Re: [Qemu-devel] [PATCH v5 7/7] Add vhost-user reconnection

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Jan 09, 2014 at 04:00:01PM +0100, Antonios Motakis wrote:
> At runtime vhost-user netdev will detect if the vhost backend is up or down.
> Upon disconnection it will set link_down accordingly and notify virtio-net.

And then what happens?

> 
> Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
> Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
> ---
>  hw/net/vhost_net.c                | 16 +++++++++++
>  hw/virtio/vhost-backend.c         | 16 +++++++++++
>  include/hw/virtio/vhost-backend.h |  2 ++
>  include/net/vhost_net.h           |  1 +
>  net/vhost-user.c                  | 56 +++++++++++++++++++++++++++++++++++++++
>  5 files changed, 91 insertions(+)
> 
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index e42f4d6..56c218e 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -304,6 +304,17 @@ void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
>      vhost_virtqueue_mask(&net->dev, dev, idx, mask);
>  }
>  
> +int vhost_net_link_status(VHostNetState *net)
> +{
> +    int r = 0;
> +
> +    if (net->dev.vhost_ops->vhost_status) {
> +        r = net->dev.vhost_ops->vhost_status(&net->dev);
> +    }
> +
> +    return r;
> +}
> +
>  VHostNetState *get_vhost_net(NetClientState *nc)
>  {
>      VHostNetState *vhost_net = 0;
> @@ -372,6 +383,11 @@ void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
>  {
>  }
>  
> +int vhost_net_link_status(VHostNetState *net)
> +{
> +    return 0;
> +}
> +
>  VHostNetState *get_vhost_net(NetClientState *nc)
>  {
>      return 0;
> diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
> index 50ea307..fcd274f 100644
> --- a/hw/virtio/vhost-backend.c
> +++ b/hw/virtio/vhost-backend.c
> @@ -350,9 +350,23 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
>          }
>      }
>  
> +    /* mark the backend non operational */
> +    if (result < 0) {
> +        error_report("%s: Connection break detected\n", __func__);
> +        vhost_user_cleanup(dev);
> +        return 0;
> +    }
> +
>      return result;
>  }
>  
> +static int vhost_user_status(struct vhost_dev *dev)
> +{
> +    vhost_user_echo(dev);
> +
> +    return (dev->control >= 0);
> +}
> +
>  static int vhost_user_init(struct vhost_dev *dev, const char *devpath)
>  {
>      int fd = -1;
> @@ -432,6 +446,7 @@ static int vhost_user_cleanup(struct vhost_dev *dev)
>  static const VhostOps user_ops = {
>          .backend_type = VHOST_BACKEND_TYPE_USER,
>          .vhost_call = vhost_user_call,
> +        .vhost_status = vhost_user_status,
>          .vhost_backend_init = vhost_user_init,
>          .vhost_backend_cleanup = vhost_user_cleanup
>  };
> @@ -464,6 +479,7 @@ static int vhost_kernel_cleanup(struct vhost_dev *dev)
>  static const VhostOps kernel_ops = {
>          .backend_type = VHOST_BACKEND_TYPE_KERNEL,
>          .vhost_call = vhost_kernel_call,
> +        .vhost_status = 0,
>          .vhost_backend_init = vhost_kernel_init,
>          .vhost_backend_cleanup = vhost_kernel_cleanup
>  };
> diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
> index ef87ffa..f2b4a6c 100644
> --- a/include/hw/virtio/vhost-backend.h
> +++ b/include/hw/virtio/vhost-backend.h
> @@ -22,12 +22,14 @@ struct vhost_dev;
>  
>  typedef int (*vhost_call)(struct vhost_dev *dev, unsigned long int request,
>               void *arg);
> +typedef int (*vhost_status)(struct vhost_dev *dev);
>  typedef int (*vhost_backend_init)(struct vhost_dev *dev, const char *devpath);
