linux-kernel - Re: [PATCH] drm/amdgpu: do not initialise global variables to 0 or NULL

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Message-ID: <bc1fcda4-d229-c5a1-bea4-eda646a12bd0@amd.com>
Date:   Tue, 3 Nov 2020 09:23:51 +0100
From:   Christian König <christian.koenig@....com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Alex Deucher <alexdeucher@...il.com>,
        Deepak R Varma <mh12gx2825@...il.com>,
        David Airlie <airlied@...ux.ie>,
        LKML <linux-kernel@...r.kernel.org>,
        Maling list - DRI developers 
        <dri-devel@...ts.freedesktop.org>,
        Melissa Wen <melissa.srw@...il.com>,
        amd-gfx list <amd-gfx@...ts.freedesktop.org>,
        Daniel Vetter <daniel@...ll.ch>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Alex Deucher <alexander.deucher@....com>
Subject: Re: [PATCH] drm/amdgpu: do not initialise global variables to 0 or
 NULL

Am 03.11.20 um 08:53 schrieb Greg KH:
> On Mon, Nov 02, 2020 at 09:48:25PM +0100, Christian König wrote:
>> Am 03.11.20 um 07:53 schrieb Greg KH:
>>> On Mon, Nov 02, 2020 at 09:06:21PM +0100, Christian König wrote:
>>>> Am 02.11.20 um 20:43 schrieb Alex Deucher:
>>>>> On Mon, Nov 2, 2020 at 1:42 PM Deepak R Varma <mh12gx2825@...il.com> wrote:
>>>>>> Initializing global variable to 0 or NULL is not necessary and should
>>>>>> be avoided. Issue reported by checkpatch script as:
>>>>>> ERROR: do not initialise globals to 0 (or NULL).
>>>>> I agree that this is technically correct, but a lot of people don't
>>>>> seem to know that so we get a lot of comments about this code for the
>>>>> variables that are not explicitly set.  Seems less confusing to
>>>>> initialize them even if it not necessary.  I don't have a particularly
>>>>> strong opinion on it however.
>>>> Agree with Alex.
>>>>
>>>> Especially for the module parameters we should have a explicit init value
>>>> for documentation purposes, even when it is 0.
>>> Why is this one tiny driver somehow special compared to the entire rest
>>> of the kernel?  (hint, it isn't...)
>> And it certainly shouldn't :)
>>
>>> Please follow the normal coding style rules, there's no reason to ignore
>>> them unless you like to constantly reject patches like this that get
>>> sent to you.
>> Yeah, that's a rather good point.
>>
>> Not a particular strong opinion on this either, but when something global is
>> set to 0 people usually do this to emphases that it is important that it is
>> zero.
> Again, no, that's not what we have been doing in the kernel for the past
> 20+ years.  If you do not set it to anything, we all know it is
> important for it to be set to 0.  Otherwise we would explicitly set it
> to something else.  And if we don't care, then that too doesn't matter
> so we let it be 0 by not initializing it, it doesn't matter.
>
> I think this very change is what started the whole "kernel janitor"
> movement all those years ago, because it was easily proven that this
> simple change saved both time and memory.

Ok, well that is even better because it is a technical argument.

You have convinced me, the patch is Reviewed-by: Christian König 
<christian.koenig@....com>.

Regards,
Christian.

>
> This shouldn't even be an argument we are having anymore...
>
> thanks,
>
> greg k-h