Re: [PATCH v4 20/21] media: videobuf2: Stop using internal dma-buf lock

[Christian König <christian.koenig@xxxxxxx>]

Am 31.08.22 um 17:37 schrieb Dmitry Osipenko:
> All drivers that use dma-bufs have been moved to the updated locking
> specification and now dma-buf reservation is guaranteed to be locked
> by importers during the mapping operations. There is no need to take
> the internal dma-buf lock anymore. Remove locking from the videobuf2
> memory allocators.
>
> Acked-by: Tomasz Figa <tfiga@xxxxxxxxxxxx>
> Acked-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>

Acked-by: Christian König <christian.koenig@xxxxxxx>

> ---
>   drivers/media/common/videobuf2/videobuf2-dma-contig.c | 11 +----------
>   drivers/media/common/videobuf2/videobuf2-dma-sg.c     | 11 +----------
>   drivers/media/common/videobuf2/videobuf2-vmalloc.c    | 11 +----------
>   3 files changed, 3 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> index 79f4d8301fbb..555bd40fa472 100644
> --- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> +++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> @@ -382,18 +382,12 @@ static struct sg_table *vb2_dc_dmabuf_ops_map(
>   	struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
>   {
>   	struct vb2_dc_attachment *attach = db_attach->priv;
> -	/* stealing dmabuf mutex to serialize map/unmap operations */
> -	struct mutex *lock = &db_attach->dmabuf->lock;
>   	struct sg_table *sgt;
>   
> -	mutex_lock(lock);
> -
>   	sgt = &attach->sgt;
>   	/* return previously mapped sg table */
> -	if (attach->dma_dir == dma_dir) {
> -		mutex_unlock(lock);
> +	if (attach->dma_dir == dma_dir)
>   		return sgt;
> -	}
>   
>   	/* release any previous cache */
>   	if (attach->dma_dir != DMA_NONE) {
> @@ -409,14 +403,11 @@ static struct sg_table *vb2_dc_dmabuf_ops_map(
>   	if (dma_map_sgtable(db_attach->dev, sgt, dma_dir,
>   			    DMA_ATTR_SKIP_CPU_SYNC)) {
>   		pr_err("failed to map scatterlist\n");
> -		mutex_unlock(lock);
>   		return ERR_PTR(-EIO);
>   	}
>   
>   	attach->dma_dir = dma_dir;
>   
> -	mutex_unlock(lock);
> -
>   	return sgt;
>   }
>   
> diff --git a/drivers/media/common/videobuf2/videobuf2-dma-sg.c b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> index 36ecdea8d707..36981a5b5c53 100644
> --- a/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> +++ b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> @@ -424,18 +424,12 @@ static struct sg_table *vb2_dma_sg_dmabuf_ops_map(
>   	struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
>   {
>   	struct vb2_dma_sg_attachment *attach = db_attach->priv;
> -	/* stealing dmabuf mutex to serialize map/unmap operations */
> -	struct mutex *lock = &db_attach->dmabuf->lock;
>   	struct sg_table *sgt;
>   
> -	mutex_lock(lock);
> -
>   	sgt = &attach->sgt;
>   	/* return previously mapped sg table */
> -	if (attach->dma_dir == dma_dir) {
> -		mutex_unlock(lock);
> +	if (attach->dma_dir == dma_dir)
>   		return sgt;
> -	}
>   
>   	/* release any previous cache */
>   	if (attach->dma_dir != DMA_NONE) {
> @@ -446,14 +440,11 @@ static struct sg_table *vb2_dma_sg_dmabuf_ops_map(
>   	/* mapping to the client with new direction */
>   	if (dma_map_sgtable(db_attach->dev, sgt, dma_dir, 0)) {
>   		pr_err("failed to map scatterlist\n");
> -		mutex_unlock(lock);
>   		return ERR_PTR(-EIO);
>   	}
>   
>   	attach->dma_dir = dma_dir;
>   
> -	mutex_unlock(lock);
> -
>   	return sgt;
>   }
>   
> diff --git a/drivers/media/common/videobuf2/videobuf2-vmalloc.c b/drivers/media/common/videobuf2/videobuf2-vmalloc.c
> index 7831bf545874..41db707e43a4 100644
> --- a/drivers/media/common/videobuf2/videobuf2-vmalloc.c
> +++ b/drivers/media/common/videobuf2/videobuf2-vmalloc.c
> @@ -267,18 +267,12 @@ static struct sg_table *vb2_vmalloc_dmabuf_ops_map(
>   	struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
>   {
>   	struct vb2_vmalloc_attachment *attach = db_attach->priv;
> -	/* stealing dmabuf mutex to serialize map/unmap operations */
> -	struct mutex *lock = &db_attach->dmabuf->lock;
>   	struct sg_table *sgt;
>   
> -	mutex_lock(lock);
> -
>   	sgt = &attach->sgt;
>   	/* return previously mapped sg table */
> -	if (attach->dma_dir == dma_dir) {
> -		mutex_unlock(lock);
> +	if (attach->dma_dir == dma_dir)
>   		return sgt;
> -	}
>   
>   	/* release any previous cache */
>   	if (attach->dma_dir != DMA_NONE) {
> @@ -289,14 +283,11 @@ static struct sg_table *vb2_vmalloc_dmabuf_ops_map(
>   	/* mapping to the client with new direction */
>   	if (dma_map_sgtable(db_attach->dev, sgt, dma_dir, 0)) {
>   		pr_err("failed to map scatterlist\n");
> -		mutex_unlock(lock);
>   		return ERR_PTR(-EIO);
>   	}
>   
>   	attach->dma_dir = dma_dir;
>   
> -	mutex_unlock(lock);
> -
>   	return sgt;
>   }
>