linux-kernel - [PATCH] watchdog: iTCO_wdt: Report error if timeout configuration fails

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Message-ID: <20250704073518.7838-1-13281011316@163.com>
Date: Fri,  4 Jul 2025 15:35:18 +0800
From: Ziyan Fu <13281011316@....com>
To: wim@...ux-watchdog.org,
	linux@...ck-us.net
Cc: linux-watchdog@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	fuzy5@...ovo.com
Subject: [PATCH] watchdog: iTCO_wdt: Report error if timeout configuration fails

From: Ziyan Fu <fuzy5@...ovo.com>

The driver probes with the invalid timeout value when
'iTCO_wdt_set_timeout()' fails, as its return value is not checked. In
this case, when executing "wdctl", we may get:

Device:        /dev/watchdog0
Timeout:       30 seconds
Timeleft:      613 seconds

The timeout value is the value of "heartbeat" or "WATCHDOG_TIMEOUT", and
the timeleft value is calculated from the register value we actually read
(0xffff) by masking with 0x3ff and converting ticks to seconds (* 6 / 10).

Add error handling to return the failure code if 'iTCO_wdt_set_timeout()'
fails, ensuring the driver probe fails and prevents invalid operation.

Signed-off-by: Ziyan Fu <fuzy5@...ovo.com>
---
 drivers/watchdog/iTCO_wdt.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
index 9ab769aa0244..4ab3405ef8e6 100644
--- a/drivers/watchdog/iTCO_wdt.c
+++ b/drivers/watchdog/iTCO_wdt.c
@@ -577,7 +577,11 @@ static int iTCO_wdt_probe(struct platform_device *pdev)
 	/* Check that the heartbeat value is within it's range;
 	   if not reset to the default */
 	if (iTCO_wdt_set_timeout(&p->wddev, heartbeat)) {
-		iTCO_wdt_set_timeout(&p->wddev, WATCHDOG_TIMEOUT);
+		ret = iTCO_wdt_set_timeout(&p->wddev, WATCHDOG_TIMEOUT);
+		if (ret != 0) {
+			dev_err(dev, "Failed to set watchdog timeout (%d)\n", WATCHDOG_TIMEOUT);
+			return ret;
+		}
 		dev_info(dev, "timeout value out of range, using %d\n",
 			WATCHDOG_TIMEOUT);
 		heartbeat = WATCHDOG_TIMEOUT;
-- 
2.27.0