[dpdk-dev,2/6] vhost: add vhost-user client mode

Message ID 1462603224-29510-3-git-send-email-yuanhan.liu@linux.intel.com (mailing list archive)
State Changes Requested, archived
Delegated to: Yuanhan Liu
Headers

Commit Message

Yuanhan Liu May 7, 2016, 6:40 a.m. UTC
  Add a new paramter (flags) to rte_vhost_driver_register(). DPDK
vhost-user acts as client mode when RTE_VHOST_USER_CLIENT flag
is set.

The flags would also allow future extensions without breaking the
API (again).

The rest is straingfoward then: allocate a unix socket, and
bind/listen for server, connect for client.

Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
---
 drivers/net/vhost/rte_eth_vhost.c            |   2 +-
 examples/vhost/main.c                        |   2 +-
 lib/librte_vhost/rte_virtio_net.h            |  11 +-
 lib/librte_vhost/vhost_user/vhost-net-user.c | 215 ++++++++++++++++-----------
 4 files changed, 142 insertions(+), 88 deletions(-)
  

Comments

Victor Kaplansky May 9, 2016, 10:33 a.m. UTC | #1
Adding a flag for a future extension seems fine to me.
Could we manage without adding a flag?
For example, could we always try a client mode for a while at first,
and if unsuccessful, then come up with server mode?

