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Subject: Re: [PATCH] crypto: hisilicon - check if debugfs opened
To:     Greg KH <gregkh@linuxfoundation.org>
References: <1616833980-11006-1-git-send-email-tanghui20@huawei.com>
 <YGCcQnFHXEMW9Jz/@kroah.com>
 <17d627e8-b89a-bbb8-f5d7-11210b859ac7@huawei.com>
 <YGMYKquXSaju9H+A@kroah.com>
CC:     <herbert@gondor.apana.org.au>, <davem@davemloft.net>,
        <linux-crypto@vger.kernel.org>, <xuzaibo@huawei.com>,
        <wangzhou1@hisilicon.com>, <linux-kernel@vger.kernel.org>
From:   tanghui20 <tanghui20@huawei.com>
Message-ID: <4b3dc5bb-e6d0-4cfb-c3ca-d3b652879823@huawei.com>
Date:   Tue, 30 Mar 2021 20:40:07 +0800
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On 2021/3/30 20:23, Greg KH wrote:
> On Tue, Mar 30, 2021 at 08:09:46PM +0800, tanghui20 wrote:
>>
>>
>> On 2021/3/28 23:09, Greg KH wrote:
>>> On Sat, Mar 27, 2021 at 04:33:00PM +0800, Hui Tang wrote:
>>>> 'xx_debugfs_init' check if debugfs opened.
>>>>
>>>> Signed-off-by: Hui Tang <tanghui20@huawei.com>
>>>> ---
>>>>  drivers/crypto/hisilicon/hpre/hpre_main.c | 5 ++++-
>>>>  drivers/crypto/hisilicon/qm.c             | 3 +++
>>>>  drivers/crypto/hisilicon/sec2/sec_main.c  | 5 ++++-
>>>>  drivers/crypto/hisilicon/zip/zip_main.c   | 3 +++
>>>>  4 files changed, 14 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/crypto/hisilicon/hpre/hpre_main.c b/drivers/crypto/hisilicon/hpre/hpre_main.c
>>>> index c7ab06d..f2605c4 100644
>>>> --- a/drivers/crypto/hisilicon/hpre/hpre_main.c
>>>> +++ b/drivers/crypto/hisilicon/hpre/hpre_main.c
>>>> @@ -779,6 +779,9 @@ static int hpre_debugfs_init(struct hisi_qm *qm)
>>>>  	struct device *dev = &qm->pdev->dev;
>>>>  	int ret;
>>>>
>>>> +	if (!debugfs_initialized())
>>>> +		return -ENOENT;
>>>
>>> Why?  What does this help with?  Why does the code care if debugfs is
>>> running or not?
>>>
>> When !CONFIG_DEBUG_FS, there is no problem if debugfs is not checked,
>> but if checking debugfs, a series of stub functions of debugfs can be
>> skipped and 'xx_debugfs_init' will be return immediately.
>
> And have you measured an actual speed difference for that?  I would be
> amazed if you could...
>

I think what you said makes sense.
I am confused when to use 'debugfs_initialized'.

Thanks