From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751056AbdALU4A (ORCPT ); Thu, 12 Jan 2017 15:56:00 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:26617 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751026AbdALUz6 (ORCPT ); Thu, 12 Jan 2017 15:55:58 -0500 Subject: Re: [PATCH] tcp: fix tcp_fastopen unaligned access complaints on sparc To: David Miller References: <1484252733.13165.1.camel@edumazet-glaptop3.roam.corp.google.com> <1c39bf41-4ebf-643a-c6a0-caf98a17a89c@oracle.com> <20170112.154143.1940764507974590907.davem@davemloft.net> Cc: eric.dumazet@gmail.com, rob.gardner@oracle.com, netdev@vger.kernel.org, sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org From: Shannon Nelson Organization: Oracle Corporation Message-ID: <131ec7b7-5b74-2545-8bf7-92812443a876@oracle.com> Date: Thu, 12 Jan 2017 12:56:08 -0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 In-Reply-To: <20170112.154143.1940764507974590907.davem@davemloft.net> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/12/2017 12:41 PM, David Miller wrote: > From: Shannon Nelson > Date: Thu, 12 Jan 2017 12:30:38 -0800 > >> On 1/12/2017 12:25 PM, Eric Dumazet wrote: >>> On Thu, 2017-01-12 at 13:15 -0700, Rob Gardner wrote: >>> >>>> >>>> I suspect that someplace, somebody is casting val to an int * or >>>> something like that. >>> >>> Then that would be the bug. Can we root cause this please ? >>> >>> >> >> Look in net/ipv4/tcp_fastopen.c:tcp_fastopen_cookie_gen() for the line >> >> struct in6_addr *buf = (struct in6_addr *) tmp.val; > > Oh yeah, that's it. I didn't notice that at all. > It looked to me like swapping the data fields would be the easiest and least impactive way to fix this. I didn't want to mess with the logic. I'm certainly open to other suggestions. sln