From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from canpmsgout01.his.huawei.com (canpmsgout01.his.huawei.com [113.46.200.216]) (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 50B3B24677A; Sun, 4 Jan 2026 02:41:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=113.46.200.216 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767494469; cv=none; b=b35AN0OzzRBpMEtusJ1eDeBE1T9hFT/NJheJnLda81W2pQvPjF3hXrBpq0qysMt0LrIlL65B9dp7quks7vLv/K2p6+aCDj7C1q1sARLiKOu4gMDJeMRKryYxzhOGY5+cJxTncrNxV2DUTx3GTaHF92XeqizCKwJgCXrv8osJJCM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767494469; c=relaxed/simple; bh=TQHpzrwoQ28NDVKC+pDXMsp73dIDCLWwSbsV+GFBH58=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=Ac3wYoLtsRHz6wuXRb8YePpDDx++fAz5GMxLrvtQvg55axMXFAoQEBhVTjsNodyUzEloqtjqlgZhAagxiJDF4ktgCIO37IdIHb/yFABTK2qZtM0O8tSszj94pBgsLUQAFpXeKa8VoVWh78e2HpAtTSHSlUpKaI5gkh6CobP4NHA= 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=OtaWa7wd; arc=none smtp.client-ip=113.46.200.216 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="OtaWa7wd" dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=Eshj1pMdOkNSTmIqxXIMTa4E03hzJgGq2pDyzNFRaTs=; b=OtaWa7wdLA13kJlNO/94WQ2Jj8drLXq0BcBoLS7UnF3ihl5I090G6sqljOrImec8SuwnLNCqF 1mlOG/ewO90mRFBga60bkauEDo2ZCzAuIJ8wnDa1/lfY3NJEPeCoe2rJzfyHZ/5zr6fYCQ/0HSp ayOIiT9btBJf4BzZkTbmxwM= Received: from mail.maildlp.com (unknown [172.19.163.0]) by canpmsgout01.his.huawei.com (SkyGuard) with ESMTPS id 4dkM752Nwvz1T4FZ; Sun, 4 Jan 2026 10:38:25 +0800 (CST) Received: from kwepemf200001.china.huawei.com (unknown [7.202.181.227]) by mail.maildlp.com (Postfix) with ESMTPS id 5D5004056B; Sun, 4 Jan 2026 10:41:02 +0800 (CST) Received: from [10.67.121.90] (10.67.121.90) by kwepemf200001.china.huawei.com (7.202.181.227) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Sun, 4 Jan 2026 10:41:01 +0800 Message-ID: <1a50df36-4f56-4ea3-a049-07b909deb3ed@huawei.com> Date: Sun, 4 Jan 2026 10:41:01 +0800 Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5] PM / devfreq: use _visible attribute to replace create/remove_sysfs_files() To: Pengjie Zhang , , , CC: , , , , , , , , References: <20251216031153.2242306-1-zhangpengjie2@huawei.com> From: "zhenglifeng (A)" In-Reply-To: <20251216031153.2242306-1-zhangpengjie2@huawei.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: kwepems500002.china.huawei.com (7.221.188.17) To kwepemf200001.china.huawei.com (7.202.181.227) On 2025/12/16 11:11, Pengjie Zhang wrote: > 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-zhangpengjie2@huawei.com/ > > changes in v4: > -Remove the DEFINE_SYSFS_GROUP_VISIBLE macro and directly set the is_visible function. > -Remove unnecessary ret variables > Link to v3:https://lore.kernel.org/lkml/20251107031706.1698396-1-zhangpengjie2@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-zhangpengjie2@huawei.com/ > > Changes in v2: > - Fix one problem reported by the kernel test robot. > - Redirect all error paths in timer_store() to out to ensure locks are not > left unReleased. > Link to v1:https://lore.kernel.org/lkml/20251025135238.3576861-1-zhangpengjie2@huawei.com/ LGTM. Reviewed-by: Lifeng Zheng > > 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 @@ > > static struct class *devfreq_class; > static struct dentry *devfreq_debugfs; > +static const struct attribute_group gov_attr_group; > > /* > * devfreq core provides delayed work based load monitoring helper > @@ -785,11 +786,6 @@ static void devfreq_dev_release(struct device *dev) > kfree(devfreq); > } > > -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 = sysfs_update_group(&devfreq->dev.kobj, &gov_attr_group); > + if (err) > + goto err_init; > > list_add(&devfreq->node, &devfreq_list); > > @@ -995,12 +994,9 @@ int devfreq_remove_device(struct devfreq *devfreq) > > devfreq_cooling_unregister(devfreq->cdev); > > - 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); > > return 0; > @@ -1460,7 +1456,6 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr, > __func__, df->governor->name, ret); > goto out; > } > - remove_sysfs_files(df, df->governor); > > /* > * Start the new governor and create the specific sysfs files > @@ -1489,7 +1484,7 @@ static ssize_t governor_store(struct device *dev, struct 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 = sysfs_update_group(&df->dev.kobj, &gov_attr_group); > > out: > mutex_unlock(&devfreq_list_lock); > @@ -1807,14 +1802,17 @@ static struct attribute *devfreq_attrs[] = { > &dev_attr_trans_stat.attr, > NULL, > }; > -ATTRIBUTE_GROUPS(devfreq); > > static ssize_t polling_interval_show(struct device *dev, > struct device_attribute *attr, char *buf) > { > struct devfreq *df = to_devfreq(dev); > > - 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; > > 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; > > - if (!df->governor) > + guard(mutex)(&devfreq_list_lock); > + > + if (!df->governor || > + !IS_SUPPORTED_ATTR(df->governor->attrs, POLLING_INTERVAL)) > return -EINVAL; > > ret = sscanf(buf, "%u", &value); > @@ -1847,7 +1848,10 @@ static ssize_t timer_show(struct device *dev, > { > struct devfreq *df = to_devfreq(dev); > > - if (!df->profile) > + guard(mutex)(&devfreq_list_lock); > + > + if (!df->profile || !df->governor || > + !IS_SUPPORTED_ATTR(df->governor->attrs, TIMER)) > return -EINVAL; > > return sprintf(buf, "%s\n", timer_name[df->profile->timer]); > @@ -1861,7 +1865,10 @@ static ssize_t timer_store(struct device *dev, struct device_attribute *attr, > int timer = -1; > int ret = 0, i; > > - if (!df->governor || !df->profile) > + guard(mutex)(&devfreq_list_lock); > + > + if (!df->governor || !df->profile || > + !IS_SUPPORTED_ATTR(df->governor->attrs, TIMER)) > return -EINVAL; > > ret = sscanf(buf, "%16s", str_timer); > @@ -1905,37 +1912,47 @@ static ssize_t timer_store(struct device *dev, struct device_attribute *attr, > } > static DEVICE_ATTR_RW(timer); > > -#define CREATE_SYSFS_FILE(df, name) \ > -{ \ > - int ret; \ > - ret = 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[] = { > + &dev_attr_polling_interval.attr, > + &dev_attr_timer.attr, > + NULL > +}; > > -/* 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 = kobj_to_dev(kobj); > + struct devfreq *df = to_devfreq(dev); > > -/* 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 == &dev_attr_polling_interval.attr && > + IS_SUPPORTED_ATTR(df->governor->attrs, POLLING_INTERVAL)) > + return attr->mode; > + > + if (attr == &dev_attr_timer.attr && > + IS_SUPPORTED_ATTR(df->governor->attrs, TIMER)) > + return attr->mode; > + > + return 0; > } > > +static const struct attribute_group devfreq_group = { > + .attrs = devfreq_attrs, > +}; > + > +static const struct attribute_group gov_attr_group = { > + .attrs = governor_attrs, > + .is_visible = gov_attr_visible, > +}; > + > +static const struct attribute_group *devfreq_groups[] = { > + &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