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,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 BE5EEC3276C for ; Thu, 2 Jan 2020 22:37:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 924A72253D for ; Thu, 2 Jan 2020 22:37:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578004624; bh=0BY+Su5Ly6B2LWFqAP1C7t6yhbWjY9neoXDkJ7q4lu0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=TRBo6fyEbiaJjE0PumsN0YFV7HZ3i8UMBaQdTQnyyeD5fTWPQ3614e1VphD3xTEYv whbgbwh8kYuEf3H6AupsrvSn5dNKKg9/YyvD2JYli6E5ZsVM0MJYZusSStYtMLZJOW w9E2VbGY2PGtYr9gbfpayNUWwjEQoJJzBfNC+Dlo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731035AbgABWhD (ORCPT ); Thu, 2 Jan 2020 17:37:03 -0500 Received: from mail.kernel.org ([198.145.29.99]:48840 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731032AbgABWg7 (ORCPT ); Thu, 2 Jan 2020 17:36:59 -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 DD50220866; Thu, 2 Jan 2020 22:36:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578004619; bh=0BY+Su5Ly6B2LWFqAP1C7t6yhbWjY9neoXDkJ7q4lu0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IeWkJh1C+AEJYmr58mwM+1WruTuDDFD2gDSLr6Y6XH0+pB9jg6DXy8B92Ru4xIXdo cGOlkmhnPyG+hY9g/3fqlyftLfmURchDoPF+rvkVd9SxOhm1umimakOdqL1McmZtpV /A2p6gl7i8CVfHAXyq1t3PybZXS0pASPE+Z1p4yk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Bjorn Andersson , Viresh Kumar , Amit Kucheria , "Rafael J. Wysocki" , Sasha Levin Subject: [PATCH 4.4 056/137] cpufreq: Register drivers only after CPU devices have been registered Date: Thu, 2 Jan 2020 23:07:09 +0100 Message-Id: <20200102220554.086138680@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200102220546.618583146@linuxfoundation.org> References: <20200102220546.618583146@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: Viresh Kumar [ Upstream commit 46770be0cf94149ca48be87719bda1d951066644 ] The cpufreq core heavily depends on the availability of the struct device for CPUs and if they aren't available at the time cpufreq driver is registered, we will never succeed in making cpufreq work. This happens due to following sequence of events: - cpufreq_register_driver() - subsys_interface_register() - return 0; //successful registration of driver ... at a later point of time - register_cpu(); - device_register(); - bus_probe_device(); - sif->add_dev(); - cpufreq_add_dev(); - get_cpu_device(); //FAILS - per_cpu(cpu_sys_devices, num) = &cpu->dev; //used by get_cpu_device() - return 0; //CPU registered successfully Because the per-cpu variable cpu_sys_devices is set only after the CPU device is regsitered, cpufreq will never be able to get it when cpufreq_add_dev() is called. This patch avoids this failure by making sure device structure of at least CPU0 is available when the cpufreq driver is registered, else return -EPROBE_DEFER. Reported-by: Bjorn Andersson Co-developed-by: Amit Kucheria Signed-off-by: Viresh Kumar Tested-by: Amit Kucheria Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin --- drivers/cpufreq/cpufreq.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 2239d42bdadd..49aa58e617db 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -2426,6 +2426,13 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) if (cpufreq_disabled()) return -ENODEV; + /* + * The cpufreq core depends heavily on the availability of device + * structure, make sure they are available before proceeding further. + */ + if (!get_cpu_device(0)) + return -EPROBE_DEFER; + if (!driver_data || !driver_data->verify || !driver_data->init || !(driver_data->setpolicy || driver_data->target_index || driver_data->target) || -- 2.20.1