From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: panics in tcp_ack Date: Sun, 02 Jun 2013 20:32:50 -0700 Message-ID: <1370230370.24311.121.camel@edumazet-glaptop> References: <51ABE067.2050507@gmail.com> <1370219787.24311.113.camel@edumazet-glaptop> <51ABFE10.1030206@gmail.com> <1370228594.24311.114.camel@edumazet-glaptop> <51AC0B0C.7070306@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: Rob Herring Return-path: Received: from mail-pd0-f169.google.com ([209.85.192.169]:33042 "EHLO mail-pd0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750824Ab3FCDcw (ORCPT ); Sun, 2 Jun 2013 23:32:52 -0400 Received: by mail-pd0-f169.google.com with SMTP id y11so5000099pdj.0 for ; Sun, 02 Jun 2013 20:32:52 -0700 (PDT) In-Reply-To: <51AC0B0C.7070306@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: On Sun, 2013-06-02 at 22:18 -0500, Rob Herring wrote: > Ah, missed that there are 2 versions of skb_transport_header. So on > 32-bit it is skb->transport_header. > > Here's the ARM disassembly: > > c040796c : > c040796c: e92d45f0 push {r4, r5, r6, r7, r8, sl, lr} > c0407970: e1a06002 mov r6, r2 > c0407974: e5d023e4 ldrb r2, [r0, #996] ; 0x3e4 > c0407978: e1a05001 mov r5, r1 > c040797c: e5901344 ldr r1, [r0, #836] ; 0x344 > c0407980: e24dd014 sub sp, sp, #20 > c0407984: e7c0201f bfc r2, #0, #1 > c0407988: e5c023e4 strb r2, [r0, #996] ; 0x3e4 > panic>c040798c: e596200c ldr r2, [r6, #12] > > r6 is NULL. r6 came from r2 which is the 3rd function argument. > > The 3rd arg is tcp_hdr(skb) which is skb->transport_header. > > Rob Interesting. transport header should be set in IP stack before TCP. What is the driver delivering this packet ? Do you have commit fda55eca5a33f33ffcd4192c6b2d75179714a52c ("net: introduce skb_transport_header_was_set()")