[v2,2/2] vhost: add thread-safe API for clearing in-flight packets in async vhost

diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
index 9ed544db7a..bc21c879f3 100644
--- a/doc/guides/prog_guide/vhost_lib.rst
+++ b/doc/guides/prog_guide/vhost_lib.rst
@@ -300,7 +300,13 @@  The following is an overview of some key Vhost API functions:
 
 * ``rte_vhost_clear_queue_thread_unsafe(vid, queue_id, **pkts, count)``
 
-  Clear inflight packets which are submitted to DMA engine in vhost async data
+  Clear in-flight packets which are submitted to async channel in vhost
+  async data path without performing any locking. Completed packets are
+  returned to applications through ``pkts``.
+
+* ``rte_vhost_clear_queue(vid, queue_id, **pkts, count)``
+
+  Clear in-flight packets which are submitted to async channel in vhost async data
   path. Completed packets are returned to applications through ``pkts``.
 
 * ``rte_vhost_async_try_dequeue_burst(vid, queue_id, mbuf_pool, pkts, count, nr_inflight)``
diff --git a/lib/vhost/rte_vhost_async.h b/lib/vhost/rte_vhost_async.h
index 973efa19b1..887fc2fa47 100644
--- a/lib/vhost/rte_vhost_async.h
+++ b/lib/vhost/rte_vhost_async.h
@@ -256,6 +256,27 @@  int rte_vhost_async_get_inflight(int vid, uint16_t queue_id);
 __rte_experimental
 uint16_t rte_vhost_clear_queue_thread_unsafe(int vid, uint16_t queue_id,
 		struct rte_mbuf **pkts, uint16_t count);
+
+/**
+ * This function checks async completion status and clear packets for
+ * a specific vhost device queue. Packets which are inflight will be
+ * returned in an array.
+ *
+ * @param vid
+ *  ID of vhost device to clear data
+ * @param queue_id
+ *  Queue id to clear data
+ * @param pkts
+ *  Blank array to get return packet pointer
+ * @param count
+ *  Size of the packet array
+ * @return
+ *  Number of packets returned
+ */
+__rte_experimental
+uint16_t rte_vhost_clear_queue(int vid, uint16_t queue_id,
+		struct rte_mbuf **pkts, uint16_t count);
+
 /**
  * This function tries to receive packets from the guest with offloading
  * copies to the async channel. The packets that are transfer completed
diff --git a/lib/vhost/version.map b/lib/vhost/version.map
index 8eb7e92c32..b87d5906b8 100644
--- a/lib/vhost/version.map
+++ b/lib/vhost/version.map
@@ -88,4 +88,5 @@  EXPERIMENTAL {
 
 	# added in 21.11
 	rte_vhost_async_try_dequeue_burst;
+	rte_vhost_clear_queue;
 };
diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
index cc84a9d21e..e7292332a8 100644
--- a/lib/vhost/virtio_net.c
+++ b/lib/vhost/virtio_net.c
@@ -2154,6 +2154,55 @@  rte_vhost_clear_queue_thread_unsafe(int vid, uint16_t queue_id,
 	return n_pkts_cpl;
 }
 
+uint16_t
+rte_vhost_clear_queue(int vid, uint16_t queue_id, struct rte_mbuf **pkts, uint16_t count)
+{
+	struct virtio_net *dev = get_device(vid);
+	struct vhost_virtqueue *vq;
+	uint16_t n_pkts_cpl;
+
+	if (!dev)
+		return 0;
+
+	VHOST_LOG_DATA(DEBUG, "(%d) %s\n", dev->vid, __func__);
+	if (unlikely(queue_id >= dev->nr_vring)) {
+		VHOST_LOG_DATA(ERR, "(%d) %s: invalid virtqueue idx %d.\n",
+			dev->vid, __func__, queue_id);
+		return 0;
+	}
+
+	vq = dev->virtqueue[queue_id];
+
+	if (unlikely(!vq->async_registered)) {
+		VHOST_LOG_DATA(ERR, "(%d) %s: async not registered for queue id %d.\n",
+			dev->vid, __func__, queue_id);
+		return 0;
+	}
+
+	if (!rte_spinlock_trylock(&vq->access_lock)) {
+		VHOST_LOG_DATA(ERR,
+			"(%d) %s: failed to clear async queue id %d, virtqueue busy.\n",
+			dev->vid, __func__, queue_id);
+		return 0;
+	}
+
+	if (queue_id % 2 == 0)
+		n_pkts_cpl = vhost_poll_enqueue_completed(dev, queue_id, pkts, count);
+	else {
+		if (unlikely(vq_is_packed(dev)))
+			VHOST_LOG_DATA(ERR,
+				"(%d) %s: async dequeue does not support packed ring.\n",
+				dev->vid, __func__);
+		else
+			n_pkts_cpl = async_poll_dequeue_completed_split(dev, vq, queue_id, pkts,
+						count, dev->flags & VIRTIO_DEV_LEGACY_OL_FLAGS);
+	}
+
+	rte_spinlock_unlock(&vq->access_lock);
+
+	return n_pkts_cpl;
+}
+
 static __rte_always_inline uint32_t
 virtio_dev_rx_async_submit(struct virtio_net *dev, uint16_t queue_id,
 	struct rte_mbuf **pkts, uint32_t count)