ath10k: use msdu headroom to store txfrag

Instead of allocating sk_buff for a mere 16-byte
tx fragment list buffer use headroom of the
original msdu sk_buff.

This decreases CPU cache pressure and improves
performance.

Measured improvement on AP135 is 560mbps ->
590mbps of UDP TX briding traffic.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

1 files changed, 6 insertions, 10 deletions

diff --git a/drivers/net/wireless/ath/ath10k/txrx.c b/drivers/net/wireless/ath/ath10k/txrx.c
index 15395afae957..57931d0fae4b 100644
--- a/drivers/net/wireless/ath/ath10k/txrx.c
+++ b/drivers/net/wireless/ath/ath10k/txrx.c
@@ -49,7 +49,8 @@ void ath10k_txrx_tx_unref(struct ath10k_htt *htt,
 {
         struct device *dev = htt->ar->dev;
         struct ieee80211_tx_info *info;
-        struct sk_buff *msdu, *txfrag;
+        struct ath10k_skb_cb *skb_cb;
+        struct sk_buff *msdu;
         int ret;
 
         ath10k_dbg(ATH10K_DBG_HTT, "htt tx completion msdu_id %u discard %d no_ack %d\n",
@@ -62,20 +63,15 @@ void ath10k_txrx_tx_unref(struct ath10k_htt *htt,
         }
 
         msdu = htt->pending_tx[tx_done->msdu_id];
-        txfrag = ATH10K_SKB_CB(msdu)->htt.txfrag;
-
-        if (txfrag) {
-                ret = ath10k_skb_unmap(dev, txfrag);
-                if (ret)
-                        ath10k_warn("txfrag unmap failed (%d)\n", ret);
-
-                dev_kfree_skb_any(txfrag);
-        }
+        skb_cb = ATH10K_SKB_CB(msdu);
 
         ret = ath10k_skb_unmap(dev, msdu);
         if (ret)
                 ath10k_warn("data skb unmap failed (%d)\n", ret);
 
+        if (skb_cb->htt.frag_len)
+                skb_pull(msdu, skb_cb->htt.frag_len + skb_cb->htt.pad_len);
+
         ath10k_report_offchan_tx(htt->ar, msdu);
 
         info = IEEE80211_SKB_CB(msdu);