[PATCH] watchdog: only run driver set_pretimeout op if device supports it

From: Curtis Klein <curtis.klein@hpe.com>
To: wim@linux-watchdog.org, linux@roeck-us.net
Cc: linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org,
	Curtis Klein <curtis.klein@hpe.com>
Subject: [PATCH] watchdog: only run driver set_pretimeout op if device supports it
Date: Sat, 26 Jun 2021 16:47:45 -0700	[thread overview]
Message-ID: <1624751265-24785-1-git-send-email-curtis.klein@hpe.com> (raw)

Some watchdog devices might conditionally support pretimeouts (e.g. if
an interrupt is exposed for the device) but some watchdog drivers might
still define the set_pretimeout operation (e.g. the mtk_wdt driver) and
indicate support at runtime through the WDIOF_PRETIMEOUT flag. If the
kernel is compiled with CONFIG_WATCHDOG_HRTIMER_PRETIMEOUT enabled,
watchdog_set_pretimeout would run the driver specific set_pretimeout
even if WDIOF_PRETIMEOUT is not set which might have unintended
consequences.

So this change checks that the device flags and only runs the driver
operation if pretimeouts are supported.

Signed-off-by: Curtis Klein <curtis.klein@hpe.com>
---
 drivers/watchdog/watchdog_dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 3bab324..5bf795c 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -401,7 +401,7 @@ static int watchdog_set_pretimeout(struct watchdog_device *wdd,
 	if (watchdog_pretimeout_invalid(wdd, timeout))
 		return -EINVAL;
 
-	if (wdd->ops->set_pretimeout)
+	if (wdd->ops->set_pretimeout && (wdd->info->options & WDIOF_PRETIMEOUT))
 		err = wdd->ops->set_pretimeout(wdd, timeout);
 	else
 		wdd->pretimeout = timeout;
-- 
2.7.4

