[dpdk-dev] [PATCH v2] vhost: added user callbacks for socket open/close

Dariusz Stojaczyk dariuszx.stojaczyk at intel.com
Tue Aug 22 18:24:52 CEST 2017


When user receives destroy_device signal, he does not know *why* that
event happened. He does not differ between socket shutdown and virtio
processing pause. User could completely delete device during transition
from BIOS to kernel, causing freeze or possibly kernel panic. Instead
of changing new_device/destroy_device callbacks and breaking the ABI,
a set of new functions new_connection/destroy_connection has been added.

Signed-off-by: Dariusz Stojaczyk <dariuszx.stojaczyk at intel.com>
---
v2: also updated vhost_lib.rst
 doc/guides/prog_guide/vhost_lib.rst | 15 +++++++++++++--
 lib/librte_vhost/rte_vhost.h        |  5 ++++-
 lib/librte_vhost/socket.c           | 23 +++++++++++++++++++----
 3 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
index 5979290..861a0e2 100644
--- a/doc/guides/prog_guide/vhost_lib.rst
+++ b/doc/guides/prog_guide/vhost_lib.rst
@@ -129,8 +129,7 @@ The following is an overview of some key Vhost API functions:
 
   * ``destroy_device(int vid)``
 
-    This callback is invoked when a virtio device shuts down (or when the
-    vhost connection is broken).
+    This callback is invoked when a virtio device is paused or shut down.
 
   * ``vring_state_changed(int vid, uint16_t queue_id, int enable)``
 
@@ -143,6 +142,18 @@ The following is an overview of some key Vhost API functions:
     ``VHOST_F_LOG_ALL`` will be set/cleared at the start/end of live
     migration, respectively.
 
+  * ``new_connection(int vid)``
+
+    This callback is invoked on new vhost-user socket connection. If DPDK
+    acts as the server the device should not be deleted before
+     ``destroy_connection`` callback is received.
+
+  * ``destroy_connection(int vid)``
+
+    This callback is invoked when vhost-user socket connection is closed.
+    It indicates that device with id ``vid`` is no longer in use and can be
+    safely deleted.
+
 * ``rte_vhost_driver_disable/enable_features(path, features))``
 
   This function disables/enables some features. For example, it can be used to
diff --git a/lib/librte_vhost/rte_vhost.h b/lib/librte_vhost/rte_vhost.h
index 8c974eb..8f86167 100644
--- a/lib/librte_vhost/rte_vhost.h
+++ b/lib/librte_vhost/rte_vhost.h
@@ -107,7 +107,10 @@ struct vhost_device_ops {
 	 */
 	int (*features_changed)(int vid, uint64_t features);
 
-	void *reserved[4]; /**< Reserved for future extension */
+	int (*new_connection)(int vid);		/**< Connect to socket. */
+	void (*destroy_connection)(int vid);	/**< Disconnect from socket */
+
+	void *reserved[2]; /**< Reserved for future extension */
 };
 
 /**
diff --git a/lib/librte_vhost/socket.c b/lib/librte_vhost/socket.c
index 41aa3f9..4ab4ff7 100644
--- a/lib/librte_vhost/socket.c
+++ b/lib/librte_vhost/socket.c
@@ -230,24 +230,36 @@ vhost_user_add_connection(int fd, struct vhost_user_socket *vsocket)
 
 	RTE_LOG(INFO, VHOST_CONFIG, "new device, handle is %d\n", vid);
 
+	if (vsocket->notify_ops->new_connection) {
+		ret = vsocket->notify_ops->new_connection(vid);
+		if (ret < 0) {
+			RTE_LOG(ERR, VHOST_CONFIG,
+				"failed to add vhost user connection with fd %d\n",
+				fd);
+			goto err;
+		}
+	}
+
 	conn->connfd = fd;
 	conn->vsocket = vsocket;
 	conn->vid = vid;
 	ret = fdset_add(&vhost_user.fdset, fd, vhost_user_read_cb,
 			NULL, conn);
 	if (ret < 0) {
-		conn->connfd = -1;
-		free(conn);
-		close(fd);
 		RTE_LOG(ERR, VHOST_CONFIG,
 			"failed to add fd %d into vhost server fdset\n",
 			fd);
-		return;
+		goto err;
 	}
 
 	pthread_mutex_lock(&vsocket->conn_mutex);
 	TAILQ_INSERT_TAIL(&vsocket->conn_list, conn, next);
 	pthread_mutex_unlock(&vsocket->conn_mutex);
+	return;
+
+err:
+	free(conn);
+	close(fd);
 }
 
 /* call back when there is new vhost-user connection from client  */
@@ -277,6 +289,9 @@ vhost_user_read_cb(int connfd, void *dat, int *remove)
 		*remove = 1;
 		vhost_destroy_device(conn->vid);
 
+		if (vsocket->notify_ops->destroy_connection)
+			vsocket->notify_ops->destroy_connection(conn->vid);
+
 		pthread_mutex_lock(&vsocket->conn_mutex);
 		TAILQ_REMOVE(&vsocket->conn_list, conn, next);
 		pthread_mutex_unlock(&vsocket->conn_mutex);
-- 
2.7.4



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