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Date: Thu, 21 Mar 2024 14:49:52 +0100
From: Mauro Carvalho Chehab <mchehab@kernel.org>
To: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Cc: tfiga@chromium.org, m.szyprowski@samsung.com,
 ezequiel@vanguardiasur.com.ar, p.zabel@pengutronix.de,
 hverkuil-cisco@xs4all.nl, nicolas@ndufresne.ca,
 linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
 linux-rockchip@lists.infradead.org, kernel@collabora.com
Subject: Re: [PATCH v21 1/9] media: videobuf2: Update vb2_is_busy() logic
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In-Reply-To: <20240314153226.197445-2-benjamin.gaignard@collabora.com>
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	<20240314153226.197445-2-benjamin.gaignard@collabora.com>
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Em Thu, 14 Mar 2024 16:32:18 +0100
Benjamin Gaignard <benjamin.gaignard@collabora.com> escreveu:

> Do not rely on the number of allocated buffers to know if the
> queue is busy but on a flag set when at least one buffer has been allocated
> 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 remove 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@collabora.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>

> ---
>  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 8b86996b2719..667bf9ee1101 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -582,6 +582,7 @@ struct vb2_buf_ops {
>   *		released. Used to prevent destroying the queue by other threads.
>   * @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
> @@ -647,6 +648,7 @@ 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;
>  
> @@ -1166,7 +1168,7 @@ 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;
>  }
>  
>  /**


Thanks,
Mauro