[dpdk-dev] [PATCH v2 37/44] net/virtio: make server mode blocking

[Maxime Coquelin <maxime.coquelin@redhat.com>]

This patch makes the Vhost-user backend server mode
blocking at init, waiting for the client connection.

The goal is to make the driver more reliable, as without
waiting for client connection, the Virtio driver has to
assume the Vhost-user backend will support all the
features it has advertized, which could lead to undefined
behaviour.

For example, without this patch, if the user enables packed
ring Virtio feature but the backend does not support it,
the ring initialized by the driver will not be compatible
with the backend.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 drivers/net/virtio/virtio_user/vhost_user.c   |   9 +-
 .../net/virtio/virtio_user/virtio_user_dev.c  | 121 +++++++-----------
 drivers/net/virtio/virtio_user_ethdev.c       |   5 -
 3 files changed, 55 insertions(+), 80 deletions(-)

diff --git a/drivers/net/virtio/virtio_user/vhost_user.c b/drivers/net/virtio/virtio_user/vhost_user.c
index fb6fcc82c9..a48fadd8c9 100644
--- a/drivers/net/virtio/virtio_user/vhost_user.c
+++ b/drivers/net/virtio/virtio_user/vhost_user.c
@@ -692,6 +692,14 @@ virtio_user_start_server(struct virtio_user_dev *dev, struct sockaddr_un *un)
 	if (ret < 0)
 		return -1;
 
+	PMD_DRV_LOG(NOTICE, "(%s) waiting for client connection...", dev->path);
+	dev->vhostfd = accept(fd, NULL, NULL);
+	if (dev->vhostfd < 0) {
+		PMD_DRV_LOG(ERR, "Failed to accept initial client connection (%s)",
+				strerror(errno));
+		return -1;
+	}
+
 	flag = fcntl(fd, F_GETFL);
 	if (fcntl(fd, F_SETFL, flag | O_NONBLOCK) < 0) {
 		PMD_DRV_LOG(ERR, "fcntl failed, %s", strerror(errno));
@@ -736,7 +744,6 @@ vhost_user_setup(struct virtio_user_dev *dev)
 			close(fd);
 			return -1;
 		}
-		dev->vhostfd = -1;
 	} else {
 		if (connect(fd, (struct sockaddr *)&un, sizeof(un)) < 0) {
 			PMD_DRV_LOG(ERR, "connect error, %s", strerror(errno));
diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.c b/drivers/net/virtio/virtio_user/virtio_user_dev.c
index 95204ea955..c2a41fe3a0 100644
--- a/drivers/net/virtio/virtio_user/virtio_user_dev.c
+++ b/drivers/net/virtio/virtio_user/virtio_user_dev.c
@@ -144,10 +144,6 @@ virtio_user_dev_set_features(struct virtio_user_dev *dev)
 
 	pthread_mutex_lock(&dev->mutex);
 
-	if (dev->backend_type == VIRTIO_USER_BACKEND_VHOST_USER &&
-			dev->vhostfd < 0)
-		goto error;
-
 	/* Step 0: tell vhost to create queues */
 	if (virtio_user_queue_setup(dev, virtio_user_create_queue) < 0)
 		goto error;
@@ -190,11 +186,6 @@ virtio_user_start_device(struct virtio_user_dev *dev)
 	rte_mcfg_mem_read_lock();
 	pthread_mutex_lock(&dev->mutex);
 
-	/* Vhost-user client not connected yet, will start later */
-	if (dev->backend_type == VIRTIO_USER_BACKEND_VHOST_USER &&
-			dev->vhostfd < 0)
-		goto out;
-
 	/* Step 2: share memory regions */
 	ret = dev->ops->set_memory_table(dev);
 	if (ret < 0)
@@ -213,7 +204,7 @@ virtio_user_start_device(struct virtio_user_dev *dev)
 		goto error;
 
 	dev->started = true;
-out:
+
 	pthread_mutex_unlock(&dev->mutex);
 	rte_mcfg_mem_read_unlock();
 
@@ -422,36 +413,36 @@ virtio_user_dev_setup(struct virtio_user_dev *dev)
 			PMD_DRV_LOG(ERR, "Server mode only supports vhost-user!");
 			return -1;
 		}
+	}
+
+	if (dev->backend_type == VIRTIO_USER_BACKEND_VHOST_USER) {
 		dev->ops = &virtio_ops_user;
-	} else {
-		if (dev->backend_type == VIRTIO_USER_BACKEND_VHOST_USER) {
-			dev->ops = &virtio_ops_user;
-		} else if (dev->backend_type ==
-					VIRTIO_USER_BACKEND_VHOST_KERNEL) {
-			dev->ops = &virtio_ops_kernel;
-
-			dev->vhostfds = malloc(dev->max_queue_pairs *
-					       sizeof(int));
-			dev->tapfds = malloc(dev->max_queue_pairs *
-					     sizeof(int));
-			if (!dev->vhostfds || !dev->tapfds) {
-				PMD_INIT_LOG(ERR, "(%s) Failed to allocate FDs", dev->path);
-				return -1;
-			}
-
-			for (q = 0; q < dev->max_queue_pairs; ++q) {
-				dev->vhostfds[q] = -1;
-				dev->tapfds[q] = -1;
-			}
-		} else if (dev->backend_type ==
-				VIRTIO_USER_BACKEND_VHOST_VDPA) {
-			dev->ops = &virtio_ops_vdpa;
-		} else {
-			PMD_DRV_LOG(ERR, "(%s) Unknown backend type", dev->path);
+	} else if (dev->backend_type ==
+			VIRTIO_USER_BACKEND_VHOST_KERNEL) {
+		dev->ops = &virtio_ops_kernel;
+
+		dev->vhostfds = malloc(dev->max_queue_pairs *
+				sizeof(int));
+		dev->tapfds = malloc(dev->max_queue_pairs *
+				sizeof(int));
+		if (!dev->vhostfds || !dev->tapfds) {
+			PMD_INIT_LOG(ERR, "(%s) Failed to allocate FDs", dev->path);
 			return -1;
 		}
+
+		for (q = 0; q < dev->max_queue_pairs; ++q) {
+			dev->vhostfds[q] = -1;
+			dev->tapfds[q] = -1;
+		}
+	} else if (dev->backend_type ==
+			VIRTIO_USER_BACKEND_VHOST_VDPA) {
+		dev->ops = &virtio_ops_vdpa;
+	} else {
+		PMD_DRV_LOG(ERR, "(%s) Unknown backend type", dev->path);
+		return -1;
 	}
 
