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

[Xie, Huawei]

On 9/25/2015 5:01 AM, Stephen Hemminger wrote:
> On Thu, 24 Sep 2015 18:35:37 +0000
> "Xie, Huawei" <huawei.xie at 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 at 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 at 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.
>
Exactly the same code (if no dependency and no other issue) or copy and
convert it to DPDK style? By DPDK style, i mean like using RTE_ALIGN macro.