Re: [PATCH v2 1/7] media: videobuf2: Don't assert held reservation lock for dma-buf mmapping

[Hans Verkuil]

On 06/04/2023 18:06, Dmitry Osipenko wrote:
> Don't assert held dma-buf reservation lock on memory mapping of exported
> buffer.
> 
> We're going to change dma-buf mmap() locking policy such that exporters
> will have to handle the lock. The previous locking policy caused deadlock
> problem for DRM drivers in a case of self-imported dma-bufs once these
> drivers are moved to use reservation lock universally. The problem is
> solved by moving the lock down to exporters. This patch prepares videobuf2
> for the locking policy update.
> 
> Reviewed-by: Emil Velikov <emil.l.velikov@xxxxxxxxx>
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>

Reviewed-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>

Regards,

	Hans

> ---
>  drivers/media/common/videobuf2/videobuf2-dma-contig.c | 3 ---
>  drivers/media/common/videobuf2/videobuf2-dma-sg.c     | 3 ---
>  drivers/media/common/videobuf2/videobuf2-vmalloc.c    | 3 ---
>  3 files changed, 9 deletions(-)
> 
> diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> index 205d3cac425c..2fa455d4a048 100644
> --- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> +++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> @@ -11,7 +11,6 @@
>   */
>  
>  #include <linux/dma-buf.h>
> -#include <linux/dma-resv.h>
>  #include <linux/module.h>
>  #include <linux/refcount.h>
>  #include <linux/scatterlist.h>
> @@ -456,8 +455,6 @@ static int vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf, struct iosys_map *map)
>  static int vb2_dc_dmabuf_ops_mmap(struct dma_buf *dbuf,
>  	struct vm_area_struct *vma)
>  {
> -	dma_resv_assert_held(dbuf->resv);
> -
>  	return vb2_dc_mmap(dbuf->priv, vma);
>  }
>  
> diff --git a/drivers/media/common/videobuf2/videobuf2-dma-sg.c b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> index 183037fb1273..28f3fdfe23a2 100644
> --- a/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> +++ b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> @@ -10,7 +10,6 @@
>   * the Free Software Foundation.
>   */
>  
> -#include <linux/dma-resv.h>
>  #include <linux/module.h>
>  #include <linux/mm.h>
>  #include <linux/refcount.h>
> @@ -498,8 +497,6 @@ static int vb2_dma_sg_dmabuf_ops_vmap(struct dma_buf *dbuf,
>  static int vb2_dma_sg_dmabuf_ops_mmap(struct dma_buf *dbuf,
>  	struct vm_area_struct *vma)
>  {
> -	dma_resv_assert_held(dbuf->resv);
> -
>  	return vb2_dma_sg_mmap(dbuf->priv, vma);
>  }
>  
> diff --git a/drivers/media/common/videobuf2/videobuf2-vmalloc.c b/drivers/media/common/videobuf2/videobuf2-vmalloc.c
> index a6c6d2fcaaa4..7c635e292106 100644
> --- a/drivers/media/common/videobuf2/videobuf2-vmalloc.c
> +++ b/drivers/media/common/videobuf2/videobuf2-vmalloc.c
> @@ -10,7 +10,6 @@
>   * the Free Software Foundation.
>   */
>  
> -#include <linux/dma-resv.h>
>  #include <linux/io.h>
>  #include <linux/module.h>
>  #include <linux/mm.h>
> @@ -319,8 +318,6 @@ static int vb2_vmalloc_dmabuf_ops_vmap(struct dma_buf *dbuf,
>  static int vb2_vmalloc_dmabuf_ops_mmap(struct dma_buf *dbuf,
>  	struct vm_area_struct *vma)
>  {
> -	dma_resv_assert_held(dbuf->resv);
> -
>  	return vb2_vmalloc_mmap(dbuf->priv, vma);
>  }
>