From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johann Baudy Subject: Re: [PATCH] TX_RING and packet mmap Date: Sun, 12 Apr 2009 13:23:30 +0200 Message-ID: <7e0dd21a0904120423v4296898fl7ce82ec8c3e42d3a@mail.gmail.com> References: <1238701718.5669.26.camel@bender> <1239108520.32737.28.camel@dogo.mojatatu.com> <20090407130447.GA14329@gondor.apana.org.au> <1239112067.32737.51.camel@dogo.mojatatu.com> <7e0dd21a0904070738jd8a2714wd840352699f1e9f1@mail.gmail.com> <1239137800.21227.10.camel@dogo.mojatatu.com> <20090407211130.GA5918@ioremap.net> <7e0dd21a0904081406w31da460pe1c0c7153538f283@mail.gmail.com> <7e0dd21a0904120327q537956abkf75a17d477cc2e61@mail.gmail.com> <20090412103212.GA28397@ioremap.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Herbert Xu , netdev@vger.kernel.org, "David S. Miller" , Patrick McHardy , jamal To: Evgeniy Polyakov Return-path: Received: from mail-bw0-f169.google.com ([209.85.218.169]:37633 "EHLO mail-bw0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753155AbZDLLXc (ORCPT ); Sun, 12 Apr 2009 07:23:32 -0400 Received: by bwz17 with SMTP id 17so1688087bwz.37 for ; Sun, 12 Apr 2009 04:23:30 -0700 (PDT) In-Reply-To: <20090412103212.GA28397@ioremap.net> Sender: netdev-owner@vger.kernel.org List-ID: Thanks Evgeniy, > Page itself will live until destruction time, when skb is linearized > page is freed, so your own destructor will find that given page is no > longer used, and appropriate memory area can be overwritten. Ok, so if my understanding is correct, fragment data is copied, frags info (page, offset, size ...) of skb_shinfo(skb) remain available and skb->data_len is equal to 0 (to tag it as linear). Then I can use address of skb_shinfo(n)->frags[0].page to derive my header whatever sending path. Is it correct? Best regards, Johann -- Johann Baudy johaahn@gmail.com