-- Victor

----- Original Message -----
> From: "Yuanhan Liu" <yuanhan.liu@linux.intel.com>
> To: dev@dpdk.org
> Cc: "huawei xie" <huawei.xie@intel.com>, "Yuanhan Liu" <yuanhan.liu@linux.intel.com>
> Sent: Saturday, May 7, 2016 9:40:20 AM
> Subject: [dpdk-dev] [PATCH 2/6] vhost: add vhost-user client mode
> 
> Add a new paramter (flags) to rte_vhost_driver_register(). DPDK
> vhost-user acts as client mode when RTE_VHOST_USER_CLIENT flag
> is set.
> 
> The flags would also allow future extensions without breaking the
> API (again).
> 
> The rest is straingfoward then: allocate a unix socket, and
> bind/listen for server, connect for client.
> 
> Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
> ---
>  drivers/net/vhost/rte_eth_vhost.c            |   2 +-
>  examples/vhost/main.c                        |   2 +-
>  lib/librte_vhost/rte_virtio_net.h            |  11 +-
>  lib/librte_vhost/vhost_user/vhost-net-user.c | 215
>  ++++++++++++++++-----------
>  4 files changed, 142 insertions(+), 88 deletions(-)
> 
> diff --git a/drivers/net/vhost/rte_eth_vhost.c
> b/drivers/net/vhost/rte_eth_vhost.c
> index a9dada5..36697cf 100644
> --- a/drivers/net/vhost/rte_eth_vhost.c
> +++ b/drivers/net/vhost/rte_eth_vhost.c
> @@ -456,7 +456,7 @@ eth_dev_start(struct rte_eth_dev *dev)
>  	int ret = 0;
>  
>  	if (rte_atomic16_cmpset(&internal->once, 0, 1)) {
> -		ret = rte_vhost_driver_register(internal->iface_name);
> +		ret = rte_vhost_driver_register(internal->iface_name, 0);
>  		if (ret)
>  			return ret;
>  	}
> diff --git a/examples/vhost/main.c b/examples/vhost/main.c
> index bbf0d28..6899189 100644
> --- a/examples/vhost/main.c
> +++ b/examples/vhost/main.c
> @@ -1499,7 +1499,7 @@ main(int argc, char *argv[])
>  		rte_vhost_feature_disable(1ULL << VIRTIO_NET_F_MRG_RXBUF);
>  
>  	/* Register vhost(cuse or user) driver to handle vhost messages. */
> -	ret = rte_vhost_driver_register((char *)&dev_basename);
> +	ret = rte_vhost_driver_register(dev_basename, 0);
>  	if (ret != 0)
>  		rte_exit(EXIT_FAILURE, "vhost driver register failure.\n");
>  
> diff --git a/lib/librte_vhost/rte_virtio_net.h
> b/lib/librte_vhost/rte_virtio_net.h
> index 4e50425..c84e7ab 100644
> --- a/lib/librte_vhost/rte_virtio_net.h
> +++ b/lib/librte_vhost/rte_virtio_net.h
> @@ -51,6 +51,8 @@
>  #include <rte_mempool.h>
>  #include <rte_ether.h>
>  
> +#define RTE_VHOST_USER_CLIENT		(1ULL << 0)
> +
>  struct rte_mbuf;
>  
>  #define VHOST_MEMORY_MAX_NREGIONS 8
> @@ -96,11 +98,14 @@ uint64_t rte_vhost_feature_get(void);
>  
>  int rte_vhost_enable_guest_notification(int vid, uint16_t queue_id, int
>  enable);
>  
> -/* Register vhost driver. dev_name could be different for multiple instance
> support. */
> -int rte_vhost_driver_register(const char *dev_name);
> +/**
> + * Register vhost driver. path could be different for multiple
> + * instance support.
> + */
> +int rte_vhost_driver_register(const char *path, uint64_t flags);
>  
>  /* Unregister vhost driver. This is only meaningful to vhost user. */
> -int rte_vhost_driver_unregister(const char *dev_name);
> +int rte_vhost_driver_unregister(const char *path);
>  
>  /* Register callbacks. */
>  int rte_vhost_driver_callback_register(struct virtio_net_device_ops const *
>  const);
> diff --git a/lib/librte_vhost/vhost_user/vhost-net-user.c
> b/lib/librte_vhost/vhost_user/vhost-net-user.c
> index f485a3b..aa98717 100644
> --- a/lib/librte_vhost/vhost_user/vhost-net-user.c
> +++ b/lib/librte_vhost/vhost_user/vhost-net-user.c
> @@ -58,6 +58,7 @@
>  struct vhost_user_socket {
>  	char *path;
>  	int listenfd;
> +	int is_server;
>  };
>  
>  struct vhost_user_connection {
> @@ -75,7 +76,7 @@ struct vhost_user {
>  
>  #define MAX_VIRTIO_BACKLOG 128
>  
> -static void vhost_user_new_connection(int fd, void *data, int *remove);
> +static void vhost_user_server_new_connection(int fd, void *data, int
> *remove);
>  static void vhost_user_msg_handler(int fd, void *dat, int *remove);
>  
>  static struct vhost_user vhost_user = {
> @@ -111,48 +112,6 @@ static const char *vhost_message_str[VHOST_USER_MAX] = {
>  	[VHOST_USER_SEND_RARP]  = "VHOST_USER_SEND_RARP",
>  };
>  
> -/**
> - * Create a unix domain socket, bind to path and listen for connection.
> - * @return
> - *  socket fd or -1 on failure
> - */
> -static int
> -uds_socket(const char *path)
> -{
> -	struct sockaddr_un un;
> -	int sockfd;
> -	int ret;
> -
> -	if (path == NULL)
> -		return -1;
> -
> -	sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
> -	if (sockfd < 0)
> -		return -1;
> -	RTE_LOG(INFO, VHOST_CONFIG, "socket created, fd:%d\n", sockfd);
> -
> -	memset(&un, 0, sizeof(un));
> -	un.sun_family = AF_UNIX;
> -	snprintf(un.sun_path, sizeof(un.sun_path), "%s", path);
> -	ret = bind(sockfd, (struct sockaddr *)&un, sizeof(un));
> -	if (ret == -1) {
> -		RTE_LOG(ERR, VHOST_CONFIG, "fail to bind fd:%d, remove file:%s and try
> again.\n",
> -			sockfd, path);
> -		goto err;
> -	}
> -	RTE_LOG(INFO, VHOST_CONFIG, "bind to %s\n", path);
> -
> -	ret = listen(sockfd, MAX_VIRTIO_BACKLOG);
> -	if (ret == -1)
> -		goto err;
> -
> -	return sockfd;
> -
> -err:
> -	close(sockfd);
> -	return -1;
> -}
> -
>  /* return bytes# of read on success or negative val on failure. */
>  static int
>  read_fd_message(int sockfd, char *buf, int buflen, int *fds, int fd_num)
> @@ -287,32 +246,24 @@ send_vhost_message(int sockfd, struct VhostUserMsg
> *msg)
>  	return ret;
>  }
>  
> -/* call back when there is new vhost-user connection.  */
> +
>  static void
> -vhost_user_new_connection(int fd, void *dat, int *remove __rte_unused)
> +vhost_user_add_connection(int fd, struct vhost_user_socket *vsocket)
>  {
> -	struct vhost_user_socket *vsocket = dat;
> -	int conn_fd;
> -	struct vhost_user_connection *conn;
>  	int vid;
> -	unsigned int size;
> -
> -	conn_fd = accept(fd, NULL, NULL);
> -	RTE_LOG(INFO, VHOST_CONFIG,
> -		"new virtio connection is %d\n", conn_fd);
> -	if (conn_fd < 0)
> -		return;
> +	size_t size;
> +	struct vhost_user_connection *conn;
>  
> -	conn = calloc(1, sizeof(*conn));
> +	conn = malloc(sizeof(*conn));
>  	if (conn == NULL) {
> -		close(conn_fd);
> +		close(fd);
>  		return;
>  	}
>  
>  	vid = vhost_new_device();
>  	if (vid == -1) {
> +		close(fd);
>  		free(conn);
> -		close(conn_fd);
>  		return;
>  	}
>  
> @@ -323,8 +274,21 @@ vhost_user_new_connection(int fd, void *dat, int *remove
> __rte_unused)
>  
>  	conn->vsocket = vsocket;
>  	conn->vid = vid;
> -	fdset_add(&vhost_user.fdset,
> -		conn_fd, vhost_user_msg_handler, NULL, conn);
> +	fdset_add(&vhost_user.fdset, fd, vhost_user_msg_handler, NULL, conn);
> +}
> +
> +/* call back when there is new vhost-user connection from client  */
> +static void
> +vhost_user_server_new_connection(int fd, void *dat, int *remove
> __rte_unused)
> +{
> +	struct vhost_user_socket *vsocket = dat;
> +
> +	fd = accept(fd, NULL, NULL);
> +	if (fd < 0)
> +		return;
> +
> +	RTE_LOG(INFO, VHOST_CONFIG, "new vhost user connection is %d\n", fd);
> +	vhost_user_add_connection(fd, vsocket);
>  }
>  
>  /* callback when there is message on the connfd */
> @@ -452,50 +416,135 @@ vhost_user_msg_handler(int connfd, void *dat, int
> *remove)
>  	}
>  }
>  
> -/**
> - * Creates and initialise the vhost server.
> - */
> -int
> -rte_vhost_driver_register(const char *path)
> +static int
> +create_unix_socket(const char *path, struct sockaddr_un *un, int is_server)
>  {
> -	struct vhost_user_socket *vsocket;
> +	int fd;
>  
> -	pthread_mutex_lock(&vhost_user.mutex);
> +	fd = socket(AF_UNIX, SOCK_STREAM, 0);
> +	if (fd < 0)
> +		return -1;
> +	RTE_LOG(INFO, VHOST_CONFIG, "vhost-user %s: socket created, fd: %d\n",
> +		is_server ? "server" : "client", fd);
>  
> -	if (vhost_user.vsocket_cnt == MAX_VHOST_SOCKET) {
> -		RTE_LOG(ERR, VHOST_CONFIG,
> -			"error: the number of servers reaches maximum\n");
> -		pthread_mutex_unlock(&vhost_user.mutex);
> +	memset(un, 0, sizeof(*un));
> +	un->sun_family = AF_UNIX;
> +	strncpy(un->sun_path, path, sizeof(un->sun_path));
> +
> +	return fd;
> +}
> +
> +static int
> +vhost_user_create_server(struct vhost_user_socket *vsocket)
> +{
> +	int fd;
> +	int ret;
> +	struct sockaddr_un un;
> +	const char *path = vsocket->path;
> +
> +	fd = create_unix_socket(path, &un, vsocket->is_server);
> +	if (fd < 0)
>  		return -1;
> +
> +	ret = bind(fd, (struct sockaddr *)&un, sizeof(un));
> +	if (ret < 0) {
> +		RTE_LOG(ERR, VHOST_CONFIG,
> +			"failed to bind to %s: %s; remove it and try again\n",
> +			path, strerror(errno));
> +		goto err;
>  	}
> +	RTE_LOG(INFO, VHOST_CONFIG, "bind to %s\n", path);
>  
> -	vsocket = calloc(sizeof(struct vhost_user_socket), 1);
> -	if (vsocket == NULL) {
> -		pthread_mutex_unlock(&vhost_user.mutex);
> +	ret = listen(fd, MAX_VIRTIO_BACKLOG);
> +	if (ret < 0)
> +		goto err;
> +
> +	vsocket->listenfd = fd;
> +	fdset_add(&vhost_user.fdset, fd, vhost_user_server_new_connection,
> +		  NULL, vsocket);
> +
> +	return 0;
> +
> +err:
> +	close(fd);
> +	return -1;
> +}
> +
> +static int
> +vhost_user_create_client(struct vhost_user_socket *vsocket)
> +{
> +	int fd;
> +	int ret;
> +	struct sockaddr_un un;
> +	const char *path = vsocket->path;
> +
> +	fd = create_unix_socket(path, &un, vsocket->is_server);
> +	if (fd < 0)
> +		return -1;
> +
> +	ret = connect(fd, (struct sockaddr *)&un, sizeof(un));
> +	if (ret < 0) {
> +		RTE_LOG(ERR, VHOST_CONFIG, "failed to connect to %s: %s\n",
> +			path, strerror(errno));
> +		close(fd);
>  		return -1;
>  	}
>  
> -	vsocket->listenfd = uds_socket(path);
> -	if (vsocket->listenfd < 0) {
> -		free(vsocket);
> -		pthread_mutex_unlock(&vhost_user.mutex);
> +	vhost_user_add_connection(fd, vsocket);
> +
> +	return 0;
> +}
> +
> +/*
> + * Register a new vhost-user socket; here we could act as server
> + * (the default case), or client (when RTE_VHOST_USER_CLIENT) flag
> + * is set.
> + */
> +int
> +rte_vhost_driver_register(const char *path, uint64_t flags)
> +{
> +	int ret = -1;
> +	struct vhost_user_socket *vsocket;
> +
> +	if (!path)
>  		return -1;
> +
> +	pthread_mutex_lock(&vhost_user.mutex);
> +
> +	if (vhost_user.vsocket_cnt == MAX_VHOST_SOCKET) {
> +		RTE_LOG(ERR, VHOST_CONFIG,
> +			"error: the number of vhost sockets reaches maximum\n");
> +		goto out;
>  	}
>  
> +	vsocket = malloc(sizeof(struct vhost_user_socket));
> +	if (!vsocket)
> +		goto out;
> +	memset(vsocket, 0, sizeof(struct vhost_user_socket));
>  	vsocket->path = strdup(path);
>  
> -	fdset_add(&vhost_user.fdset, vsocket->listenfd,
> -		vhost_user_new_connection, NULL, vsocket);
> +	if ((flags & RTE_VHOST_USER_CLIENT) != 0) {
> +		ret = vhost_user_create_client(vsocket);
> +	} else {
> +		vsocket->is_server = 1;
> +		ret = vhost_user_create_server(vsocket);
> +	}
> +	if (ret < 0) {
> +		free(vsocket->path);
> +		free(vsocket);
> +		goto out;
> +	}
>  
>  	vhost_user.vsockets[vhost_user.vsocket_cnt++] = vsocket;
> +
> +out:
>  	pthread_mutex_unlock(&vhost_user.mutex);
>  
> -	return 0;
> +	return ret;
>  }
>  
> -
>  /**
> - * Unregister the specified vhost server
> + * Unregister the specified vhost socket
>   */
>  int
>  rte_vhost_driver_unregister(const char *path)
> --
> 1.9.0
> 
>
  
