wifi: mac80211: add flush_sta method

Some drivers like iwlwifi might have per-STA queues, so we
may want to flush/drop just those queues rather than all
when removing a station. Add a separate method for that.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/mac80211.h

@@ -3950,6 +3950,10 @@ struct ieee80211_prep_tx_info {
  *	Note that vif can be NULL.
  *	The callback can sleep.
  *
+ * @flush_sta: Flush or drop all pending frames from the hardware queue(s) for
+ *	the given station, as it's about to be removed.
+ *	The callback can sleep.
+ *
  * @channel_switch: Drivers that need (or want) to offload the channel
  *	switch operation for CSAs received from the AP may implement this
  *	callback. They must then call ieee80211_chswitch_done() to indicate
@@ -4415,6 +4419,8 @@ struct ieee80211_ops {
 #endif
 	void (*flush)(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 		      u32 queues, bool drop);
+	void (*flush_sta)(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
+			  struct ieee80211_sta *sta);
 	void (*channel_switch)(struct ieee80211_hw *hw,
 			       struct ieee80211_vif *vif,
 			       struct ieee80211_channel_switch *ch_switch);

net/mac80211/driver-ops.h

@@ -649,6 +649,21 @@ static inline void drv_flush(struct ieee80211_local *local,
 	trace_drv_return_void(local);
 }
 
+static inline void drv_flush_sta(struct ieee80211_local *local,
+				 struct ieee80211_sub_if_data *sdata,
+				 struct sta_info *sta)
+{
+	might_sleep();
+
+	if (sdata && !check_sdata_in_driver(sdata))
+		return;
+
+	trace_drv_flush_sta(local, sdata, &sta->sta);
+	if (local->ops->flush_sta)
+		local->ops->flush_sta(&local->hw, &sdata->vif, &sta->sta);
+	trace_drv_return_void(local);
+}
+
 static inline void drv_channel_switch(struct ieee80211_local *local,
 				      struct ieee80211_sub_if_data *sdata,
 				      struct ieee80211_channel_switch *ch_switch)

net/mac80211/sta_info.c

@@ -1299,8 +1299,12 @@ static void __sta_info_destroy_part2(struct sta_info *sta)
 	 * frames sitting on hardware queues might be sent out without
 	 * any encryption at all.
 	 */
-	if (local->ops->set_key)
+	if (local->ops->set_key) {
+		if (local->ops->flush_sta)
+			drv_flush_sta(local, sta->sdata, sta);
+		else
 			ieee80211_flush_queues(local, sta->sdata, false);
+	}
 
 	/* now keys can no longer be reached */
 	ieee80211_free_sta_keys(local, sta);

net/mac80211/trace.h

@@ -1177,6 +1177,13 @@ TRACE_EVENT(drv_flush,
 	)
 );
 
+DEFINE_EVENT(sta_event, drv_flush_sta,
+	TP_PROTO(struct ieee80211_local *local,
+		 struct ieee80211_sub_if_data *sdata,
+		 struct ieee80211_sta *sta),
+	TP_ARGS(local, sdata, sta)
+);
+
 TRACE_EVENT(drv_channel_switch,
 	TP_PROTO(struct ieee80211_local *local,
 		 struct ieee80211_sub_if_data *sdata,