On Monday 09 March 2009 02:07:33 Trent Piepho wrote:
> On Sun, 8 Mar 2009, Hans Verkuil wrote:
> > The last one fixes an ivtv regression caused by this change:
> >
> > changeset: 10811:0a0eba8e64d5
> > user: Trent Piepho <[email protected]>
> > date: Tue Mar 03 20:21:02 2009 -0800
> > summary: videodev: only copy needed part of RW ioctl's parameter
> >
> > The fix is simple: switch on the full ioctl command instead of just the
> > NR field.
> >
> > Thanks to Martin Dauskardt for doing the bisect and tracing the
> > breakage to this change.
>
> Switching on the whole ioctl makes the switch statement a lot less
> efficient. I'd rather just put a if (_IOC_TYPE(cmd) != 'V') return 0; in
> there. That should fix the non-v4l2 ioctls, right?
That was my first thought as well, but I realized that this is one area
where you really do not want to take any risk.
Personally I think this code is overoptimization. In my view the performance
advantage is minimal while reducing the readability of the code.
Regards,
Hans
--
Hans Verkuil - video4linux developer - sponsored by TANDBERG
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