Re: [RFCv12 PATCH 05/29] media-request: add media_request_find

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Hi Hans,

Thanks for the update.

On Tue, May 01, 2018 at 11:00:27AM +0200, Hans Verkuil wrote:
> From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> 
> Add media_request_find() to find a request based on the file
> descriptor.

What would you think of calling this media_request_get_by_fd() instead?

I think what the function does has changed over the time a bit but the name
has stayed.

> 
> 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@xxxxxxxxx>
> ---
>  drivers/media/media-request.c | 44 +++++++++++++++++++++++++++++++++++
>  include/media/media-request.h | 10 ++++++++
>  2 files changed, 54 insertions(+)
> 
> diff --git a/drivers/media/media-request.c b/drivers/media/media-request.c
> index 22881d5700c8..a186db290d51 100644
> --- a/drivers/media/media-request.c
> +++ b/drivers/media/media-request.c
> @@ -234,6 +234,50 @@ static const struct file_operations request_fops = {
>  	.release = media_request_close,
>  };
>  
> +/**
> + * media_request_find - Find a request based on the file descriptor
> + * @mdev: The media device
> + * @request_fd: The request file handle
> + *
> + * Find and return the request associated with the given file descriptor, or
> + * an error if no such request exists.
> + *
> + * When the function returns a request it increases its reference count. The
> + * caller is responsible for releasing the reference by calling
> + * media_request_put() on the request.
> + */
> +struct media_request *
> +media_request_find(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);
> +
> +	filp = fget(request_fd);
> +	if (!filp)
> +		return ERR_PTR(-ENOENT);
> +
> +	if (filp->f_op != &request_fops)
> +		goto err_fput;
> +	req = filp->private_data;
> +	if (req->mdev != mdev)
> +		goto err_fput;
> +
> +	media_request_get(req);
> +	fput(filp);
> +
> +	return req;
> +
> +err_fput:
> +	fput(filp);
> +
> +	return ERR_PTR(-ENOENT);
> +}
> +EXPORT_SYMBOL_GPL(media_request_find);
> +
>  int media_request_alloc(struct media_device *mdev,
>  			struct media_request_alloc *alloc)
>  {
> diff --git a/include/media/media-request.h b/include/media/media-request.h
> index 9051dfbc7d30..ce62fe74ebd6 100644
> --- a/include/media/media-request.h
> +++ b/include/media/media-request.h
> @@ -70,6 +70,9 @@ static inline void media_request_get(struct media_request *req)
>  void media_request_put(struct media_request *req);
>  void media_request_cancel(struct media_request *req);
>  
> +struct media_request *
> +media_request_find(struct media_device *mdev, int request_fd);
> +
>  int media_request_alloc(struct media_device *mdev,
>  			struct media_request_alloc *alloc);
>  #else
> @@ -85,6 +88,12 @@ static inline void media_request_cancel(struct media_request *req)
>  {
>  }
>  
> +static inline struct media_request *
> +media_request_find(struct media_device *mdev, int request_fd)
> +{
> +	return ERR_PTR(-ENOENT);
> +}
> +
>  #endif
>  
>  struct media_request_object_ops {
> @@ -188,6 +197,7 @@ static inline void media_request_object_unbind(struct media_request_object *obj)
>  static inline void media_request_object_complete(struct media_request_object *obj)
>  {
>  }
> +
>  #endif
>  
>  #endif
> -- 
> 2.17.0
> 

-- 
Sakari Ailus
e-mail: sakari.ailus@xxxxxx



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