[dpdk-dev] [PATCH v5 7/9] net/virtio: support in-order Rx and Tx

[Ferruh Yigit]

On 7/2/2018 5:53 PM, Maxime Coquelin wrote:
> 
> 
> On 07/02/2018 06:52 PM, Ferruh Yigit wrote:
>> On 7/2/2018 5:41 PM, Ferruh Yigit wrote:
>>> On 7/2/2018 2:56 PM, Marvin Liu wrote:
>>>> IN_ORDER Rx function depends on merge-able feature. Descriptors
>>>> allocation and free will be done in bulk.
>>>>
>>>> Virtio dequeue logic:
>>>>      dequeue_burst_rx(burst mbufs)
>>>>      for (each mbuf b) {
>>>>              if (b need merge) {
>>>>                      merge remained mbufs
>>>>                      add merged mbuf to return mbufs list
>>>>              } else {
>>>>                      add mbuf to return mbufs list
>>>>              }
>>>>      }
>>>>      if (last mbuf c need merge) {
>>>>              dequeue_burst_rx(required mbufs)
>>>>              merge last mbuf c
>>>>      }
>>>>      refill_avail_ring_bulk()
>>>>      update_avail_ring()
>>>>      return mbufs list
>>>>
>>>> IN_ORDER Tx function can support offloading features. Packets which
>>>> matched "can_push" option will be handled by simple xmit function. Those
>>>> packets can't match "can_push" will be handled by original xmit function
>>>> with in-order flag.
>>>>
>>>> Virtio enqueue logic:
>>>>      xmit_cleanup(used descs)
>>>>      for (each xmit mbuf b) {
>>>>              if (b can inorder xmit) {
>>>>                      add mbuf b to inorder burst list
>>>>                      continue
>>>>              } else {
>>>>                      xmit inorder burst list
>>>>                      xmit mbuf b by original function
>>>>              }
>>>>      }
>>>>      if (inorder burst list not empty) {
>>>>              xmit inorder burst list
>>>>      }
>>>>      update_avail_ring()
>>>>
>>>> Signed-off-by: Marvin Liu <yong.liu at intel.com>
>>>> Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>
>>>
>>> <...>
>>>
>>>> @@ -150,6 +188,83 @@ virtio_xmit_cleanup(struct virtqueue *vq, uint16_t num)
>>>>   	}
>>>>   }
>>>>   
>>>> +/* Cleanup from completed inorder transmits. */
>>>> +static void
>>>> +virtio_xmit_cleanup_inorder(struct virtqueue *vq, uint16_t num)
>>>> +{
>>>> +	uint16_t i, used_idx, desc_idx, last_idx;
>>>
>>>
>>> Getting following build error [1], from code it looks like false positive, but
>>> to get rid of the build error would it be OK to set initial value to "desc_idx"?
>>
>> I applied this while merging, if this is wrong please let me know, we can fix in
>> next-net, Thanks.
> 
> Looks good to me. I didn't catch it with the GCC version I use.

I didn't dig more but I also didn't get the error with regular build, the one
with all DEBUGs enabled and mach=default combination gave the error, not sure why.

> 
> Thanks,
> Maxime
> 
>>>
>>>
>>> [1]
>>> .../dpdk/drivers/net/virtio/virtio_rxtx.c:195:24: error: ‘desc_idx’ may be used
>>> uninitialized in this function [-Werror=maybe-uninitialized]
>>>
>>>
>>>    uint16_t i, used_idx, desc_idx, last_idx;
>>>
>>>
>>>
>>>                          ^~~~~~~~
>>>
>>