mac80211: fix configure_filter invocation after stop

Since configure_filter can sleep now, any multicast
configuration needed to be postponed to a work struct.
This, however, lead to a problem that we could queue
the work, stop the device and then afterwards invoke
configure_filter which may lead to driver hangs and is
a bug. To fix this, we can just cancel the filter work
since it's unnecessary to do after stopping the hw.

Since there are various places that call drv_stop, and
two of them do very similar things, the code for them
can be put into a shared function at the same time.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Reported-by: Lennert Buytenhek <buytenh@wantstofly.org>
Tested-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/ieee80211_i.h

@@ -1086,6 +1086,7 @@ void ieee80211_process_measurement_req(struct ieee80211_sub_if_data *sdata,
 
 /* Suspend/resume and hw reconfiguration */
 int ieee80211_reconfig(struct ieee80211_local *local);
+void ieee80211_stop_device(struct ieee80211_local *local);
 
 #ifdef CONFIG_PM
 int __ieee80211_suspend(struct ieee80211_hw *hw);

net/mac80211/iface.c

@@ -552,11 +552,7 @@ static int ieee80211_stop(struct net_device *dev)
 	ieee80211_recalc_ps(local, -1);
 
 	if (local->open_count == 0) {
-		drv_stop(local);
-
-		ieee80211_led_radio(local, false);
-
-		flush_workqueue(local->workqueue);
+		ieee80211_stop_device(local);
 
 		tasklet_disable(&local->tx_pending_tasklet);
 		tasklet_disable(&local->tasklet);

net/mac80211/pm.c

@@ -107,17 +107,8 @@ int __ieee80211_suspend(struct ieee80211_hw *hw)
 	}
 
 	/* stop hardware - this must stop RX */
-	if (local->open_count) {
-		ieee80211_led_radio(local, false);
-		drv_stop(local);
-	}
-
-	/*
-	 * flush again, in case driver queued work -- it
-	 * shouldn't be doing (or cancel everything in the
-	 * stop callback) that but better safe than sorry.
-	 */
-	flush_workqueue(local->workqueue);
+	if (local->open_count)
+		ieee80211_stop_device(local);
 
 	local->suspended = true;
 	/* need suspended to be visible before quiescing is false */

net/mac80211/util.c

@@ -1007,6 +1007,16 @@ u32 ieee80211_sta_get_rates(struct ieee80211_local *local,
 	return supp_rates;
 }
 
+void ieee80211_stop_device(struct ieee80211_local *local)
+{
+	ieee80211_led_radio(local, false);
+
+	cancel_work_sync(&local->reconfig_filter);
+	drv_stop(local);
+
+	flush_workqueue(local->workqueue);
+}
+
 int ieee80211_reconfig(struct ieee80211_local *local)
 {
 	struct ieee80211_hw *hw = &local->hw;