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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 2D925C432C0 for ; Fri, 22 Nov 2019 11:12:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 027AF2070E for ; Fri, 22 Nov 2019 11:12:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574421160; bh=MHLTiLMo6OoNuIgCw9aGwbaQZgICcAPVVuPD8MIH+yM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=1+r+ivk+Q7qOEovoY1rOKRK9FBjG+quGnqE4hxGLwy7j+3zcydCfVCfUQbJlI9S3V QQOvfUBY+rIuPn6TKCXi4KYr1LoW5SqTEstIgNRyscGwY2WUTJYiyr1FMI4cRyiqH8 umupGIaY8FJ3+vN2Mx0qdjRcMAzILwcPntRwaeS0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730685AbfKVK5f (ORCPT ); Fri, 22 Nov 2019 05:57:35 -0500 Received: from mail.kernel.org ([198.145.29.99]:46230 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730068AbfKVK5X (ORCPT ); Fri, 22 Nov 2019 05:57:23 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E30DE2071C; Fri, 22 Nov 2019 10:57:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574420242; bh=MHLTiLMo6OoNuIgCw9aGwbaQZgICcAPVVuPD8MIH+yM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=r1ssk3W7EKQZOmyJ9rHCEd3qVuX0ozDgWu5oV1cvLwZrxRmCb3RUz401gr+kEOsKQ meC4mXxM3sjbymPVWJSEp22uUzRSraucD5YqGEwU5jqlof9/BOcYq9SKwlu7y0ErEf +7yPHvM1+GtYqLpSu+TrJJP/R51VvHtYGJdtV/rM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Enric Balletbo i Serra , Chanwoo Choi , MyungJoo Ham , Sasha Levin Subject: [PATCH 4.19 041/220] PM / devfreq: Fix devfreq_add_device() when drivers are built as modules. Date: Fri, 22 Nov 2019 11:26:46 +0100 Message-Id: <20191122100915.244786602@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191122100912.732983531@linuxfoundation.org> References: <20191122100912.732983531@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Enric Balletbo i Serra [ Upstream commit 23c7b54ca1cd1797ef39169ab85e6d46f1c2d061 ] When the devfreq driver and the governor driver are built as modules, the call to devfreq_add_device() or governor_store() fails because the governor driver is not loaded at the time the devfreq driver loads. The devfreq driver has a build dependency on the governor but also should have a runtime dependency. We need to make sure that the governor driver is loaded before the devfreq driver. This patch fixes this bug by adding a try_then_request_governor() function. First tries to find the governor, and then, if it is not found, it requests the module and tries again. Fixes: 1b5c1be2c88e (PM / devfreq: map devfreq drivers to governor using name) Signed-off-by: Enric Balletbo i Serra Reviewed-by: Chanwoo Choi Signed-off-by: MyungJoo Ham Signed-off-by: Sasha Levin --- drivers/devfreq/devfreq.c | 53 ++++++++++++++++++++++++++++++++++++--- 1 file changed, 49 insertions(+), 4 deletions(-) diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 4c49bb1330b52..62ead442a8721 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -11,6 +11,7 @@ */ #include +#include #include #include #include @@ -221,6 +222,49 @@ static struct devfreq_governor *find_devfreq_governor(const char *name) return ERR_PTR(-ENODEV); } +/** + * try_then_request_governor() - Try to find the governor and request the + * module if is not found. + * @name: name of the governor + * + * Search the list of devfreq governors and request the module and try again + * if is not found. This can happen when both drivers (the governor driver + * and the driver that call devfreq_add_device) are built as modules. + * devfreq_list_lock should be held by the caller. Returns the matched + * governor's pointer. + */ +static struct devfreq_governor *try_then_request_governor(const char *name) +{ + struct devfreq_governor *governor; + int err = 0; + + if (IS_ERR_OR_NULL(name)) { + pr_err("DEVFREQ: %s: Invalid parameters\n", __func__); + return ERR_PTR(-EINVAL); + } + WARN(!mutex_is_locked(&devfreq_list_lock), + "devfreq_list_lock must be locked."); + + governor = find_devfreq_governor(name); + if (IS_ERR(governor)) { + mutex_unlock(&devfreq_list_lock); + + if (!strncmp(name, DEVFREQ_GOV_SIMPLE_ONDEMAND, + DEVFREQ_NAME_LEN)) + err = request_module("governor_%s", "simpleondemand"); + else + err = request_module("governor_%s", name); + /* Restore previous state before return */ + mutex_lock(&devfreq_list_lock); + if (err) + return NULL; + + governor = find_devfreq_governor(name); + } + + return governor; +} + static int devfreq_notify_transition(struct devfreq *devfreq, struct devfreq_freqs *freqs, unsigned int state) { @@ -646,9 +690,8 @@ struct devfreq *devfreq_add_device(struct device *dev, mutex_unlock(&devfreq->lock); mutex_lock(&devfreq_list_lock); - list_add(&devfreq->node, &devfreq_list); - governor = find_devfreq_governor(devfreq->governor_name); + governor = try_then_request_governor(devfreq->governor_name); if (IS_ERR(governor)) { dev_err(dev, "%s: Unable to find governor for the device\n", __func__); @@ -664,12 +707,14 @@ struct devfreq *devfreq_add_device(struct device *dev, __func__); goto err_init; } + + list_add(&devfreq->node, &devfreq_list); + mutex_unlock(&devfreq_list_lock); return devfreq; err_init: - list_del(&devfreq->node); mutex_unlock(&devfreq_list_lock); device_unregister(&devfreq->dev); @@ -991,7 +1036,7 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr, 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; -- 2.20.1