On Mon, 17 Oct 2022 at 19:25, Dmitry Osipenko
<dmitry.osipenko@xxxxxxxxxxxxx> wrote:
>
> Move dma_buf_mmap() function to the dynamic locking specification by
> taking the reservation lock. Neither of the today's drivers take the
> reservation lock within the mmap() callback, hence it's safe to enforce
> the locking.
>
> Acked-by: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
> Acked-by: Christian König <christian.koenig@xxxxxxx>
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
Just noticed this while reading code ... this patch seems to have
missed dma_buf_mmap_internal()?
Might be good if at least some drivers gain a dma_resv_assert_held in
that path to make sure we're not quite this bad, together with fixing
this issue.
-Daniel
> ---
> drivers/dma-buf/dma-buf.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index f54c649f922a..f149b384f4dd 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -1390,6 +1390,8 @@ EXPORT_SYMBOL_NS_GPL(dma_buf_end_cpu_access, DMA_BUF);
> int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
> unsigned long pgoff)
> {
> + int ret;
> +
> if (WARN_ON(!dmabuf || !vma))
> return -EINVAL;
>
> @@ -1410,7 +1412,11 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
> vma_set_file(vma, dmabuf->file);
> vma->vm_pgoff = pgoff;
>
> - return dmabuf->ops->mmap(dmabuf, vma);
> + dma_resv_lock(dmabuf->resv, NULL);
> + ret = dmabuf->ops->mmap(dmabuf, vma);
> + dma_resv_unlock(dmabuf->resv);
> +
> + return ret;
> }
> EXPORT_SYMBOL_NS_GPL(dma_buf_mmap, DMA_BUF);
>
> --
> 2.37.3
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
