mac80211: stop Rx during HW reconfig

While HW reconfig is in progress, drop all incoming Rx. This prevents
incoming packets from changing the internal state of the driver or
calling callbacks of the low level driver while it is in inconsistent
state.
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/ieee80211_i.h

@@ -881,6 +881,9 @@ struct ieee80211_local {
 	/* device is started */
 	bool started;
 
+	/* device is during a HW reconfig */
+	bool in_reconfig;
+
 	/* wowlan is enabled -- don't reconfig on resume */
 	bool wowlan;
 

net/mac80211/main.c

@@ -345,6 +345,13 @@ void ieee80211_restart_hw(struct ieee80211_hw *hw)
 	ieee80211_stop_queues_by_reason(hw,
 		IEEE80211_QUEUE_STOP_REASON_SUSPEND);
 
+	/*
+	 * Stop all Rx during the reconfig. We don't want state changes
+	 * or driver callbacks while this is in progress.
+	 */
+	local->in_reconfig = true;
+	barrier();
+
 	schedule_work(&local->restart_work);
 }
 EXPORT_SYMBOL(ieee80211_restart_hw);

net/mac80211/rx.c

@@ -3027,6 +3027,10 @@ void ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb)
 	if (unlikely(local->quiescing || local->suspended))
 		goto drop;
 
+	/* We might be during a HW reconfig, prevent Rx for the same reason */
+	if (unlikely(local->in_reconfig))
+		goto drop;
+
 	/*
 	 * The same happens when we're not even started,
 	 * but that's worth a warning.

net/mac80211/util.c

@@ -1411,6 +1411,9 @@ int ieee80211_reconfig(struct ieee80211_local *local)
 		if (ieee80211_sdata_running(sdata))
 			ieee80211_enable_keys(sdata);
 
+	local->in_reconfig = false;
+	barrier();
+
  wake_up:
 	/*
 	 * Clear the WLAN_STA_BLOCK_BA flag so new aggregation