dm ioctl: fix error return code in target_message

Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.

Fixes: 2ca4c92 ("dm ioctl: prevent empty message")
Reported-by: Hulk Robot <[email protected]>
Signed-off-by: Qinglang Miao <[email protected]>
Signed-off-by: Mike Snitzer <[email protected]>

Author: Qinglang Miao

drivers/md/dm-ioctl.c

@@ -1600,6 +1600,7 @@ static int target_message(struct file *filp, struct dm_ioctl *param, size_t para
 
 	if (!argc) {
 		DMWARN("Empty message received.");
+		r = -EINVAL;
 		goto out_argv;
 	}