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- From: Sujith Manoharan <[email protected]>
- Date: Fri, 17 Oct 2014 07:40:30 +0530
- Subject: [PATCH] ath9k: Do not start BA when scanning
- mac80211 currently has a race which can be hit
- with this sequence:
- * Start a scan operation.
- * TX BA is initiated by ieee80211_start_tx_ba_session().
- * Driver sets up internal state and calls
- ieee80211_start_tx_ba_cb_irqsafe().
- * mac80211 adds a packet to sdata->skb_queue with
- type IEEE80211_SDATA_QUEUE_AGG_START.
- * ieee80211_iface_work() doesn't process the
- packet because scan is in progress.
- * ADDBA response timer expires and the sta/tid is
- torn down.
- * Driver receives BA stop notification and calls
- ieee80211_stop_tx_ba_cb_irqsafe().
- * This is also added to the queue by mac80211.
- * Now, scan finishes.
- At this point, the queued up packets might be processed
- if some other operation schedules the sdata work. Since
- the tids have been cleaned up already, warnings are hit.
- If this doesn't happen, the packets are left in the queue
- until the interface is torn down.
- Since initiating a BA session when scan is in progress
- leads to flaky connections, especially in MCC mode, we
- can drop the TX BA request. This improves connectivity
- with legacy clients in MCC mode.
- Signed-off-by: Sujith Manoharan <[email protected]>
- ---
- --- a/drivers/net/wireless/ath/ath9k/main.c
- +++ b/drivers/net/wireless/ath/ath9k/main.c
- @@ -1885,6 +1885,7 @@ static int ath9k_ampdu_action(struct iee
- u16 tid, u16 *ssn, u8 buf_size)
- {
- struct ath_softc *sc = hw->priv;
- + struct ath_common *common = ath9k_hw_common(sc->sc_ah);
- bool flush = false;
- int ret = 0;
-
- @@ -1896,6 +1897,12 @@ static int ath9k_ampdu_action(struct iee
- case IEEE80211_AMPDU_RX_STOP:
- break;
- case IEEE80211_AMPDU_TX_START:
- + if (ath9k_is_chanctx_enabled()) {
- + if (test_bit(ATH_OP_SCANNING, &common->op_flags)) {
- + ret = -EBUSY;
- + break;
- + }
- + }
- ath9k_ps_wakeup(sc);
- ret = ath_tx_aggr_start(sc, sta, tid, ssn);
- if (!ret)
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