Michael S. Tsirkin May 9, 2016, 8:30 p.m. UTC | #2
On Mon, May 09, 2016 at 01:33:08PM -0700, Yuanhan Liu wrote:
> On Mon, May 09, 2016 at 06:33:45AM -0400, Victor Kaplansky wrote:
> > Adding a flag for a future extension seems fine to me.
> > Could we manage without adding a flag?
> > For example, could we always try a client mode for a while at first,
> > and if unsuccessful, then come up with server mode?
> 
> It's hard to define "how long is for a while". And I don't think
> there is a way to switch it back to client mode from server mode
> if you do so.
> 
> So, assume you create a vhost-user port (as client), and you
> start QEMU (as server) later, after the gap you mentioned of
> auto-turn into server, it simply doesn't work then.
> 
> 	--yliu

I think I agree - I don't know of other software doing
such an automatic switch. Correctly setting server/client mode
seems easy enough.


> > ----- Original Message -----
> > > From: "Yuanhan Liu" <yuanhan.liu@linux.intel.com>
> > > To: dev@dpdk.org
> > > Cc: "huawei xie" <huawei.xie@intel.com>, "Yuanhan Liu" <yuanhan.liu@linux.intel.com>
> > > Sent: Saturday, May 7, 2016 9:40:20 AM
> > > Subject: [dpdk-dev] [PATCH 2/6] vhost: add vhost-user client mode
> > > 
> > > Add a new paramter (flags) to rte_vhost_driver_register(). DPDK
> > > vhost-user acts as client mode when RTE_VHOST_USER_CLIENT flag
> > > is set.
> > > 
> > > The flags would also allow future extensions without breaking the
> > > API (again).
> > > 
> > > The rest is straingfoward then: allocate a unix socket, and
> > > bind/listen for server, connect for client.
> > > 
> > > Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
> > > ---
> > >  drivers/net/vhost/rte_eth_vhost.c            |   2 +-
> > >  examples/vhost/main.c                        |   2 +-
> > >  lib/librte_vhost/rte_virtio_net.h            |  11 +-
> > >  lib/librte_vhost/vhost_user/vhost-net-user.c | 215
> > >  ++++++++++++++++-----------
> > >  4 files changed, 142 insertions(+), 88 deletions(-)
> > > 
> > > diff --git a/drivers/net/vhost/rte_eth_vhost.c
> > > b/drivers/net/vhost/rte_eth_vhost.c
> > > index a9dada5..36697cf 100644
> > > --- a/drivers/net/vhost/rte_eth_vhost.c
> > > +++ b/drivers/net/vhost/rte_eth_vhost.c
> > > @@ -456,7 +456,7 @@ eth_dev_start(struct rte_eth_dev *dev)
> > >  	int ret = 0;
> > >  
> > >  	if (rte_atomic16_cmpset(&internal->once, 0, 1)) {
> > > -		ret = rte_vhost_driver_register(internal->iface_name);
> > > +		ret = rte_vhost_driver_register(internal->iface_name, 0);
> > >  		if (ret)
> > >  			return ret;
> > >  	}
> > > diff --git a/examples/vhost/main.c b/examples/vhost/main.c
> > > index bbf0d28..6899189 100644
> > > --- a/examples/vhost/main.c
> > > +++ b/examples/vhost/main.c
> > > @@ -1499,7 +1499,7 @@ main(int argc, char *argv[])
> > >  		rte_vhost_feature_disable(1ULL << VIRTIO_NET_F_MRG_RXBUF);
> > >  
> > >  	/* Register vhost(cuse or user) driver to handle vhost messages. */
> > > -	ret = rte_vhost_driver_register((char *)&dev_basename);
> > > +	ret = rte_vhost_driver_register(dev_basename, 0);
> > >  	if (ret != 0)
> > >  		rte_exit(EXIT_FAILURE, "vhost driver register failure.\n");
> > >  
> > > diff --git a/lib/librte_vhost/rte_virtio_net.h
> > > b/lib/librte_vhost/rte_virtio_net.h
> > > index 4e50425..c84e7ab 100644
> > > --- a/lib/librte_vhost/rte_virtio_net.h
> > > +++ b/lib/librte_vhost/rte_virtio_net.h
> > > @@ -51,6 +51,8 @@
> > >  #include <rte_mempool.h>
> > >  #include <rte_ether.h>
> > >  
> > > +#define RTE_VHOST_USER_CLIENT		(1ULL << 0)
> > > +
> > >  struct rte_mbuf;
> > >  
> > >  #define VHOST_MEMORY_MAX_NREGIONS 8
> > > @@ -96,11 +98,14 @@ uint64_t rte_vhost_feature_get(void);
> > >  
> > >  int rte_vhost_enable_guest_notification(int vid, uint16_t queue_id, int
> > >  enable);
> > >  
> > > -/* Register vhost driver. dev_name could be different for multiple instance
> > > support. */
> > > -int rte_vhost_driver_register(const char *dev_name);
> > > +/**
> > > + * Register vhost driver. path could be different for multiple
> > > + * instance support.
> > > + */
> > > +int rte_vhost_driver_register(const char *path, uint64_t flags);
> > >  
> > >  /* Unregister vhost driver. This is only meaningful to vhost user. */
> > > -int rte_vhost_driver_unregister(const char *dev_name);
> > > +int rte_vhost_driver_unregister(const char *path);
> > >  
> > >  /* Register callbacks. */
> > >  int rte_vhost_driver_callback_register(struct virtio_net_device_ops const *
> > >  const);
> > > diff --git a/lib/librte_vhost/vhost_user/vhost-net-user.c
> > > b/lib/librte_vhost/vhost_user/vhost-net-user.c
> > > index f485a3b..aa98717 100644
> > > --- a/lib/librte_vhost/vhost_user/vhost-net-user.c
> > > +++ b/lib/librte_vhost/vhost_user/vhost-net-user.c
> > > @@ -58,6 +58,7 @@
> > >  struct vhost_user_socket {
> > >  	char *path;
> > >  	int listenfd;
> > > +	int is_server;
> > >  };
> > >  
> > >  struct vhost_user_connection {
> > > @@ -75,7 +76,7 @@ struct vhost_user {
> > >  
> > >  #define MAX_VIRTIO_BACKLOG 128
> > >  
> > > -static void vhost_user_new_connection(int fd, void *data, int *remove);
> > > +static void vhost_user_server_new_connection(int fd, void *data, int
> > > *remove);
> > >  static void vhost_user_msg_handler(int fd, void *dat, int *remove);
> > >  
> > >  static struct vhost_user vhost_user = {
> > > @@ -111,48 +112,6 @@ static const char *vhost_message_str[VHOST_USER_MAX] = {
> > >  	[VHOST_USER_SEND_RARP]  = "VHOST_USER_SEND_RARP",
> > >  };
> > >  
> > > -/**
> > > - * Create a unix domain socket, bind to path and listen for connection.
> > > - * @return
> > > - *  socket fd or -1 on failure
> > > - */
> > > -static int
> > > -uds_socket(const char *path)
> > > -{
> > > -	struct sockaddr_un un;
> > > -	int sockfd;
> > > -	int ret;
> > > -
> > > -	if (path == NULL)
> > > -		return -1;
> > > -
> > > -	sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
> > > -	if (sockfd < 0)
> > > -		return -1;
> > > -	RTE_LOG(INFO, VHOST_CONFIG, "socket created, fd:%d\n", sockfd);
> > > -
> > > -	memset(&un, 0, sizeof(un));
> > > -	un.sun_family = AF_UNIX;
> > > -	snprintf(un.sun_path, sizeof(un.sun_path), "%s", path);
> > > -	ret = bind(sockfd, (struct sockaddr *)&un, sizeof(un));
> > > -	if (ret == -1) {
> > > -		RTE_LOG(ERR, VHOST_CONFIG, "fail to bind fd:%d, remove file:%s and try
> > > again.\n",
> > > -			sockfd, path);
> > > -		goto err;
> > > -	}
> > > -	RTE_LOG(INFO, VHOST_CONFIG, "bind to %s\n", path);
> > > -
> > > -	ret = listen(sockfd, MAX_VIRTIO_BACKLOG);
> > > -	if (ret == -1)
> > > -		goto err;
> > > -
> > > -	return sockfd;
> > > -
> > > -err:
> > > -	close(sockfd);
> > > -	return -1;
> > > -}
> > > -
> > >  /* return bytes# of read on success or negative val on failure. */
> > >  static int
