From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [PATCH] input: tsc2005: fix locking issue Date: Tue, 22 Mar 2011 08:42:02 -0700 Message-ID: <20110322154202.GA24772@core.coreip.homeip.net> References: <1300724650-6641-1-git-send-email-aaro.koskinen@nokia.com> <20110322061958.GA7990@core.coreip.homeip.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-iy0-f174.google.com ([209.85.210.174]:35107 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751733Ab1CVPmJ (ORCPT ); Tue, 22 Mar 2011 11:42:09 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Aaro Koskinen Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org On Tue, Mar 22, 2011 at 04:59:02PM +0200, Aaro Koskinen wrote: > Hi, > > On Mon, 21 Mar 2011, Dmitry Torokhov wrote: > >On Mon, Mar 21, 2011 at 06:24:10PM +0200, Aaro Koskinen wrote: > >>Commit 0b950d3 (Input: tsc2005 - add open/close) introduced a > >>locking issue with the ESD watchdog: __tsc2005_disable() is calling > >>cancel_delayed_work_sync() with mutex held, and the work also needs the > >>same mutex. > >> > >>Fix the problem by using cancel_delayed_work() on disable. If > >>the ESD work was running it will check if the device is closed > >>or suspended, and in that case it will do nothing and skip > >>re-arming. cancel_delayed_work_sync() is still needed when the module > >>is removed. > > > >Hmm, indeed. However, instead of moving cancel_delayed_work_sync() to > >remove maybe we should use mutex_trylock() in tsc2005_esd_work()? > >If trylock fails that means that device is in the middle of open/close > >transition. We should just reschedule the work and get out of there. > > But I guess the reschedule should not happen if we are in the middle of > close/disable? And without the mutex we cannot know that. It should be OK to reschedule even as we enabling/disabling because cancel_delayed_work_sync() handles re-arming works so even if ESD work is being executed at the time we closing the device it will be killed off completely. Thanks. -- Dmitry