Xen devel - Jan 2009 - [PATCH] netfront/back: do not mark packets of length < MSS as GSO

# HG changeset patch
# User Ian Campbell <ian.campbell@citrix.com>
# Date 1231847296 0
# Node ID 5b29f1081b2061cf56fa57ed67fef25cc1426a57
# Parent  28acedb66302a29c9ef14a3084b4736d3fc192f1
netfront/back: do not mark packets of length < MSS as GSO

Linux assumes that skbs marked for GSO are longer than MSS. In
particular tcp_tso_segment assumes that skb_segment will return a
chain of at least 2 skbs.

Both netfront and back should therefor not pass such a packet up the
stack.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>

diff -r 28acedb66302 -r 5b29f1081b20 drivers/xen/netback/netback.c
--- a/drivers/xen/netback/netback.c	Wed Jan 07 12:21:54 2009 +0900
+++ b/drivers/xen/netback/netback.c	Tue Jan 13 11:48:16 2009 +0000
@@ -1345,6 +1345,9 @@ static void net_tx_action(unsigned long 
 			skb_shinfo(skb)->frags[0].page = (void *)~0UL;
 		}
 
+		if (skb->data_len < skb_shinfo(skb)->gso_size)
+			skb_shinfo(skb)->gso_size = 0;
+
 		__skb_queue_tail(&tx_queue, skb);
 
 		pending_cons++;
diff -r 28acedb66302 -r 5b29f1081b20 drivers/xen/netfront/netfront.c
--- a/drivers/xen/netfront/netfront.c	Wed Jan 07 12:21:54 2009 +0900
+++ b/drivers/xen/netfront/netfront.c	Tue Jan 13 11:48:16 2009 +0000
@@ -1439,6 +1439,10 @@ err:
 		np->stats.rx_packets++;
 		np->stats.rx_bytes += skb->len;
 
+#ifdef HAVE_TSO
+		if (skb->data_len < skb_shinfo(skb)->gso_size)
+			skb_shinfo(skb)->gso_size = 0;
+#endif
 		__skb_queue_tail(&rxq, skb);
 
 		np->rx.rsp_cons = ++i;

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Should clear gso_type too:

changeset:   774:cb5ad51f5206cb2b756ac1c5731ee47f7e3b8273
tag:         tip
user:        Ian Campbell <ian.campbell@citrix.com>
date:        Tue Jan 13 12:50:26 2009 +0000
files:       drivers/xen/netback/netback.c drivers/xen/netfront/netfront.c
description:
netfront/back: do not mark packets of length < MSS as GSO

Linux assumes that skbs marked for GSO are longer than MSS. In
particular tcp_tso_segment assumes that skb_segment will return a
chain of at least 2 skbs.

Both netfront and back should therefor not pass such a packet up the
stack.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>


diff -r 28acedb66302a29c9ef14a3084b4736d3fc192f1 -r
cb5ad51f5206cb2b756ac1c5731ee47f7e3b8273 drivers/xen/netback/netback.c
--- a/drivers/xen/netback/netback.c	Wed Jan 07 12:21:54 2009 +0900
+++ b/drivers/xen/netback/netback.c	Tue Jan 13 12:50:26 2009 +0000
@@ -1345,6 +1345,11 @@ static void net_tx_action(unsigned long 
 			skb_shinfo(skb)->frags[0].page = (void *)~0UL;
 		}
 
+		if (skb->data_len < skb_shinfo(skb)->gso_size) {
+			skb_shinfo(skb)->gso_size = 0;
+			skb_shinfo(skb)->gso_type = 0;
+		}
+
 		__skb_queue_tail(&tx_queue, skb);
 
 		pending_cons++;
diff -r 28acedb66302a29c9ef14a3084b4736d3fc192f1 -r
cb5ad51f5206cb2b756ac1c5731ee47f7e3b8273 drivers/xen/netfront/netfront.c
--- a/drivers/xen/netfront/netfront.c	Wed Jan 07 12:21:54 2009 +0900
+++ b/drivers/xen/netfront/netfront.c	Tue Jan 13 12:50:26 2009 +0000
@@ -1439,6 +1439,14 @@ err:
 		np->stats.rx_packets++;
 		np->stats.rx_bytes += skb->len;
 
+#if HAVE_TSO
+		if (skb->data_len < skb_shinfo(skb)->gso_size) {
+			skb_shinfo(skb)->gso_size = 0;
+#if HAVE_GSO
+			skb_shinfo(skb)->gso_type = 0;
+#endif
+		}
+#endif
 		__skb_queue_tail(&rxq, skb);
 
 		np->rx.rsp_cons = ++i;



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