From patchwork Fri Nov 18 12:40:45 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Rafael J. Wysocki" X-Patchwork-Id: 9436381 X-Patchwork-Delegate: rjw@sisk.pl Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id ACC5E6047D for ; Fri, 18 Nov 2016 12:33:11 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B543929885 for ; Fri, 18 Nov 2016 12:33:11 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A705529898; Fri, 18 Nov 2016 12:33:11 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 81F0F29885 for ; Fri, 18 Nov 2016 12:33:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752995AbcKRMdJ (ORCPT ); Fri, 18 Nov 2016 07:33:09 -0500 Received: from cloudserver094114.home.net.pl ([79.96.170.134]:42407 "EHLO cloudserver094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752821AbcKRMdI (ORCPT ); Fri, 18 Nov 2016 07:33:08 -0500 Received: from 217.96.253.85.ipv4.supernova.orange.pl (217.96.253.85) (HELO vostro.rjw.lan) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.81) id 1bd090a771c1f39b; Fri, 18 Nov 2016 13:33:06 +0100 From: "Rafael J. Wysocki" To: Linux PM list , Viresh Kumar Cc: Linux Kernel Mailing List , Srinivas Pandruvada Subject: [PATCH v2] cpufreq: Avoid using inactive policies Date: Fri, 18 Nov 2016 13:40:45 +0100 Message-ID: <2709142.YWmMDScDNY@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/4.9.0-rc5+; KDE/4.11.5; x86_64; ; ) MIME-Version: 1.0 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Rafael J. Wysocki There are two places in the cpufreq core in which low-level driver callbacks may be invoked for an inactive cpufreq policy, which isn't guaranteed to work in general. Both are due to possible races with CPU offline. First, in cpufreq_get(), the policy may become inactive after the check against policy->cpus in cpufreq_cpu_get() and before policy->rwsem is acquired, in which case using it going forward may not be correct. Second, an analogous situation is possible in cpufreq_update_policy(). Avoid using inactive policies by adding policy_is_inactive() checks to the code in the above places. Signed-off-by: Rafael J. Wysocki Acked-by: Viresh Kumar --- -> v2: Initialize ret in cpufreq_update_policy() if the inactive policy check doesn't pass. --- drivers/cpufreq/cpufreq.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Index: linux-pm/drivers/cpufreq/cpufreq.c =================================================================== --- linux-pm.orig/drivers/cpufreq/cpufreq.c +++ linux-pm/drivers/cpufreq/cpufreq.c @@ -1526,7 +1526,10 @@ unsigned int cpufreq_get(unsigned int cp if (policy) { down_read(&policy->rwsem); - ret_freq = __cpufreq_get(policy); + + if (!policy_is_inactive(policy)) + ret_freq = __cpufreq_get(policy); + up_read(&policy->rwsem); cpufreq_cpu_put(policy); @@ -2265,6 +2268,11 @@ int cpufreq_update_policy(unsigned int c down_write(&policy->rwsem); + if (policy_is_inactive(policy)) { + ret = -ENODEV; + goto unlock; + } + pr_debug("updating policy for CPU %u\n", cpu); memcpy(&new_policy, policy, sizeof(*policy)); new_policy.min = policy->user_policy.min;