From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: [RFC PATCH] tuntap: Fix for a race in accessing numqueue Date: Sat, 18 Jan 2014 21:43:17 +0400 Message-ID: <52DABD35.3030408@cogentembedded.com> References: <1390004815-7052-1-git-send-email-dominic.curran@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Jason Wang , Maxim Krasnyansky To: Dominic Curran , netdev@vger.kernel.org Return-path: Received: from mail-la0-f53.google.com ([209.85.215.53]:59819 "EHLO mail-la0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751064AbaARRnJ (ORCPT ); Sat, 18 Jan 2014 12:43:09 -0500 Received: by mail-la0-f53.google.com with SMTP id e16so4438456lan.26 for ; Sat, 18 Jan 2014 09:43:06 -0800 (PST) In-Reply-To: <1390004815-7052-1-git-send-email-dominic.curran@citrix.com> Sender: netdev-owner@vger.kernel.org List-ID: Hello. On 18-01-2014 4:26, Dominic Curran wrote: > A patch for fixing a race between queue selection and changing queues > was introduced in commit 92bb73ea2c434618a68a5. Please also specify that commit's summary line in parens. > The fix was to prevent the driver from re-reading the tun->numqueues > more than once within tun_select_queue(). > We have been experiancing 'Divide-by-zero' errors in > tun_net_xmit() since we moved from 3.6 to 3.10, and believe that they > come from a simular source where the value of tun->numqueues changes > to zero between the first and second read of tun->numqueues. > Signed-off-by: Dominic Curran > Cc: Jason Wang > Cc: Maxim Krasnyansky WBR, Sergei