watchdog: core: propagate ping error code to the user space

Watchdog ping return errors are ignored by watchdog core,
Whatchdog daemon should be informed about possible hardware error or
underlaying device driver get unregistered.

Signed-off-by: Alexander Usyskin <[e-mail]>
Signed-off-by: Tomas Winkler <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

drivers/watchdog/watchdog_dev.c

···
 	struct watchdog_device *wdd = file->private_data;
 	size_t i;
 	char c;
+	int err;
 
 	if (len == 0)
 		return 0;
···
 	}
 
 	/* someone wrote to us, so we send the watchdog a keepalive ping */
-	watchdog_ping(wdd);
+	err = watchdog_ping(wdd);
+	if (err < 0)
+		return err;
 
 	return len;
 }
···
 	case WDIOC_KEEPALIVE:
 		if (!(wdd->info->options & WDIOF_KEEPALIVEPING))
 			return -EOPNOTSUPP;
-		watchdog_ping(wdd);
-		return 0;
+		return watchdog_ping(wdd);
 	case WDIOC_SETTIMEOUT:
 		if (get_user(val, p))
 			return -EFAULT;
···
 		/* If the watchdog is active then we send a keepalive ping
 		 * to make sure that the watchdog keep's running (and if
 		 * possible that it takes the new timeout) */
-		watchdog_ping(wdd);
+		err = watchdog_ping(wdd);
+		if (err < 0)
+			return err;
 		/* Fall */
 	case WDIOC_GETTIMEOUT:
 		/* timeout == 0 means that we don't know the timeout */