mac80211: cancel scan in ieee80211_restart_hw if software scan pending

This function exists to clean-up after a hardware error or something
similar.  The restart is accomplished using the same infrastructure used
to resume after a suspend.  The suspend path cancels running scans, so
it seems appropriate to do that here as well for software-based scans.
If a hardware-based scan is pending, issue a warning message since this
indicates that the drivers has failed to clean-up after itself.
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

net/mac80211/main.c

@@ -305,7 +305,13 @@ void ieee80211_restart_hw(struct ieee80211_hw *hw)
 
 	trace_api_restart_hw(local);
 
-	/* use this reason, __ieee80211_resume will unblock it */
+	WARN(test_bit(SCAN_HW_SCANNING, &local->scanning),
+		"%s called with hardware scan in progress\n", __func__);
+
+	if (unlikely(test_bit(SCAN_SW_SCANNING, &local->scanning)))
+		ieee80211_scan_cancel(local);
+
+	/* use this reason, ieee80211_reconfig will unblock it */
 	ieee80211_stop_queues_by_reason(hw,
 		IEEE80211_QUEUE_STOP_REASON_SUSPEND);