ar71xx: ethernet: cache skb->len in the tx function to avoid accessing it again in completion

Improves ethernet performance, especially during bridging

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@37761 3c298f89-4303-0410-b956-a3cf2f4a3e73

2 files changed, 10 insertions, 5 deletions

diff --git a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx.h b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx.h
index b9d95adaf6..6d51e722b0 100644
--- a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx.h
+++ b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx.h
@@ -91,8 +91,11 @@ struct ag71xx_buf {
 		void		*rx_buf;
 	};
 	struct ag71xx_desc	*desc;
-	dma_addr_t		dma_addr;
-	unsigned long		timestamp;
+	union {
+		dma_addr_t	dma_addr;
+		unsigned long	timestamp;
+	};
+	unsigned int		len;
 };
 
 struct ag71xx_ring {
diff --git a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c
index 93071690e8..fc6be0e001 100644
--- a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c
+++ b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c
@@ -145,7 +145,7 @@ static void ag71xx_ring_tx_clean(struct ag71xx *ag)
 		}
 
 		if (ring->buf[i].skb) {
-			bytes_compl += ring->buf[i].skb->len;
+			bytes_compl += ring->buf[i].len;
 			pkts_compl++;
 			dev_kfree_skb_any(ring->buf[i].skb);
 		}
@@ -684,6 +684,7 @@ static netdev_tx_t ag71xx_hard_start_xmit(struct sk_buff *skb,
 				  DMA_TO_DEVICE);
 
 	netdev_sent_queue(dev, skb->len);
+	ring->buf[i].len = skb->len;
 	ring->buf[i].skb = skb;
 	ring->buf[i].timestamp = jiffies;
 
@@ -824,6 +825,7 @@ static int ag71xx_tx_packets(struct ag71xx *ag)
 		unsigned int i = ring->dirty % ring->size;
 		struct ag71xx_desc *desc = ring->buf[i].desc;
 		struct sk_buff *skb = ring->buf[i].skb;
+		int len = ring->buf[i].len;
 
 		if (!ag71xx_desc_empty(desc)) {
 			if (pdata->is_ar7240 &&
@@ -834,8 +836,8 @@ static int ag71xx_tx_packets(struct ag71xx *ag)
 
 		ag71xx_wr(ag, AG71XX_REG_TX_STATUS, TX_STATUS_PS);
 
-		bytes_compl += skb->len;
-		ag->dev->stats.tx_bytes += skb->len;
+		bytes_compl += len;
+		ag->dev->stats.tx_bytes += len;
 		ag->dev->stats.tx_packets++;
 
 		dev_kfree_skb_any(skb);