From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933045AbbCRNhV (ORCPT ); Wed, 18 Mar 2015 09:37:21 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:46595 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756818AbbCRNhE (ORCPT ); Wed, 18 Mar 2015 09:37:04 -0400 Date: Wed, 18 Mar 2015 16:36:51 +0300 From: Dan Carpenter To: Quentin Lambert Cc: Lidza Louina , devel@driverdev.osuosl.org, Greg Kroah-Hartman , driverdev-devel@linuxdriverproject.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] Staging: dgnc: release the lock before testing for nullity Message-ID: <20150318133651.GS10964@mwanda> References: <1426684868-24402-1-git-send-email-lambert.quentin@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1426684868-24402-1-git-send-email-lambert.quentin@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: userv0021.oracle.com [156.151.31.71] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 18, 2015 at 02:21:08PM +0100, Quentin Lambert wrote: > The refactoring intrduced in > c84a083b995b ("Staging: dgnc: Use goto for spinlock release before return") > inverts the order in which the lock is released and ld is tested for nullity. > > This patch restores the execution flow. > This changelog still doesn't make sense so I took a look at the code. tty_ldisc_deref() is an unlock function. So this is a lock ordering bug. What makes you think the original ordering was correct? Who reported this bug? What are the effects of this bug? Please answer the questions and we can work together on a proper fix if needed. regards, dan carpenter