ath9k: prevent aggregation session deadlocks
Waiting for all subframes of an existing aggregation session to drain before allowing mac80211 to start a new one is fragile and deadlocks caused by this behavior have been observed. Since mac80211 has proper synchronization for aggregation session start/stop handling, a better approach to session handling is to simply allow mac80211 to start a new session at any time. This requires changing the code to discard any packets outside of the BlockAck window in the A-MPDU software retry code. This patch implements the above and also simplifies the code. Signed-off-by: Felix Fietkau <nbd@openwrt.org> Signed-off-by: John W. Linville <linville@tuxdriver.com>
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@ -251,10 +251,9 @@ struct ath_atx_tid {
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int tidno;
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int baw_head; /* first un-acked tx buffer */
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int baw_tail; /* next unused tx buffer slot */
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int sched;
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int paused;
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u8 state;
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bool stop_cb;
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bool sched;
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bool paused;
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bool active;
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};
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struct ath_node {
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@ -275,10 +274,6 @@ struct ath_node {
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#endif
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};
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#define AGGR_CLEANUP BIT(1)
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#define AGGR_ADDBA_COMPLETE BIT(2)
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#define AGGR_ADDBA_PROGRESS BIT(3)
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struct ath_tx_control {
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struct ath_txq *txq;
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struct ath_node *an;
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@ -352,8 +347,7 @@ void ath_tx_tasklet(struct ath_softc *sc);
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void ath_tx_edma_tasklet(struct ath_softc *sc);
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int ath_tx_aggr_start(struct ath_softc *sc, struct ieee80211_sta *sta,
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u16 tid, u16 *ssn);
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bool ath_tx_aggr_stop(struct ath_softc *sc, struct ieee80211_sta *sta, u16 tid,
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bool flush);
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void ath_tx_aggr_stop(struct ath_softc *sc, struct ieee80211_sta *sta, u16 tid);
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void ath_tx_aggr_resume(struct ath_softc *sc, struct ieee80211_sta *sta, u16 tid);
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void ath_tx_aggr_wakeup(struct ath_softc *sc, struct ath_node *an);
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@ -1709,7 +1709,8 @@ static int ath9k_ampdu_action(struct ieee80211_hw *hw,
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flush = true;
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case IEEE80211_AMPDU_TX_STOP_CONT:
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ath9k_ps_wakeup(sc);
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if (ath_tx_aggr_stop(sc, sta, tid, flush))
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ath_tx_aggr_stop(sc, sta, tid);
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if (!flush)
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ieee80211_stop_tx_ba_cb_irqsafe(vif, sta->addr, tid);
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ath9k_ps_restore(sc);
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break;
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@ -1227,10 +1227,7 @@ static bool ath_tx_aggr_check(struct ath_softc *sc, struct ieee80211_sta *sta,
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return false;
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txtid = ATH_AN_2_TID(an, tidno);
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if (!(txtid->state & (AGGR_ADDBA_COMPLETE | AGGR_ADDBA_PROGRESS)))
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return true;
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return false;
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return !txtid->active;
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}
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@ -125,24 +125,6 @@ static void ath_tx_queue_tid(struct ath_txq *txq, struct ath_atx_tid *tid)
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list_add_tail(&ac->list, &txq->axq_acq);
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}
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static void ath_tx_resume_tid(struct ath_softc *sc, struct ath_atx_tid *tid)
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{
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struct ath_txq *txq = tid->ac->txq;
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WARN_ON(!tid->paused);
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ath_txq_lock(sc, txq);
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tid->paused = false;
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if (skb_queue_empty(&tid->buf_q))
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goto unlock;
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ath_tx_queue_tid(txq, tid);
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ath_txq_schedule(sc, txq);
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unlock:
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ath_txq_unlock_complete(sc, txq);
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}
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static struct ath_frame_info *get_frame_info(struct sk_buff *skb)
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{
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struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
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@ -164,20 +146,7 @@ static void ath_set_rates(struct ieee80211_vif *vif, struct ieee80211_sta *sta,
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ARRAY_SIZE(bf->rates));
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}
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static void ath_tx_clear_tid(struct ath_softc *sc, struct ath_atx_tid *tid)
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{
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tid->state &= ~AGGR_ADDBA_COMPLETE;
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tid->state &= ~AGGR_CLEANUP;
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if (!tid->stop_cb)
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return;
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ieee80211_start_tx_ba_cb_irqsafe(tid->an->vif, tid->an->sta->addr,
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tid->tidno);