> > >  read_fd_message(int sockfd, char *buf, int buflen, int *fds, int fd_num)
> > > @@ -287,32 +246,24 @@ send_vhost_message(int sockfd, struct VhostUserMsg
> > > *msg)
> > >  	return ret;
> > >  }
> > >  
> > > -/* call back when there is new vhost-user connection.  */
> > > +
> > >  static void
> > > -vhost_user_new_connection(int fd, void *dat, int *remove __rte_unused)
> > > +vhost_user_add_connection(int fd, struct vhost_user_socket *vsocket)
> > >  {
> > > -	struct vhost_user_socket *vsocket = dat;
> > > -	int conn_fd;
> > > -	struct vhost_user_connection *conn;
> > >  	int vid;
> > > -	unsigned int size;
> > > -
> > > -	conn_fd = accept(fd, NULL, NULL);
> > > -	RTE_LOG(INFO, VHOST_CONFIG,
> > > -		"new virtio connection is %d\n", conn_fd);
> > > -	if (conn_fd < 0)
> > > -		return;
> > > +	size_t size;
> > > +	struct vhost_user_connection *conn;
> > >  
> > > -	conn = calloc(1, sizeof(*conn));
> > > +	conn = malloc(sizeof(*conn));
> > >  	if (conn == NULL) {
> > > -		close(conn_fd);
> > > +		close(fd);
> > >  		return;
> > >  	}
> > >  
> > >  	vid = vhost_new_device();
> > >  	if (vid == -1) {
> > > +		close(fd);
> > >  		free(conn);
> > > -		close(conn_fd);
> > >  		return;
> > >  	}
> > >  
> > > @@ -323,8 +274,21 @@ vhost_user_new_connection(int fd, void *dat, int *remove
> > > __rte_unused)
> > >  
> > >  	conn->vsocket = vsocket;
> > >  	conn->vid = vid;
> > > -	fdset_add(&vhost_user.fdset,
> > > -		conn_fd, vhost_user_msg_handler, NULL, conn);
> > > +	fdset_add(&vhost_user.fdset, fd, vhost_user_msg_handler, NULL, conn);
> > > +}
> > > +
> > > +/* call back when there is new vhost-user connection from client  */
> > > +static void
> > > +vhost_user_server_new_connection(int fd, void *dat, int *remove
> > > __rte_unused)
> > > +{
> > > +	struct vhost_user_socket *vsocket = dat;
> > > +
> > > +	fd = accept(fd, NULL, NULL);
> > > +	if (fd < 0)
> > > +		return;
> > > +
> > > +	RTE_LOG(INFO, VHOST_CONFIG, "new vhost user connection is %d\n", fd);
> > > +	vhost_user_add_connection(fd, vsocket);
> > >  }
> > >  
> > >  /* callback when there is message on the connfd */
> > > @@ -452,50 +416,135 @@ vhost_user_msg_handler(int connfd, void *dat, int
> > > *remove)
> > >  	}
> > >  }
> > >  
> > > -/**
> > > - * Creates and initialise the vhost server.
> > > - */
> > > -int
> > > -rte_vhost_driver_register(const char *path)
> > > +static int
> > > +create_unix_socket(const char *path, struct sockaddr_un *un, int is_server)
> > >  {
> > > -	struct vhost_user_socket *vsocket;
> > > +	int fd;
> > >  
> > > -	pthread_mutex_lock(&vhost_user.mutex);
> > > +	fd = socket(AF_UNIX, SOCK_STREAM, 0);
> > > +	if (fd < 0)
> > > +		return -1;
> > > +	RTE_LOG(INFO, VHOST_CONFIG, "vhost-user %s: socket created, fd: %d\n",
> > > +		is_server ? "server" : "client", fd);
> > >  
> > > -	if (vhost_user.vsocket_cnt == MAX_VHOST_SOCKET) {
> > > -		RTE_LOG(ERR, VHOST_CONFIG,
> > > -			"error: the number of servers reaches maximum\n");
> > > -		pthread_mutex_unlock(&vhost_user.mutex);
> > > +	memset(un, 0, sizeof(*un));
> > > +	un->sun_family = AF_UNIX;
> > > +	strncpy(un->sun_path, path, sizeof(un->sun_path));
> > > +
> > > +	return fd;
> > > +}
> > > +
> > > +static int
> > > +vhost_user_create_server(struct vhost_user_socket *vsocket)
> > > +{
> > > +	int fd;
> > > +	int ret;
> > > +	struct sockaddr_un un;
> > > +	const char *path = vsocket->path;
> > > +
> > > +	fd = create_unix_socket(path, &un, vsocket->is_server);
> > > +	if (fd < 0)
> > >  		return -1;
> > > +
> > > +	ret = bind(fd, (struct sockaddr *)&un, sizeof(un));
> > > +	if (ret < 0) {
> > > +		RTE_LOG(ERR, VHOST_CONFIG,
> > > +			"failed to bind to %s: %s; remove it and try again\n",
> > > +			path, strerror(errno));
> > > +		goto err;
> > >  	}
> > > +	RTE_LOG(INFO, VHOST_CONFIG, "bind to %s\n", path);
> > >  
> > > -	vsocket = calloc(sizeof(struct vhost_user_socket), 1);
> > > -	if (vsocket == NULL) {
> > > -		pthread_mutex_unlock(&vhost_user.mutex);
> > > +	ret = listen(fd, MAX_VIRTIO_BACKLOG);
> > > +	if (ret < 0)
> > > +		goto err;
> > > +
> > > +	vsocket->listenfd = fd;
> > > +	fdset_add(&vhost_user.fdset, fd, vhost_user_server_new_connection,
> > > +		  NULL, vsocket);
> > > +
> > > +	return 0;
> > > +
> > > +err:
> > > +	close(fd);
> > > +	return -1;
> > > +}
> > > +
> > > +static int
> > > +vhost_user_create_client(struct vhost_user_socket *vsocket)
> > > +{
> > > +	int fd;
> > > +	int ret;
> > > +	struct sockaddr_un un;
> > > +	const char *path = vsocket->path;
> > > +
> > > +	fd = create_unix_socket(path, &un, vsocket->is_server);
> > > +	if (fd < 0)
> > > +		return -1;
> > > +
> > > +	ret = connect(fd, (struct sockaddr *)&un, sizeof(un));
> > > +	if (ret < 0) {
> > > +		RTE_LOG(ERR, VHOST_CONFIG, "failed to connect to %s: %s\n",
> > > +			path, strerror(errno));
> > > +		close(fd);
> > >  		return -1;
> > >  	}
> > >  
> > > -	vsocket->listenfd = uds_socket(path);
> > > -	if (vsocket->listenfd < 0) {
> > > -		free(vsocket);
> > > -		pthread_mutex_unlock(&vhost_user.mutex);
> > > +	vhost_user_add_connection(fd, vsocket);
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +/*
> > > + * Register a new vhost-user socket; here we could act as server
> > > + * (the default case), or client (when RTE_VHOST_USER_CLIENT) flag
> > > + * is set.
> > > + */
> > > +int
> > > +rte_vhost_driver_register(const char *path, uint64_t flags)
> > > +{
> > > +	int ret = -1;
> > > +	struct vhost_user_socket *vsocket;
> > > +
> > > +	if (!path)
> > >  		return -1;
> > > +
> > > +	pthread_mutex_lock(&vhost_user.mutex);
> > > +
> > > +	if (vhost_user.vsocket_cnt == MAX_VHOST_SOCKET) {
> > > +		RTE_LOG(ERR, VHOST_CONFIG,
> > > +			"error: the number of vhost sockets reaches maximum\n");
> > > +		goto out;
> > >  	}
> > >  
> > > +	vsocket = malloc(sizeof(struct vhost_user_socket));
> > > +	if (!vsocket)
> > > +		goto out;
> > > +	memset(vsocket, 0, sizeof(struct vhost_user_socket));
> > >  	vsocket->path = strdup(path);
> > >  
> > > -	fdset_add(&vhost_user.fdset, vsocket->listenfd,
> > > -		vhost_user_new_connection, NULL, vsocket);
> > > +	if ((flags & RTE_VHOST_USER_CLIENT) != 0) {
> > > +		ret = vhost_user_create_client(vsocket);
> > > +	} else {
> > > +		vsocket->is_server = 1;
> > > +		ret = vhost_user_create_server(vsocket);
> > > +	}
> > > +	if (ret < 0) {
> > > +		free(vsocket->path);
> > > +		free(vsocket);
> > > +		goto out;
> > > +	}
> > >  
> > >  	vhost_user.vsockets[vhost_user.vsocket_cnt++] = vsocket;
> > > +
> > > +out:
> > >  	pthread_mutex_unlock(&vhost_user.mutex);
> > >  
> > > -	return 0;
> > > +	return ret;
> > >  }
> > >  
> > > -
> > >  /**
> > > - * Unregister the specified vhost server
> > > + * Unregister the specified vhost socket
> > >   */
> > >  int
> > >  rte_vhost_driver_unregister(const char *path)
> > > --
> > > 1.9.0
> > > 
> > >
  
