Re: [PATCH 01/23] uvc: Replace memcpy with struct assignment

Laurent Pinchart
2012-10-24T22:35:30Z

Hi Ezequiel,

Thanks for the patch.

On Tuesday 23 October 2012 16:57:04 Ezequiel Garcia wrote:
> This kind of memcpy() is error-prone. Its replacement with a struct
> assignment is prefered because it's type-safe and much easier to read.
>
> Found by coccinelle. Hand patched and reviewed.
> Tested by compilation only.

This looks good, but there's one more memcpy that can be replaced by a direct
structure assignment in uvc_ctrl_add_info()
(drivers/media/usb/uvc/uvc_ctrl.c). You might want to check why it hasn't been
caught by the semantic patch.

> A simplified version of the semantic match that finds this problem is as
> follows: (http://coccinelle.lip6.fr/)
>
> // <smpl>
> @@
> identifier struct_name;
> struct struct_name to;
> struct struct_name from;
> expression E;
> @@
> -memcpy(&(to), &(from), E);
> +to = from;
> // </smpl>
>
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Signed-off-by: Peter Senna Tschudin <peter.senna@gmail.com>
> Signed-off-by: Ezequiel Garcia <elezegarcia@gmail.com>
> ---
> drivers/media/usb/uvc/uvc_v4l2.c | 6 +++---
> 1 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c
> b/drivers/media/usb/uvc/uvc_v4l2.c index f00db30..4fc8737 100644
> --- a/drivers/media/usb/uvc/uvc_v4l2.c
> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> @@ -314,7 +314,7 @@ static int uvc_v4l2_set_format(struct uvc_streaming
> *stream, goto done;
> }
>
> - memcpy(&stream->ctrl, &probe, sizeof probe);
> + stream->ctrl = probe;
> stream->cur_format = format;
> stream->cur_frame = frame;
>
> @@ -386,7 +386,7 @@ static int uvc_v4l2_set_streamparm(struct uvc_streaming
> *stream, return -EBUSY;
> }
>
> - memcpy(&probe, &stream->ctrl, sizeof probe);
> + probe = stream->ctrl;
> probe.dwFrameInterval > uvc_try_frame_interval(stream->cur_frame, interval);
>
> @@ -397,7 +397,7 @@ static int uvc_v4l2_set_streamparm(struct uvc_streaming
> *stream, return ret;
> }
>
> - memcpy(&stream->ctrl, &probe, sizeof probe);
> + stream->ctrl = probe;
> mutex_unlock(&stream->mutex);
>
> /* Return the actual frame period. */

--
Regards,

Laurent Pinchart