mac80211: fix aggregation for hardware with ampdu queues

Hardware with AMPDU queues currently has broken aggregation.

This patch fixes it by making all A-MPDUs go over the regular AC queues,
but keeping track of the hardware queues in mac80211. As a first rough
version, it actually stops the AC queue for extended periods of time,
which can be removed by adding buffering internal to mac80211, but is
currently not a huge problem because people rarely use multiple TIDs
that are in the same AC (and iwlwifi currently doesn't operate as AP).

This is a short-term fix, my current medium-term plan, which I hope to
execute soon as well, but am not sure can finish before .30, looks like
this:
 1) rework the internal queuing layer in mac80211 that we use for
    fragments if the driver stopped queue in the middle of a fragmented
    frame to be able to queue more frames at once (rather than just a
    single frame with its fragments)
 2) instead of stopping the entire AC queue, queue up the frames in a
    per-station/per-TID queue during aggregation session initiation,
    when the session has come up take all those frames and put them
    onto the queue from 1)
 3) push the ampdu queue layer abstraction this patch introduces in
    mac80211 into the driver, and remove the virtual queue stuff from
    mac80211 again

This plan will probably also affect ath9k in that mac80211 queues the
frames instead of passing them down, even when there are no ampdu queues.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 4 insertions, 157 deletions

diff --git a/net/mac80211/wme.c b/net/mac80211/wme.c
index ac71b38f7cb5..093a4ab7f28b 100644
--- a/net/mac80211/wme.c
+++ b/net/mac80211/wme.c
@@ -114,9 +114,7 @@ u16 ieee80211_select_queue(struct net_device *dev, struct sk_buff *skb)
 {
         struct ieee80211_master_priv *mpriv = netdev_priv(dev);
         struct ieee80211_local *local = mpriv->local;
-        struct ieee80211_hw *hw = &local->hw;
         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
-        struct sta_info *sta;
         u16 queue;
         u8 tid;
 
@@ -124,29 +122,11 @@ u16 ieee80211_select_queue(struct net_device *dev, struct sk_buff *skb)
         if (unlikely(queue >= local->hw.queues))
                 queue = local->hw.queues - 1;
 
-        if (skb->requeue) {
-                if (!hw->ampdu_queues)
-                        return queue;
-
-                rcu_read_lock();
-                sta = sta_info_get(local, hdr->addr1);
-                tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;
-                if (sta) {
-                        int ampdu_queue = sta->tid_to_tx_q[tid];
-
-                        if ((ampdu_queue < ieee80211_num_queues(hw)) &&
-                            test_bit(ampdu_queue, local->queue_pool))
-                                queue = ampdu_queue;
-                }
-                rcu_read_unlock();
-
-                return queue;
-        }
-
-        /* Now we know the 1d priority, fill in the QoS header if
-         * there is one.
+        /*
+         * Now we know the 1d priority, fill in the QoS header if
+         * there is one (and we haven't done this before).
          */
-        if (ieee80211_is_data_qos(hdr->frame_control)) {
+        if (!skb->requeue && ieee80211_is_data_qos(hdr->frame_control)) {
                 u8 *p = ieee80211_get_qos_ctl(hdr);
                 u8 ack_policy = 0;
                 tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;
@@ -156,140 +136,7 @@ u16 ieee80211_select_queue(struct net_device *dev, struct sk_buff *skb)
                 /* qos header is 2 bytes, second reserved */
                 *p++ = ack_policy | tid;
                 *p = 0;
-
-                if (!hw->ampdu_queues)
-                        return queue;
-
-                rcu_read_lock();
-
-                sta = sta_info_get(local, hdr->addr1);
-                if (sta) {
-                        int ampdu_queue = sta->tid_to_tx_q[tid];
-
-                        if ((ampdu_queue < ieee80211_num_queues(hw)) &&
-                            test_bit(ampdu_queue, local->queue_pool))
-                                queue = ampdu_queue;
-                }
-
-                rcu_read_unlock();
         }
 
