mac80211: don't stop a single aggregation session twice

Nikolay noticed (by code review) that mac80211 can attempt to stop an aggregation session while it is already being stopped. So to fix it, check whether stop is already being done and bail out if so. Also move setting the STOPPING state into the lock so things are properly atomic. Cc: [email protected] Reported-by: Nikolay Martynov <[email protected]> Signed-off-by: Johannes Berg <[email protected]> Signed-off-by: John W. Linville <[email protected]>
neviim · Nov 28, 2011 · 24f50a9 · 24f50a9
1 parent e007b85
commit 24f50a9
Showing 1 changed file with 8 additions and 2 deletions.
diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c
@@ -160,6 +160,12 @@ int ___ieee80211_stop_tx_ba_session(struct sta_info *sta, u16 tid,
 		return -ENOENT;
 	}
 
+	/* if we're already stopping ignore any new requests to stop */
+	if (test_bit(HT_AGG_STATE_STOPPING, &tid_tx->state)) {
+		spin_unlock_bh(&sta->lock);
+		return -EALREADY;
+	}
+
 	if (test_bit(HT_AGG_STATE_WANT_START, &tid_tx->state)) {
 		/* not even started yet! */
 		ieee80211_assign_tid_tx(sta, tid, NULL);
@@ -168,15 +174,15 @@ int ___ieee80211_stop_tx_ba_session(struct sta_info *sta, u16 tid,
 		return 0;
 	}
 
+	set_bit(HT_AGG_STATE_STOPPING, &tid_tx->state);
+
 	spin_unlock_bh(&sta->lock);
 
 #ifdef CONFIG_MAC80211_HT_DEBUG
 	printk(KERN_DEBUG "Tx BA session stop requested for %pM tid %u\n",
 	       sta->sta.addr, tid);
 #endif /* CONFIG_MAC80211_HT_DEBUG */
 
-	set_bit(HT_AGG_STATE_STOPPING, &tid_tx->state);
-
 	del_timer_sync(&tid_tx->addba_resp_timer);
 
 	/*