From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759652AbaHHWbE (ORCPT ); Fri, 8 Aug 2014 18:31:04 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:40176 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756521AbaHHUlu (ORCPT ); Fri, 8 Aug 2014 16:41:50 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Viresh Kumar , "Rafael J. Wysocki" , Kamal Mostafa Subject: [PATCH 3.13 148/259] cpufreq: move policy kobj to policy->cpu at resume Date: Fri, 8 Aug 2014 13:39:31 -0700 Message-Id: <1407530482-4483-149-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1407530482-4483-1-git-send-email-kamal@canonical.com> References: <1407530482-4483-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11.6 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Viresh Kumar commit 92c14bd9477a20a83144f08c0ca25b0308bf0730 upstream. This is only relevant to implementations with multiple clusters, where clusters have separate clock lines but all CPUs within a cluster share it. Consider a dual cluster platform with 2 cores per cluster. During suspend we start hot unplugging CPUs in order 1 to 3. When CPU2 is removed, policy->kobj would be moved to CPU3 and when CPU3 goes down we wouldn't free policy or its kobj as we want to retain permissions/values/etc. Now on resume, we will get CPU2 before CPU3 and will call __cpufreq_add_dev(). We will recover the old policy and update policy->cpu from 3 to 2 from update_policy_cpu(). But the kobj is still tied to CPU3 and isn't moved to CPU2. We wouldn't create a link for CPU2, but would try that for CPU3 while bringing it online. Which will report errors as CPU3 already has kobj assigned to it. This bug got introduced with commit 42f921a, which overlooked this scenario. To fix this, lets move kobj to the new policy->cpu while bringing first CPU of a cluster back. Also do a WARN_ON() if kobject_move failed, as we would reach here only for the first CPU of a non-boot cluster. And we can't recover from this situation, if kobject_move() fails. Fixes: 42f921a6f10c (cpufreq: remove sysfs files for CPUs which failed to come back after resume) Reported-and-tested-by: Bu Yitian Reported-by: Saravana Kannan Reviewed-by: Srivatsa S. Bhat Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki [ kamal: backport to 3.13-stable (context) ] Signed-off-by: Kamal Mostafa --- drivers/cpufreq/cpufreq.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 99a443e..c166b4a 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1031,10 +1031,12 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif, * the creation of a brand new one. So we need to perform this update * by invoking update_policy_cpu(). */ - if (frozen && cpu != policy->cpu) + if (frozen && cpu != policy->cpu) { update_policy_cpu(policy, cpu); - else + WARN_ON(kobject_move(&policy->kobj, &dev->kobj)); + } else { policy->cpu = cpu; + } policy->governor = CPUFREQ_DEFAULT_GOVERNOR; cpumask_copy(policy->cpus, cpumask_of(cpu)); -- 1.9.1