patch 'vhost: fix memory leak in Virtio Tx split path' has been queued to stable release 23.11.1

[Xueming Li]

Hi,

FYI, your patch has been queued to stable release 23.11.1

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 03/31/24. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://git.dpdk.org/dpdk-stable/log/?h=23.11-staging

This queued commit can be viewed at:
https://git.dpdk.org/dpdk-stable/commit/?h=23.11-staging&id=e951bbbd186c29ef86a3016ff30bc33b9dac35fa

Thanks.

Xueming Li <xuemingl at nvidia.com>

---
>From e951bbbd186c29ef86a3016ff30bc33b9dac35fa Mon Sep 17 00:00:00 2001
From: Maxime Coquelin <maxime.coquelin at redhat.com>
Date: Wed, 31 Jan 2024 20:53:08 +0100
Subject: [PATCH] vhost: fix memory leak in Virtio Tx split path
Cc: Xueming Li <xuemingl at nvidia.com>

[ upstream commit 7746fba831509fdb4c528266d0b38a89566e01e5 ]

When vIOMMU is enabled, rte_vhost_dequeue_burst() can return early
because of IOTLB misses.
Such IOTLB misses are especially frequent when a Virtio device is
bound to a kernel driver in guest.

This patch fixes a mbuf leak occurring in this case.

Fixes: 242695f6122a ("vhost: allocate and free packets in bulk in Tx split")

Signed-off-by: Maxime Coquelin <maxime.coquelin at redhat.com>
Signed-off-by: David Marchand <david.marchand at redhat.com>
Reviewed-by: David Marchand <david.marchand at redhat.com>
---
 lib/vhost/virtio_net.c | 24 ++++++------------------
 1 file changed, 6 insertions(+), 18 deletions(-)

diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
index d00f4b03aa..895a79cf51 100644
--- a/lib/vhost/virtio_net.c
+++ b/lib/vhost/virtio_net.c
@@ -3104,7 +3104,6 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
 {
 	uint16_t i;
 	uint16_t avail_entries;
-	uint16_t dropped = 0;
 	static bool allocerr_warned;

 	/*
@@ -3143,11 +3142,8 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,

 		update_shadow_used_ring_split(vq, head_idx, 0);

-		if (unlikely(buf_len <= dev->vhost_hlen)) {
-			dropped += 1;
-			i++;
+		if (unlikely(buf_len <= dev->vhost_hlen))
 			break;
-		}

 		buf_len -= dev->vhost_hlen;

@@ -3164,8 +3160,6 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
 					buf_len, mbuf_pool->name);
 				allocerr_warned = true;
 			}
-			dropped += 1;
-			i++;
 			break;
 		}

@@ -3176,27 +3170,21 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
 				VHOST_LOG_DATA(dev->ifname, ERR, "failed to copy desc to mbuf.\n");
 				allocerr_warned = true;
 			}
-			dropped += 1;
-			i++;
 			break;
 		}
-
 	}

-	if (dropped)
-		rte_pktmbuf_free_bulk(&pkts[i - 1], count - i + 1);
+	if (unlikely(count != i))
+		rte_pktmbuf_free_bulk(&pkts[i], count - i);

-	vq->last_avail_idx += i;
-
-	do_data_copy_dequeue(vq);
-	if (unlikely(i < count))
-		vq->shadow_used_idx = i;
 	if (likely(vq->shadow_used_idx)) {
+		vq->last_avail_idx += vq->shadow_used_idx;
+		do_data_copy_dequeue(vq);
 		flush_shadow_used_ring_split(dev, vq);
 		vhost_vring_call_split(dev, vq);
 	}

-	return (i - dropped);
+	return i;
 }

 __rte_noinline
--
2.34.1

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2024-03-05 17:39:32.803090760 +0800
+++ 0061-vhost-fix-memory-leak-in-Virtio-Tx-split-path.patch	2024-03-05 17:39:30.783566493 +0800
@@ -1 +1 @@
-From 7746fba831509fdb4c528266d0b38a89566e01e5 Mon Sep 17 00:00:00 2001
+From e951bbbd186c29ef86a3016ff30bc33b9dac35fa Mon Sep 17 00:00:00 2001
@@ -4,0 +5,3 @@
+Cc: Xueming Li <xuemingl at nvidia.com>
+
+[ upstream commit 7746fba831509fdb4c528266d0b38a89566e01e5 ]
@@ -14 +16,0 @@
-Cc: stable at dpdk.org
@@ -24 +26 @@
-index c738b7edc9..9951842b9f 100644
+index d00f4b03aa..895a79cf51 100644
@@ -58 +60 @@
- 				VHOST_DATA_LOG(dev->ifname, ERR, "failed to copy desc to mbuf.");
+ 				VHOST_LOG_DATA(dev->ifname, ERR, "failed to copy desc to mbuf.\n");