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tid->stop_cb = false;
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}
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static void ath_tx_flush_tid(struct ath_softc *sc, struct ath_atx_tid *tid,
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bool flush_packets)
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static void ath_tx_flush_tid(struct ath_softc *sc, struct ath_atx_tid *tid)
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{
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struct ath_txq *txq = tid->ac->txq;
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struct sk_buff *skb;
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@ -194,15 +163,16 @@ static void ath_tx_flush_tid(struct ath_softc *sc, struct ath_atx_tid *tid,
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while ((skb = __skb_dequeue(&tid->buf_q))) {
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fi = get_frame_info(skb);
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bf = fi->bf;
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if (!bf && !flush_packets)
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bf = ath_tx_setup_buffer(sc, txq, tid, skb);
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if (!bf) {
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ieee80211_free_txskb(sc->hw, skb);
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continue;
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bf = ath_tx_setup_buffer(sc, txq, tid, skb);
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if (!bf) {
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ieee80211_free_txskb(sc->hw, skb);
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continue;
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}
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}
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if (fi->retries || flush_packets) {
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if (fi->retries) {
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list_add_tail(&bf->list, &bf_head);
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ath_tx_update_baw(sc, tid, bf->bf_state.seqno);
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ath_tx_complete_buf(sc, bf, txq, &bf_head, &ts, 0);
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@ -213,10 +183,7 @@ static void ath_tx_flush_tid(struct ath_softc *sc, struct ath_atx_tid *tid,
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}
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}
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if (tid->baw_head == tid->baw_tail)
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ath_tx_clear_tid(sc, tid);
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if (sendbar && !flush_packets) {
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if (sendbar) {
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ath_txq_unlock(sc, txq);
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ath_send_bar(tid, tid->seq_start);
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ath_txq_lock(sc, txq);
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@ -499,19 +466,19 @@ static void ath_tx_complete_aggr(struct ath_softc *sc, struct ath_txq *txq,
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tx_info = IEEE80211_SKB_CB(skb);
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fi = get_frame_info(skb);
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if (ATH_BA_ISSET(ba, ATH_BA_INDEX(seq_st, seqno))) {
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if (!BAW_WITHIN(tid->seq_start, tid->baw_size, seqno)) {
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/*
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* Outside of the current BlockAck window,
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* maybe part of a previous session
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*/
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txfail = 1;
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} else if (ATH_BA_ISSET(ba, ATH_BA_INDEX(seq_st, seqno))) {
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/* transmit completion, subframe is
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* acked by block ack */
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acked_cnt++;
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} else if (!isaggr && txok) {
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/* transmit completion */
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acked_cnt++;
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} else if (tid->state & AGGR_CLEANUP) {
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/*
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* cleanup in progress, just fail
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* the un-acked sub-frames
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*/
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txfail = 1;
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} else if (flush) {
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txpending = 1;
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} else if (fi->retries < ATH_MAX_SW_RETRIES) {
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@ -535,7 +502,7 @@ static void ath_tx_complete_aggr(struct ath_softc *sc, struct ath_txq *txq,
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if (bf_next != NULL || !bf_last->bf_stale)
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list_move_tail(&bf->list, &bf_head);
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if (!txpending || (tid->state & AGGR_CLEANUP)) {
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if (!txpending) {
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/*
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* complete the acked-ones/xretried ones; update
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* block-ack window
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@ -609,9 +576,6 @@ static void ath_tx_complete_aggr(struct ath_softc *sc, struct ath_txq *txq,
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ath_txq_lock(sc, txq);
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}
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if (tid->state & AGGR_CLEANUP)
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ath_tx_flush_tid(sc, tid, false);
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rcu_read_unlock();
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if (needreset)
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@ -1244,9 +1208,6 @@ int ath_tx_aggr_start(struct ath_softc *sc, struct ieee80211_sta *sta,
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an = (struct ath_node *)sta->drv_priv;
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txtid = ATH_AN_2_TID(an, tid);
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if (txtid->state & (AGGR_CLEANUP | AGGR_ADDBA_COMPLETE))
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return -EAGAIN;
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/* update ampdu factor/density, they may have changed. This may happen
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* in HT IBSS when a beacon with HT-info is received after the station
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* has already been added.
