From nobody Fri Dec 19 15:52:07 2025 Received: from canpmsgout03.his.huawei.com (canpmsgout03.his.huawei.com [113.46.200.218]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DC6F32DFA54; Tue, 16 Dec 2025 03:11:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=113.46.200.218 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765854720; cv=none; b=E5YHYlrezkO1iLvrtsYRqXWYnMbxQdc6nfksK2dzC1Zhkid9ZVy5gvwwu3hb3OoCgg5GVIs5alHI0dLo/wTqondJPyN4+g8KdUOa6rRKAf9vm/UP22GDaBvww9WUdAZ7NnqQsEfdm9vpP6gXJaekct5Fy1qKRk2mDDNqAiNYid0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765854720; c=relaxed/simple; bh=+9Xs7NKOWIT8PTSx+wZ0+myyGBHe3hy2rOz60DtsJ+E=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=YoJ3x87JTwYfff7Nf/5Ga1Hu6hfGsHP41WXQXRIAOTmbSyGkABU2fNej/GrgdTVqkV9szrEItbydtRffWyZhYa1bVQFlYpfyAhyouKjULH2yLBPidgv2w/QMA5H8lJssUOxnAC6lw1hRfcidGzzWSz/pOVUdaJ6sHHVu0yXAZts= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b=W7j8I0br; arc=none smtp.client-ip=113.46.200.218 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b="W7j8I0br" dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=6uNVjK19RCa/YM6Kz8qwWD4i5YK9Fc8dRpq1+OHXIhE=; b=W7j8I0brb+bYWFTjB9pAfjuIAbCKaYuYmoGvQJrBRUqhNwP27MisfbezNLgO6wnktPxI79n7F O60oZAwOFVXoX+eve3GCeA9nylueto+aO2xlviqYRR6LCrpr1EYq7fUMDVv5PutwrAlSmRQZumW Lj/mfnrX24ECDjf7w/udurc= Received: from mail.maildlp.com (unknown [172.19.163.174]) by canpmsgout03.his.huawei.com (SkyGuard) with ESMTPS id 4dVhjN1tPJzpSvn; Tue, 16 Dec 2025 11:09:12 +0800 (CST) Received: from kwepemr200004.china.huawei.com (unknown [7.202.195.241]) by mail.maildlp.com (Postfix) with ESMTPS id 282C514011A; Tue, 16 Dec 2025 11:11:54 +0800 (CST) Received: from huawei.com (10.50.163.32) by kwepemr200004.china.huawei.com (7.202.195.241) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Tue, 16 Dec 2025 11:11:53 +0800 From: Pengjie Zhang To: , , CC: , , , , , , , , , , Subject: [PATCH v5] PM / devfreq: use _visible attribute to replace create/remove_sysfs_files() Date: Tue, 16 Dec 2025 11:11:53 +0800 Message-ID: <20251216031153.2242306-1-zhangpengjie2@huawei.com> X-Mailer: git-send-email 2.33.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: kwepems100002.china.huawei.com (7.221.188.206) To kwepemr200004.china.huawei.com (7.202.195.241) Content-Type: text/plain; charset="utf-8" Previously, non-generic attributes (polling_interval, timer) used separate create/delete logic, leading to race conditions during concurrent access in creation/deletion. Multi-threaded operations also caused inconsistencies between governor capabilities and attribute states. 1.Use is_visible + sysfs_update_group() to unify management of these attributes, eliminating creation/deletion races. 2.Add locks and validation to these attributes, ensuring consistency between current governor capabilities and attribute operations in multi-threaded environments. Reviewed-by: Jonathan Cameron Reviewed-by: Jie Zhan Signed-off-by: Pengjie Zhang --- changes in v5: -Remove the curly braces of an if statement -Added a note explaining why locking is necessary. Link to v4:https://lore.kernel.org/all/20251205083724.4068896-1-zhangpengji= e2@huawei.com/ changes in v4: -Remove the DEFINE_SYSFS_GROUP_VISIBLE macro and directly set the is_visibl= e function. -Remove unnecessary