vhost: remove unnecessary descriptor length updates

Remove these unnecessary vring descriptor length updating, vhost should
not change them.
virtio in front end should assign value to desc.len for both rx and tx.

Test report: http://dpdk.org/ml/archives/dev/2015-June/018610.html

Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
Acked-by: Huawei Xie <huawei.xie@intel.com>

diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
index 37609e0..151d781 100644 (file)
--- a/lib/librte_vhost/vhost_rxtx.c
+++ b/lib/librte_vhost/vhost_rxtx.c
@@ -290,7 +290,6 @@ copy_from_mbuf_to_vring(struct virtio_net *dev, uint16_t res_base_idx,
        if (vb_avail == 0) {
                uint32_t desc_idx =
                        vq->buf_vec[vec_idx].desc_idx;
-               vq->desc[desc_idx].len = vq->vhost_hlen;
 
                if ((vq->desc[desc_idx].flags
                        & VRING_DESC_F_NEXT) == 0) {
@@ -374,7 +373,6 @@ copy_from_mbuf_to_vring(struct virtio_net *dev, uint16_t res_base_idx,
                                         */
                                        uint32_t desc_idx =
                                                vq->buf_vec[vec_idx].desc_idx;
-                                       vq->desc[desc_idx].len = vb_offset;
 
                                        if ((vq->desc[desc_idx].flags &
                                                VRING_DESC_F_NEXT) == 0) {
@@ -409,26 +407,13 @@ copy_from_mbuf_to_vring(struct virtio_net *dev, uint16_t res_base_idx,
                                /*
                                 * This whole packet completes.
                                 */
-                               uint32_t desc_idx =
-                                       vq->buf_vec[vec_idx].desc_idx;
-                               vq->desc[desc_idx].len = vb_offset;
-
-                               while (vq->desc[desc_idx].flags &
-                                       VRING_DESC_F_NEXT) {
-                                       desc_idx = vq->desc[desc_idx].next;
-                                        vq->desc[desc_idx].len = 0;
-                               }
-
                                /* Update used ring with desc information */
                                vq->used->ring[cur_idx & (vq->size - 1)].id
                                        = vq->buf_vec[vec_idx].desc_idx;
                                vq->used->ring[cur_idx & (vq->size - 1)].len
                                        = entry_len;
-                               entry_len = 0;
-                               cur_idx++;
                                entry_success++;
-                               seg_avail = 0;
-                               cpy_len = RTE_MIN(vb_avail, seg_avail);
+                               break;
                        }
                }
        }