watchdog: iTCO_wdt: Report error if timeout configuration fails

[ Upstream commit 40efc43eb7ffb5a4e2f998c13b8cfb555e671b92 ]

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@lenovo.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20250704073518.7838-1-13281011316@163.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
index 7672582fa407649285e78c26d46b188b8f24e0c4..e9bf53929b53d0c7bd2b531e2ff4b844e493c50b 100644 (file)
--- a/drivers/watchdog/iTCO_wdt.c
+++ b/drivers/watchdog/iTCO_wdt.c
@@ -601,7 +601,11 @@ 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);
        }