Re: [PATCHv17 05/34] media-request: add media_request_get_by_fd

[Mauro Carvalho Chehab <mchehab+samsung@kernel.org>]

Em Fri, 10 Aug 2018 09:32:53 +0200
Hans Verkuil <hverkuil@xs4all.nl> escreveu:

> On 08/09/2018 09:55 PM, Mauro Carvalho Chehab wrote:
> > Em Sat,  4 Aug 2018 14:44:57 +0200
> > Hans Verkuil <hverkuil@xs4all.nl> escreveu:
> >   
> >> From: Hans Verkuil <hans.verkuil@cisco.com>
> >>
> >> Add media_request_get_by_fd() to find a request based on the file
> >> descriptor.
> >>
> >> The caller has to call media_request_put() for the returned
> >> request since this function increments the refcount.
> >>
> >> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
> >> Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> >> ---
> >>  drivers/media/media-request.c | 40 +++++++++++++++++++++++++++++++++++
> >>  include/media/media-request.h | 24 +++++++++++++++++++++
> >>  2 files changed, 64 insertions(+)
> >>
> >> diff --git a/drivers/media/media-request.c b/drivers/media/media-request.c
> >> index 253068f51a1f..4b523f3a03a3 100644
> >> --- a/drivers/media/media-request.c
> >> +++ b/drivers/media/media-request.c
> >> @@ -231,6 +231,46 @@ static const struct file_operations request_fops = {
> >>  	.release = media_request_close,
> >>  };
> >>  
> >> +struct media_request *
> >> +media_request_get_by_fd(struct media_device *mdev, int request_fd)
> >> +{
> >> +	struct file *filp;
> >> +	struct media_request *req;
> >> +
> >> +	if (!mdev || !mdev->ops ||
> >> +	    !mdev->ops->req_validate || !mdev->ops->req_queue)
> >> +		return ERR_PTR(-EPERM);  
> > 
> > EPERM? I guess ENOTTY would be better.
> > 
> > Any reason why using EPERM?  
> 
> This is called by e.g. VIDIOC_QBUF or VIDIOC_S/G/TRY_EXT_CTRLS where someone
> sets request_fd. Then this function is called to obtain the corresponding
> media_request struct. If requests are not supported, then EPERM is returned.
> 
> Returning ENOTTY would be wrong, since VIDIOC_QBUF etc. are definitely implemented,
> instead they just do not permit the use of requests.
> 
> Let me know if I can add your Reviewed-by after this explanation.

Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

> 
> Regards,
> 
> 	Hans



Thanks,
Mauro