From patchwork Mon Nov 29 08:02:48 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiongfeng Wang X-Patchwork-Id: 12643755 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 67184C433F5 for ; Mon, 29 Nov 2021 07:53:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236816AbhK2H5M (ORCPT ); Mon, 29 Nov 2021 02:57:12 -0500 Received: from szxga01-in.huawei.com ([45.249.212.187]:31919 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241805AbhK2HzM (ORCPT ); Mon, 29 Nov 2021 02:55:12 -0500 Received: from dggpemm500021.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4J2cxb5sT0zcbbD; Mon, 29 Nov 2021 15:51:47 +0800 (CST) Received: from dggpemm500002.china.huawei.com (7.185.36.229) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Mon, 29 Nov 2021 15:51:53 +0800 Received: from localhost.localdomain.localdomain (10.175.113.25) by dggpemm500002.china.huawei.com (7.185.36.229) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Mon, 29 Nov 2021 15:51:52 +0800 From: Xiongfeng Wang To: , CC: , , , Subject: [PATCH] cpufreq: Fix get_cpu_device() failed in add_cpu_dev_symlink() Date: Mon, 29 Nov 2021 16:02:48 +0800 Message-ID: <20211129080248.46240-1-wangxiongfeng2@huawei.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-Originating-IP: [10.175.113.25] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpemm500002.china.huawei.com (7.185.36.229) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org When I hot added a CPU, I found 'cpufreq' directory is not created below /sys/devices/system/cpu/cpuX/. It is because get_cpu_device() failed in add_cpu_dev_symlink(). cpufreq_add_dev() is the .add_dev callback of a CPU subsys interface. It will be called when the CPU device registered into the system. The stack is as follows. register_cpu() ->device_register() ->device_add() ->bus_probe_device() ->cpufreq_add_dev() But only after the CPU device has been registered, we can get the CPU device by get_cpu_device(), otherwise it will return NULL. Since we already have the CPU device in cpufreq_add_dev(), pass it to add_cpu_dev_symlink(). I noticed that the 'kobj' of the cpu device has been added into the system before cpufreq_add_dev(). Signed-off-by: Xiongfeng Wang Acked-by: Viresh Kumar --- drivers/cpufreq/cpufreq.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index e338d2f010fe..22aa2793e4d2 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1004,10 +1004,9 @@ static struct kobj_type ktype_cpufreq = { .release = cpufreq_sysfs_release, }; -static void add_cpu_dev_symlink(struct cpufreq_policy *policy, unsigned int cpu) +static void add_cpu_dev_symlink(struct cpufreq_policy *policy, unsigned int cpu, + struct device *dev) { - struct device *dev = get_cpu_device(cpu); - if (unlikely(!dev)) return; @@ -1391,7 +1390,7 @@ static int cpufreq_online(unsigned int cpu) if (new_policy) { for_each_cpu(j, policy->related_cpus) { per_cpu(cpufreq_cpu_data, j) = policy; - add_cpu_dev_symlink(policy, j); + add_cpu_dev_symlink(policy, j, get_cpu_device(j)); } policy->min_freq_req = kzalloc(2 * sizeof(*policy->min_freq_req), @@ -1565,7 +1564,7 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) /* Create sysfs link on CPU registration */ policy = per_cpu(cpufreq_cpu_data, cpu); if (policy) - add_cpu_dev_symlink(policy, cpu); + add_cpu_dev_symlink(policy, cpu, dev); return 0; }