watchdog_active(wdd) &&
 	    test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) {
 		watchdog_stop(wdd);
@@ -1102,7 +1104,6 @@ static void watchdog_cdev_unregister(struct watchdog_device *wdd)
 
 	watchdog_hrtimer_pretimeout_stop(wdd);
 
-	mutex_lock(&wd_data->lock);
 	wd_data->wdd = NULL;
 	wdd->wd_data = NULL;
 	mutex_unlock(&wd_data->lock);
-- 
2.37.2