package/kernel/mac80211/patches/subsys/355-mac80211-run-late-dequeue-late-tx-handlers-without-h.patch

   1 From: Felix Fietkau <nbd@nbd.name>
   2 Date: Sat, 16 Mar 2019 18:00:12 +0100
   3 Subject: [PATCH] mac80211: run late dequeue late tx handlers without
   4  holding fq->lock
   5
   6 Reduces lock contention on enqueue/dequeue of iTXQ packets
   7
   8 Signed-off-by: Felix Fietkau <nbd@nbd.name>
   9 ---
  10
  11 --- a/net/mac80211/tx.c
  12 +++ b/net/mac80211/tx.c
  13 @@ -3538,6 +3538,7 @@ struct sk_buff *ieee80211_tx_dequeue(str
  14         ieee80211_tx_result r;
  15         struct ieee80211_vif *vif = txq->vif;
  16
  17 +begin:
  18         spin_lock_bh(&fq->lock);
  19
  20         if (test_bit(IEEE80211_TXQ_STOP, &txqi->flags) ||
  21 @@ -3554,11 +3555,12 @@ struct sk_buff *ieee80211_tx_dequeue(str
  22         if (skb)
  23                 goto out;
  24
  25 -begin:
  26         skb = fq_tin_dequeue(fq, tin, fq_tin_dequeue_func);
  27         if (!skb)
  28                 goto out;
  29
  30 +       spin_unlock_bh(&fq->lock);
  31 +
  32         hdr = (struct ieee80211_hdr *)skb->data;
  33         info = IEEE80211_SKB_CB(skb);
  34
  35 @@ -3622,8 +3624,11 @@ begin:
  36
  37                 skb = __skb_dequeue(&tx.skbs);
  38
  39 -               if (!skb_queue_empty(&tx.skbs))
  40 +               if (!skb_queue_empty(&tx.skbs)) {
  41 +                       spin_lock_bh(&fq->lock);
  42                         skb_queue_splice_tail(&tx.skbs, &txqi->frags);
  43 +                       spin_unlock_bh(&fq->lock);
  44 +               }
  45         }
  46
  47         if (skb && skb_has_frag_list(skb) &&
  48 @@ -3662,6 +3667,7 @@ begin:
  49         }
  50
  51         IEEE80211_SKB_CB(skb)->control.vif = vif;
  52 +       return skb;
  53
  54  out:
  55         spin_unlock_bh(&fq->lock);