[Cerowrt-devel] [bug #442] tearing apart ath_tx_start in search of the hang

[Robert Bradley]

On 15/04/14 00:08, Dave Taht wrote:
> So what we are seeing here is some sort of problem with accounting
> for pending_frames on a given queue. And since we've had a reminder
> of how useful code review can be - and I'd rather like to understand
> this logic anyway -
>
> // my comments in //
>
> /* Upon failure caller should free skb */
> int ath_tx_start(struct ieee80211_hw *hw, struct sk_buff *skb,
>                  struct ath_tx_control *txctl)
> {
<snip>
> // I haven't looked at what skb_get_queue_mapping can return yet
>
>        q = skb_get_queue_mapping(skb);
>
>         ath_txq_lock(sc, txq);
>         if (txq == sc->tx.txq_map[q] &&
>             ++txq->pending_frames > sc->tx.txq_max_pending[q] &&
>             !txq->stopped) {
>                 ieee80211_stop_queue(sc->hw, q);
>                 txq->stopped = true;
>
> // is there a difference between stopped and sleeping?
>
>         }
>

Not as far as I can tell from the documentation.  I did notice though
that the wakeup code in ath_tx_complete() lacks the
ath_txq_lock()/ath_txq_unlock() calls around it.  I don't know if that
helps or not...

-- 
Robert Bradley