Yuanhan Liu May 9, 2016, 8:33 p.m. UTC | #3
On Mon, May 09, 2016 at 06:33:45AM -0400, Victor Kaplansky wrote:
> Adding a flag for a future extension seems fine to me.
> Could we manage without adding a flag?
> For example, could we always try a client mode for a while at first,
> and if unsuccessful, then come up with server mode?

It's hard to define "how long is for a while". And I don't think
there is a way to switch it back to client mode from server mode
if you do so.

So, assume you create a vhost-user port (as client), and you
start QEMU (as server) later, after the gap you mentioned of
auto-turn into server, it simply doesn't work then.

	--yliu

> ----- Original Message -----
> > From: "Yuanhan Liu" <yuanhan.liu@linux.intel.com>
> > To: dev@dpdk.org
> > Cc: "huawei xie" <huawei.xie@intel.com>, "Yuanhan Liu" <yuanhan.liu@linux.intel.com>
> > Sent: Saturday, May 7, 2016 9:40:20 AM
> > Subject: [dpdk-dev] [PATCH 2/6] vhost: add vhost-user client mode
> > 
> > Add a new paramter (flags) to rte_vhost_driver_register(). DPDK
> > vhost-user acts as client mode when RTE_VHOST_USER_CLIENT flag
> > is set.
> > 
> > The flags would also allow future extensions without breaking the
> > API (again).
> > 
> > The rest is straingfoward then: allocate a unix socket, and
> > bind/listen for server, connect for client.
> > 
> > Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
> > ---
> >  drivers/net/vhost/rte_eth_vhost.c            |   2 +-
> >  examples/vhost/main.c                        |   2 +-
> >  lib/librte_vhost/rte_virtio_net.h            |  11 +-
> >  lib/librte_vhost/vhost_user/vhost-net-user.c | 215
> >  ++++++++++++++++-----------
> >  4 files changed, 142 insertions(+), 88 deletions(-)
> > 
> > diff --git a/drivers/net/vhost/rte_eth_vhost.c
> > b/drivers/net/vhost/rte_eth_vhost.c
> > index a9dada5..36697cf 100644
> > --- a/drivers/net/vhost/rte_eth_vhost.c
> > +++ b/drivers/net/vhost/rte_eth_vhost.c
> > @@ -456,7 +456,7 @@ eth_dev_start(struct rte_eth_dev *dev)
> >  	int ret = 0;
> >  
> >  	if (rte_atomic16_cmpset(&internal->once, 0, 1)) {
> > -		ret = rte_vhost_driver_register(internal->iface_name);
> > +		ret = rte_vhost_driver_register(internal->iface_name, 0);
> >  		if (ret)
> >  			return ret;
> >  	}
> > diff --git a/examples/vhost/main.c b/examples/vhost/main.c
> > index bbf0d28..6899189 100644
> > --- a/examples/vhost/main.c
> > +++ b/examples/vhost/main.c
> > @@ -1499,7 +1499,7 @@ main(int argc, char *argv[])
> >  		rte_vhost_feature_disable(1ULL << VIRTIO_NET_F_MRG_RXBUF);
> >  
> >  	/* Register vhost(cuse or user) driver to handle vhost messages. */
> > -	ret = rte_vhost_driver_register((char *)&dev_basename);
> > +	ret = rte_vhost_driver_register(dev_basename, 0);
> >  	if (ret != 0)
> >  		rte_exit(EXIT_FAILURE, "vhost driver register failure.\n");
> >  
> > diff --git a/lib/librte_vhost/rte_virtio_net.h
> > b/lib/librte_vhost/rte_virtio_net.h
> > index 4e50425..c84e7ab 100644
> > --- a/lib/librte_vhost/rte_virtio_net.h
> > +++ b/lib/librte_vhost/rte_virtio_net.h
> > @@ -51,6 +51,8 @@
> >  #include <rte_mempool.h>
> >  #include <rte_ether.h>
> >  
> > +#define RTE_VHOST_USER_CLIENT		(1ULL << 0)
> > +
> >  struct rte_mbuf;
> >  
> >  #define VHOST_MEMORY_MAX_NREGIONS 8
> > @@ -96,11 +98,14 @@ uint64_t rte_vhost_feature_get(void);
> >  
> >  int rte_vhost_enable_guest_notification(int vid, uint16_t queue_id, int
> >  enable);
> >  
> > -/* Register vhost driver. dev_name could be different for multiple instance
> > support. */
> > -int rte_vhost_driver_register(const char *dev_name);
> > +/**
> > + * Register vhost driver. path could be different for multiple
> > + * instance support.
> > + */
> > +int rte_vhost_driver_register(const char *path, uint64_t flags);
> >  
> >  /* Unregister vhost driver. This is only meaningful to vhost user. */
> > -int rte_vhost_driver_unregister(const char *dev_name);
> > +int rte_vhost_driver_unregister(const char *path);
> >  
> >  /* Register callbacks. */
> >  int rte_vhost_driver_callback_register(struct virtio_net_device_ops const *
> >  const);
> > diff --git a/lib/librte_vhost/vhost_user/vhost-net-user.c
> > b/lib/librte_vhost/vhost_user/vhost-net-user.c
> > index f485a3b..aa98717 100644
> > --- a/lib/librte_vhost/vhost_user/vhost-net-user.c
> > +++ b/lib/librte_vhost/vhost_user/vhost-net-user.c
> > @@ -58,6 +58,7 @@
> >  struct vhost_user_socket {
> >  	char *path;
> >  	int listenfd;
> > +	int is_server;
> >  };
> >  
> >  struct vhost_user_connection {
> > @@ -75,7 +76,7 @@ struct vhost_user {
> >  
> >  #define MAX_VIRTIO_BACKLOG 128
> >  
> > -static void vhost_user_new_connection(int fd, void *data, int *remove);
> > +static void vhost_user_server_new_connection(int fd, void *data, int
> > *remove);
> >  static void vhost_user_msg_handler(int fd, void *dat, int *remove);
> >  
> >  static struct vhost_user vhost_user = {
> > @@ -111,48 +112,6 @@ static const char *vhost_message_str[VHOST_USER_MAX] = {
> >  	[VHOST_USER_SEND_RARP]  = "VHOST_USER_SEND_RARP",
> >  };
> >  
> > -/**
> > - * Create a unix domain socket, bind to path and listen for connection.
> > - * @return
> > - *  socket fd or -1 on failure
> > - */
> > -static int
> > -uds_socket(const char *path)
> > -{
> > -	struct sockaddr_un un;
> > -	int sockfd;
> > -	int ret;
> > -
> > -	if (path == NULL)
> > -		return -1;
> > -
> > -	sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
> > -	if (sockfd < 0)
> > -		return -1;
> > -	RTE_LOG(INFO, VHOST_CONFIG, "socket created, fd:%d\n", sockfd);
> > -
> > -	memset(&un, 0, sizeof(un));
> > -	un.sun_family = AF_UNIX;
> > -	snprintf(un.sun_path, sizeof(un.sun_path), "%s", path);
> > -	ret = bind(sockfd, (struct sockaddr *)&un, sizeof(un));
> > -	if (ret == -1) {
> > -		RTE_LOG(ERR, VHOST_CONFIG, "fail to bind fd:%d, remove file:%s and try
> > again.\n",
> > -			sockfd, path);
> > -		goto err;
> > -	}
> > -	RTE_LOG(INFO, VHOST_CONFIG, "bind to %s\n", path);
> > -
> > -	ret = listen(sockfd, MAX_VIRTIO_BACKLOG);
> > -	if (ret == -1)
> > -		goto err;
> > -
> > -	return sockfd;
> > -
> > -err:
> > -	close(sockfd);
> > -	return -1;
> > -}
> > -
> >  /* return bytes# of read on success or negative val on failure. */
> >  static int
> >  read_fd_message(int sockfd, char *buf, int buflen, int *fds, int fd_num)
