Patch "tcp: gso: fix truesize tracking" has been added to the 3.10-stable tree

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This is a note to let you know that I've just added the patch titled

    tcp: gso: fix truesize tracking

to the 3.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tcp-gso-fix-truesize-tracking.patch
and it can be found in the queue-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 934c8b7de7c0632cf0dbaa5d9c9dcdcdc23cb33c Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Fri, 25 Oct 2013 17:26:17 -0700
Subject: tcp: gso: fix truesize tracking

From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit 0d08c42cf9a71530fef5ebcfe368f38f2dd0476f ]

commit 6ff50cd55545 ("tcp: gso: do not generate out of order packets")
had an heuristic that can trigger a warning in skb_try_coalesce(),
because skb->truesize of the gso segments were exactly set to mss.

This breaks the requirement that

skb->truesize >= skb->len + truesizeof(struct sk_buff);

It can trivially be reproduced by :

ifconfig lo mtu 1500
ethtool -K lo tso off
netperf

As the skbs are looped into the TCP networking stack, skb_try_coalesce()
warns us of these skb under-estimating their truesize.

Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reported-by: Alexei Starovoitov <ast@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/ipv4/tcp.c |   13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2899,6 +2899,7 @@ struct sk_buff *tcp_tso_segment(struct s
 	netdev_features_t features)
 {
 	struct sk_buff *segs = ERR_PTR(-EINVAL);
+	unsigned int sum_truesize = 0;
 	struct tcphdr *th;
 	unsigned int thlen;
 	unsigned int seq;
@@ -2982,13 +2983,7 @@ struct sk_buff *tcp_tso_segment(struct s
 		if (copy_destructor) {
 			skb->destructor = gso_skb->destructor;
 			skb->sk = gso_skb->sk;
-			/* {tcp|sock}_wfree() use exact truesize accounting :
-			 * sum(skb->truesize) MUST be exactly be gso_skb->truesize
-			 * So we account mss bytes of 'true size' for each segment.
-			 * The last segment will contain the remaining.
-			 */
-			skb->truesize = mss;
-			gso_skb->truesize -= mss;
+			sum_truesize += skb->truesize;
 		}
 		skb = skb->next;
 		th = tcp_hdr(skb);
@@ -3005,7 +3000,9 @@ struct sk_buff *tcp_tso_segment(struct s
 	if (copy_destructor) {
 		swap(gso_skb->sk, skb->sk);
 		swap(gso_skb->destructor, skb->destructor);
-		swap(gso_skb->truesize, skb->truesize);
+		sum_truesize += skb->truesize;
+		atomic_add(sum_truesize - gso_skb->truesize,
+			   &skb->sk->sk_wmem_alloc);
 	}
 
 	delta = htonl(oldlen + (skb->tail - skb->transport_header) +


Patches currently in stable-queue which might be from edumazet@xxxxxxxxxx are

queue-3.10/net-8139cp-fix-a-bug_on-triggered-by-wrong-bytes_compl.patch
queue-3.10/net-tcp-fix-panic-in-tcp_fastopen_cache_set.patch
queue-3.10/tcp-tsq-restore-minimal-amount-of-queueing.patch
queue-3.10/ipv6-fix-possible-seqlock-deadlock-in-ip6_finish_output2.patch
queue-3.10/tcp-don-t-update-snd_nxt-when-a-socket-is-switched-from-repair-mode.patch
queue-3.10/inet-fix-possible-seqlock-deadlocks.patch
queue-3.10/net-clamp-msg_namelen-instead-of-returning-an-error.patch
queue-3.10/af_packet-block-bh-in-prb_shutdown_retire_blk_timer.patch
queue-3.10/ipv4-fix-possible-seqlock-deadlock.patch
queue-3.10/tcp-gso-fix-truesize-tracking.patch
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