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

Oleksandr Andrushchenko
2018-06-13T09:05:01Z

On 06/13/2018 06:14 AM, Boris Ostrovsky wrote:
>
>
> On 06/12/2018 09:42 AM, Oleksandr Andrushchenko wrote:
>
>>   int gntdev_dmabuf_imp_release(struct gntdev_dmabuf_priv *priv, u32 fd)
>>   {
>> -    return -EINVAL;
>> +    struct gntdev_dmabuf *gntdev_dmabuf;
>> +    struct dma_buf_attachment *attach;
>> +    struct dma_buf *dma_buf;
>> +
>> +    gntdev_dmabuf = dmabuf_imp_find_unlink(priv, fd);
>> +    if (IS_ERR(gntdev_dmabuf))
>> +        return PTR_ERR(gntdev_dmabuf);
>> +
>> +    pr_debug("Releasing DMA buffer with fd %d\n", fd);
>> +
>> +    attach = gntdev_dmabuf->u.imp.attach;
>> +
>> +    if (gntdev_dmabuf->u.imp.sgt)
>> +        dma_buf_unmap_attachment(attach, gntdev_dmabuf->u.imp.sgt,
>> +                     DMA_BIDIRECTIONAL);
>> +    dma_buf = attach->dmabuf;
>> +    dma_buf_detach(attach->dmabuf, attach);
>> +    dma_buf_put(dma_buf);
>> +
>> +    dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs,
>> +                      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);
>> +    return 0;
>>   }