From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Henrik Rydberg" Subject: Re: [PATCH v2] Input: evdev - Add EVIOC mechanism to extract the MT slot state Date: Fri, 6 Jan 2012 20:18:35 +0100 Message-ID: <20120106191835.GA2998@polaris.bitmath.org> References: <1325863019-2242-1-git-send-email-rydberg@euromail.se> <20120106181845.GA22653@core.coreip.homeip.net> <20120106185544.GB2795@polaris.bitmath.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from smtprelay-b11.telenor.se ([62.127.194.20]:52326 "EHLO smtprelay-b11.telenor.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750762Ab2AFTSk (ORCPT ); Fri, 6 Jan 2012 14:18:40 -0500 Content-Disposition: inline In-Reply-To: <20120106185544.GB2795@polaris.bitmath.org> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Dmitry Torokhov Cc: Benjamin Tissoires , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Chase Douglas On Fri, Jan 06, 2012 at 07:55:44PM +0100, Henrik Rydberg wrote: > > 2 different processes should be fine; the problem would be if 2 threads > > of the same process share the same file descriptor. So far the rest of > > evdev copes just fine with multiple threads using the same fd (all > > operations are atomic in this regard), setting ABS_MT_SLOT before > > fetching the state break this property. > > Are we talking about the need for a per-client mutex, or something > more subtle, like introducing indirect coupling between threads > through per-client states? The former ought to be easily remedied. Ok, maybe not to so easy after all, which probably answers my own question. Looks like a EVIOCGMTSLOT, taking both slot and event code as argument, would be the cleaner route to take. Another ioctl, how do we feel about that? Henrik