From patchwork Tue Mar 5 10:37:18 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Rafael J. Wysocki" X-Patchwork-Id: 10839247 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6CD141390 for ; Tue, 5 Mar 2019 10:44:29 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 54FD62A838 for ; Tue, 5 Mar 2019 10:44:29 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 48CB32A8D7; Tue, 5 Mar 2019 10:44:29 +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=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, 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 1A9B22A838 for ; Tue, 5 Mar 2019 10:44:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727450AbfCEKo1 (ORCPT ); Tue, 5 Mar 2019 05:44:27 -0500 Received: from cloudserver094114.home.pl ([79.96.170.134]:42331 "EHLO cloudserver094114.home.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727362AbfCEKo1 (ORCPT ); Tue, 5 Mar 2019 05:44:27 -0500 Received: from 79.184.253.110.ipv4.supernova.orange.pl (79.184.253.110) (HELO aspire.rjw.lan) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.83.213) id f28a257d37f4d0ac; Tue, 5 Mar 2019 11:44:24 +0100 From: "Rafael J. Wysocki" To: Linux PM Cc: LKML , Viresh Kumar , Srinivas Pandruvada , Chen Yu , Gabriele Mazzotta Subject: [PATCH v2 2/3] cpufreq: Add cpufreq_cpu_acquire() and cpufreq_cpu_release() Date: Tue, 05 Mar 2019 11:37:18 +0100 Message-ID: <2924036.MijKVBYPyq@aspire.rjw.lan> In-Reply-To: <1755407.S0oJirvq9V@aspire.rjw.lan> References: <1755407.S0oJirvq9V@aspire.rjw.lan> 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 It sometimes is necessary to find a cpufreq policy for a given CPU and acquire its rwsem (for writing) immediately after that, so introduce cpufreq_cpu_acquire() as a helper for that and the complementary cpufreq_cpu_release(). Make cpufreq_update_policy() use the new functions. Signed-off-by: Rafael J. Wysocki --- -> v2: New patch. --- drivers/cpufreq/cpufreq.c | 56 ++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 47 insertions(+), 9 deletions(-) Index: linux-pm/drivers/cpufreq/cpufreq.c =================================================================== --- linux-pm.orig/drivers/cpufreq/cpufreq.c +++ linux-pm/drivers/cpufreq/cpufreq.c @@ -256,6 +256,51 @@ void cpufreq_cpu_put(struct cpufreq_poli } EXPORT_SYMBOL_GPL(cpufreq_cpu_put); +/** + * cpufreq_cpu_release - Unlock a policy and decrement its usage counter. + * @policy: cpufreq policy returned by cpufreq_cpu_acquire(). + */ +static void cpufreq_cpu_release(struct cpufreq_policy *policy) +{ + if (WARN_ON(!policy)) + return; + + lockdep_assert_held(&policy->rwsem); + + up_write(&policy->rwsem); + + cpufreq_cpu_put(policy); +} + +/** + * cpufreq_cpu_acquire - Find policy for a CPU, mark it as busy and lock it. + * @cpu: CPU to find the policy for. + * + * Call cpufreq_cpu_get() to get a reference on the cpufreq policy for @cpu and + * if the policy returned by it is not NULL, acquire its rwsem for writing. + * Return the policy if it is active or release it and return NULL otherwise. + * + * The policy returned by this function has to be released with the help of + * cpufreq_cpu_release() in order to release its rwsem and balance its usage + * counter properly. + */ +static struct cpufreq_policy *cpufreq_cpu_acquire(unsigned int cpu) +{ + struct cpufreq_policy *policy = cpufreq_cpu_get(cpu); + + if (!policy) + return NULL; + + down_write(&policy->rwsem); + + if (policy_is_inactive(policy)) { + cpufreq_cpu_release(policy); + return NULL; + } + + return policy; +} + /********************************************************************* * EXTERNALLY AFFECTING FREQUENCY CHANGES * *********************************************************************/ @@ -2343,17 +2388,12 @@ static int cpufreq_set_policy(struct cpu */ void cpufreq_update_policy(unsigned int cpu) { - struct cpufreq_policy *policy = cpufreq_cpu_get(cpu); + struct cpufreq_policy *policy = cpufreq_cpu_acquire(cpu); struct cpufreq_policy new_policy; if (!policy) return; - down_write(&policy->rwsem); - - if (policy_is_inactive(policy)) - goto unlock; - /* * BIOS might change freq behind our back * -> ask driver for current freq and notify governors about a change @@ -2370,9 +2410,7 @@ void cpufreq_update_policy(unsigned int cpufreq_set_policy(policy, &new_policy); unlock: - up_write(&policy->rwsem); - - cpufreq_cpu_put(policy); + cpufreq_cpu_release(policy); } EXPORT_SYMBOL(cpufreq_update_policy);