ret variables Link to v3:https://lore.kernel.org/lkml/20251107031706.1698396-1-zhangpengj= ie2@huawei.com/ changes in v3: - Use guard() to simplify lock acquisition and destruction. - Eliminate redundant checks for df. Link to v2:https://lore.kernel.org/lkml/20251028022458.2824872-1-zhangpengj= ie2@huawei.com/ Changes in v2:=20 - Fix one problem reported by the kernel test robot. - Redirect all error paths in timer_store() to out to ensure locks are not=20 left unReleased. Link to v1:https://lore.kernel.org/lkml/20251025135238.3576861-1-zhangpengj= ie2@huawei.com/ drivers/devfreq/devfreq.c | 103 ++++++++++++++++++++++---------------- 1 file changed, 60 insertions(+), 43 deletions(-) diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 2e8d01d47f69..7673a39baaa6 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -38,6 +38,7 @@ =20 static struct class *devfreq_class; static struct dentry *devfreq_debugfs; +static const struct attribute_group gov_attr_group; =20 /* * devfreq core provides delayed work based load monitoring helper @@ -785,11 +786,6 @@ static void devfreq_dev_release(struct device *dev) kfree(devfreq); } =20 -static void create_sysfs_files(struct devfreq *devfreq, - const struct devfreq_governor *gov); -static void remove_sysfs_files(struct devfreq *devfreq, - const struct devfreq_governor *gov); - /** * devfreq_add_device() - Add devfreq feature to the device * @dev: the device to add devfreq feature. @@ -956,7 +952,10 @@ struct devfreq *devfreq_add_device(struct device *dev, __func__); goto err_init; } - create_sysfs_files(devfreq, devfreq->governor); + + err =3D sysfs_update_group(&devfreq->dev.kobj, &gov_attr_group); + if (err) + goto err_init; =20 list_add(&devfreq->node, &devfreq_list); =20 @@ -995,12 +994,9 @@ int devfreq_remove_device(struct devfreq *devfreq) =20 devfreq_cooling_unregister(devfreq->cdev); =20 - if (devfreq->governor) { + if (devfreq->governor) devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_STOP, NULL); - remove_sysfs_files(devfreq, devfreq->governor); - } - device_unregister(&devfreq->dev); =20 return 0; @@ -1460,7 +1456,6 @@ static ssize_t governor_store(struct device *dev, str= uct device_attribute *attr, __func__, df->governor->name, ret); goto out; } - remove_sysfs_files(df, df->governor); =20 /* * Start the new governor and create the specific sysfs files @@ -1489,7 +1484,7 @@ static ssize_t governor_store(struct device *dev, str= uct device_attribute *attr, * Create the sysfs files for the new governor. But if failed to start * the new governor, restore the sysfs files of previous governor. */ - create_sysfs_files(df, df->governor); + ret =3D sysfs_update_group(&df->dev.kobj, &gov_attr_group); =20 out: mutex_unlock(&devfreq_list_lock); @@ -1807,14 +1802,17 @@ static struct attribute *devfreq_attrs[] =3D { &dev_attr_trans_stat.attr, NULL, }; -ATTRIBUTE_GROUPS(devfreq); =20 static ssize_t polling_interval_show(struct device *dev, struct device_attribute *attr, char *buf) { struct devfreq *df =3D to_devfreq(dev); =20 - if (!df->profile) + /* Protect against race between sysfs attrs update and read/write */ + guard(mutex)(&devfreq_list_lock); + + if (!df->profile || !df->governor || + !IS_SUPPORTED_ATTR(df->governor->attrs, POLLING_INTERVAL)) return -EINVAL; =20 return