Re: [PATCH v3 9/9] xen/gntdev: Implement dma-buf import functionality

[Oleksandr Andrushchenko]

On 06/13/2018 06:14 AM, Boris Ostrovsky wrote:
> On 06/12/2018 09:42 AM, Oleksandr Andrushchenko wrote:
>
> > Â int gntdev_dmabuf_imp_release(struct gntdev_dmabuf_priv *priv, u32 fd)
> > Â {
> > -ÂÂÂ return -EINVAL;
> > +ÂÂÂ struct gntdev_dmabuf *gntdev_dmabuf;
> > +ÂÂÂ struct dma_buf_attachment *attach;
> > +ÂÂÂ struct dma_buf *dma_buf;
> > +
> > +ÂÂÂ gntdev_dmabuf = dmabuf_imp_find_unlink(priv, fd);
> > +ÂÂÂ if (IS_ERR(gntdev_dmabuf))
> > +ÂÂÂÂÂÂÂ return PTR_ERR(gntdev_dmabuf);
> > +
> > +ÂÂÂ pr_debug("Releasing DMA buffer with fd %d\n", fd);
> > +
> > +ÂÂÂ attach = gntdev_dmabuf->u.imp.attach;
> > +
> > +ÂÂÂ if (gntdev_dmabuf->u.imp.sgt)
> > +ÂÂÂÂÂÂÂ dma_buf_unmap_attachment(attach, gntdev_dmabuf->u.imp.sgt,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ DMA_BIDIRECTIONAL);
> > +ÂÂÂ dma_buf = attach->dmabuf;
> > +ÂÂÂ dma_buf_detach(attach->dmabuf, attach);
> > +ÂÂÂ dma_buf_put(dma_buf);
> > +
> > +ÂÂÂ dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ gntdev_dmabuf->nr_pages);
>
>
>
> Should you first end foreign access, before doing anything?
I am rolling back in reverse order here, so I think we first need
to finish local activities with the buffer and then end foreign
access.
> -boris
>
>
> > + dmabuf_imp_free_storage(gntdev_dmabuf);
> > +ÂÂÂ return 0;
> > Â }