ath9k: fix an aggregation start related race condition

A new aggregation session start can be issued by mac80211, even when the
cleanup of the previous session has not completed yet. Since the data structure
for the session is not recreated, this could corrupt the block ack window
and lock up the aggregation session. Fix this by delaying the new session
until the old one has been cleaned up.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Cc: stable@kernel.org
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index 5323a4d9ebb8..d629bfbdfab4 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -783,17 +783,23 @@ static void ath_tx_sched_aggr(struct ath_softc *sc, struct ath_txq *txq,
                  status != ATH_AGGR_BAW_CLOSED);
 }
 
-void ath_tx_aggr_start(struct ath_softc *sc, struct ieee80211_sta *sta,
-                       u16 tid, u16 *ssn)
+int ath_tx_aggr_start(struct ath_softc *sc, struct ieee80211_sta *sta,
+                      u16 tid, u16 *ssn)
 {
         struct ath_atx_tid *txtid;
         struct ath_node *an;
 
         an = (struct ath_node *)sta->drv_priv;
         txtid = ATH_AN_2_TID(an, tid);
+
+        if (txtid->state & (AGGR_CLEANUP | AGGR_ADDBA_COMPLETE))
+                return -EAGAIN;
+
         txtid->state |= AGGR_ADDBA_PROGRESS;
         txtid->paused = true;
         *ssn = txtid->seq_start;
+
+        return 0;
 }
 
 void ath_tx_aggr_stop(struct ath_softc *sc, struct ieee80211_sta *sta, u16 tid)