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[209.132.180.67]) by mx.google.com with ESMTP id g8si627522pdk.182.2015.01.27.00.37.28; Tue, 27 Jan 2015 00:37:29 -0800 (PST) Received-SPF: none (google.com: linux-pm-owner@vger.kernel.org does not designate permitted sender hosts) client-ip=209.132.180.67; Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757900AbbA0IhW (ORCPT + 11 others); Tue, 27 Jan 2015 03:37:22 -0500 Received: from mail-pd0-f172.google.com ([209.85.192.172]:41463 "EHLO mail-pd0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757884AbbA0IhT (ORCPT ); Tue, 27 Jan 2015 03:37:19 -0500 Received: by mail-pd0-f172.google.com with SMTP id v10so17617683pde.3 for ; Tue, 27 Jan 2015 00:37:18 -0800 (PST) X-Received: by 10.68.68.131 with SMTP id w3mr140225pbt.132.1422347838471; Tue, 27 Jan 2015 00:37:18 -0800 (PST) Received: from localhost ([122.178.198.250]) by mx.google.com with ESMTPSA id ji5sm835613pbd.22.2015.01.27.00.37.17 (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Tue, 27 Jan 2015 00:37:17 -0800 (PST) From: Viresh Kumar To: Rafael Wysocki Cc: linaro-kernel@lists.linaro.org, linux-pm@vger.kernel.org, sboyd@codeaurora.org, prarit@redhat.com, skannan@codeaurora.org, Viresh Kumar Subject: [PATCH 10/18] cpufreq: Don't allow updating inactive-policies from sysfs Date: Tue, 27 Jan 2015 14:06:16 +0530 Message-Id: <935ec6b1fe24e17a95c71cfb01ea1bf27d03a5d5.1422346933.git.viresh.kumar@linaro.org> X-Mailer: git-send-email 2.3.0.rc0.44.ga94655d In-Reply-To: References: In-Reply-To: References: Sender: linux-pm-owner@vger.kernel.org Precedence: list List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Removed-Original-Auth: Dkim didn't pass. X-Original-Sender: viresh.kumar@linaro.org X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of patch+caf_=patchwork-forward=linaro.org@linaro.org designates 209.85.215.52 as permitted sender) smtp.mail=patch+caf_=patchwork-forward=linaro.org@linaro.org Mailing-list: list patchwork-forward@linaro.org; contact patchwork-forward+owners@linaro.org X-Google-Group-Id: 836684582541 List-Post: , List-Help: , List-Archive: List-Unsubscribe: , Later commits would change the way policies are managed today. Policies wouldn't be freed on cpu hotplug (currently they aren't freed on suspend), and while the CPU is offline, the sysfs cpufreq files would still be present. User may accidentally try to update the sysfs files in following directory: '/sys/devices/system/cpu/cpuX/cpufreq/'. And that would result in undefined behavior as policy wouldn't be active then. To disallow such accesses, sense if a policy is active or not while doing such operations. This can be done easily by getting the policy again with cpufreq_cpu_get_raw(), as that would traverse the list of active policies. Apart from updating the store() routine, we also update __cpufreq_get() which can call cpufreq_out_of_sync(). The later routine tries to update policy->cur and start notifying kernel about it. Signed-off-by: Viresh Kumar --- drivers/cpufreq/cpufreq.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index ed36c09f83cc..fffa37136b7b 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -826,11 +826,22 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr, down_write(&policy->rwsem); + /* + * Policy might not be active currently, and so we shouldn't try + * updating any values here. An inactive policy is moved to fallback + * list and so cpufreq_cpu_get_raw() should fail. + */ + if (unlikely(!cpufreq_cpu_get_raw(policy->cpu))) { + ret = -EPERM; + goto unlock_policy_rwsem; + } + if (fattr->store) ret = fattr->store(policy, buf, count); else ret = -EIO; +unlock_policy_rwsem: up_write(&policy->rwsem); up_read(&cpufreq_rwsem); @@ -1587,6 +1598,14 @@ static unsigned int __cpufreq_get(struct cpufreq_policy *policy) ret_freq = cpufreq_driver->get(policy->cpu); + /* + * Policy might not be active currently, and so we shouldn't try + * updating any values here. An inactive policy is moved to fallback + * list and so cpufreq_cpu_get_raw() should fail. + */ + if (unlikely(!cpufreq_cpu_get_raw(policy->cpu))) + return ret_freq; + if (ret_freq && policy->cur && !(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) { /* verify no discrepancy between actual and