[dpdk-dev] *rte_vhost_rx_queue_count* should be protected by vq->access_lock

[He Peng]

Hi，


We found that *rte_vhost_rx_queue_count* is not protected by vq->access_lock,
and the access to vq->avail->idx is not thread-safe, since at the same time, the 
vq->avail  might be 

set by *vring_invalidate* when some vhost-user messages arrived, such as 
VRING_SET_ADDRESS,
VRING_SET_MEM_TABLE, etc.


Thanks.