From mboxrd@z Thu Jan 1 00:00:00 1970 From: Evgeniy Polyakov Subject: Re: [PATCH] TX_RING and packet mmap Date: Sun, 12 Apr 2009 18:24:51 +0400 Message-ID: <20090412142451.GA2694@ioremap.net> References: <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> <7e0dd21a0904120423v4296898fl7ce82ec8c3e42d3a@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Herbert Xu , netdev@vger.kernel.org, "David S. Miller" , Patrick McHardy , jamal To: Johann Baudy Return-path: Received: from cs-studio.ru ([195.178.208.66]:48156 "EHLO tservice.net.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753123AbZDLOZK (ORCPT ); Sun, 12 Apr 2009 10:25:10 -0400 Content-Disposition: inline In-Reply-To: <7e0dd21a0904120423v4296898fl7ce82ec8c3e42d3a@mail.gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: On Sun, Apr 12, 2009 at 01:23:30PM +0200, Johann Baudy (johann.baudy@gnu-log.net) wrote: > > 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. No, I was wrong, linearization may silently put pages without calling a destructor. -- Evgeniy Polyakov