From 0ace285605314c54339710484b54814945a60df8 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ilpo=20J=C3=A4rvinen?= Date: Mon, 24 Nov 2008 21:30:21 -0800 Subject: [PATCH] tcp: handle shift/merge of cloned skbs too MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit This caused me to get repeatably: tcpdump: pcap_loop: recvfrom: Bad address Happens occassionally when I tcpdump my for-looped test xfers: while [ : ]; do echo -n "$(date '+%s.%N') "; ./sendfile; sleep 20; done Rest of the relevant commands: ethtool -K eth0 tso off tc qdisc add dev eth0 root netem drop 4% tcpdump -n -s0 -i eth0 -w sacklog.all Running net-next under kvm, connection goes to the same host (basically just out of kvm). The connection itself works ok and data gets sent without corruption even with a large number of tests while tcpdump fails usually within less than 5 tests. Whether it only happens because of this change or not, I don't know for sure but it's the only thing with which I've seen that error. The non-cloned variant works w/o it for much longer time. I'm yet to debug where the error actually comes from. Signed-off-by: Ilpo Järvinen Signed-off-by: David S. Miller --- net/core/skbuff.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 844b8abeb18c..57555a4525da 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -2018,13 +2018,10 @@ void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len) skb_split_no_header(skb, skb1, len, pos); } -/* Shifting from/to a cloned skb is a no-go. - * - * TODO: handle cloned skbs by using pskb_expand_head() - */ +/* Shifting from/to a cloned skb is a no-go. */ static int skb_prepare_for_shift(struct sk_buff *skb) { - return skb_cloned(skb); + return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC); } /** -- 2.30.2