From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752883AbdCASaD (ORCPT ); Wed, 1 Mar 2017 13:30:03 -0500 Received: from mail-pf0-f193.google.com ([209.85.192.193]:36169 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751673AbdCASaC (ORCPT ); Wed, 1 Mar 2017 13:30:02 -0500 Date: Wed, 1 Mar 2017 10:19:16 -0800 From: Dmitry Torokhov To: =?utf-8?B?TWljaGHFgiBLxJlwaWXFhA==?= Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Input: sparse-keymap - add managed version of sparse_keymap_setup() Message-ID: <20170301181916.GE30349@dtor-ws> References: <20170228094525.26683-1-kernel@kempniu.pl> <20170228184558.GG20776@dtor-ws> <20170301103714.GA973@ozzy.nask.waw.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20170301103714.GA973@ozzy.nask.waw.pl> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 01, 2017 at 11:37:14AM +0100, Michał Kępień wrote: > > On Tue, Feb 28, 2017 at 10:45:25AM +0100, Michał Kępień wrote: > > > Some platform drivers use devm_input_allocate_device() together with > > > sparse_keymap_setup() in their .probe callbacks. While using the former > > > simplifies error handling, using the latter necessitates calling > > > sparse_keymap_free() in the error path and upon module unloading to > > > avoid leaking the copy of the keymap allocated by sparse_keymap_setup(). > > > > > > To help prevent such leaks and enable simpler error handling in these > > > drivers, add a new function which allows automatic freeing of the keymap > > > copy upon probe failure and on driver detach. > > > > > > As devm_input_allocate_device() adds its devres to the device owning the > > > input device, we do the same for managed input devices to ensure freeing > > > the keymap copy is properly slotted in the devres stack. > > > > > > The new function can also be used by non-managed input devices, though > > > in this case the devres is attached to the struct device embedded inside > > > the input device itself. > > > > This is wrong and does not work as input devices are never probed and > > never unbound, so the cleanup will never happen. > > > > Either pass device explicitly, or always take input's parent. > > Thank you for taking a look, Dmitry. I may be missing something, but > please bear with me. AFAICT, in the non-managed input device case the > devres release callback is called when the last reference to that input > device is dropped, i.e. after input_unregister_device() is called. > Setting devres.log=1 confirms this, so does putting a WARN_ON() inside > devm_sparse_keymap_free(). Could you please elaborate? Perhaps I am > misunderstanding your argument. Ah, I missed the fact that we drop devres resources when we destroy the device. OK, in this case why don't we make sparse keymap always use devm-allocated memory and make sparse_keymap_free() a noop for the time being? Once we remove it from all the drivers we can kill the stub. Thanks. -- Dmitry