[PATCH 4.4 40/45] ibmveth: calculate gso_segs for large packets

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Falcon <tlfalcon@xxxxxxxxxxxxxxxxxx>

commit 94acf164dc8f1184e8d0737be7125134c2701dbe upstream.

Include calculations to compute the number of segments
that comprise an aggregated large packet.

Signed-off-by: Thomas Falcon <tlfalcon@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>
Reviewed-by: Jonathan Maxwell <jmaxwell37@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/net/ethernet/ibm/ibmveth.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/ibm/ibmveth.c
+++ b/drivers/net/ethernet/ibm/ibmveth.c
@@ -1179,7 +1179,9 @@ map_failed:
 
 static void ibmveth_rx_mss_helper(struct sk_buff *skb, u16 mss, int lrg_pkt)
 {
+	struct tcphdr *tcph;
 	int offset = 0;
+	int hdr_len;
 
 	/* only TCP packets will be aggregated */
 	if (skb->protocol == htons(ETH_P_IP)) {
@@ -1206,14 +1208,20 @@ static void ibmveth_rx_mss_helper(struct
 	/* if mss is not set through Large Packet bit/mss in rx buffer,
 	 * expect that the mss will be written to the tcp header checksum.
 	 */
+	tcph = (struct tcphdr *)(skb->data + offset);
 	if (lrg_pkt) {
 		skb_shinfo(skb)->gso_size = mss;
 	} else if (offset) {
-		struct tcphdr *tcph = (struct tcphdr *)(skb->data + offset);
-
 		skb_shinfo(skb)->gso_size = ntohs(tcph->check);
 		tcph->check = 0;
 	}
+
+	if (skb_shinfo(skb)->gso_size) {
+		hdr_len = offset + tcph->doff * 4;
+		skb_shinfo(skb)->gso_segs =
+				DIV_ROUND_UP(skb->len - hdr_len,
+					     skb_shinfo(skb)->gso_size);
+	}
 }
 
 static int ibmveth_poll(struct napi_struct *napi, int budget)