[dpdk-dev] [PATCH 35/40] net/virtio: make server mode blocking

Xia, Chenbo chenbo.xia at intel.com
Thu Jan 7 04:20:53 CET 2021


Hi Maxime,

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin at redhat.com>
> Sent: Monday, December 21, 2020 5:14 AM
> To: dev at dpdk.org; Xia, Chenbo <chenbo.xia at intel.com>; olivier.matz at 6wind.com;
> amorenoz at redhat.com; david.marchand at redhat.com
> Cc: Maxime Coquelin <maxime.coquelin at redhat.com>
> Subject: [PATCH 35/40] net/virtio: make server mode blocking
> 
> 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 at redhat.com>
> ---
>  drivers/net/virtio/virtio_user/vhost_user.c   |   9 +-
>  .../net/virtio/virtio_user/virtio_user_dev.c  | 118 +++++++-----------
>  drivers/net/virtio/virtio_user_ethdev.c       |   5 -
>  3 files changed, 54 insertions(+), 78 deletions(-)
> 
> diff --git a/drivers/net/virtio/virtio_user/vhost_user.c
> b/drivers/net/virtio/virtio_user/vhost_user.c
> index a57106a468..94a33326ae 100644
> --- a/drivers/net/virtio/virtio_user/vhost_user.c
> +++ b/drivers/net/virtio/virtio_user/vhost_user.c
> @@ -677,6 +677,14 @@ 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));
> @@ -721,7 +729,6 @@ 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 b92b7f7aae..19d59d401e 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();
> 
> @@ -421,36 +412,36 @@ 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;

If tapfds failed on malloc, this will lead to vhostfds not freed?

And, should we free the fds when errors happen later in this function?

Thanks!
Chenbo

> -			}
> -
> -			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);


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