linux-kernel - Re: [PATCH] dma-buf: Make mmap callback actually optional

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Date:   Wed, 3 Apr 2019 13:30:55 +0700
From:   Sumit Semwal <sumit.semwal@...aro.org>
To:     Christian Koenig <christian.koenig@....com>
Cc:     "Andrew F. Davis" <afd@...com>,
        LKML <linux-kernel@...r.kernel.org>,
        DRI mailing list <dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH] dma-buf: Make mmap callback actually optional

Hi Andrew,

On Mon, 1 Apr 2019 at 20:38, Christian König
<ckoenig.leichtzumerken@...il.com> wrote:
>
> Am 29.03.19 um 17:52 schrieb Andrew F. Davis:
> > The docs state the callback is optional but it is not, make it optional.
> >
> > Signed-off-by: Andrew F. Davis <afd@...com>
>
> Reviewed-by: Christian König <christian.koenig@....com>

Thanks for the patch; I will queue it up within this week (at a
conference atm, but will squeeze out time for doing this).

>
> > ---
> >   drivers/dma-buf/dma-buf.c | 11 +++++++++--
> >   1 file changed, 9 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> > index 7c858020d14b..4d4ae9fe9ac8 100644
> > --- a/drivers/dma-buf/dma-buf.c
> > +++ b/drivers/dma-buf/dma-buf.c
> > @@ -90,6 +90,10 @@ static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
> >
> >       dmabuf = file->private_data;
> >
> > +     /* check if buffer supports mmap */
> > +     if (!dmabuf->ops->mmap)
> > +             return -EINVAL;
> > +
> >       /* check for overflowing the buffer's size */
> >       if (vma->vm_pgoff + vma_pages(vma) >
> >           dmabuf->size >> PAGE_SHIFT)
> > @@ -404,8 +408,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
> >                         || !exp_info->ops
> >                         || !exp_info->ops->map_dma_buf
> >                         || !exp_info->ops->unmap_dma_buf
> > -                       || !exp_info->ops->release
> > -                       || !exp_info->ops->mmap)) {
> > +                       || !exp_info->ops->release)) {
> >               return ERR_PTR(-EINVAL);
> >       }
> >
> > @@ -906,6 +909,10 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
> >       if (WARN_ON(!dmabuf || !vma))
> >               return -EINVAL;
> >
> > +     /* check if buffer supports mmap */
> > +     if (!dmabuf->ops->mmap)
> > +             return -EINVAL;
> > +
> >       /* check for offset overflow */
> >       if (pgoff + vma_pages(vma) < pgoff)
> >               return -EOVERFLOW;
>

Best,
Sumit.