Re: [PATCH][net-next] gianfar: Fix reported sent bytes to BQL for Tx timestamping

[Eric Dumazet <eric.dumazet@gmail.com>]

On Mon, 2013-04-29 at 08:28 -0700, Eric Dumazet wrote:

> If at tx completion skb->len might be different, then store the true
> skb->len in skb->cb[]

Something like :

diff --git a/drivers/net/ethernet/freescale/gianfar.c
b/drivers/net/ethernet/freescale/gianfar.c
index 2375a01..5cd306f 100644
--- a/drivers/net/ethernet/freescale/gianfar.c
+++ b/drivers/net/ethernet/freescale/gianfar.c
@@ -2065,6 +2065,7 @@ static int gfar_start_xmit(struct sk_buff *skb,
struct net_device *dev)
 	u32 bufaddr;
 	unsigned long flags;
 	unsigned int nr_frags, nr_txbds, length, fcb_length = GMAC_FCB_LEN;
+	unsigned int len;
 
 	/* TOE=1 frames larger than 2500 bytes may see excess delays
 	 * before start of transmission.
@@ -2130,7 +2131,9 @@ static int gfar_start_xmit(struct sk_buff *skb,
struct net_device *dev)
 	}
 
 	/* Update transmit stats */
-	tx_queue->stats.tx_bytes += skb->len;
+	len = skb->len;
+	*(unsigned int)skb->cb = len;
+	tx_queue->stats.tx_bytes += len;
 	tx_queue->stats.tx_packets++;
 
 	txbdp = txbdp_start = tx_queue->cur_tx;
@@ -2231,7 +2234,7 @@ static int gfar_start_xmit(struct sk_buff *skb,
struct net_device *dev)
 		lstatus |= BD_LFLAG(TXBD_CRC | TXBD_READY) | skb_headlen(skb);
 	}
 
-	netdev_tx_sent_queue(txq, skb->len);
+	netdev_tx_sent_queue(txq, len);
 
 	/* We can work in parallel with gfar_clean_tx_ring(), except
 	 * when modifying num_txbdfree. Note that we didn't grab the lock
@@ -2551,7 +2554,7 @@ static void gfar_clean_tx_ring(struct
gfar_priv_tx_q *tx_queue)
 			bdp = next_txbd(bdp, base, tx_ring_size);
 		}
 
-		bytes_sent += skb->len;
+		bytes_sent += *(unsigned int)skb->cb;
 
 		dev_kfree_skb_any(skb);