> > @@ -287,32 +246,24 @@ send_vhost_message(int sockfd, struct VhostUserMsg
> > *msg)
> >  	return ret;
> >  }
> >  
> > -/* call back when there is new vhost-user connection.  */
> > +
> >  static void
> > -vhost_user_new_connection(int fd, void *dat, int *remove __rte_unused)
> > +vhost_user_add_connection(int fd, struct vhost_user_socket *vsocket)
> >  {
> > -	struct vhost_user_socket *vsocket = dat;
> > -	int conn_fd;
> > -	struct vhost_user_connection *conn;
> >  	int vid;
> > -	unsigned int size;
> > -
> > -	conn_fd = accept(fd, NULL, NULL);
> > -	RTE_LOG(INFO, VHOST_CONFIG,
> > -		"new virtio connection is %d\n", conn_fd);
> > -	if (conn_fd < 0)
> > -		return;
> > +	size_t size;
> > +	struct vhost_user_connection *conn;
> >  
> > -	conn = calloc(1, sizeof(*conn));
> > +	conn = malloc(sizeof(*conn));
> >  	if (conn == NULL) {
> > -		close(conn_fd);
> > +		close(fd);
> >  		return;
> >  	}
> >  
> >  	vid = vhost_new_device();
> >  	if (vid == -1) {
> > +		close(fd);
> >  		free(conn);
> > -		close(conn_fd);
> >  		return;
> >  	}
> >  
> > @@ -323,8 +274,21 @@ vhost_user_new_connection(int fd, void *dat, int *remove
> > __rte_unused)
> >  
> >  	conn->vsocket = vsocket;
> >  	conn->vid = vid;
> > -	fdset_add(&vhost_user.fdset,
> > -		conn_fd, vhost_user_msg_handler, NULL, conn);
> > +	fdset_add(&vhost_user.fdset, fd, vhost_user_msg_handler, NULL, conn);
> > +}
> > +
> > +/* call back when there is new vhost-user connection from client  */
> > +static void
> > +vhost_user_server_new_connection(int fd, void *dat, int *remove
> > __rte_unused)
> > +{
> > +	struct vhost_user_socket *vsocket = dat;
> > +
> > +	fd = accept(fd, NULL, NULL);
> > +	if (fd < 0)
> > +		return;
> > +
> > +	RTE_LOG(INFO, VHOST_CONFIG, "new vhost user connection is %d\n", fd);
> > +	vhost_user_add_connection(fd, vsocket);
> >  }
> >  
> >  /* callback when there is message on the connfd */
> > @@ -452,50 +416,135 @@ vhost_user_msg_handler(int connfd, void *dat, int
> > *remove)
> >  	}
> >  }
> >  
> > -/**
> > - * Creates and initialise the vhost server.
> > - */
> > -int
> > -rte_vhost_driver_register(const char *path)
> > +static int
> > +create_unix_socket(const char *path, struct sockaddr_un *un, int is_server)
> >  {
> > -	struct vhost_user_socket *vsocket;
> > +	int fd;
> >  
> > -	pthread_mutex_lock(&vhost_user.mutex);
> > +	fd = socket(AF_UNIX, SOCK_STREAM, 0);
> > +	if (fd < 0)
> > +		return -1;
> > +	RTE_LOG(INFO, VHOST_CONFIG, "vhost-user %s: socket created, fd: %d\n",
> > +		is_server ? "server" : "client", fd);
> >  
> > -	if (vhost_user.vsocket_cnt == MAX_VHOST_SOCKET) {
> > -		RTE_LOG(ERR, VHOST_CONFIG,
> > -			"error: the number of servers reaches maximum\n");
> > -		pthread_mutex_unlock(&vhost_user.mutex);
> > +	memset(un, 0, sizeof(*un));
> > +	un->sun_family = AF_UNIX;
> > +	strncpy(un->sun_path, path, sizeof(un->sun_path));
> > +
> > +	return fd;
> > +}
> > +
> > +static int
> > +vhost_user_create_server(struct vhost_user_socket *vsocket)
> > +{
> > +	int fd;
> > +	int ret;
> > +	struct sockaddr_un un;
> > +	const char *path = vsocket->path;
> > +
> > +	fd = create_unix_socket(path, &un, vsocket->is_server);
> > +	if (fd < 0)
> >  		return -1;
> > +
> > +	ret = bind(fd, (struct sockaddr *)&un, sizeof(un));
> > +	if (ret < 0) {
> > +		RTE_LOG(ERR, VHOST_CONFIG,
> > +			"failed to bind to %s: %s; remove it and try again\n",
> > +			path, strerror(errno));
> > +		goto err;
> >  	}
> > +	RTE_LOG(INFO, VHOST_CONFIG, "bind to %s\n", path);
> >  
> > -	vsocket = calloc(sizeof(struct vhost_user_socket), 1);
> > -	if (vsocket == NULL) {
> > -		pthread_mutex_unlock(&vhost_user.mutex);
> > +	ret = listen(fd, MAX_VIRTIO_BACKLOG);
> > +	if (ret < 0)
> > +		goto err;
> > +
> > +	vsocket->listenfd = fd;
> > +	fdset_add(&vhost_user.fdset, fd, vhost_user_server_new_connection,
> > +		  NULL, vsocket);
> > +
> > +	return 0;
> > +
> > +err:
> > +	close(fd);
> > +	return -1;
> > +}
> > +
> > +static int
> > +vhost_user_create_client(struct vhost_user_socket *vsocket)
> > +{
> > +	int fd;
> > +	int ret;
> > +	struct sockaddr_un un;
> > +	const char *path = vsocket->path;
> > +
> > +	fd = create_unix_socket(path, &un, vsocket->is_server);
> > +	if (fd < 0)
> > +		return -1;
> > +
> > +	ret = connect(fd, (struct sockaddr *)&un, sizeof(un));
> > +	if (ret < 0) {
> > +		RTE_LOG(ERR, VHOST_CONFIG, "failed to connect to %s: %s\n",
> > +			path, strerror(errno));
> > +		close(fd);
> >  		return -1;
> >  	}
> >  
> > -	vsocket->listenfd = uds_socket(path);
> > -	if (vsocket->listenfd < 0) {
> > -		free(vsocket);
> > -		pthread_mutex_unlock(&vhost_user.mutex);
> > +	vhost_user_add_connection(fd, vsocket);
> > +
> > +	return 0;
> > +}
> > +
> > +/*
> > + * Register a new vhost-user socket; here we could act as server
> > + * (the default case), or client (when RTE_VHOST_USER_CLIENT) flag
> > + * is set.
> > + */
> > +int
> > +rte_vhost_driver_register(const char *path, uint64_t flags)
> > +{
> > +	int ret = -1;
> > +	struct vhost_user_socket *vsocket;
> > +
> > +	if (!path)
> >  		return -1;
> > +
> > +	pthread_mutex_lock(&vhost_user.mutex);
> > +
> > +	if (vhost_user.vsocket_cnt == MAX_VHOST_SOCKET) {
> > +		RTE_LOG(ERR, VHOST_CONFIG,
> > +			"error: the number of vhost sockets reaches maximum\n");
> > +		goto out;
> >  	}
> >  
> > +	vsocket = malloc(sizeof(struct vhost_user_socket));
> > +	if (!vsocket)
> > +		goto out;
> > +	memset(vsocket, 0, sizeof(struct vhost_user_socket));
> >  	vsocket->path = strdup(path);
> >  
> > -	fdset_add(&vhost_user.fdset, vsocket->listenfd,
> > -		vhost_user_new_connection, NULL, vsocket);
> > +	if ((flags & RTE_VHOST_USER_CLIENT) != 0) {
> > +		ret = vhost_user_create_client(vsocket);
> > +	} else {
> > +		vsocket->is_server = 1;
> > +		ret = vhost_user_create_server(vsocket);
> > +	}
> > +	if (ret < 0) {
> > +		free(vsocket->path);
> > +		free(vsocket);
> > +		goto out;
> > +	}
> >  
> >  	vhost_user.vsockets[vhost_user.vsocket_cnt++] = vsocket;
> > +
> > +out:
> >  	pthread_mutex_unlock(&vhost_user.mutex);
> >  
> > -	return 0;
> > +	return ret;
> >  }
> >  
> > -
> >  /**
> > - * Unregister the specified vhost server
> > + * Unregister the specified vhost socket
> >   */
> >  int
> >  rte_vhost_driver_unregister(const char *path)
> > --
> > 1.9.0
> > 
> >
  

