netdev - Re: [PATCH v2] netfilter: take care of timewait sockets

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Date:	Mon, 03 Sep 2012 11:57:18 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Florian Westphal <fw@...len.de>, David Miller <davem@...emloft.net>
Cc:	Sami Farin <hvtaifwkbgefbaei@...il.com>, netdev@...r.kernel.org,
	e1000-devel@...ts.sourceforge.net
Subject: Re: [PATCH v2] netfilter: take care of timewait sockets

From: Eric Dumazet <edumazet@...gle.com>

On Mon, 2012-09-03 at 09:47 +0200, Florian Westphal wrote:
> Eric Dumazet <eric.dumazet@...il.com> wrote:
> > Sami Farin reported crashes in xt_LOG because it assumes skb->sk is a
> > full blown socket.
> > 
> > But with TCP early demux, we can have skb->sk pointing to a timewait
> > socket.
> > 
> > Same fix is needed in netfnetlink_log
> 
> Looks good, but IMHO it is very un-intuitive that
> skb->sk might be a pointer to an object that is not struct sock (or
> a compatible object).

Its kind of a compatible object, if all skb->sk users are aware of it.

You are totally right, this is messy, but TCP edemux is a layering
violation helping a bit performance...

sock_edemux() should also be fixed.

David, tell me if you prefer to change TCP demux to avoid timewait,
as I have no strong opinion.

[PATCH] net: sock_edemux() should take care of timewait sockets

sock_edemux() can handle either a regular socket or a timewait socket

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/core/sock.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index 8f67ced..7f64467 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1523,7 +1523,12 @@ EXPORT_SYMBOL(sock_rfree);
 
 void sock_edemux(struct sk_buff *skb)
 {
-	sock_put(skb->sk);
+	struct sock *sk = skb->sk;
+
+	if (sk->sk_state == TCP_TIME_WAIT)
+		inet_twsk_put(inet_twsk(sk));
+	else
+		sock_put(sk);
 }
 EXPORT_SYMBOL(sock_edemux);
 


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