net/vhost: emulate device start/stop behavior

.dev_start()/.dev_stop() roughly corresponds to the local device's port
being ready.  This is different from the remote client being connected
which is roughly link up or down.  Emulate the device start/stop behavior
by separately tracking the start/stop state to determine if we should
allow packets to be queued to/from the remote client.

Signed-off-by: Chas Williams <ciwillia@brocade.com>
Acked-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>

drivers/net/vhost/rte_eth_vhost.c

@@ -112,9 +112,11 @@ struct vhost_queue {
 };
 
 struct pmd_internal {
+	rte_atomic32_t dev_attached;
 	char *dev_name;
 	char *iface_name;
 	uint16_t max_queues;
+	rte_atomic32_t started;
 };
 
 struct internal_list {
@@ -494,6 +496,38 @@ find_internal_resource(char *ifname)
 	return list;
 }
 
+static void
+update_queuing_status(struct rte_eth_dev *dev)
+{
+	struct pmd_internal *internal = dev->data->dev_private;
+	struct vhost_queue *vq;
+	unsigned int i;
+	int allow_queuing = 1;
+
+	if (rte_atomic32_read(&internal->started) == 0 ||
+	    rte_atomic32_read(&internal->dev_attached) == 0)
+		allow_queuing = 0;
+
+	/* Wait until rx/tx_pkt_burst stops accessing vhost device */
+	for (i = 0; i < dev->data->nb_rx_queues; i++) {
+		vq = dev->data->rx_queues[i];
+		if (vq == NULL)
+			continue;
+		rte_atomic32_set(&vq->allow_queuing, allow_queuing);
+		while (rte_atomic32_read(&vq->while_queuing))
+			rte_pause();
+	}
+
+	for (i = 0; i < dev->data->nb_tx_queues; i++) {
+		vq = dev->data->tx_queues[i];
+		if (vq == NULL)
+			continue;
+		rte_atomic32_set(&vq->allow_queuing, allow_queuing);
+		while (rte_atomic32_read(&vq->while_queuing))
+			rte_pause();
+	}
+}
+
 static int
 new_device(int vid)
 {
@@ -545,18 +579,8 @@ new_device(int vid)
 
 	eth_dev->data->dev_link.link_status = ETH_LINK_UP;
 
-	for (i = 0; i < eth_dev->data->nb_rx_queues; i++) {
-		vq = eth_dev->data->rx_queues[i];
-		if (vq == NULL)
-			continue;
-		rte_atomic32_set(&vq->allow_queuing, 1);
-	}
-	for (i = 0; i < eth_dev->data->nb_tx_queues; i++) {
-		vq = eth_dev->data->tx_queues[i];
-		if (vq == NULL)
-			continue;
-		rte_atomic32_set(&vq->allow_queuing, 1);
-	}
+	rte_atomic32_set(&internal->dev_attached, 1);
+	update_queuing_status(eth_dev);
 
 	RTE_LOG(INFO, PMD, "New connection established\n");
 
@@ -569,6 +593,7 @@ static void
 destroy_device(int vid)
 {
 	struct rte_eth_dev *eth_dev;
+	struct pmd_internal *internal;
 	struct vhost_queue *vq;
 	struct internal_list *list;
 	char ifname[PATH_MAX];
@@ -582,24 +607,10 @@ destroy_device(int vid)
 		return;
 	}
 	eth_dev = list->eth_dev;
+	internal = eth_dev->data->dev_private;
 
-	/* Wait until rx/tx_pkt_burst stops accessing vhost device */
-	for (i = 0; i < eth_dev->data->nb_rx_queues; i++) {
-		vq = eth_dev->data->rx_queues[i];
-		if (vq == NULL)
-			continue;
-		rte_atomic32_set(&vq->allow_queuing, 0);
-		while (rte_atomic32_read(&vq->while_queuing))
-			rte_pause();
-	}
-	for (i = 0; i < eth_dev->data->nb_tx_queues; i++) {
-		vq = eth_dev->data->tx_queues[i];
-		if (vq == NULL)
-			continue;
-		rte_atomic32_set(&vq->allow_queuing, 0);
-		while (rte_atomic32_read(&vq->while_queuing))
-			rte_pause();
-	}
+	rte_atomic32_set(&internal->dev_attached, 0);
+	update_queuing_status(eth_dev);
 
 	eth_dev->data->dev_link.link_status = ETH_LINK_DOWN;
 
@@ -773,14 +784,23 @@ vhost_driver_session_stop(void)
 }
 
 static int
-eth_dev_start(struct rte_eth_dev *dev __rte_unused)
+eth_dev_start(struct rte_eth_dev *dev)
 {
+	struct pmd_internal *internal = dev->data->dev_private;
+
+	rte_atomic32_set(&internal->started, 1);
+	update_queuing_status(dev);
+
 	return 0;
 }
 
 static void
-eth_dev_stop(struct rte_eth_dev *dev __rte_unused)
+eth_dev_stop(struct rte_eth_dev *dev)
 {
+	struct pmd_internal *internal = dev->data->dev_private;
+
+	rte_atomic32_set(&internal->started, 0);
+	update_queuing_status(dev);
 }
 
 static int