Re: [PATCH v3 2/7] dma-buf: Always build with DMABUF_MOVE_NOTIFY

Leon Romanovsky
2026-01-21T10:14:28Z

On Wed, Jan 21, 2026 at 09:55:38AM +0100, Christian König wrote:
> On 1/20/26 15:07, Leon Romanovsky wrote:
> > From: Leon Romanovsky <leonro@nvidia.com>
> >
> > DMABUF_MOVE_NOTIFY was introduced in 2018 and has been marked as
> > experimental and disabled by default ever since. Six years later,
> > all new importers implement this callback.
> >
> > It is therefore reasonable to drop CONFIG_DMABUF_MOVE_NOTIFY and
> > always build DMABUF with support for it enabled.
> >
> > Suggested-by: Christian König <christian.koenig@amd.com>
> > Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> > ---
> > drivers/dma-buf/Kconfig | 12 ------------
> > drivers/dma-buf/dma-buf.c | 12 ++----------
> > drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 10 +++-------
> > drivers/gpu/drm/amd/amdkfd/Kconfig | 2 +-
> > drivers/gpu/drm/xe/tests/xe_dma_buf.c | 3 +--
> > drivers/gpu/drm/xe/xe_dma_buf.c | 12 ++++--------
> > 6 files changed, 11 insertions(+), 40 deletions(-)
> >
> > diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig
> > index b46eb8a552d7..84d5e9b24e20 100644
> > --- a/drivers/dma-buf/Kconfig
> > +++ b/drivers/dma-buf/Kconfig
> > @@ -40,18 +40,6 @@ config UDMABUF
> > A driver to let userspace turn memfd regions into dma-bufs.
> > Qemu can use this to create host dmabufs for guest framebuffers.
> >
> > -config DMABUF_MOVE_NOTIFY
> > - bool "Move notify between drivers (EXPERIMENTAL)"
> > - default n
> > - depends on DMA_SHARED_BUFFER
> > - help
> > - Don't pin buffers if the dynamic DMA-buf interface is available on
> > - both the exporter as well as the importer. This fixes a security
> > - problem where userspace is able to pin unrestricted amounts of memory
> > - through DMA-buf.
> > - This is marked experimental because we don't yet have a consistent
> > - execution context and memory management between drivers.
> > -
> > config DMABUF_DEBUG
> > bool "DMA-BUF debug checks"
> > depends on DMA_SHARED_BUFFER
> > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> > index 59cc647bf40e..cd3b60ce4863 100644
> > --- a/drivers/dma-buf/dma-buf.c
> > +++ b/drivers/dma-buf/dma-buf.c
> > @@ -837,18 +837,10 @@ static void mangle_sg_table(struct sg_table *sg_table)
> >
> > }
> >
> > -static inline bool
> > -dma_buf_attachment_is_dynamic(struct dma_buf_attachment *attach)
>
> I would rather like to keep the wrapper and even add some explanation what it means when true is returned.

We have different opinion here. I don't like single line functions which
are called only twice. I'll keep this function to ensure progress the
series.

Thanks

>
> Apart from that looks good to me.
>
> Regards,
> Christian.