>  typedef int (*vhost_backend_cleanup)(struct vhost_dev *dev);
>  
>  typedef struct VhostOps {
>      VhostBackendType backend_type;
>      vhost_call vhost_call;
> +    vhost_status vhost_status;
>      vhost_backend_init vhost_backend_init;
>      vhost_backend_cleanup vhost_backend_cleanup;
>  } VhostOps;
> diff --git a/include/net/vhost_net.h b/include/net/vhost_net.h
> index abd3d0b..6390907 100644
> --- a/include/net/vhost_net.h
> +++ b/include/net/vhost_net.h
> @@ -31,5 +31,6 @@ void vhost_net_ack_features(VHostNetState *net, unsigned features);
>  bool vhost_net_virtqueue_pending(VHostNetState *net, int n);
>  void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
>                                int idx, bool mask);
> +int vhost_net_link_status(VHostNetState *net);
>  VHostNetState *get_vhost_net(NetClientState *nc);
>  #endif
> diff --git a/net/vhost-user.c b/net/vhost-user.c
> index 6fd5afc..56f7dd4 100644
> --- a/net/vhost-user.c
> +++ b/net/vhost-user.c
> @@ -12,6 +12,7 @@
>  #include "net/vhost_net.h"
>  #include "net/vhost-user.h"
>  #include "qemu/error-report.h"
> +#include "qemu/timer.h"
>  
>  typedef struct VhostUserState {
>      NetClientState nc;
> @@ -19,6 +20,9 @@ typedef struct VhostUserState {
>      char *devpath;
>  } VhostUserState;
>  
> +static QEMUTimer *vhost_user_timer;
> +#define VHOST_USER_TIMEOUT  (1*1000)
> +
>  VHostNetState *vhost_user_get_vhost_net(NetClientState *nc)
>  {
>      VhostUserState *s = DO_UPCAST(VhostUserState, nc, nc);
> @@ -31,6 +35,11 @@ static int vhost_user_running(VhostUserState *s)
>      return (s->vhost_net) ? 1 : 0;
>  }
>  
> +static int vhost_user_link_status(VhostUserState *s)
> +{
> +    return (!s->nc.link_down) && vhost_net_link_status(s->vhost_net);
> +}
> +
>  static int vhost_user_start(VhostUserState *s)
>  {
>      VhostNetOptions options;
> @@ -59,6 +68,48 @@ static void vhost_user_stop(VhostUserState *s)
>      s->vhost_net = 0;
>  }
>  
> +static void vhost_user_timer_handler(void *opaque)
> +{
> +    VhostUserState *s = opaque;
> +    int link_down = 0;
> +
> +    if (vhost_user_running(s)) {
> +        if (!vhost_user_link_status(s)) {
> +            link_down = 1;
> +        }
> +    } else {
> +        vhost_user_start(s);
> +        if (!vhost_user_running(s)) {
> +            link_down = 1;
> +        }
> +    }
> +
> +    if (link_down != s->nc.link_down) {
> +
> +        s->nc.link_down = link_down;
> +
> +        if (s->nc.peer) {
> +            s->nc.peer->link_down = link_down;
> +        }
> +
> +        if (s->nc.info->link_status_changed) {
> +            s->nc.info->link_status_changed(&s->nc);
> +        }
> +
> +        if (s->nc.peer && s->nc.peer->info->link_status_changed) {
> +            s->nc.peer->info->link_status_changed(s->nc.peer);
> +        }
> +
> +        if (link_down) {
> +            vhost_user_stop(s);
> +        }
> +    }
> +
> +    /* reschedule */
> +    timer_mod(vhost_user_timer,
> +              qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + VHOST_USER_TIMEOUT);
> +}
> +
>  static void vhost_user_cleanup(NetClientState *nc)
>  {
>      VhostUserState *s = DO_UPCAST(VhostUserState, nc, nc);
> @@ -93,6 +144,11 @@ static int net_vhost_user_init(NetClientState *peer, const char *device,
>  
>      r = vhost_user_start(s);
>  
> +    vhost_user_timer = timer_new_ms(QEMU_CLOCK_REALTIME,
> +            vhost_user_timer_handler, s);
> +    timer_mod(vhost_user_timer,
> +            qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + VHOST_USER_TIMEOUT);
> +
>      return r;
>  }
>  
> -- 
> 1.8.3.2
>