From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,UNPARSEABLE_RELAY autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B08CFC6778A for ; Tue, 3 Jul 2018 13:16:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 625FA23F62 for ; Tue, 3 Jul 2018 13:16:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 625FA23F62 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=collabora.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753302AbeGCNQl (ORCPT ); Tue, 3 Jul 2018 09:16:41 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:60416 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752423AbeGCNQk (ORCPT ); Tue, 3 Jul 2018 09:16:40 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: eballetbo) with ESMTPSA id 066B4260185 Subject: Re: [PATCH v3] PM / devfreq: Fix devfreq_add_device() when drivers are built as modules. To: myungjoo.ham@samsung.com, "linux-kernel@vger.kernel.org" Cc: "kernel@collabora.com" , Chanwoo Choi , Kyungmin Park , "linux-pm@vger.kernel.org" References: <20180621220430.25644-1-enric.balletbo@collabora.com> <20180703105723epcms1p63bd7b3cf49722b204d7ca0dfd98d5d15@epcms1p6> From: Enric Balletbo i Serra Message-ID: <60b611ac-69e0-1339-599a-299483b6df3d@collabora.com> Date: Tue, 3 Jul 2018 15:16:35 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180703105723epcms1p63bd7b3cf49722b204d7ca0dfd98d5d15@epcms1p6> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi MyungJoo On 03/07/18 12:57, MyungJoo Ham wrote: >> @@ -988,12 +1030,13 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr, >> if (ret != 1) >> return -EINVAL; >> >> - mutex_lock(&devfreq_list_lock); >> - governor = find_devfreq_governor(str_governor); >> + governor = try_then_request_governor(str_governor); >> if (IS_ERR(governor)) { >> - ret = PTR_ERR(governor); >> - goto out; >> + return PTR_ERR(governor); >> } >> + >> + mutex_lock(&devfreq_list_lock); >> + >> if (df->governor == governor) { >> ret = 0; >> goto out; >> -- > > The possibility that the result of try_then_request_governor is > not kept protected until the line of > "if (df->governor == governor)" is itching. > > Can you make it kept "locked" from the return of > find_devfreq_governor() (either in try_then... or in this function) > to the unlock of governor_store()? > Sure, I'll send v4 in a minute. Thanks, Enric > > Cheers, > MyungJoo >