Patch

diff --git a/drivers/net/vhost/rte_eth_vhost.c b/drivers/net/vhost/rte_eth_vhost.c
index a9dada5..36697cf 100644
--- a/drivers/net/vhost/rte_eth_vhost.c
+++ b/drivers/net/vhost/rte_eth_vhost.c
@@ -456,7 +456,7 @@  eth_dev_start(struct rte_eth_dev *dev)
 	int ret = 0;
 
 	if (rte_atomic16_cmpset(&internal->once, 0, 1)) {
-		ret = rte_vhost_driver_register(internal->iface_name);
+		ret = rte_vhost_driver_register(internal->iface_name, 0);
 		if (ret)
 			return ret;
 	}
diff --git a/examples/vhost/main.c b/examples/vhost/main.c
index bbf0d28..6899189 100644
--- a/examples/vhost/main.c
+++ b/examples/vhost/main.c
@@ -1499,7 +1499,7 @@  main(int argc, char *argv[])
 		rte_vhost_feature_disable(1ULL << VIRTIO_NET_F_MRG_RXBUF);
 
 	/* Register vhost(cuse or user) driver to handle vhost messages. */
-	ret = rte_vhost_driver_register((char *)&dev_basename);
+	ret = rte_vhost_driver_register(dev_basename, 0);
 	if (ret != 0)
 		rte_exit(EXIT_FAILURE, "vhost driver register failure.\n");
 
diff --git a/lib/librte_vhost/rte_virtio_net.h b/lib/librte_vhost/rte_virtio_net.h
index 4e50425..c84e7ab 100644
--- a/lib/librte_vhost/rte_virtio_net.h
+++ b/lib/librte_vhost/rte_virtio_net.h
@@ -51,6 +51,8 @@ 
 #include <rte_mempool.h>
 #include <rte_ether.h>
 
+#define RTE_VHOST_USER_CLIENT		(1ULL << 0)
+
 struct rte_mbuf;
 
 #define VHOST_MEMORY_MAX_NREGIONS 8
@@ -96,11 +98,14 @@  uint64_t rte_vhost_feature_get(void);
 
 int rte_vhost_enable_guest_notification(int vid, uint16_t queue_id, int enable);
 
-/* Register vhost driver. dev_name could be different for multiple instance support. */
-int rte_vhost_driver_register(const char *dev_name);
+/**
+ * Register vhost driver. path could be different for multiple
+ * instance support.
+ */
+int rte_vhost_driver_register(const char *path, uint64_t flags);
 
 /* Unregister vhost driver. This is only meaningful to vhost user. */
-int rte_vhost_driver_unregister(const char *dev_name);
+int rte_vhost_driver_unregister(const char *path);
 
 /* Register callbacks. */
 int rte_vhost_driver_callback_register(struct virtio_net_device_ops const * const);
diff --git a/lib/librte_vhost/vhost_user/vhost-net-user.c b/lib/librte_vhost/vhost_user/vhost-net-user.c
index f485a3b..aa98717 100644
--- a/lib/librte_vhost/vhost_user/vhost-net-user.c
+++ b/lib/librte_vhost/vhost_user/vhost-net-user.c
@@ -58,6 +58,7 @@ 
 struct vhost_user_socket {
 	char *path;
 	int listenfd;
+	int is_server;
 };
 
 struct vhost_user_connection {
@@ -75,7 +76,7 @@  struct vhost_user {
 
 #define MAX_VIRTIO_BACKLOG 128
 
-static void vhost_user_new_connection(int fd, void *data, int *remove);
+static void vhost_user_server_new_connection(int fd, void *data, int *remove);
 static void vhost_user_msg_handler(int fd, void *dat, int *remove);
 
 static struct vhost_user vhost_user = {
@@ -111,48 +112,6 @@  static const char *vhost_message_str[VHOST_USER_MAX] = {
 	[VHOST_USER_SEND_RARP]  = "VHOST_USER_SEND_RARP",
 };
 
-/**
- * Create a unix domain socket, bind to path and listen for connection.
- * @return
- *  socket fd or -1 on failure
- */
-static int
-uds_socket(const char *path)
-{
-	struct sockaddr_un un;
-	int sockfd;
-	int ret;
-
-	if (path == NULL)
-		return -1;
-
-	sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
-	if (sockfd < 0)
-		return -1;
-	RTE_LOG(INFO, VHOST_CONFIG, "socket created, fd:%d\n", sockfd);
-
-	memset(&un, 0, sizeof(un));
-	un.sun_family = AF_UNIX;
-	snprintf(un.sun_path, sizeof(un.sun_path), "%s", path);
-	ret = bind(sockfd, (struct sockaddr *)&un, sizeof(un));
-	if (ret == -1) {
-		RTE_LOG(ERR, VHOST_CONFIG, "fail to bind fd:%d, remove file:%s and try again.\n",
-			sockfd, path);
-		goto err;
-	}
-	RTE_LOG(INFO, VHOST_CONFIG, "bind to %s\n", path);
-
-	ret = listen(sockfd, MAX_VIRTIO_BACKLOG);
-	if (ret == -1)
-		goto err;
-
-	return sockfd;
-
-err:
-	close(sockfd);
-	return -1;
-}
-
 /* return bytes# of read on success or negative val on failure. */
 static int
 read_fd_message(int sockfd, char *buf, int buflen, int *fds, int fd_num)
@@ -287,32 +246,24 @@  send_vhost_message(int sockfd, struct VhostUserMsg *msg)
 	return ret;
 }
 
