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

[Ferruh Yigit]

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.

> 
> 
> [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;
> 
> 
> 
>                         ^~~~~~~~
>