         return queue;
 }
-
-int ieee80211_ht_agg_queue_add(struct ieee80211_local *local,
-                               struct sta_info *sta, u16 tid)
-{
-        int i;
-
-        /* XXX: currently broken due to cb/requeue use */
-        return -EPERM;
-
-        /* prepare the filter and save it for the SW queue
-         * matching the received HW queue */
-
-        if (!local->hw.ampdu_queues)
-                return -EPERM;
-
-        /* try to get a Qdisc from the pool */
-        for (i = local->hw.queues; i < ieee80211_num_queues(&local->hw); i++)
-                if (!test_and_set_bit(i, local->queue_pool)) {
-                        ieee80211_stop_queue(local_to_hw(local), i);
-                        sta->tid_to_tx_q[tid] = i;
-
-                        /* IF there are already pending packets
-                         * on this tid first we need to drain them
-                         * on the previous queue
-                         * since HT is strict in order */
-#ifdef CONFIG_MAC80211_HT_DEBUG
-                        if (net_ratelimit())
-                                printk(KERN_DEBUG "allocated aggregation queue"
-                                        " %d tid %d addr %pM pool=0x%lX\n",
-                                        i, tid, sta->sta.addr,
-                                        local->queue_pool[0]);
-#endif /* CONFIG_MAC80211_HT_DEBUG */
-                        return 0;
-                }
-
-        return -EAGAIN;
-}
-
-/**
- * the caller needs to hold netdev_get_tx_queue(local->mdev, X)->lock
- */
-void ieee80211_ht_agg_queue_remove(struct ieee80211_local *local,
-                                   struct sta_info *sta, u16 tid,
-                                   u8 requeue)
-{
-        int agg_queue = sta->tid_to_tx_q[tid];
-        struct ieee80211_hw *hw = &local->hw;
-
-        /* return the qdisc to the pool */
-        clear_bit(agg_queue, local->queue_pool);
-        sta->tid_to_tx_q[tid] = ieee80211_num_queues(hw);
-
-        if (requeue) {
-                ieee80211_requeue(local, agg_queue);
-        } else {
-                struct netdev_queue *txq;
-                spinlock_t *root_lock;
-                struct Qdisc *q;
-
-                txq = netdev_get_tx_queue(local->mdev, agg_queue);
-                q = rcu_dereference(txq->qdisc);
-                root_lock = qdisc_lock(q);
-
-                spin_lock_bh(root_lock);
-                qdisc_reset(q);
-                spin_unlock_bh(root_lock);
-        }
-}
-
-void ieee80211_requeue(struct ieee80211_local *local, int queue)
-{
-        struct netdev_queue *txq = netdev_get_tx_queue(local->mdev, queue);
-        struct sk_buff_head list;
-        spinlock_t *root_lock;
-        struct Qdisc *qdisc;
-        u32 len;
-
-        rcu_read_lock_bh();
-
-        qdisc = rcu_dereference(txq->qdisc);
-        if (!qdisc || !qdisc->dequeue)
-                goto out_unlock;
-
-        skb_queue_head_init(&list);
-
-        root_lock = qdisc_root_lock(qdisc);
-        spin_lock(root_lock);
-        for (len = qdisc->q.qlen; len > 0; len--) {
-                struct sk_buff *skb = qdisc->dequeue(qdisc);
-
-                if (skb)
-                        __skb_queue_tail(&list, skb);
-        }
-        spin_unlock(root_lock);
-
-        for (len = list.qlen; len > 0; len--) {
-                struct sk_buff *skb = __skb_dequeue(&list);
-                u16 new_queue;
-
-                BUG_ON(!skb);
-                new_queue = ieee80211_select_queue(local->mdev, skb);
-                skb_set_queue_mapping(skb, new_queue);
-
-                txq = netdev_get_tx_queue(local->mdev, new_queue);
-
-
-                qdisc = rcu_dereference(txq->qdisc);
-                root_lock = qdisc_root_lock(qdisc);
-
-                spin_lock(root_lock);
-                qdisc_enqueue_root(skb, qdisc);
-                spin_unlock(root_lock);
-        }
-
-out_unlock:
-        rcu_read_unlock_bh();
-}