3 files changed, 42 insertions, 12 deletions

diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c
index 63d852cb4ca2..f614ee602089 100644
--- a/net/mac80211/agg-tx.c
+++ b/net/mac80211/agg-tx.c
@@ -136,6 +136,14 @@ void ieee80211_send_bar(struct ieee80211_sub_if_data *sdata, u8 *ra, u16 tid, u1
         ieee80211_tx_skb(sdata, skb);
 }
 
+void ieee80211_assign_tid_tx(struct sta_info *sta, int tid,
+                             struct tid_ampdu_tx *tid_tx)
+{
+        lockdep_assert_held(&sta->ampdu_mlme.mtx);
+        lockdep_assert_held(&sta->lock);
+        rcu_assign_pointer(sta->ampdu_mlme.tid_tx[tid], tid_tx);
+}
+
 static void kfree_tid_tx(struct rcu_head *rcu_head)
 {
         struct tid_ampdu_tx *tid_tx =
@@ -161,7 +169,7 @@ int ___ieee80211_stop_tx_ba_session(struct sta_info *sta, u16 tid,
 
         if (test_bit(HT_AGG_STATE_WANT_START, &tid_tx->state)) {
                 /* not even started yet! */
-                rcu_assign_pointer(sta->ampdu_mlme.tid_tx[tid], NULL);
+                ieee80211_assign_tid_tx(sta, tid, NULL);
                 spin_unlock_bh(&sta->lock);
                 call_rcu(&tid_tx->rcu_head, kfree_tid_tx);
                 return 0;
@@ -318,7 +326,7 @@ void ieee80211_tx_ba_session_handle_start(struct sta_info *sta, int tid)
                                         " tid %d\n", tid);
 #endif
                 spin_lock_bh(&sta->lock);
-                rcu_assign_pointer(sta->ampdu_mlme.tid_tx[tid], NULL);
+                ieee80211_assign_tid_tx(sta, tid, NULL);
                 spin_unlock_bh(&sta->lock);
 
                 ieee80211_wake_queue_agg(local, tid);
@@ -398,7 +406,7 @@ int ieee80211_start_tx_ba_session(struct ieee80211_sta *pubsta, u16 tid,
 
         tid_tx = sta->ampdu_mlme.tid_tx[tid];
         /* check if the TID is not in aggregation flow already */
-        if (tid_tx) {
+        if (tid_tx || sta->ampdu_mlme.tid_start_tx[tid]) {
 #ifdef CONFIG_MAC80211_HT_DEBUG
                 printk(KERN_DEBUG "BA request denied - session is not "
                                  "idle on tid %u\n", tid);
@@ -433,8 +441,11 @@ int ieee80211_start_tx_ba_session(struct ieee80211_sta *pubsta, u16 tid,
         sta->ampdu_mlme.dialog_token_allocator++;
         tid_tx->dialog_token = sta->ampdu_mlme.dialog_token_allocator;
 
-        /* finally, assign it to the array */
-        rcu_assign_pointer(sta->ampdu_mlme.tid_tx[tid], tid_tx);
+        /*
+         * Finally, assign it to the start array; the work item will
+         * collect it and move it to the normal array.
+         */
+        sta->ampdu_mlme.tid_start_tx[tid] = tid_tx;
 
         ieee80211_queue_work(&local->hw, &sta->ampdu_mlme.work);
 
@@ -697,7 +708,7 @@ void ieee80211_stop_tx_ba_cb(struct ieee80211_vif *vif, u8 *ra, u8 tid)
         ieee80211_agg_splice_packets(local, tid_tx, tid);
 
         /* future packets must not find the tid_tx struct any more */
-        rcu_assign_pointer(sta->ampdu_mlme.tid_tx[tid], NULL);
+        ieee80211_assign_tid_tx(sta, tid, NULL);
 
         ieee80211_agg_splice_finish(local, tid);
 
diff --git a/net/mac80211/ht.c b/net/mac80211/ht.c
index b9e4b9bd2179..9f5842a43111 100644
--- a/net/mac80211/ht.c
+++ b/net/mac80211/ht.c
@@ -140,14 +140,29 @@ void ieee80211_ba_session_work(struct work_struct *work)
                                 sta, tid, WLAN_BACK_RECIPIENT,
                                 WLAN_REASON_QSTA_TIMEOUT, true);
 
-                tid_tx = sta->ampdu_mlme.tid_tx[tid];
-                if (!tid_tx)
-                        continue;
+                tid_tx = sta->ampdu_mlme.tid_start_tx[tid];
+                if (tid_tx) {
+                        /*
+                         * Assign it over to the normal tid_tx array
+                         * where it "goes live".
+                         */
+                        spin_lock_bh(&sta->lock);
+
+                        sta->ampdu_mlme.tid_start_tx[tid] = NULL;
+                        /* could there be a race? */
+                        if (sta->ampdu_mlme.tid_tx[tid])
+                                kfree(tid_tx);
+                        else
+                                ieee80211_assign_tid_tx(sta, tid, tid_tx);
+                        spin_unlock_bh(&sta->lock);
 
-                if (test_bit(HT_AGG_STATE_WANT_START, &tid_tx->state))
                         ieee80211_tx_ba_session_handle_start(sta, tid);
-                else if (test_and_clear_bit(HT_AGG_STATE_WANT_STOP,
-                                            &tid_tx->state))
+                        continue;
+                }
+
+                tid_tx = sta->ampdu_mlme.tid_tx[tid];
+                if (tid_tx && test_and_clear_bit(HT_AGG_STATE_WANT_STOP,
+                                                 &tid_tx->state))
                         ___ieee80211_stop_tx_ba_session(sta, tid,
                                                         WLAN_BACK_INITIATOR,
                                                         true);
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index f00b4dcb49d7..55c51855ceb7 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -152,6 +152,7 @@ struct tid_ampdu_rx {
  *
  * @tid_rx: aggregation info for Rx per TID -- RCU protected
  * @tid_tx: aggregation info for Tx per TID
+ * @tid_start_tx: sessions where start was requested
  * @addba_req_num: number of times addBA request has been sent.
  * @dialog_token_allocator: dialog token enumerator for each new session;
  * @work: work struct for starting/stopping aggregation
@@ -168,6 +169,7 @@ struct sta_ampdu_mlme {
         /* tx */
         struct work_struct work;
         struct tid_ampdu_tx *tid_tx[STA_TID_NUM];
+        struct tid_ampdu_tx *tid_start_tx[STA_TID_NUM];
         u8 addba_req_num[STA_TID_NUM];
         u8 dialog_token_allocator;
 };
@@ -398,6 +400,8 @@ static inline u32 get_sta_flags(struct sta_info *sta)
         return ret;
 }
 
+void ieee80211_assign_tid_tx(struct sta_info *sta, int tid,
+                             struct tid_ampdu_tx *tid_tx);
 
 
 #define STA_HASH_SIZE 256