[dpdk-dev] [PATCH v1] vhost: fix mbuf allocation failures

[Sivaprasad Tummala <Sivaprasad.Tummala@intel.com>]

vhost buffer allocation is successful for packets that fit
into a linear buffer. If it fails, vhost library is expected
to drop the current buffer descriptor and skip to the next.

The patch fixes the error scenario by skipping to next descriptor.
Note: Drop counters are not currently supported.

Signed-off-by: Sivaprasad Tummala <Sivaprasad.Tummala@intel.com>
---
 lib/librte_vhost/virtio_net.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index 37c47c7dc..b0d3a85c2 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -1688,6 +1688,7 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
 {
 	uint16_t i;
 	uint16_t free_entries;
+	uint16_t dropped = 0;
 
 	if (unlikely(dev->dequeue_zero_copy)) {
 		struct zcopy_mbuf *zmbuf, *next;
@@ -1751,8 +1752,19 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
 			update_shadow_used_ring_split(vq, head_idx, 0);
 
 		pkts[i] = virtio_dev_pktmbuf_alloc(dev, mbuf_pool, buf_len);
-		if (unlikely(pkts[i] == NULL))
+		if (unlikely(pkts[i] == NULL)) {
+			/*
+			 * mbuf allocation fails for jumbo packets with
+			 * linear buffer flag set. Drop this packet and
+			 * proceed with the next available descriptor to
+			 * avoid HOL blocking
+			 */
+			VHOST_LOG_DATA(WARNING,
+				"Failed to allocate memory for mbuf. Packet dropped!\n");
+			dropped += 1;
+			i++;
 			break;
+		}
 
 		err = copy_desc_to_mbuf(dev, vq, buf_vec, nr_vec, pkts[i],
 				mbuf_pool);
@@ -1796,7 +1808,7 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
 		}
 	}
 
-	return i;
+	return (i - dropped);
 }
 
 static __rte_always_inline int
-- 
2.17.1