1 files changed, 39 insertions, 3 deletions

diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c
index b3f65520e7a7..b064e4df12c6 100644
--- a/net/mac80211/agg-tx.c
+++ b/net/mac80211/agg-tx.c
@@ -161,6 +161,12 @@ 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);
@@ -169,6 +175,8 @@ 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
@@ -176,8 +184,6 @@ int ___ieee80211_stop_tx_ba_session(struct sta_info *sta, u16 tid,
                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);
 
         /*
@@ -187,6 +193,20 @@ int ___ieee80211_stop_tx_ba_session(struct sta_info *sta, u16 tid,
          */
         clear_bit(HT_AGG_STATE_OPERATIONAL, &tid_tx->state);
 
+        /*
+         * There might be a few packets being processed right now (on
+         * another CPU) that have already gotten past the aggregation
+         * check when it was still OPERATIONAL and consequently have
+         * IEEE80211_TX_CTL_AMPDU set. In that case, this code might
+         * call into the driver at the same time or even before the
+         * TX paths calls into it, which could confuse the driver.
+         *
+         * Wait for all currently running TX paths to finish before
+         * telling the driver. New packets will not go through since
+         * the aggregation session is no longer OPERATIONAL.
+         */
+        synchronize_net();
+
         tid_tx->stop_initiator = initiator;
         tid_tx->tx_stop = tx;
 
@@ -757,11 +777,27 @@ void ieee80211_process_addba_resp(struct ieee80211_local *local,
                 goto out;
         }
 
-        del_timer(&tid_tx->addba_resp_timer);
+        del_timer_sync(&tid_tx->addba_resp_timer);
 
 #ifdef CONFIG_MAC80211_HT_DEBUG
         printk(KERN_DEBUG "switched off addBA timer for tid %d\n", tid);
 #endif
+
+        /*
+         * addba_resp_timer may have fired before we got here, and
+         * caused WANT_STOP to be set. If the stop then was already
+         * processed further, STOPPING might be set.
+         */
+        if (test_bit(HT_AGG_STATE_WANT_STOP, &tid_tx->state) ||
+            test_bit(HT_AGG_STATE_STOPPING, &tid_tx->state)) {
+#ifdef CONFIG_MAC80211_HT_DEBUG
+                printk(KERN_DEBUG
+                       "got addBA resp for tid %d but we already gave up\n",
+                       tid);
+#endif
+                goto out;
+        }
+
         /*
          * IEEE 802.11-2007 7.3.1.14:
          * In an ADDBA Response frame, when the Status Code field