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 948F8CA9EAF for ; Sun, 27 Oct 2019 21:36:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 66AD020B7C for ; Sun, 27 Oct 2019 21:36:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572212205; bh=HD9mHCLH10oaeXqUmRtcah0sFgC/axtPSfwRW0zPG2Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=RECgTOdzeoEEo29mWVIPVz0u/J5HodP5OoRAUE3vJftu4aiR+/O45bUmc3KUwu6DS dJ+GpMPloU820pEszGepzyVhPnTWmdnXgbn8bsk1WHA01KiEndzUBVwiWhpr7hThlu FzoEUuctlDPoHYcodKIJsgMq/fwlJnfze10WR3CM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729003AbfJ0VG2 (ORCPT ); Sun, 27 Oct 2019 17:06:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:52252 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728974AbfJ0VGS (ORCPT ); Sun, 27 Oct 2019 17:06:18 -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 C121721D80; Sun, 27 Oct 2019 21:06:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572210377; bh=HD9mHCLH10oaeXqUmRtcah0sFgC/axtPSfwRW0zPG2Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=T2cD3IVBTH7+OYjIL/zZ2P/sVrvvdh2M2wSQnDg0grt8VvOlfZgKjRJT/QLP7chyw iYE8B6I93A7JCtGANAN7EEwIRh3khCdpt0hMG3lRDQ7blkr3zCRwdcGnRLIvfITKHk 7DCn4XQD529niCicfgM6RlpFA76BoTpk5wdrqta4= 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 4.9 45/49] cpufreq: Avoid cpufreq_suspend() deadlock on system shutdown Date: Sun, 27 Oct 2019 22:01:23 +0100 Message-Id: <20191027203202.190338203@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191027203119.468466356@linuxfoundation.org> References: <20191027203119.468466356@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 @@ -10,6 +10,7 @@ * */ +#include #include #include #include @@ -2128,6 +2129,8 @@ 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 @@ -2543,14 +2543,6 @@ 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); @@ -2562,8 +2554,6 @@ 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; } core_initcall(cpufreq_core_init);