mac80211: split TX aggregation stop action

When TX aggregation is stopped, there are a few
different cases:
 - connection with the peer was dropped
 - session stop was requested locally
 - session stop was requested by the peer
 - connection was dropped while a session is stopping

The behaviour in these cases should be different, if
the connection is dropped then the driver should drop
all frames, otherwise the frames may continue to be
transmitted, aggregated in the case of a locally
requested session stop or unaggregated in the case of
the peer requesting session stop.

Split these different cases so that the driver can
act accordingly; however, treat local and remote stop
the same way and ask the driver to not send frames as
aggregated packets any more.

In the case of connection drop, the stop callback the
driver is otherwise supposed to call is no longer
required.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/agg-tx.c

diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c
index dda8d7d..2f0ccbc 100644
--- a/net/mac80211/agg-tx.c
+++ b/net/mac80211/agg-tx.c
@@ -257,10 +257,25 @@
 {
 	struct ieee80211_local *local = sta->local;
 	struct tid_ampdu_tx *tid_tx;
+	enum ieee80211_ampdu_mlme_action action;
 	int ret;
 
 	lockdep_assert_held(&sta->ampdu_mlme.mtx);
 
+	switch (reason) {
+	case AGG_STOP_DECLINED:
+	case AGG_STOP_LOCAL_REQUEST:
+	case AGG_STOP_PEER_REQUEST:
+		action = IEEE80211_AMPDU_TX_STOP_CONT;
+		break;
+	case AGG_STOP_DESTROY_STA:
+		action = IEEE80211_AMPDU_TX_STOP_FLUSH;
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		return -EINVAL;
+	}
+
 	spin_lock_bh(&sta->lock);
 
 	tid_tx = rcu_dereference_protected_tid_tx(sta, tid);
@@ -269,10 +284,19 @@
 		return -ENOENT;
 	}
 
-	/* if we're already stopping ignore any new requests to stop */
+	/*
+	 * if we're already stopping ignore any new requests to stop
+	 * unless we're destroying it in which case notify the driver
+	 */
 	if (test_bit(HT_AGG_STATE_STOPPING, &tid_tx->state)) {
 		spin_unlock_bh(&sta->lock);
-		return -EALREADY;
+		if (reason != AGG_STOP_DESTROY_STA)
+			return -EALREADY;
+		ret = drv_ampdu_action(local, sta->sdata,
+				       IEEE80211_AMPDU_TX_STOP_FLUSH_CONT,
+				       &sta->sta, tid, NULL, 0);
+		WARN_ON_ONCE(ret);
+		goto remove_tid_tx;
 	}
 
 	if (test_bit(HT_AGG_STATE_WANT_START, &tid_tx->state)) {
@@ -319,8 +343,7 @@
 					WLAN_BACK_INITIATOR;
 	tid_tx->tx_stop = reason == AGG_STOP_LOCAL_REQUEST;
 
-	ret = drv_ampdu_action(local, sta->sdata,
-			       IEEE80211_AMPDU_TX_STOP,
+	ret = drv_ampdu_action(local, sta->sdata, action,
 			       &sta->sta, tid, NULL, 0);
 
 	/* HW shall not deny going back to legacy */
@@ -331,7 +354,14 @@
 		 */
 	}
 
-	return ret;
+	if (reason == AGG_STOP_DESTROY_STA) {
+ remove_tid_tx:
+		spin_lock_bh(&sta->lock);
+		ieee80211_remove_tid_tx(sta, tid);
+		spin_unlock_bh(&sta->lock);
+	}
+
+	return 0;
 }
 
 /*