From mboxrd@z Thu Jan 1 00:00:00 1970 From: Evgeniy Polyakov Subject: Re: Data corruption issue with splice() on 2.6.27.10 Date: Wed, 7 Jan 2009 15:15:30 +0300 Message-ID: <20090107121530.GA30164@ioremap.net> References: <20081224152841.GB13113@1wt.eu> <20090106183223.GA11964@ioremap.net> <20090106183704.GC32491@kernel.dk> <20090107044232.GA22218@gondor.apana.org.au> <20090107112906.GA28161@ioremap.net> <20090107115032.GA25198@gondor.apana.org.au> <20090107115605.GA29250@ioremap.net> <20090107115921.GA25323@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jens Axboe , Willy Tarreau , linux-kernel@vger.kernel.org, netdev@vger.kernel.org To: Herbert Xu Return-path: Received: from kandzendo.ru ([195.178.208.66]:42895 "EHLO tservice.net.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750924AbZAGMPb (ORCPT ); Wed, 7 Jan 2009 07:15:31 -0500 Content-Disposition: inline In-Reply-To: <20090107115921.GA25323@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Jan 07, 2009 at 10:59:21PM +1100, Herbert Xu (herbert@gondor.apana.org.au) wrote: > On Wed, Jan 07, 2009 at 02:56:05PM +0300, Evgeniy Polyakov wrote: > > > > But it will not push pages into the stack, but copy them including copy > > of the submitted head? > > It will use a single page entry for skb->head with splice, see > skb_splice_bits. Looks like we are talking about different directions of the dataflow. I meant that set of pages submitted into the sending part will be copied if sending interface does not support acceleration, and thus it will copy part of the page corresponding to the linear part of the skb prior the transmission, so even if skb will be freed right after that call (prior data transmission by the hardware), it should not affect copied data. -- Evgeniy Polyakov