mac80211: move blockack stop due to fragmentation

There's a corner case where we receive a fragmented
frame during a blockack session, in which case we
will terminate that session. To simplify future work
in this area that will culminate in allowing the
driver callbacks for aggregation to sleep, move the
processing of this case out of the RX path into the
interface work.

This will simplify future work because the new place
for this code doesn't require that the function will
always be atomic, which the RX path needs.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/iface.c

@@ -707,6 +707,7 @@ static void ieee80211_iface_work(struct work_struct *work)
 		container_of(work, struct ieee80211_sub_if_data, work);
 	struct ieee80211_local *local = sdata->local;
 	struct sk_buff *skb;
+	struct sta_info *sta;
 
 	if (!ieee80211_sdata_running(sdata))
 		return;
@@ -729,7 +730,6 @@ static void ieee80211_iface_work(struct work_struct *work)
 		if (ieee80211_is_action(mgmt->frame_control) &&
 		    mgmt->u.action.category == WLAN_CATEGORY_BACK) {
 			int len = skb->len;
-			struct sta_info *sta;
 
 			rcu_read_lock();
 			sta = sta_info_get(sdata, mgmt->sa);
@@ -753,6 +753,36 @@ static void ieee80211_iface_work(struct work_struct *work)
 				}
 			}
 			rcu_read_unlock();
+		} else if (ieee80211_is_data_qos(mgmt->frame_control)) {
+			struct ieee80211_hdr *hdr = (void *)mgmt;
+			/*
+			 * So the frame isn't mgmt, but frame_control
+			 * is at the right place anyway, of course, so
+			 * the if statement is correct.
+			 *
+			 * Warn if we have other data frame types here,
+			 * they must not get here.
+			 */
+			WARN_ON(hdr->frame_control &
+					cpu_to_le16(IEEE80211_STYPE_NULLFUNC));
+			WARN_ON(!(hdr->seq_ctrl &
+					cpu_to_le16(IEEE80211_SCTL_FRAG)));
+			/*
+			 * This was a fragment of a frame, received while
+			 * a block-ack session was active. That cannot be
+			 * right, so terminate the session.
+			 */
+			rcu_read_lock();
+			sta = sta_info_get(sdata, mgmt->sa);
+			if (sta) {
+				u16 tid = *ieee80211_get_qos_ctl(hdr) &
+						IEEE80211_QOS_CTL_TID_MASK;
+
+				__ieee80211_stop_rx_ba_session(
+					sta, tid, WLAN_BACK_RECIPIENT,
+					WLAN_REASON_QSTA_REQUIRE_SETUP);
+			}
+			rcu_read_unlock();
 		} else switch (sdata->vif.type) {
 		case NL80211_IFTYPE_STATION:
 			ieee80211_sta_rx_queued_mgmt(sdata, skb);

net/mac80211/rx.c

@@ -741,9 +741,8 @@ static void ieee80211_rx_reorder_ampdu(struct ieee80211_rx_data *rx,
 	sc = le16_to_cpu(hdr->seq_ctrl);
 	if (sc & IEEE80211_SCTL_FRAG) {
 		spin_unlock(&sta->lock);
-		__ieee80211_stop_rx_ba_session(sta, tid, WLAN_BACK_RECIPIENT,
-					       WLAN_REASON_QSTA_REQUIRE_SETUP);
-		dev_kfree_skb(skb);
+		skb_queue_tail(&rx->sdata->skb_queue, skb);
+		ieee80211_queue_work(&local->hw, &rx->sdata->work);
 		return;
 	}