On Fri, Apr 14, 2017 at 05:53:55AM +0000, Tan, Jianfeng wrote:
> > > diff --git a/drivers/net/virtio/virtqueue.h
> > > b/drivers/net/virtio/virtqueue.h
> > > index f9e3736..f43ea70 100644
> > > --- a/drivers/net/virtio/virtqueue.h
> > > +++ b/drivers/net/virtio/virtqueue.h
> > > @@ -72,7 +72,8 @@ struct rte_mbuf;
> > > * Return the physical address (or virtual address in case of
> > > * virtio-user) of mbuf data buffer.
> > > */
> > > -#define VIRTIO_MBUF_ADDR(mb, vq) (*(uint64_t *)((uintptr_t)(mb) +
> > (vq)->offset))
> > > +#define VIRTIO_MBUF_ADDR(mb, vq) \
> > > + ((uint64_t)((uintptr_t)(*(void **)((uintptr_t)(mb) + (vq)->offset))))
> >
> > The "void **" cast makes it a bit complex (thus hard to read). I think
> > following should work?
>
> Yes, uintptr_t can work. I thought void ** is easier to understand, meaning a
> convert to a pointer which pointing to a pointer.
It's twisted, isn't it? :)
> I usually use uintptr_t only for converter from pointer to integer, not the
> opposite way.
Yes, that's a typical usage. But the fact of the matter is uintptr_t
represents the word size, which is exactly what needed in this case.
--yliu
>
> >
> > (uint64_t(*(uintptr_t *)((uintptr_t)(mb) + (vq)->offset)))
> >
> > Besides, it deserves a comment.
>
> Will add comment in next version.
>
> Thanks,
> Jianfeng
>
> >
> > --yliu
> >
> > > #else
> > > #define VIRTIO_MBUF_ADDR(mb, vq) ((mb)->buf_physaddr)
> > > #endif
> > > --
> > > 2.7.4
