From: Sakari Ailus <sakari.ailus@linux.intel.com>
To: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Linux Media Mailing List <linux-media@vger.kernel.org>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Subject: Re: [PATCH] v4l2-subdev.h: v4l2_subdev_call: use temp __sd variable
Date: Fri, 8 Feb 2019 11:06:29 +0200 [thread overview]
Message-ID: <20190208090629.vta7rf2vvpzftgsp@paasikivi.fi.intel.com> (raw)
In-Reply-To: <c3a4c93b-e331-b049-fddf-7f7196bc362a@xs4all.nl>
On Fri, Feb 08, 2019 at 09:49:23AM +0100, Hans Verkuil wrote:
> The sd argument of this macro can be a more complex expression. Since it
> is used 5 times in the macro it can be evaluated that many times as well.
>
> So assign it to a temp variable in the beginning and use that instead.
>
> This also avoids any potential side-effects of evaluating sd.
>
> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Nice one!
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
I wonder if this addresses some of the sparse issues related to using a
macro to come up with sd?
> ---
> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> index 47af609dc8f1..34da094a3f40 100644
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
> @@ -1093,13 +1093,14 @@ void v4l2_subdev_init(struct v4l2_subdev *sd,
> */
> #define v4l2_subdev_call(sd, o, f, args...) \
> ({ \
> + struct v4l2_subdev *__sd = (sd); \
> int __result; \
> - if (!(sd)) \
> + if (!__sd) \
> __result = -ENODEV; \
> - else if (!((sd)->ops->o && (sd)->ops->o->f)) \
> + else if (!(__sd->ops->o && __sd->ops->o->f)) \
> __result = -ENOIOCTLCMD; \
> else \
> - __result = (sd)->ops->o->f((sd), ##args); \
> + __result = __sd->ops->o->f(__sd, ##args); \
> __result; \
> })
>
--
Sakari Ailus
sakari.ailus@linux.intel.com
next prev parent reply other threads:[~2019-02-08 9:06 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-08 8:49 [PATCH] v4l2-subdev.h: v4l2_subdev_call: use temp __sd variable Hans Verkuil
2019-02-08 9:06 ` Sakari Ailus [this message]
2019-02-08 9:08 ` Hans Verkuil
2019-02-08 10:37 ` Laurent Pinchart
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