Re: [dpdk-dev] [PATCH] virtio: fix used ring address calculation

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu, 24 Sep 2015 18:35:37 +0000
"Xie, Huawei" <huawei.xie@intel.com> wrote:

> On 9/25/2015 12:36 AM, Stephen Hemminger wrote:
> > On Thu, 24 Sep 2015 07:30:41 +0000
> > "Xie, Huawei" <huawei.xie@intel.com> wrote:
> >
> >> On 9/21/2015 11:39 AM, Xie, Huawei wrote:
> >> vring_size calculation should consider both used_event_idx at the tail
> >> of avail ring and avail_event_idx at the tail of used ring.
> >> Will merge those two fixes and send a new patch.
> >>> used event idx is put at the end of available ring. It isn't taken into account
> >>> when we calculate the address of used ring. Fortunately, it doesn't introduce
> >>> the bug with fixed queue number 256 and 4KB alignment.
> >>>
> >>> Signed-off-by: hxie5 <huawei.xie@intel.com>
> >>> ---
> >>>  drivers/net/virtio/virtio_ring.h | 2 +-
> >>>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/net/virtio/virtio_ring.h b/drivers/net/virtio/virtio_ring.h
> >>> index a16c499..92e430d 100644
> >>> --- a/drivers/net/virtio/virtio_ring.h
> >>> +++ b/drivers/net/virtio/virtio_ring.h
> >>> @@ -145,7 +145,7 @@ vring_init(struct vring *vr, unsigned int num, uint8_t *p,
> >>>  	vr->avail = (struct vring_avail *) (p +
> >>>  		num * sizeof(struct vring_desc));
> >>>  	vr->used = (void *)
> >>> -		RTE_ALIGN_CEIL((uintptr_t)(&vr->avail->ring[num]), align);
> >>> +		RTE_ALIGN_CEIL((uintptr_t)(&vr->avail->ring[num + 1]), align);
> >>>  }
> >>>  
> >>>  /*
> > Why aren't we just using the standard Linux includes for this?
> > See <linux/virtio_ring.h> and the function vring_init()
> >
> > Keeping parallel copies of headers is prone to failures.
> Agree.
> Using standard Linux includes then at least we don't need to redefine
> the feature and other related MACRO.
> This applies to vhost as well.
> For vring, vring_init, we could also reuse the linux implementation
> unless we have strong reason to define our own structure.
> One reason was to support both FreeBSD and Linux. FreeBSD should have
> its own header file. To avoid the case they have different vring
> structure or VIRTIO_F_xx macro name, they are redefined here.
> 
> >
> 

The Linux headers for virtio are explictly BSD licensed.
You could at least just have a local copy of same code.