-/* call back when there is new vhost-user connection.  */
+
 static void
-vhost_user_new_connection(int fd, void *dat, int *remove __rte_unused)
+vhost_user_add_connection(int fd, struct vhost_user_socket *vsocket)
 {
-	struct vhost_user_socket *vsocket = dat;
-	int conn_fd;
-	struct vhost_user_connection *conn;
 	int vid;
-	unsigned int size;
-
-	conn_fd = accept(fd, NULL, NULL);
-	RTE_LOG(INFO, VHOST_CONFIG,
-		"new virtio connection is %d\n", conn_fd);
-	if (conn_fd < 0)
-		return;
+	size_t size;
+	struct vhost_user_connection *conn;
 
-	conn = calloc(1, sizeof(*conn));
+	conn = malloc(sizeof(*conn));
 	if (conn == NULL) {
-		close(conn_fd);
+		close(fd);
 		return;
 	}
 
 	vid = vhost_new_device();
 	if (vid == -1) {
+		close(fd);
 		free(conn);
-		close(conn_fd);
 		return;
 	}
 
@@ -323,8 +274,21 @@  vhost_user_new_connection(int fd, void *dat, int *remove __rte_unused)
 
 	conn->vsocket = vsocket;
 	conn->vid = vid;
-	fdset_add(&vhost_user.fdset,
-		conn_fd, vhost_user_msg_handler, NULL, conn);
+	fdset_add(&vhost_user.fdset, fd, vhost_user_msg_handler, NULL, conn);
+}
+
+/* call back when there is new vhost-user connection from client  */
+static void
+vhost_user_server_new_connection(int fd, void *dat, int *remove __rte_unused)
+{
+	struct vhost_user_socket *vsocket = dat;
+
+	fd = accept(fd, NULL, NULL);
+	if (fd < 0)
+		return;
+
+	RTE_LOG(INFO, VHOST_CONFIG, "new vhost user connection is %d\n", fd);
+	vhost_user_add_connection(fd, vsocket);
 }
 
 /* callback when there is message on the connfd */
@@ -452,50 +416,135 @@  vhost_user_msg_handler(int connfd, void *dat, int *remove)
 	}
 }
 
-/**
- * Creates and initialise the vhost server.
- */
-int
-rte_vhost_driver_register(const char *path)
+static int
+create_unix_socket(const char *path, struct sockaddr_un *un, int is_server)
 {
-	struct vhost_user_socket *vsocket;
+	int fd;
 
-	pthread_mutex_lock(&vhost_user.mutex);
+	fd = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (fd < 0)
+		return -1;
+	RTE_LOG(INFO, VHOST_CONFIG, "vhost-user %s: socket created, fd: %d\n",
+		is_server ? "server" : "client", fd);
 
-	if (vhost_user.vsocket_cnt == MAX_VHOST_SOCKET) {
-		RTE_LOG(ERR, VHOST_CONFIG,
-			"error: the number of servers reaches maximum\n");
-		pthread_mutex_unlock(&vhost_user.mutex);
+	memset(un, 0, sizeof(*un));
+	un->sun_family = AF_UNIX;
+	strncpy(un->sun_path, path, sizeof(un->sun_path));
+
+	return fd;
+}
+
+static int
+vhost_user_create_server(struct vhost_user_socket *vsocket)
+{
+	int fd;
+	int ret;
+	struct sockaddr_un un;
+	const char *path = vsocket->path;
+
+	fd = create_unix_socket(path, &un, vsocket->is_server);
+	if (fd < 0)
 		return -1;
+
+	ret = bind(fd, (struct sockaddr *)&un, sizeof(un));
+	if (ret < 0) {
+		RTE_LOG(ERR, VHOST_CONFIG,
+			"failed to bind to %s: %s; remove it and try again\n",
+			path, strerror(errno));
+		goto err;
 	}
+	RTE_LOG(INFO, VHOST_CONFIG, "bind to %s\n", path);
 
-	vsocket = calloc(sizeof(struct vhost_user_socket), 1);
-	if (vsocket == NULL) {
-		pthread_mutex_unlock(&vhost_user.mutex);
+	ret = listen(fd, MAX_VIRTIO_BACKLOG);
+	if (ret < 0)
+		goto err;
+
+	vsocket->listenfd = fd;
+	fdset_add(&vhost_user.fdset, fd, vhost_user_server_new_connection,
+		  NULL, vsocket);
+
+	return 0;
+
+err:
+	close(fd);
+	return -1;
+}
+
+static int
+vhost_user_create_client(struct vhost_user_socket *vsocket)
+{
+	int fd;
+	int ret;
+	struct sockaddr_un un;
+	const char *path = vsocket->path;
+
+	fd = create_unix_socket(path, &un, vsocket->is_server);
+	if (fd < 0)
+		return -1;
+
+	ret = connect(fd, (struct sockaddr *)&un, sizeof(un));
+	if (ret < 0) {
+		RTE_LOG(ERR, VHOST_CONFIG, "failed to connect to %s: %s\n",
+			path, strerror(errno));
+		close(fd);
 		return -1;
 	}
 
-	vsocket->listenfd = uds_socket(path);
-	if (vsocket->listenfd < 0) {
-		free(vsocket);
-		pthread_mutex_unlock(&vhost_user.mutex);
+	vhost_user_add_connection(fd, vsocket);
+
+	return 0;
+}
+
+/*
+ * Register a new vhost-user socket; here we could act as server
+ * (the default case), or client (when RTE_VHOST_USER_CLIENT) flag
+ * is set.
+ */
+int
+rte_vhost_driver_register(const char *path, uint64_t flags)
+{
+	int ret = -1;
+	struct vhost_user_socket *vsocket;
+
+	if (!path)
 		return -1;
+
+	pthread_mutex_lock(&vhost_user.mutex);
+
+	if (vhost_user.vsocket_cnt == MAX_VHOST_SOCKET) {
+		RTE_LOG(ERR, VHOST_CONFIG,
+			"error: the number of vhost sockets reaches maximum\n");
+		goto out;
 	}
 
+	vsocket = malloc(sizeof(struct vhost_user_socket));
+	if (!vsocket)
+		goto out;
+	memset(vsocket, 0, sizeof(struct vhost_user_socket));
 	vsocket->path = strdup(path);
 
-	fdset_add(&vhost_user.fdset, vsocket->listenfd,
-		vhost_user_new_connection, NULL, vsocket);
+	if ((flags & RTE_VHOST_USER_CLIENT) != 0) {
+		ret = vhost_user_create_client(vsocket);
+	} else {
+		vsocket->is_server = 1;
+		ret = vhost_user_create_server(vsocket);
+	}
+	if (ret < 0) {
+		free(vsocket->path);
+		free(vsocket);
+		goto out;
+	}
 
 	vhost_user.vsockets[vhost_user.vsocket_cnt++] = vsocket;
+
+out:
 	pthread_mutex_unlock(&vhost_user.mutex);
 
-	return 0;
+	return ret;
 }
 
-
 /**
- * Unregister the specified vhost server
+ * Unregister the specified vhost socket
  */
 int
 rte_vhost_driver_unregister(const char *path)