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From: Andy Walls <awalls@md.metrocast.net>
To: Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: Hans Verkuil <hverkuil@xs4all.nl>,
	Sakari Ailus <sakari.ailus@iki.fi>,
	linux-media@vger.kernel.org, laurent.pinchart@ideasonboard.com,
	remi@remlab.net, nbowler@elliptictech.com,
	james.dutton@gmail.com
Subject: Re: [RFC v3 1/2] v4l: Do not use enums in IOCTL structs
Date: Wed, 02 May 2012 20:42:59 -0400	[thread overview]
Message-ID: <1336005780.24477.7.camel@palomino.walls.org> (raw)
In-Reply-To: <4FA1B27A.2030405@redhat.com>

On Wed, 2012-05-02 at 19:17 -0300, Mauro Carvalho Chehab wrote:

> We can speed-up the conversions, with something like:
> 
> enum foo {
> 	BAR
> };
> 
> if (sizeof(foo) != sizeof(u32))
> 	call_compat_logic().
> 
> I suspect that sizeof() won't work inside a macro. 

sizeof() is evaluated at compile time, after preprocessing. 
It should work inside of a macro.

See the ARRAY_SIZE() macro in include/linux/kernel.h for a well tested
example.

Regards,
Andy




  reply	other threads:[~2012-05-03  0:43 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-05-02 19:13 [RFC v2 0/2] V4L2 IOCTL enum compat wrapper Sakari Ailus
2012-05-02 19:13 ` [RFC v3 1/2] v4l: Do not use enums in IOCTL structs Sakari Ailus
2012-05-02 20:45   ` Hans Verkuil
2012-05-02 21:39     ` Sakari Ailus
2012-05-03  7:02       ` Hans Verkuil
2012-05-03 13:42         ` Mauro Carvalho Chehab
2012-05-03 14:12           ` Hans Verkuil
2012-05-03 10:57       ` Rémi Denis-Courmont
2012-05-03 10:58         ` Rémi Denis-Courmont
2012-05-03 12:20           ` Sakari Ailus
2012-05-02 22:17     ` Mauro Carvalho Chehab
2012-05-03  0:42       ` Andy Walls [this message]
2012-05-03 10:22         ` Mauro Carvalho Chehab
2012-05-03 10:35           ` Sakari Ailus
2012-05-03 12:07             ` Mauro Carvalho Chehab
2012-05-03 10:45           ` Sylwester Nawrocki
2012-05-03 23:02           ` Andy Walls
2012-05-03 10:39         ` Mauro Carvalho Chehab
2012-05-02 19:13 ` [RFC v3 2/2] v4l: Implement compat functions for enum to __u32 change Sakari Ailus
2012-05-02 22:32   ` Mauro Carvalho Chehab
2012-05-02 23:38     ` Laurent Pinchart
2012-05-03 12:20       ` Mauro Carvalho Chehab

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