Re: [PATCH v19 1/9] media: videobuf2: Update vb2_is_busy() logic

[Hans Verkuil]

On 06/02/2024 09:02, Benjamin Gaignard wrote:
> Do not rely on the number of allocated buffers to know if the
> queue is busy but on a flag set when at least buffer has been allocated

You missed one change: least buffer -> least one buffer

Can you post a v19.1 for just this patch with that typo fixed? It's a
rather important typo.

Regards,

	Hans

> by REQBUFS or CREATE_BUFS ioctl.
> The flag is reset when REQBUFS is called with count = 0 or the file
> handle is closed.
> This is needed because delete buffers feature will be able to remove
> all the buffers from a queue while streaming so relying on the number
> of allocated buffers in the queue won't be possible.
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>
> ---
> version 19:
> - Add q->is_busy = 0 in vb2_core_queue_release()
> - Fix q->is_busy usage in vb2_core_reqbufs()
> - Reword commit message.
> 
>  drivers/media/common/videobuf2/videobuf2-core.c | 4 ++++
>  include/media/videobuf2-core.h                  | 4 +++-
>  2 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
> index b6bf8f232f48..d8b3c04cb3b5 100644
> --- a/drivers/media/common/videobuf2/videobuf2-core.c
> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> @@ -854,6 +854,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
>  		__vb2_queue_free(q, q_num_bufs);
>  		mutex_unlock(&q->mmap_lock);
>  
> +		q->is_busy = 0;
>  		/*
>  		 * In case of REQBUFS(0) return immediately without calling
>  		 * driver's queue_setup() callback and allocating resources.
> @@ -966,6 +967,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
>  	 */
>  	*count = allocated_buffers;
>  	q->waiting_for_buffers = !q->is_output;
> +	q->is_busy = 1;
>  
>  	return 0;
>  
> @@ -1091,6 +1093,7 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
>  	 * to the userspace.
>  	 */
>  	*count = allocated_buffers;
> +	q->is_busy = 1;
>  
>  	return 0;
>  
> @@ -2555,6 +2558,7 @@ void vb2_core_queue_release(struct vb2_queue *q)
>  	__vb2_queue_free(q, vb2_get_num_buffers(q));
>  	kfree(q->bufs);
>  	q->bufs = NULL;
> +	q->is_busy = 0;
>  	mutex_unlock(&q->mmap_lock);
>  }
>  EXPORT_SYMBOL_GPL(vb2_core_queue_release);
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index 56719a26a46c..b317286a7b08 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -579,6 +579,7 @@ struct vb2_buf_ops {
>   *		called since poll() needs to return %EPOLLERR in that situation.
>   * @is_multiplanar: set if buffer type is multiplanar
>   * @is_output:	set if buffer type is output
> + * @is_busy:	set if at least one buffer has been allocated at some time.
>   * @copy_timestamp: set if vb2-core should set timestamps
>   * @last_buffer_dequeued: used in poll() and DQBUF to immediately return if the
>   *		last decoded buffer was already dequeued. Set for capture queues
> @@ -644,6 +645,7 @@ struct vb2_queue {
>  	unsigned int			waiting_in_dqbuf:1;
>  	unsigned int			is_multiplanar:1;
>  	unsigned int			is_output:1;
> +	unsigned int			is_busy:1;
>  	unsigned int			copy_timestamp:1;
>  	unsigned int			last_buffer_dequeued:1;
>  
> @@ -1163,7 +1165,7 @@ static inline unsigned int vb2_get_num_buffers(struct vb2_queue *q)
>   */
>  static inline bool vb2_is_busy(struct vb2_queue *q)
>  {
> -	return vb2_get_num_buffers(q) > 0;
> +	return !!q->is_busy;
>  }
>  
>  /**