linux-kernel - Re: [PATCH 1/2] staging: dgnc: remove redundant NULL check for brd

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Message-ID: <CAHb8M2Cs4qi2vamBVBNZpvUZNQrSNpz_zxs8yNbzedboL_oGsw@mail.gmail.com>
Date:	Fri, 27 May 2016 10:31:53 +0900
From:	DaeSeok Youn <daeseok.youn@...il.com>
To:	Luis de Bethencourt <luisbg@....samsung.com>
Cc:	Lidza Louina <lidza.louina@...il.com>,
	devel <devel@...verdev.osuosl.org>,
	Greg KH <gregkh@...uxfoundation.org>,
	"driverdev-devel@...uxdriverproject.org" 
	<driverdev-devel@...uxdriverproject.org>,
	kernel-janitors <kernel-janitors@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] staging: dgnc: remove redundant NULL check for brd

2016-05-26 21:29 GMT+09:00 Luis de Bethencourt <luisbg@....samsung.com>:
> On 26/05/16 05:56, DaeSeok Youn wrote:
>> 2016-05-26 6:48 GMT+09:00 Luis de Bethencourt <luisbg@....samsung.com>:
>>> On 20/05/16 10:51, Daeseok Youn wrote:
>>>> the "brd" value cannot be NULL in dgnc_finalize_board_init().
>>>> Because "brd" as a parameter of this function was already
>>>> checked for NULL.
>>>>
>>>> Signed-off-by: Daeseok Youn <daeseok.youn@...il.com>
>>>> ---
>>>>  drivers/staging/dgnc/dgnc_driver.c | 3 ---
>>>>  1 file changed, 3 deletions(-)
>>>>
>>>> diff --git a/drivers/staging/dgnc/dgnc_driver.c b/drivers/staging/dgnc/dgnc_driver.c
>>>> index af2e835..22257d2 100644
>>>> --- a/drivers/staging/dgnc/dgnc_driver.c
>>>> +++ b/drivers/staging/dgnc/dgnc_driver.c
>>>> @@ -579,9 +579,6 @@ static int dgnc_finalize_board_init(struct dgnc_board *brd)
>>>>  {
>>>>       int rc = 0;
>>>>
>>>> -     if (!brd || brd->magic != DGNC_BOARD_MAGIC)
>>>> -             return -ENODEV;
>>>> -
>>>>       if (brd->irq) {
>>>>               rc = request_irq(brd->irq, brd->bd_ops->intr,
>>>>                                IRQF_SHARED, "DGNC", brd);
>>>>
>>>
>>> This is partially correct, the check for brd being NULL is in line 371.
>> Hi Luis,
>>
>> Yes, right. but also brd was assigned the value DGNC_BOARD_MAGIC in line 384.
>> brd->magic = DGNC_BOARD_MAGIC;
>> and also dgnc_finalize_board_init() as a static function is only
>> called in dgnc_found_board(), right?
>>
>>>
>>> But there is a second check for brd->magic != DGNC_BOARD_MAGIC. Do you want
>>> to keep that one?
>> So.. I think it doesn't need to check about DGNC_BOARD_MAGIC.
>
> This is good. I was asking just to make sure it was your intention.
>
> Please add the reason to drop that second check in the commit message as well. So people
> reading the git log can understand both parts. For both patches.
OK. I will update the change log and resend it.

Thanks.

regards,
Daeseok.
>
> Thanks for the fixes :)
>
> Luis
>
>>
>>>
>>> Also, how did you find this patch. It is useful to mention this in the commit
>>> message if it was through some static analysis tool. For people using these tools
>>> in the future.
>> There are some static analysis tool for checking linux kernel code.
>> But I didn't use
>> those tools for this patch. sometimes, I usually run "smatch" tool for
>> checking linux kernel
>> code.
>>
>> thanks.
>> regards,
>> Daeseok.
>>
>>>
>>> Thanks for the patch :)
>>> Luis
>