From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH v3] net-tcp: TCP/IP stack bypass for loopback connections Date: Wed, 19 Sep 2012 17:17:59 -0400 (EDT) Message-ID: <20120919.171759.954995920168438601.davem@davemloft.net> References: <1347913239.26523.173.camel@edumazet-glaptop> <20120919.163406.487082174277409074.davem@davemloft.net> <1348088634.31352.26.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: brutus@google.com, edumazet@google.com, netdev@vger.kernel.org To: eric.dumazet@gmail.com Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:57798 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751643Ab2ISVSD (ORCPT ); Wed, 19 Sep 2012 17:18:03 -0400 In-Reply-To: <1348088634.31352.26.camel@edumazet-glaptop> Sender: netdev-owner@vger.kernel.org List-ID: From: Eric Dumazet Date: Wed, 19 Sep 2012 23:03:54 +0200 > On Wed, 2012-09-19 at 16:34 -0400, David Miller wrote: > >> I have an idea on how to handle this. >> >> In drivers/net/loopback.c:loopback_tx(), skip the SKB orphan operation >> if there is a friend socket at skb->friend. >> >> When sending such friend SKBs out at connection startup, arrange it >> such that the skb->destructor will zap the skb->friend pointer to >> NULL. >> >> Also, in skb_orphan*(), if necessary, set skb->friend to NULL. >> >> skb->sk will hold a reference to the socket, and since skb->friend >> will be equal, this will make sure a pointer to an unreferenced >> socket does not escape. > > I now am wondering if we still need skb->friend field. > > If skb->sk is not zeroed by a premature skb_orphan(), then > > skb->sk->sk_friend gives the friend ? Good point.