+
 	if (dev->ops->setup(dev) < 0) {
 		PMD_INIT_LOG(ERR, "(%s) Failed to setup backend\n", dev->path);
 		return -1;
@@ -541,54 +532,36 @@ virtio_user_dev_init(struct virtio_user_dev *dev, char *path, int queues,
 		dev->unsupported_features |=
 			(1ULL << VHOST_USER_F_PROTOCOL_FEATURES);
 
-	if (!dev->is_server) {
-		if (dev->ops->set_owner(dev) < 0) {
-			PMD_INIT_LOG(ERR, "(%s) Failed to set backend owner", dev->path);
-			return -1;
-		}
+	if (dev->ops->set_owner(dev) < 0) {
+		PMD_INIT_LOG(ERR, "(%s) Failed to set backend owner", dev->path);
+		return -1;
+	}
+
+	if (dev->ops->get_features(dev, &dev->device_features) < 0) {
+		PMD_INIT_LOG(ERR, "(%s) Failed to get backend features", dev->path);
+		return -1;
+	}
 
-		if (dev->ops->get_features(dev, &dev->device_features) < 0) {
-			PMD_INIT_LOG(ERR, "(%s) Failed to get backend features", dev->path);
+	if ((dev->device_features & (1ULL << VHOST_USER_F_PROTOCOL_FEATURES)) ||
+			dev->backend_type == VIRTIO_USER_BACKEND_VHOST_VDPA) {
+		if (dev->ops->get_protocol_features(dev, &protocol_features)) {
+			PMD_INIT_LOG(ERR, "(%s) Failed to get backend protocol features",
+					dev->path);
 			return -1;
 		}
 
+		dev->protocol_features &= protocol_features;
 
-		if ((dev->device_features & (1ULL << VHOST_USER_F_PROTOCOL_FEATURES)) ||
-				(dev->backend_type == VIRTIO_USER_BACKEND_VHOST_VDPA)) {
-			if (dev->ops->get_protocol_features(dev, &protocol_features)) {
-				PMD_INIT_LOG(ERR, "(%s) Failed to get backend protocol features",
-						dev->path);
-				return -1;
-			}
-
-			dev->protocol_features &= protocol_features;
-
-			if (dev->ops->set_protocol_features(dev, dev->protocol_features)) {
-				PMD_INIT_LOG(ERR, "(%s) Failed to set backend protocol features",
-						dev->path);
-				return -1;
-			}
-
-			if (!(dev->protocol_features & (1ULL << VHOST_USER_PROTOCOL_F_MQ)))
-				dev->unsupported_features |= (1ull << VIRTIO_NET_F_MQ);
+		if (dev->ops->set_protocol_features(dev, dev->protocol_features)) {
+			PMD_INIT_LOG(ERR, "(%s) Failed to set backend protocol features",
+					dev->path);
+			return -1;
 		}
-	} else {
-		/* We just pretend vhost-user can support all these features.
-		 * Note that this could be problematic that if some feature is
-		 * negotiated but not supported by the vhost-user which comes
-		 * later.
-		 */
-		dev->device_features = VIRTIO_USER_SUPPORTED_FEATURES;
 
-		/* We cannot assume VHOST_USER_PROTOCOL_F_STATUS is supported
-		 * until it's negotiated
-		 */
-		dev->protocol_features &=
-			~(1ULL << VHOST_USER_PROTOCOL_F_STATUS);
+		if (!(dev->protocol_features & (1ULL << VHOST_USER_PROTOCOL_F_MQ)))
+			dev->unsupported_features |= (1ull << VIRTIO_NET_F_MQ);
 	}
 
-
-
 	if (!mrg_rxbuf)
 		dev->unsupported_features |= (1ull << VIRTIO_NET_F_MRG_RXBUF);
 
diff --git a/drivers/net/virtio/virtio_user_ethdev.c b/drivers/net/virtio/virtio_user_ethdev.c
index 5e256f4e6d..e822d93690 100644
--- a/drivers/net/virtio/virtio_user_ethdev.c
+++ b/drivers/net/virtio/virtio_user_ethdev.c
@@ -174,11 +174,6 @@ virtio_user_delayed_handler(void *param)
 		if (dev->vhostfd >= 0) {
 			close(dev->vhostfd);
 			dev->vhostfd = -1;
-			/* Until the featuers are negotiated again, don't assume
-			 * the backend supports VHOST_USER_PROTOCOL_F_STATUS
-			 */
-			dev->protocol_features &=
-				~(1ULL << VHOST_USER_PROTOCOL_F_STATUS);
 		}
 		eth_dev->intr_handle->fd = dev->listenfd;
 		rte_intr_callback_register(eth_dev->intr_handle,
-- 
2.29.2