cfg80211: return -ENOENT when stopping sched_scan while not running

If we try to stop a scheduled scan while it is not running, we should
return -ENOENT instead of simply ignoring the command and returning
success.  This is more consistent with other parts of the code.
Reported-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/linux/nl80211.h

@@ -247,7 +247,8 @@
  *	passed, all channels allowed for the current regulatory domain
  *	are used.  Extra IEs can also be passed from the userspace by
  *	using the %NL80211_ATTR_IE attribute.
- * @NL80211_CMD_STOP_SCHED_SCAN: stop a scheduled scan
+ * @NL80211_CMD_STOP_SCHED_SCAN: stop a scheduled scan.  Returns -ENOENT
+ *	if scheduled scan is not running.
  * @NL80211_CMD_SCHED_SCAN_RESULTS: indicates that there are scheduled scan
  *	results available.
  * @NL80211_CMD_SCHED_SCAN_STOPPED: indicates that the scheduled scan has

net/wireless/scan.c

@@ -137,7 +137,7 @@ int __cfg80211_stop_sched_scan(struct cfg80211_registered_device *rdev,
 	ASSERT_RDEV_LOCK(rdev);
 
 	if (!rdev->sched_scan_req)
-		return 0;
+		return -ENOENT;
 
 	dev = rdev->sched_scan_req->dev;