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an->mpdudensity = density;
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}
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txtid->state |= AGGR_ADDBA_PROGRESS;
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txtid->active = true;
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txtid->paused = true;
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*ssn = txtid->seq_start = txtid->seq_next;
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txtid->bar_index = -1;
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return 0;
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}
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bool ath_tx_aggr_stop(struct ath_softc *sc, struct ieee80211_sta *sta, u16 tid,
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bool flush)
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void ath_tx_aggr_stop(struct ath_softc *sc, struct ieee80211_sta *sta, u16 tid)
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{
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struct ath_node *an = (struct ath_node *)sta->drv_priv;
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struct ath_atx_tid *txtid = ATH_AN_2_TID(an, tid);
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struct ath_txq *txq = txtid->ac->txq;
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bool ret = !flush;
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if (flush)
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txtid->stop_cb = false;
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if (txtid->state & AGGR_CLEANUP)
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return false;
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if (!(txtid->state & AGGR_ADDBA_COMPLETE)) {
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txtid->state &= ~AGGR_ADDBA_PROGRESS;
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return ret;
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}
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ath_txq_lock(sc, txq);
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txtid->active = false;
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txtid->paused = true;
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/*
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* If frames are still being transmitted for this TID, they will be
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* cleaned up during tx completion. To prevent race conditions, this
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* TID can only be reused after all in-progress subframes have been
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* completed.
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*/
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if (txtid->baw_head != txtid->baw_tail) {
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txtid->state |= AGGR_CLEANUP;
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ret = false;
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txtid->stop_cb = !flush;
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} else {
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txtid->state &= ~AGGR_ADDBA_COMPLETE;
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}
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ath_tx_flush_tid(sc, txtid, flush);
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ath_tx_flush_tid(sc, txtid);
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ath_txq_unlock_complete(sc, txq);
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return ret;
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}
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void ath_tx_aggr_sleep(struct ieee80211_sta *sta, struct ath_softc *sc,
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}
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}
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void ath_tx_aggr_resume(struct ath_softc *sc, struct ieee80211_sta *sta, u16 tid)
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void ath_tx_aggr_resume(struct ath_softc *sc, struct ieee80211_sta *sta,
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u16 tidno)
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{
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struct ath_atx_tid *txtid;
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struct ath_atx_tid *tid;
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struct ath_node *an;
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struct ath_txq *txq;
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an = (struct ath_node *)sta->drv_priv;
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tid = ATH_AN_2_TID(an, tidno);
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txq = tid->ac->txq;
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txtid = ATH_AN_2_TID(an, tid);
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txtid->baw_size = IEEE80211_MIN_AMPDU_BUF << sta->ht_cap.ampdu_factor;
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txtid->state |= AGGR_ADDBA_COMPLETE;
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txtid->state &= ~AGGR_ADDBA_PROGRESS;
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ath_tx_resume_tid(sc, txtid);
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ath_txq_lock(sc, txq);
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tid->baw_size = IEEE80211_MIN_AMPDU_BUF << sta->ht_cap.ampdu_factor;
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tid->paused = false;
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if (!skb_queue_empty(&tid->buf_q)) {
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ath_tx_queue_tid(txq, tid);
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ath_txq_schedule(sc, txq);
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}
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ath_txq_unlock_complete(sc, txq);
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}
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/********************/
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@ -2431,13 +2374,10 @@ void ath_tx_node_init(struct ath_softc *sc, struct ath_node *an)
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tid->baw_head = tid->baw_tail = 0;
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tid->sched = false;
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tid->paused = false;
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tid->state &= ~AGGR_CLEANUP;
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tid->active = false;
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__skb_queue_head_init(&tid->buf_q);
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acno = TID_TO_WME_AC(tidno);
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tid->ac = &an->ac[acno];
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tid->state &= ~AGGR_ADDBA_COMPLETE;
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tid->state &= ~AGGR_ADDBA_PROGRESS;
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tid->stop_cb = false;
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}
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for (acno = 0, ac = &an->ac[acno];
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}
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ath_tid_drain(sc, txq, tid);
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ath_tx_clear_tid(sc, tid);
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tid->active = false;
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ath_txq_unlock(sc, txq);
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}
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