[dpdk-dev] [PATCH] vhost: fix dequeue offload support

[Tiwei Bie <tiwei.bie@intel.com>]

When offload is enabled, vhost needs to access the first mbuf
to get the packet info, e.g. TCP header. So we couldn't delay
the data copy in this case.

Fixes: e5c494a7a22b ("vhost: batch small guest memory copies")

Reported-by: Lei Yao <lei.a.yao@intel.com>
Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
---
 lib/librte_vhost/virtio_net.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index b75c93c..3c6f1a5 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -987,7 +987,8 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
 			mbuf_avail = cpy_len;
 		} else {
 			if (likely(cpy_len > MAX_BATCH_LEN ||
-				   copy_nb >= vq->size)) {
+				   copy_nb >= vq->size ||
+				   (hdr && cur == m))) {
 				rte_memcpy(rte_pktmbuf_mtod_offset(cur, void *,
 								   mbuf_offset),
 					   (void *)((uintptr_t)(desc_addr +
-- 
2.7.4