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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 AE12ACA9EAF for ; Sun, 27 Oct 2019 21:27:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7E6E9222C4 for ; Sun, 27 Oct 2019 21:27:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572211624; bh=ajNWyUIB9j30wVqpM3yEv3nGoOtf1fhGnU0PTi2r/uM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=CxV35v6KyFNNRRZN3VugwN4+knUA3AGoBowtFX6IQvBoTGIJoUpS2wfXgvA2CNev6 0tD+EuACUQ9bqDfy7pm3e7gJXDE3rlQ1NJBr+evwyiMX/oFhS9YPCNiM21FxPXTqP2 f7EML24t6ACbRn3PHnTxO2S/d7DzmpS0jwh7XBaY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732258AbfJ0V1C (ORCPT ); Sun, 27 Oct 2019 17:27:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:47664 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731951AbfJ0VZr (ORCPT ); Sun, 27 Oct 2019 17:25:47 -0400 Received: from localhost (100.50.158.77.rev.sfr.net [77.158.50.100]) (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 D5C3D21D81; Sun, 27 Oct 2019 21:25:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572211545; bh=ajNWyUIB9j30wVqpM3yEv3nGoOtf1fhGnU0PTi2r/uM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GYeb7yIdzLXM4OpttIrCEzCR+i5fCX5xPEtrAa22vM7dVOt9O2b9vCUNhjp6c1CmQ sBNIdQ9NO4RMwbsBVmmlmSx/tEkBYE4vX2ia5/mI2jQIw1WnZRARGWmX+0s2WOZAbT so2lU1oPTS6aHtp3u1/J4X/ra4YKxN/coD0EBkTQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , "Rafael J. Wysocki" , Viresh Kumar Subject: [PATCH 5.3 190/197] cpufreq: Avoid cpufreq_suspend() deadlock on system shutdown Date: Sun, 27 Oct 2019 22:01:48 +0100 Message-Id: <20191027203406.745335828@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191027203351.684916567@linuxfoundation.org> References: <20191027203351.684916567@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: Rafael J. Wysocki commit 65650b35133ff20f0c9ef0abd5c3c66dbce3ae57 upstream. It is incorrect to set the cpufreq syscore shutdown callback pointer to cpufreq_suspend(), because that function cannot be run in the syscore stage of system shutdown for two reasons: (a) it may attempt to carry out actions depending on devices that have already been shut down at that point and (b) the RCU synchronization carried out by it may not be able to make progress then. The latter issue has been present since commit 45975c7d21a1 ("rcu: Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds"), but the former one has been there since commit 90de2a4aa9f3 ("cpufreq: suspend cpufreq governors on shutdown") regardless. Fix that by dropping cpufreq_syscore_ops altogether and making device_shutdown() call cpufreq_suspend() directly before shutting down devices, which is along the lines of what system-wide power management does. Fixes: 45975c7d21a1 ("rcu: Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds") Fixes: 90de2a4aa9f3 ("cpufreq: suspend cpufreq governors on shutdown") Reported-by: Ville Syrjälä Tested-by: Ville Syrjälä Signed-off-by: Rafael J. Wysocki Acked-by: Viresh Kumar Cc: 4.0+ # 4.0+ Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 3 +++ drivers/cpufreq/cpufreq.c | 10 ---------- 2 files changed, 3 insertions(+), 10 deletions(-) --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -9,6 +9,7 @@ */ #include +#include #include #include #include @@ -3150,6 +3151,8 @@ void device_shutdown(void) wait_for_device_probe(); device_block_probing(); + cpufreq_suspend(); + spin_lock(&devices_kset->list_lock); /* * Walk the devices list backward, shutting down each in turn. --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -2746,14 +2746,6 @@ int cpufreq_unregister_driver(struct cpu } EXPORT_SYMBOL_GPL(cpufreq_unregister_driver); -/* - * Stop cpufreq at shutdown to make sure it isn't holding any locks - * or mutexes when secondary CPUs are halted. - */ -static struct syscore_ops cpufreq_syscore_ops = { - .shutdown = cpufreq_suspend, -}; - struct kobject *cpufreq_global_kobject; EXPORT_SYMBOL(cpufreq_global_kobject); @@ -2765,8 +2757,6 @@ static int __init cpufreq_core_init(void cpufreq_global_kobject = kobject_create_and_add("cpufreq", &cpu_subsys.dev_root->kobj); BUG_ON(!cpufreq_global_kobject); - register_syscore_ops(&cpufreq_syscore_ops); - return 0; } module_param(off, int, 0444);