sprintf(buf, "%d\n", df->profile->polling_ms); @@ -1828,7 +1826,10 @@ static ssize_t polling_interval_store(struct device = *dev, unsigned int value; int ret; =20 - if (!df->governor) + guard(mutex)(&devfreq_list_lock); + + if (!df->governor || + !IS_SUPPORTED_ATTR(df->governor->attrs, POLLING_INTERVAL)) return -EINVAL; =20 ret =3D sscanf(buf, "%u", &value); @@ -1847,7 +1848,10 @@ static ssize_t timer_show(struct device *dev, { struct devfreq *df =3D to_devfreq(dev); =20 - if (!df->profile) + guard(mutex)(&devfreq_list_lock); + + if (!df->profile || !df->governor || + !IS_SUPPORTED_ATTR(df->governor->attrs, TIMER)) return -EINVAL; =20 return sprintf(buf, "%s\n", timer_name[df->profile->timer]); @@ -1861,7 +1865,10 @@ static ssize_t timer_store(struct device *dev, struc= t device_attribute *attr, int timer =3D -1; int ret =3D 0, i; =20 - if (!df->governor || !df->profile) + guard(mutex)(&devfreq_list_lock); + + if (!df->governor || !df->profile || + !IS_SUPPORTED_ATTR(df->governor->attrs, TIMER)) return -EINVAL; =20 ret =3D sscanf(buf, "%16s", str_timer); @@ -1905,37 +1912,47 @@ static ssize_t timer_store(struct device *dev, stru= ct device_attribute *attr, } static DEVICE_ATTR_RW(timer); =20 -#define CREATE_SYSFS_FILE(df, name) \ -{ \ - int ret; \ - ret =3D sysfs_create_file(&df->dev.kobj, &dev_attr_##name.attr); \ - if (ret < 0) { \ - dev_warn(&df->dev, \ - "Unable to create attr(%s)\n", "##name"); \ - } \ -} \ +static struct attribute *governor_attrs[] =3D { + &dev_attr_polling_interval.attr, + &dev_attr_timer.attr, + NULL +}; =20 -/* Create the specific sysfs files which depend on each governor. */ -static void create_sysfs_files(struct devfreq *devfreq, - const struct devfreq_governor *gov) +static umode_t gov_attr_visible(struct kobject *kobj, + struct attribute *attr, int n) { - if (IS_SUPPORTED_ATTR(gov->attrs, POLLING_INTERVAL)) - CREATE_SYSFS_FILE(devfreq, polling_interval); - if (IS_SUPPORTED_ATTR(gov->attrs, TIMER)) - CREATE_SYSFS_FILE(devfreq, timer); -} + struct device *dev =3D kobj_to_dev(kobj); + struct devfreq *df =3D to_devfreq(dev); =20 -/* Remove the specific sysfs files which depend on each governor. */ -static void remove_sysfs_files(struct devfreq *devfreq, - const struct devfreq_governor *gov) -{ - if (IS_SUPPORTED_ATTR(gov->attrs, POLLING_INTERVAL)) - sysfs_remove_file(&devfreq->dev.kobj, - &dev_attr_polling_interval.attr); - if (IS_SUPPORTED_ATTR(gov->attrs, TIMER)) - sysfs_remove_file(&devfreq->dev.kobj, &dev_attr_timer.attr); + if (!df->governor || !df->governor->attrs) + return 0; + + if (attr =3D=3D &dev_attr_polling_interval.attr && + IS_SUPPORTED_ATTR(df->governor->attrs, POLLING_INTERVAL)) + return attr->mode; + + if (attr =3D=3D &dev_attr_timer.attr && + IS_SUPPORTED_ATTR(df->governor->attrs, TIMER)) + return attr->mode; + + return 0; } =20 +static const struct attribute_group devfreq_group =3D { + .attrs =3D devfreq_attrs, +}; + +static const struct attribute_group gov_attr_group =3D { + .attrs =3D governor_attrs, + .is_visible =3D gov_attr_visible, +}; + +static const struct attribute_group *devfreq_groups[] =3D { + &devfreq_group, + &gov_attr_group, + NULL +}; + /** * devfreq_summary_show() - Show the summary of the devfreq devices * @s: seq_file instance to show the summary of devfreq devices --=20 2.33.0