From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH net-next] xfrm: Call IP receive handler directly for
 inbound tunnel-mode packets
Date: Mon, 02 Jan 2012 09:18:02 +0100
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	 <20120102072828.GA5380@gondor.apana.org.au>
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Cc: David Ward <david.ward@ll.mit.edu>, netdev@vger.kernel.org
To: Herbert Xu <herbert@gondor.apana.org.au>
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Le lundi 02 janvier 2012 =C3=A0 18:28 +1100, Herbert Xu a =C3=A9crit :

> You can't do this as this may cause stack overruns if we nest
> too deeply.
>=20

I was considering adding a generic helper, for tunneling,
taking into account the depth for current packet.

[ calling netif_receive_skb() instead of netif_rx(), to solve the OOO
problem occurring on SMP when interrupts are spreaded on several cpus ]


We could use the delta between skb->data and skb->head as an estimation
of this depth, in order not adding a new skb field ?

#define DEPTH_THRESHOLD (NET_SKB_PAD + 64)

static inline void netif_reinject(struct sk_buff *skb)
{
if (skb->data - skb->head < DEPTH_THRESHOLD)
	netif_receive_skb(skb);
else
	netif_rx(skb);
}