linux-kernel - Re: [PATCH] drm: move allocation out of drm_get_format_name()

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Message-ID: <CAF6AEGuEB82fjZ_YF61MAAqU=8ahXuMo06MN0_ZuWY5fkyHnoQ@mail.gmail.com>
Date:   Sat, 5 Nov 2016 12:49:01 -0400
From:   Rob Clark <robdclark@...il.com>
To:     Eric Engestrom <eric@...estrom.ch>
Cc:     Christian König <christian.koenig@....com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Wei Yongjun <yongjun_wei@...ndmicro.com.cn>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Flora Cui <Flora.Cui@....com>,
        Gustavo Padovan <gustavo.padovan@...labora.co.uk>,
        Tom St Denis <tom.stdenis@....com>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        Xinliang Liu <z.liuxinliang@...ilicon.com>,
        VMware Graphics <linux-graphics-maintainer@...are.com>,
        Vitaly Prosyak <vitaly.prosyak@....com>,
        Alexandre Demers <alexandre.f.demers@...il.com>,
        Intel Graphics Development <intel-gfx@...ts.freedesktop.org>,
        Emily Deng <Emily.Deng@....com>,
        Ken Wang <Qingqing.Wang@....com>,
        Junwei Zhang <Jerry.Zhang@....com>,
        Michel Dänzer <michel.daenzer@....com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Alex Deucher <alexander.deucher@....com>,
        Colin Ian King <colin.king@...onical.com>
Subject: Re: [PATCH] drm: move allocation out of drm_get_format_name()

On Sat, Nov 5, 2016 at 12:38 PM, Eric Engestrom <eric@...estrom.ch> wrote:
> On Saturday, 2016-11-05 13:11:36 +0100, Christian König wrote:
>> Am 05.11.2016 um 02:33 schrieb Eric Engestrom:
>> > +typedef char drm_format_name_buf[32];
>>
>> Please don't use a typedef for this, just define the maximum size of
>> characters the function might write somewhere.
>>
>> See the kernel coding style as well:
>> > In general, a pointer, or a struct that has elements that can reasonably
>> > be directly accessed should **never** be a typedef.
>>
>
> I would normally agree as I tend to hate typedefs ($DAYJOB {ab,mis}uses
> them way too much), and your way was what I wrote at first, but Rob Clark's
> typedef idea makes it much harder for someone to allocate a buffer of
> the wrong size, which IMO is good thing here.

IMHO I would make a small test program to verify this actually helps
the compiler catch problems.  And if it does, I would stick with it.
The coding-style should be guidelines, not something that supersedes
common sense / practicality.

That is my $0.02 anyways.. if others vehemently disagree and want to
dogmatically stick to the coding-style guidelines, ok then.  OTOH, if
this approach doesn't help the compiler catch issues, then it isn't
worth it.

BR,
-R

> I can rewrite the typedef out if you think it's better.
>
> Cheers,
>   Eric
> _______________________________________________
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> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

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