Re: [RFCv11 PATCH 07/29] media-request: add media_request_object_find

[Mauro Carvalho Chehab <mchehab@s-opensource.com>]

Em Mon,  9 Apr 2018 16:20:04 +0200
Hans Verkuil <hverkuil@xs4all.nl> escreveu:

> From: Hans Verkuil <hans.verkuil@cisco.com>
> 
> Add media_request_object_find to find a request object inside a
> request based on ops and/or priv values.
> 
> Objects of the same type (vb2 buffer, control handler) will have
> the same ops value. And objects that refer to the same 'parent'
> object (e.g. the v4l2_ctrl_handler that has the current driver
> state) will have the same priv value.
> 
> The caller has to call media_request_object_put() for the returned
> object since this function increments the refcount.
> 
> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
> ---
>  drivers/media/media-request.c | 26 ++++++++++++++++++++++++++
>  include/media/media-request.h | 25 +++++++++++++++++++++++++
>  2 files changed, 51 insertions(+)
> 
> diff --git a/drivers/media/media-request.c b/drivers/media/media-request.c
> index 02b620c81de5..415f7e31019d 100644
> --- a/drivers/media/media-request.c
> +++ b/drivers/media/media-request.c
> @@ -322,6 +322,32 @@ static void media_request_object_release(struct kref *kref)
>  	obj->ops->release(obj);
>  }
>  
> +struct media_request_object *
> +media_request_object_find(struct media_request *req,
> +			  const struct media_request_object_ops *ops,
> +			  void *priv)
> +{
> +	struct media_request_object *obj;
> +	struct media_request_object *found = NULL;
> +	unsigned long flags;
> +
> +	if (!ops && !priv)
> +		return NULL;
> +
> +	spin_lock_irqsave(&req->lock, flags);
> +	list_for_each_entry(obj, &req->objects, list) {
> +		if ((!ops || obj->ops == ops) &&
> +		    (!priv || obj->priv == priv)) {
> +			media_request_object_get(obj);
> +			found = obj;
> +			break;
> +		}
> +	}
> +	spin_unlock_irqrestore(&req->lock, flags);

Huh? The spin lock were used before only to protect the req->state,
while the mutex is the one that protects the request itself.

So, here, it should be doing mutex_lock/unlock() instead.

> +	return found;
> +}
> +EXPORT_SYMBOL_GPL(media_request_object_find);
> +
>  void media_request_object_put(struct media_request_object *obj)
>  {
>  	kref_put(&obj->kref, media_request_object_release);
> diff --git a/include/media/media-request.h b/include/media/media-request.h
> index 033697d493cd..ea990c8f76bc 100644
> --- a/include/media/media-request.h
> +++ b/include/media/media-request.h
> @@ -130,6 +130,23 @@ static inline void media_request_object_get(struct media_request_object *obj)
>   */
>  void media_request_object_put(struct media_request_object *obj);
>  
> +/**
> + * media_request_object_find - Find an object in a request
> + *
> + * @ops: Find an object with this ops value, may be NULL.
> + * @priv: Find an object with this priv value, may be NULL.

@req ?

> + *
> + * At least one of @ops and @priv must be non-NULL. If one of
> + * these is NULL, then skip checking for that field.
> + *
> + * Returns NULL if not found or the object (the refcount is increased
> + * in that case).
> + */
> +struct media_request_object *
> +media_request_object_find(struct media_request *req,
> +			  const struct media_request_object_ops *ops,
> +			  void *priv);
> +
>  /**
>   * media_request_object_init - Initialise a media request object
>   *
> @@ -162,6 +179,14 @@ static inline void media_request_object_put(struct media_request_object *obj)
>  {
>  }
>  
> +static inline struct media_request_object *
> +media_request_object_find(struct media_request *req,
> +			  const struct media_request_object_ops *ops,
> +			  void *priv)
> +{
> +	return NULL;
> +}
> +
>  static inline void media_request_object_init(struct media_request_object *obj)
>  {
>  	obj->ops = NULL;



Thanks,
Mauro