[dpdk-dev] [PATCH v4 11/22] vhost: move the device ready check at proper place

[Yuanhan Liu]

Currently, we check vq->desc, vq->kickfd and vq->callfd to know whether
a virtio device is ready or not. However, we only do it when handling
SET_VRING_KICK message, which could be wrong if a vhost-user frontend
send SET_VRING_KICK first and SET_VRING_CALL later.

To work for all possible vhost-user frontend implementations, we could
move the ready check at the end of vhost-user message handler.

Meanwhile, since we do the check more often than before, the "virtio
not ready" message is dropped, to not flood the screen.

Signed-off-by: Yuanhan Liu <yuanhan.liu at linux.intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>
---
 lib/librte_vhost/vhost_user.c | 40 ++++++++++++++++++----------------------
 1 file changed, 18 insertions(+), 22 deletions(-)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index 4337ce7..9140f60 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -615,14 +615,14 @@
 	struct vhost_virtqueue *vq;
 	uint32_t i;
 
+	if (dev->nr_vring == 0)
+		return 0;
+
 	for (i = 0; i < dev->nr_vring; i++) {
 		vq = dev->virtqueue[i];
 
-		if (!vq_is_ready(vq)) {
-			RTE_LOG(INFO, VHOST_CONFIG,
-				"virtio is not ready for processing.\n");
+		if (!vq_is_ready(vq))
 			return 0;
-		}
 	}
 
 	RTE_LOG(INFO, VHOST_CONFIG,
@@ -651,10 +651,6 @@
 	vq->callfd = file.fd;
 }
 
-/*
- *  In vhost-user, when we receive kick message, will test whether virtio
- *  device is ready for packet processing.
- */
 static void
 vhost_user_set_vring_kick(struct virtio_net *dev, struct VhostUserMsg *pmsg)
 {
@@ -673,20 +669,6 @@
 	if (vq->kickfd >= 0)
 		close(vq->kickfd);
 	vq->kickfd = file.fd;
-
-	if (virtio_is_ready(dev)) {
-		dev->flags |= VIRTIO_DEV_READY;
-
-		if (!(dev->flags & VIRTIO_DEV_RUNNING)) {
-			if (dev->dequeue_zero_copy) {
-				RTE_LOG(INFO, VHOST_CONFIG,
-						"dequeue zero copy is enabled\n");
-			}
-
-			if (dev->notify_ops->new_device(dev->vid) == 0)
-				dev->flags |= VIRTIO_DEV_RUNNING;
-		}
-	}
 }
 
 static void
@@ -1108,5 +1090,19 @@
 		send_vhost_message(fd, &msg);
 	}
 
+	if (!(dev->flags & VIRTIO_DEV_RUNNING) && virtio_is_ready(dev)) {
+		dev->flags |= VIRTIO_DEV_READY;
+
+		if (!(dev->flags & VIRTIO_DEV_RUNNING)) {
+			if (dev->dequeue_zero_copy) {
+				RTE_LOG(INFO, VHOST_CONFIG,
+						"dequeue zero copy is enabled\n");
+			}
+
+			if (dev->notify_ops->new_device(dev->vid) == 0)
+				dev->flags |= VIRTIO_DEV_RUNNING;
+		}
+	}
+
 	return 0;
 }
-- 
1.9.0