Commit e33d0ba8 authored Apr 03, 2014 by Eric Dumazet Committed by David S. Miller Apr 03, 2014

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



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>

parent 240a12d5

net/core/dev.c

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -4043,6 +4043,7 @@ static void napi_reuse_skb(struct napi_struct napi, struct sk_buff skb)
	skb->vlan_tci = 0;		skb->vlan_tci = 0;
	skb->dev = napi->dev;		skb->dev = napi->dev;
	skb->skb_iif = 0;		skb->skb_iif = 0;
			skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));

	napi->skb = skb;		napi->skb = skb;
	}		}

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