From 0fd5608ef97f9c467f1ecc926463cf793189443e Mon Sep 17 00:00:00 2001
From: Sivaprasad Tummala <sivaprasad.tummala@intel.com>
Date: Fri, 8 May 2020 16:47:51 +0530
Subject: [PATCH] vhost: handle mbuf allocation failure

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

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

Fixes: c3ff0ac70acb ("vhost: improve performance by supporting large buffer")
Cc: stable@dpdk.org

Signed-off-by: Sivaprasad Tummala <sivaprasad.tummala@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Conflict: NA
Reference: https://git.dpdk.org/dpdk-stable/commit/?id=0fd5608ef9
---
 lib/librte_vhost/virtio_net.c | 70 +++++++++++++++++++++++++++--------
 1 file changed, 55 insertions(+), 15 deletions(-)

diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index 5e8c6b99c0..751c1f3733 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -1673,6 +1673,8 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
 {
 	uint16_t i;
 	uint16_t free_entries;
+	uint16_t dropped = 0;
+	static bool allocerr_warned;
 
 	if (unlikely(dev->dequeue_zero_copy)) {
 		struct zcopy_mbuf *zmbuf, *next;
@@ -1734,13 +1736,35 @@ 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 when external
+			 * buffer allocation is not allowed and linear buffer
+			 * is required. Drop this packet.
+			 */
+			if (!allocerr_warned) {
+				RTE_LOG(ERR, VHOST_DATA,
+					"Failed mbuf alloc of size %d from %s on %s.\n",
+					buf_len, mbuf_pool->name, dev->ifname);
+				allocerr_warned = true;
+			}
+			dropped += 1;
+			i++;
 			break;
+		}
 
 		err = copy_desc_to_mbuf(dev, vq, buf_vec, nr_vec, pkts[i],
 				mbuf_pool);
 		if (unlikely(err)) {
 			rte_pktmbuf_free(pkts[i]);
+			if (!allocerr_warned) {
+				RTE_LOG(ERR, VHOST_DATA,
+					"Failed to copy desc to mbuf on %s.\n",
+					dev->ifname);
+				allocerr_warned = true;
+			}
+			dropped += 1;
+			i++;
 			break;
 		}
 
@@ -1750,6 +1774,8 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
 			zmbuf = get_zmbuf(vq);
 			if (!zmbuf) {
 				rte_pktmbuf_free(pkts[i]);
+				dropped += 1;
+				i++;
 				break;
 			}
 			zmbuf->mbuf = pkts[i];
@@ -1779,7 +1805,7 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
 		}
 	}
 
-	return i;
+	return (i - dropped);
 }
 
 static __rte_always_inline int
@@ -1913,6 +1939,7 @@ vhost_dequeue_single_packed(struct virtio_net *dev,
 	uint32_t buf_len;
 	uint16_t nr_vec = 0;
 	int err;
+	static bool allocerr_warned;
 
 	if (unlikely(fill_vec_buf_packed(dev, vq,
 					 vq->last_avail_idx, desc_count,
@@ -1923,14 +1950,24 @@ vhost_dequeue_single_packed(struct virtio_net *dev,
 
 	*pkts = virtio_dev_pktmbuf_alloc(dev, mbuf_pool, buf_len);
 	if (unlikely(*pkts == NULL)) {
-		RTE_LOG(ERR, VHOST_DATA,
-			"Failed to allocate memory for mbuf.\n");
+		if (!allocerr_warned) {
+			RTE_LOG(ERR, VHOST_DATA,
+				"Failed mbuf alloc of size %d from %s on %s.\n",
+				buf_len, mbuf_pool->name, dev->ifname);
+			allocerr_warned = true;
+		}
 		return -1;
 	}
 
 	err = copy_desc_to_mbuf(dev, vq, buf_vec, nr_vec, *pkts,
 				mbuf_pool);
 	if (unlikely(err)) {
+		if (!allocerr_warned) {
+			RTE_LOG(ERR, VHOST_DATA,
+				"Failed to copy desc to mbuf on %s.\n",
+				dev->ifname);
+			allocerr_warned = true;
+		}
 		rte_pktmbuf_free(*pkts);
 		return -1;
 	}
@@ -1945,21 +1982,24 @@ virtio_dev_tx_single_packed(struct virtio_net *dev,
 			    struct rte_mbuf **pkts)
 {
 
-	uint16_t buf_id, desc_count;
+	uint16_t buf_id, desc_count = 0;
+	int ret;
 
-	if (vhost_dequeue_single_packed(dev, vq, mbuf_pool, pkts, &buf_id,
-					&desc_count))
-		return -1;
+	ret = vhost_dequeue_single_packed(dev, vq, mbuf_pool, pkts, &buf_id,
+					&desc_count);
 
-	if (virtio_net_is_inorder(dev))
-		vhost_shadow_dequeue_single_packed_inorder(vq, buf_id,
-							   desc_count);
-	else
-		vhost_shadow_dequeue_single_packed(vq, buf_id, desc_count);
+	if (likely(desc_count > 0)) {
+		if (virtio_net_is_inorder(dev))
+			vhost_shadow_dequeue_single_packed_inorder(vq, buf_id,
+								   desc_count);
+		else
+			vhost_shadow_dequeue_single_packed(vq, buf_id,
+					desc_count);
 
-	vq_inc_last_avail_packed(vq, desc_count);
+		vq_inc_last_avail_packed(vq, desc_count);
+	}
 
-	return 0;
+	return ret;
 }
 
 static __rte_always_inline int
-- 
2.23.0

