[dpdk-dev] [PATCH 13/17] vhost: packed queue enqueue path

[Tiwei Bie]

On Fri, Mar 16, 2018 at 04:21:16PM +0100, Jens Freimann wrote:
[...]
> +static inline uint32_t __attribute__((always_inline))
> +vhost_enqueue_burst_packed(struct virtio_net *dev, uint16_t queue_id,
> +	      struct rte_mbuf **pkts, uint32_t count)
> +{
> +	struct vhost_virtqueue *vq;
> +	struct vring_desc_packed *descs;
> +	uint16_t idx;
> +	uint16_t mask;
> +	uint16_t i;
> +
> +	vq = dev->virtqueue[queue_id];
> +
> +	rte_spinlock_lock(&vq->access_lock);
> +
> +	if (unlikely(vq->enabled == 0)) {
> +		i = 0;
> +		goto out_access_unlock;
> +	}
> +
> +	if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
> +		vhost_user_iotlb_rd_lock(vq);
> +
> +	descs = vq->desc_packed;
> +	mask = vq->size - 1;

Queue size may not be a power of 2 in packed ring.

> +
> +	for (i = 0; i < count; i++) {
[...]
> +		mbuf_avail  = rte_pktmbuf_data_len(m);
> +		mbuf_offset = 0;
> +		while (mbuf_avail != 0 || m->next != NULL) {
> +			/* done with current mbuf, fetch next */
> +			if (mbuf_avail == 0) {
> +				m = m->next;
> +
> +				mbuf_offset = 0;
> +				mbuf_avail  = rte_pktmbuf_data_len(m);
> +			}
> +
> +			/* done with current desc buf, fetch next */
> +			if (desc_avail == 0) {
> +				if ((desc->flags & VRING_DESC_F_NEXT) == 0) {
> +					/* Room in vring buffer is not enough */
> +					goto out;
> +				}
> +
> +				idx = (idx + 1);
> +				desc = &descs[idx];

Need to check whether idx >= queue size.

Thanks