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Date: Tue, 2 Nov 2010 19:20:16 +0100
Message-ID: <AANLkTikUUue=Nt0iFPcQC68kDCh=EeEpeBT9xnhW6bf+@mail.gmail.com>
Subject: Re: [ath9k-devel] [RFC] ath9k: fix tx queue selection
From: =?ISO-8859-1?Q?Bj=F6rn_Smedman?= <bjorn.smedman@venatech.se>
To: Felix Fietkau <nbd@openwrt.org>
Cc: ath9k-devel@lists.ath9k.org,
	linux-wireless <linux-wireless@vger.kernel.org>
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2010/11/2 Felix Fietkau <nbd@openwrt.org>:
> + ? ? ? q = ath_get_mac80211_qnum(txq->axq_class, sc);
> ? ? ? ?r = ath_tx_setup_buffer(hw, bf, skb, txctl);
> ? ? ? ?if (unlikely(r)) {
> ? ? ? ? ? ? ? ?ath_print(common, ATH_DBG_FATAL, "TX mem alloc failure\n");
> @@ -1756,8 +1757,8 @@ int ath_tx_start(struct ieee80211_hw *hw
> ? ? ? ? ? ? ? ? * we will at least have to run TX completionon one buffer
> ? ? ? ? ? ? ? ? * on the queue */
> ? ? ? ? ? ? ? ?spin_lock_bh(&txq->axq_lock);
> - ? ? ? ? ? ? ? if (!txq->stopped && txq->axq_depth > 1) {
> - ? ? ? ? ? ? ? ? ? ? ? ath_mac80211_stop_queue(sc, skb_get_queue_mapping(skb));
> + ? ? ? ? ? ? ? if (q >= 0 && !txq->stopped && txq->axq_depth > 1) {
> + ? ? ? ? ? ? ? ? ? ? ? ath_mac80211_stop_queue(sc, q);
> ? ? ? ? ? ? ? ? ? ? ? ?txq->stopped = 1;
> ? ? ? ? ? ? ? ?}

You cannot be sure that you are stopping the queue that the skb
actually came in on here since mac80211 queues are mapped to hw queues
by ath_get_hal_qnum() and that mapping is not reversible (due to the
default statement):

static int ath_get_hal_qnum(u16 queue, struct ath_softc *sc)
{
        int qnum;

        switch (queue) {
        case 0:
                qnum = sc->tx.hwq_map[WME_AC_VO];
                break;
        case 1:
                qnum = sc->tx.hwq_map[WME_AC_VI];
                break;
        case 2:
                qnum = sc->tx.hwq_map[WME_AC_BE];
                break;
        case 3:
                qnum = sc->tx.hwq_map[WME_AC_BK];
                break;
        default:
                qnum = sc->tx.hwq_map[WME_AC_BE];
                break;
        }

        return qnum;
}

/Bj?rn