linux-kernel - Re: [PATCH 0/9 linux-next] drivers/gpu/drm: use container

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Date:	Mon, 15 Sep 2014 20:15:54 +0200 (CEST)
From:	Fabian Frederick <fabf@...net.be>
To:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
Cc:	linux-kernel@...r.kernel.org, airlied@...ux.ie,
	dri-devel@...ts.freedesktop.org, peter@...leysoftware.com
Subject: Re: [PATCH 0/9 linux-next] drivers/gpu/drm: use container_of where
 possible



> On 15 September 2014 at 01:13 One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
> wrote:
>
>
> On Sun, 14 Sep 2014 18:40:13 +0200
> Fabian Frederick <fabf@...net.be> wrote:
>
> > Small patchset using container_of instead of casting on first structure
> > member address.
>
> Why. Container_of is useful for random offsets but its just convoluting
> and confusing code which is designed with the fields intentionally at the
> start.
>
> Alan

What if someone doesn't know about that intention one day and inserts
some field in the structure at the "wrong place" ?
This would need at least some comment in each declaration
but once again it's hard to control.One other way is to
commonly use container_of and get rid of every casting with
some semantic script.

Peter has been asking for container_of in the following:

http://marc.info/?l=linux-arm-kernel&m=140838705729653&w=2


struct uart_amba_port *uap = (struct uart_amba_port *)port

(port/uart_port is the first field in uart_amba_port though)

Regards,
Fabian
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