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

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Date:	Thu, 10 Jan 2013 01:19:18 +0100
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Mauro Carvalho Chehab <mchehab@...hat.com>
Cc:	Ezequiel Garcia <elezegarcia@...il.com>,
	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
	Julia.Lawall@...6.fr, kernel-janitors@...r.kernel.org,
	Peter Senna Tschudin <peter.senna@...il.com>
Subject: Re: [PATCH 01/23] uvc: Replace memcpy with struct assignment

Hi Ezequiel,

On Thursday 27 December 2012 21:49:37 Mauro Carvalho Chehab wrote:
> Em Thu, 27 Dec 2012 18:12:46 -0300 Ezequiel Garcia escreveu:
> > On Tue, Oct 23, 2012 at 4:57 PM, 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.
> > > 
> > > 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@...asonboard.com>
> > > Signed-off-by: Peter Senna Tschudin <peter.senna@...il.com>
> > > Signed-off-by: Ezequiel Garcia <elezegarcia@...il.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. */
> > 
> > It seems you've marked this one as "Changes requested" [1].
> > However, Laurent didn't request any change,
> > but just pointed out we missed one memcpy replacement candidate.
> > 
> > I believe it's safe to apply the patch (together with the other 20
> > patches) and we can fix the missing spot in another patch.
> 
> The other patches got applied already. Well just do whatever Laurent asked
> you and re-submit this one ;)

Could you please resubmit this patch with the missed memcpy replaced by a 
struct assignment ? I'll then add it to my tree.

-- 
Regards,

Laurent Pinchart

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