Re: [PATCH v3 8/9] media: videobuf2: Stop using internal dma-buf lock

Hans Verkuil
2022-08-24T10:32:57Z

Nice!

Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

Regards,

Hans

On 24/08/2022 12:22, Dmitry Osipenko wrote:
> 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@chromium.org>
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
> ---
> 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 de762dbdaf78..2c69bf0470e7 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 39e11600304a..e63e718c0bf7 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;
> }
>