Re: [PATCH v5] mac80211: Move reorder-sensitive TX handlers to after TXQ dequeue.

[Jason Andryuk <jandryuk@xxxxxxxxx>]

On Thu, Sep 1, 2016 at 12:03 PM, Toke Høiland-Jørgensen <toke@xxxxxxx> wrote:
> @@ -1481,33 +1506,57 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw,
>  {
>         struct ieee80211_local *local = hw_to_local(hw);
>         struct txq_info *txqi = container_of(txq, struct txq_info, txq);
> -       struct ieee80211_hdr *hdr;
>         struct sk_buff *skb = NULL;
>         struct fq *fq = &local->fq;
>         struct fq_tin *tin = &txqi->tin;
> +       struct ieee80211_tx_info *info;
>
>         spin_lock_bh(&fq->lock);
>
>         if (test_bit(IEEE80211_TXQ_STOP, &txqi->flags))
>                 goto out;
>
> +begin:
>         skb = fq_tin_dequeue(fq, tin, fq_tin_dequeue_func);
>         if (!skb)
>                 goto out;
>
>         ieee80211_set_skb_vif(skb, txqi);
>
> -       hdr = (struct ieee80211_hdr *)skb->data;
> -       if (txq->sta && ieee80211_is_data_qos(hdr->frame_control)) {
> +       info = IEEE80211_SKB_CB(skb);
> +       if (txq->sta && info->control.flags & IEEE80211_TX_CTRL_FAST_XMIT) {
>                 struct sta_info *sta = container_of(txq->sta, struct sta_info,
>                                                     sta);
> -               struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
> +               struct ieee80211_fast_tx *fast_tx;
>
> -               hdr->seq_ctrl = ieee80211_tx_next_seq(sta, txq->tid);
> -               if (test_bit(IEEE80211_TXQ_AMPDU, &txqi->flags))
> -                       info->flags |= IEEE80211_TX_CTL_AMPDU;
> -               else
> -                       info->flags &= ~IEEE80211_TX_CTL_AMPDU;
> +               fast_tx = rcu_dereference(sta->fast_tx);
> +               if (WARN_ON(!fast_tx)) {
> +                       /* lost the fast_tx pointer while the packet was queued */
> +                       ieee80211_free_txskb(hw, skb);
> +                       goto begin;
> +               }
> +               ieee80211_xmit_fast_finish(sta->sdata, sta, fast_tx, skb, false);
> +       } else {
> +               struct ieee80211_tx_data tx = { };
> +
> +               __skb_queue_head_init(&tx.skbs);
> +               tx.local = local;
> +               if (txq->sta) {
> +                       struct sta_info *sta = container_of(txq->sta,
> +                                                           struct sta_info,
> +                                                           sta);

sta is unneeded give the assignment below?

Regards,
Jason

> +                       tx.sta = container_of(txq->sta, struct sta_info, sta);
> +                       tx.sdata = sta->sdata;
> +               } else {
> +                       tx.sdata = vif_to_sdata(info->control.vif);
> +               }
> +
> +               __skb_queue_tail(&tx.skbs, skb);
> +
> +               if (invoke_tx_handlers_late(&tx))
> +                       goto begin;
> +
> +               __skb_unlink(skb, &tx.skbs);
>         }