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tg3: fix ipv6 header length computation

This change “tg3: fix ipv6 header length computation” (commit a5a1195) in Linux kernel is authored by Eric Dumazet <eric.dumazet [at]> on Mon Jan 23 01:22:09 2012 +0000.

Description of "tg3: fix ipv6 header length computation"

The change “tg3: fix ipv6 header length computation” introduces changes as follows.

tg3: fix ipv6 header length computation

tg3_start_xmit() makes the wrong assumption for TSOV6 that skb->head
doesnt include any payload data.

if (skb_is_gso_v6(skb))
        hdr_len = skb_headlen(skb) - ETH_HLEN;

This is not true anymore after commit f07d960df3 (tcp: avoid frag
allocation for small frames)

We should instead use : skb_transport_offset(skb) + tcp_hdrlen(skb)

Its also true for IPv4

Signed-off-by: Eric Dumazet <>
CC: Matt Carlson <>
CC: Michael Chan <>
Signed-off-by: David S. Miller <>

Linux kernel releases containing commit a5a1195

The Linux kernel releases containing this commit are as follows.

Linux kernel code changes from "tg3: fix ipv6 header length computation"

There are 9 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/net/ethernet/broadcom/tg3.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)
diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
index d529af99157d..a1f2e0fed78b 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -6667,14 +6667,9 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		iph = ip_hdr(skb);
 		tcp_opt_len = tcp_optlen(skb);
-		if (skb_is_gso_v6(skb)) {
-			hdr_len = skb_headlen(skb) - ETH_HLEN;
-		} else {
-			u32 ip_tcp_len;
-			ip_tcp_len = ip_hdrlen(skb) + sizeof(struct tcphdr);
-			hdr_len = ip_tcp_len + tcp_opt_len;
+		hdr_len = skb_transport_offset(skb) + tcp_hdrlen(skb) - ETH_HLEN;
+		if (!skb_is_gso_v6(skb)) {
 			iph->check = 0;
 			iph->tot_len = htons(mss + hdr_len);

The commit for this change in Linux stable tree is a5a1195 (patch).

Last modified: 2020/02/10