[RFC v2 1/2] vhost: support clear in-flight packets for async dequeue

[Pai G, Sunil]

Hi Yuan,

Thanks for the patch, comment inline.

> +uint16_t
> +rte_vhost_clear_queue(int vid, uint16_t queue_id, struct rte_mbuf **pkts,
> +		uint16_t count, int16_t dma_id, uint16_t vchan_id) {
> +	struct virtio_net *dev = get_device(vid);
> +	struct vhost_virtqueue *vq;
> +	uint16_t n_pkts_cpl = 0;
> +
> +	if (!dev)
> +		return 0;
> +
> +	VHOST_LOG_DATA(DEBUG, "(%s) %s\n", dev->ifname, __func__);
> +	if (unlikely(queue_id >= dev->nr_vring)) {
> +		VHOST_LOG_DATA(ERR, "(%s) %s: invalid virtqueue idx %d.\n",
> +			dev->ifname, __func__, queue_id);
> +		return 0;
> +	}
> +
> +	vq = dev->virtqueue[queue_id];
> +

I think the following checks must be protected by spinlock.
Similar to : https://patches.dpdk.org/project/dpdk/patch/20220328020754.1155063-1-jiayu.hu@intel.com/ 

> +	if (unlikely(!vq->async)) {
> +		VHOST_LOG_DATA(ERR, "(%s) %s: async not registered for queue
> id %d.\n",
> +			dev->ifname, __func__, queue_id);
> +		return 0;
> +	}
> +
> +	if (unlikely(!dma_copy_track[dma_id].vchans ||
> +
> 	!dma_copy_track[dma_id].vchans[vchan_id].pkts_cmpl_flag_addr)) {
> +		VHOST_LOG_DATA(ERR, "(%s) %s: invalid channel %d:%u.\n", dev-
> >ifname, __func__,
> +				dma_id, vchan_id);
> +		return 0;
> +	}
> +
> +	if (!rte_spinlock_trylock(&vq->access_lock)) {
> +		VHOST_LOG_DATA(ERR,
> +			"(%d) %s: failed to clear async queue id %d, virtqueue
> busy.\n",
> +			dev->vid, __func__, queue_id);
> +		return 0;
> +	}
> +

<snipped>

Thanks and regards,
Sunil