linux-kernel - Re: [PATCH V5 net-next 1/8] debugfs: Add debugfs_create_devm

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Message-ID: <6274cc5a-375f-4009-bc3e-1b1063f298bb@huawei.com>
Date: Mon, 9 Dec 2024 09:02:10 +0800
From: Jijie Shao <shaojijie@...wei.com>
To: Greg KH <gregkh@...uxfoundation.org>
CC: <shaojijie@...wei.com>, <davem@...emloft.net>, <edumazet@...gle.com>,
	<kuba@...nel.org>, <pabeni@...hat.com>, <andrew+netdev@...n.ch>,
	<horms@...nel.org>, <shenjian15@...wei.com>, <wangpeiyang1@...wei.com>,
	<liuyonglong@...wei.com>, <chenhao418@...wei.com>, <sudongming1@...wei.com>,
	<xujunsheng@...wei.com>, <shiyongbang@...wei.com>, <libaihan@...wei.com>,
	<jonathan.cameron@...wei.com>, <shameerali.kolothum.thodi@...wei.com>,
	<salil.mehta@...wei.com>, <netdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <hkelam@...vell.com>
Subject: Re: [PATCH V5 net-next 1/8] debugfs: Add debugfs_create_devm_dir()
 helper


on 2024/12/6 19:40, Greg KH wrote:
> On Fri, Dec 06, 2024 at 07:16:22PM +0800, Jijie Shao wrote:
>> Add debugfs_create_devm_dir() helper
>>
>> Signed-off-by: Jijie Shao <shaojijie@...wei.com>
>> ---
>>   fs/debugfs/inode.c      | 36 ++++++++++++++++++++++++++++++++++++
>>   include/linux/debugfs.h | 10 ++++++++++
>>   2 files changed, 46 insertions(+)
>>
>> diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
>> index 38a9c7eb97e6..f682c4952a27 100644
>> --- a/fs/debugfs/inode.c
>> +++ b/fs/debugfs/inode.c
>> @@ -610,6 +610,42 @@ struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
>>   }
>>   EXPORT_SYMBOL_GPL(debugfs_create_dir);
>>   
>> +static void debugfs_remove_devm(void *dentry_rwa)
>> +{
>> +	struct dentry *dentry = dentry_rwa;
>> +
>> +	debugfs_remove(dentry);
>> +}
>> +
>> +/**
>> + * debugfs_create_devm_dir - Managed debugfs_create_dir()
>> + * @dev: Device that owns the action
>> + * @name: a pointer to a string containing the name of the directory to
>> + *        create.
>> + * @parent: a pointer to the parent dentry for this file.  This should be a
>> + *          directory dentry if set.  If this parameter is NULL, then the
>> + *          directory will be created in the root of the debugfs filesystem.
>> + * Managed debugfs_create_dir(). dentry will automatically be remove on
>> + * driver detach.
>> + */
>> +struct dentry *debugfs_create_devm_dir(struct device *dev, const char *name,
>> +				       struct dentry *parent)
>> +{
>> +	struct dentry *dentry;
>> +	int ret;
>> +
>> +	dentry = debugfs_create_dir(name, parent);
>> +	if (IS_ERR(dentry))
>> +		return dentry;
>> +
>> +	ret = devm_add_action_or_reset(dev, debugfs_remove_devm, dentry);
>> +	if (ret)
>> +		ERR_PTR(ret);
> You don't clean up the directory you created if this failed?  Why not?

Don't need to clean up.
in devm_add_action_or_reset(), if failed, will call action: debugfs_remove_devm(),
So, not clean up again.

#define devm_add_action_or_reset(dev, action, data) \
	__devm_add_action_or_reset(dev, action, data, #action)

static inline int __devm_add_action_or_reset(struct device *dev, void (*action)(void *),
					     void *data, const char *name)
{
	int ret;

	ret = __devm_add_action(dev, action, data, name);
	if (ret)
		action(data);

	return ret;
}

But there's a problem with this, I missed return.
I will add return in v6.

Thanks,
Jijie Shao