2 files changed, 23 insertions, 9 deletions

diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
index 61e1657..9efb9da 100644
--- a/contrib/libvhost-user/libvhost-user.c
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -1031,6 +1031,11 @@ vu_queue_get_avail_bytes(VuDev *dev, VuVirtq *vq, unsigned int *in_bytes,
     idx = vq->last_avail_idx;
 
     total_bufs = in_total = out_total = 0;
+    if (unlikely(dev->broken) ||
+        unlikely(!vq->vring.avail)) {
+        goto done;
+    }
+
     while ((rc = virtqueue_num_heads(dev, vq, idx)) > 0) {
         unsigned int max, num_bufs, indirect = 0;
         struct vring_desc *desc;
@@ -1121,11 +1126,16 @@ vu_queue_avail_bytes(VuDev *dev, VuVirtq *vq, unsigned int in_bytes,
 
 /* Fetch avail_idx from VQ memory only when we really need to know if
  * guest has added some buffers. */
-int
+bool
 vu_queue_empty(VuDev *dev, VuVirtq *vq)
 {
+    if (unlikely(dev->broken) ||
+        unlikely(!vq->vring.avail)) {
+        return true;
+    }
+
     if (vq->shadow_avail_idx != vq->last_avail_idx) {
-        return 0;
+        return false;
     }
 
     return vring_avail_idx(vq) == vq->last_avail_idx;
@@ -1174,7 +1184,8 @@ vring_notify(VuDev *dev, VuVirtq *vq)
 void
 vu_queue_notify(VuDev *dev, VuVirtq *vq)
 {
-    if (unlikely(dev->broken)) {
+    if (unlikely(dev->broken) ||
+        unlikely(!vq->vring.avail)) {
         return;
     }
 
@@ -1291,7 +1302,8 @@ vu_queue_pop(VuDev *dev, VuVirtq *vq, size_t sz)
     struct vring_desc *desc;
     int rc;
 
-    if (unlikely(dev->broken)) {
+    if (unlikely(dev->broken) ||
+        unlikely(!vq->vring.avail)) {
         return NULL;
     }
 
@@ -1445,7 +1457,8 @@ vu_queue_fill(VuDev *dev, VuVirtq *vq,
 {
     struct vring_used_elem uelem;
 
-    if (unlikely(dev->broken)) {
+    if (unlikely(dev->broken) ||
+        unlikely(!vq->vring.avail)) {
         return;
     }
 
@@ -1474,7 +1487,8 @@ vu_queue_flush(VuDev *dev, VuVirtq *vq, unsigned int count)
 {
     uint16_t old, new;
 
-    if (unlikely(dev->broken)) {
+    if (unlikely(dev->broken) ||
+        unlikely(!vq->vring.avail)) {
         return;
     }
 
diff --git a/contrib/libvhost-user/libvhost-user.h b/contrib/libvhost-user/libvhost-user.h
index 156b50e..af02a31 100644
--- a/contrib/libvhost-user/libvhost-user.h
+++ b/contrib/libvhost-user/libvhost-user.h
@@ -327,13 +327,13 @@ void vu_queue_set_notification(VuDev *dev, VuVirtq *vq, int enable);
 bool vu_queue_enabled(VuDev *dev, VuVirtq *vq);
 
 /**
- * vu_queue_enabled:
+ * vu_queue_empty:
  * @dev: a VuDev context
  * @vq: a VuVirtq queue
  *
- * Returns: whether the queue is empty.
+ * Returns: true if the queue is empty or not ready.
  */
-int vu_queue_empty(VuDev *dev, VuVirtq *vq);
+bool vu_queue_empty(VuDev *dev, VuVirtq *vq);
 
 /**
  * vu_queue_notify: