Subject: Re: [PATCH 2/2] sample/mdev/mbochs: add mbochs_kunmap_dmabuf

From: "Koenig, Christian" <[email-masked]>
Date: Tue, 26 Jun 2018 07:33:53 +0000

Am 26.06.2018 09:20 schrieb Alex Williamson <[email-masked]>:
On Mon, 25 Jun 2018 08:44:52 +0200
Gerd Hoffmann <[email-masked]> wrote:

> There is no default implementation for dma_buf_ops->unmap.
> So add a function unmapping the page, otherwise we'll leak them.
>
> Signed-off-by: Gerd Hoffmann <[email-masked]>
> ---
>  samples/vfio-mdev/mbochs.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
> index aa25cda21d..85ac603769 100644
> --- a/samples/vfio-mdev/mbochs.c
> +++ b/samples/vfio-mdev/mbochs.c
> @@ -811,11 +811,18 @@ static void *mbochs_kmap_dmabuf(struct dma_buf *buf, unsigned long page_num)
>        return kmap(page);
>  }
>
> +static void mbochs_kunmap_dmabuf(struct dma_buf *buf, unsigned long page_num,
> +                              void *vaddr)
> +{
> +     kunmap(vaddr);
> +}
> +
>  static struct dma_buf_ops mbochs_dmabuf_ops = {
>        .map_dma_buf      = mbochs_map_dmabuf,
>        .unmap_dma_buf    = mbochs_unmap_dmabuf,
>        .release          = mbochs_release_dmabuf,
>        .map              = mbochs_kmap_dmabuf,
> +     .unmap            = mbochs_kunmap_dmabuf,
>        .mmap             = mbochs_mmap_dmabuf,
>  };
>

Is this a fix for v4.18?  AFAICT, the kmap_atomic removal is only in
next, not yet upstream and hopefully includes this sample driver before
hitting mainline.  Should we therefore have a v4.18-rc based patch for
this to include before v4.18 to resolve this?  Thanks,

That actually doesn't looks like it has something to do with the kmap_atomic removal. More like a general bug fix to existing code.

BTW: The kmap_atomic removal was based on an older kernel version and I've forgotten to check for new DMA-buf implementation during rebase. So sorry for the noise.

Christian.

Alex

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