From: Eric Dumazet <edumazet@google.com>
Date: Thu, 3 Apr 2014 16:28:10 +0000 (-0700)
Subject: net-gro: reset skb->truesize in napi_reuse_skb()
X-Git-Tag: firefly_0821_release~3679^2~2268
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=fd6b1194f0096af91c6e2b31065f5f9d2b066d80;p=firefly-linux-kernel-4.4.55.git

net-gro: reset skb->truesize in napi_reuse_skb()

[ Upstream commit e33d0ba8047b049c9262fdb1fcafb93cb52ceceb ]

Recycling skb always had been very tough...

This time it appears GRO layer can accumulate skb->truesize
adjustments made by drivers when they attach a fragment to skb.

skb_gro_receive() can only subtract from skb->truesize the used part
of a fragment.

I spotted this problem seeing TcpExtPruneCalled and
TcpExtTCPRcvCollapsed that were unexpected with a recent kernel, where
TCP receive window should be sized properly to accept traffic coming
from a driver not overshooting skb->truesize.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/net/core/dev.c b/net/core/dev.c
index 5bf26c4815fb..56383a3e5d71 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3898,6 +3898,7 @@ static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
 	skb->vlan_tci = 0;
 	skb->dev = napi->dev;
 	skb->skb_iif = 0;
+	skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
 
 	napi->skb = skb;
 }