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Date: Tue, 13 Feb 2018 10:10:18 +0100
From: Jens Freimann <jfreimann@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: dev@dpdk.org, tiwei.bie@intel.com, yliu@fridaylinux.org,
 maxime.coquelin@redhat.com, mst@redhat.com
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Subject: Re: [dpdk-dev] [PATCH 07/14] net/virtio: implement transmit path
 for packed queues
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On Mon, Feb 12, 2018 at 09:16:27PM +0800, Jason Wang wrote:
>
>
>On 2018???01???29??? 22:11, Jens Freimann wrote:
>>+/* Cleanup from completed transmits. */
>>+static void
>>+virtio_xmit_cleanup(struct virtqueue *vq)
>>+{
>>+	uint16_t idx;
>>+	uint16_t size = vq->vq_nentries;
>>+	struct vring_desc_1_1 *desc = vq->vq_ring.desc_1_1;
>>+
>>+	idx = vq->vq_used_cons_idx & (size - 1);
>>+	while (desc_is_used(&desc[idx]) &&
>>+	       vq->vq_free_cnt < size) {
>>+		while (desc[idx].flags & VRING_DESC_F_NEXT) {
>>+			vq->vq_free_cnt++;
>>+			idx = ++vq->vq_used_cons_idx & (size - 1);
>>+		}
>>+		vq->vq_free_cnt++;
>>+		idx = ++vq->vq_used_cons_idx & (size - 1);
>>+	}
>>+}
>
>This looks like a violation of the spec. In 2.6.6 Next Flag: 
>Descriptor Chaining. It said:
>
>"VIRTQ_DESC_F_NEXT is reserved in used descriptors, and should be 
>ignored by drivers."

I think you are right. I will rework this bit.
>
>(Looking at the device implementation, it was in fact an in order 
>device which is said to be no in the cover).

Looking into this as well.

Thanks for the review!

regards,
Jens