[dpdk-stable] [PATCH v16.11 LTS] vhost-user: fix deadlock in case of NUMA realloc

[Maxime Coquelin]

Virtqueue's access lock was recently introduced to protect
the device against async changes.

One problem with the v16.11 backport is that in case of NUMA
reallocation, the device gets stuck because the old access_lock
gets unlocked instead of its reallocated copy. On the next
vhost-user message received, the thread keeps spinning on the
lock, as it will never be unlocked.

Fixes: ce3b23dc9296 ("vhost: protect active rings from async ring changes")

Cc: stable at dpdk.org

Tested-by: Kevin Traynor <ktraynor at redhat.com>
Signed-off-by: Maxime Coquelin <maxime.coquelin at redhat.com>
---
 lib/librte_vhost/vhost_user.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index 80348dbf6..eb75e01cb 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -249,7 +249,7 @@ numa_realloc(struct virtio_net *dev, int index)
 			"Unable to get vq numa information.\n");
 		return dev;
 	}
-	if (oldnode != newnode) {
+	if (oldnode == newnode) {
 		RTE_LOG(INFO, VHOST_CONFIG,
 			"reallocate vq from %d to %d node\n", oldnode, newnode);
 		vq = rte_malloc_socket(NULL, sizeof(*vq) * VIRTIO_QNUM, 0,
@@ -269,7 +269,7 @@ numa_realloc(struct virtio_net *dev, int index)
 			"Unable to get dev numa information.\n");
 		goto out;
 	}
-	if (oldnode != newnode) {
+	if (oldnode == newnode) {
 		RTE_LOG(INFO, VHOST_CONFIG,
 			"reallocate dev from %d to %d node\n",
 			oldnode, newnode);
@@ -327,9 +327,11 @@ qva_to_vva(struct virtio_net *dev, uint64_t qva)
  * This function then converts these to our address space.
  */
 static int
-vhost_user_set_vring_addr(struct virtio_net *dev, struct vhost_vring_addr *addr)
+vhost_user_set_vring_addr(struct virtio_net **pdev,
+						  struct vhost_vring_addr *addr)
 {
 	struct vhost_virtqueue *vq;
+	struct virtio_net *dev = *pdev;
 
 	if (dev->mem == NULL)
 		return -1;
@@ -348,6 +350,8 @@ vhost_user_set_vring_addr(struct virtio_net *dev, struct vhost_vring_addr *addr)
 	}
 
 	dev = numa_realloc(dev, addr->index);
+	*pdev = dev;
+
 	vq = dev->virtqueue[addr->index];
 
 	vq->avail = (struct vring_avail *)(uintptr_t)qva_to_vva(dev,
@@ -1092,7 +1096,7 @@ vhost_user_msg_handler(int vid, int fd)
 		vhost_user_set_vring_num(dev, &msg.payload.state);
 		break;
 	case VHOST_USER_SET_VRING_ADDR:
-		vhost_user_set_vring_addr(dev, &msg.payload.addr);
+		vhost_user_set_vring_addr(&dev, &msg.payload.addr);
 		break;
 	case VHOST_USER_SET_VRING_BASE:
 		vhost_user_set_vring_base(dev, &msg.payload.state);
-- 
2.14.3