[libvirt PATCH v3 06/21] nodedev: add STOPPED/STARTED lifecycle events

[Erik Skultety]

On Thu, Dec 24, 2020 at 08:14:30AM -0600, Jonathon Jongsma wrote:
> Since a mediated device can be persistently defined by the mdevctl
> backend, we need additional lifecycle events beyond CREATED/DELETED to
> indicate that e.g. the device has been stopped but the device definition
> still exists.
> 
> Signed-off-by: Jonathon Jongsma <jjongsma at redhat.com>
> ---
>  examples/c/misc/event-test.c         |  4 ++++
>  include/libvirt/libvirt-nodedev.h    |  2 ++
>  src/conf/node_device_conf.h          |  1 +
>  src/node_device/node_device_driver.c |  1 +
>  src/node_device/node_device_udev.c   | 25 +++++++++++++++++++++++--
>  tools/virsh-nodedev.c                |  4 +++-
>  6 files changed, 34 insertions(+), 3 deletions(-)
> 
> diff --git a/examples/c/misc/event-test.c b/examples/c/misc/event-test.c
> index f164e825e1..d6eec648ec 100644
> --- a/examples/c/misc/event-test.c
> +++ b/examples/c/misc/event-test.c
> @@ -381,6 +381,10 @@ nodeDeviceEventToString(int event)
>              return "Created";
>          case VIR_NODE_DEVICE_EVENT_DELETED:
>              return "Deleted";
> +        case VIR_NODE_DEVICE_EVENT_STOPPED:
> +            return "Stopped";
> +        case VIR_NODE_DEVICE_EVENT_STARTED:
> +            return "Started";
>          case VIR_NODE_DEVICE_EVENT_LAST:
>              break;
>      }
> diff --git a/include/libvirt/libvirt-nodedev.h b/include/libvirt/libvirt-nodedev.h
> index d304283871..a473563857 100644
> --- a/include/libvirt/libvirt-nodedev.h
> +++ b/include/libvirt/libvirt-nodedev.h
> @@ -197,6 +197,8 @@ int virConnectNodeDeviceEventDeregisterAny(virConnectPtr conn,
>  typedef enum {
>      VIR_NODE_DEVICE_EVENT_CREATED = 0,
>      VIR_NODE_DEVICE_EVENT_DELETED = 1,
> +    VIR_NODE_DEVICE_EVENT_STOPPED = 2,
> +    VIR_NODE_DEVICE_EVENT_STARTED = 3,
>  
>  # ifdef VIR_ENUM_SENTINELS
>      VIR_NODE_DEVICE_EVENT_LAST
> diff --git a/src/conf/node_device_conf.h b/src/conf/node_device_conf.h
> index 3d7872fd6e..bbc28cf2b9 100644
> --- a/src/conf/node_device_conf.h
> +++ b/src/conf/node_device_conf.h
> @@ -157,6 +157,7 @@ struct _virNodeDevCapMdev {
>      char *uuid;
>      virMediatedDeviceAttrPtr *attributes;
>      size_t nattributes;
> +    bool persistent;

So, this patch is essentially unchanged since v2. In v2 I suggested ^this
attribute should be bound to the object not the capabability and you haven't
replied to those comments, is there a reason why that is not the case? It's
also consistent with what we do for other objects, like domains and networks.

...

>  
>      if (!(obj = virNodeDeviceObjListFindBySysfsPath(driver->devs, path))) {
>          VIR_DEBUG("Failed to find device to remove that has udev path '%s'",
> @@ -1409,13 +1411,32 @@ udevRemoveOneDeviceSysPath(const char *path)
>      }
>      def = virNodeDeviceObjGetDef(obj);
>  
> +    /* If the device is a mediated device that has been 'stopped', it may still
> +     * be defined by mdevctl and can therefore be started again. Don't drop it
> +     * from the list of node devices */
> +    cap = def->caps;
> +    while (cap != NULL) {
> +        if (cap->data.type == VIR_NODE_DEV_CAP_MDEV) {
> +            if (cap->data.mdev.persistent) {
> +                VIR_FREE(def->sysfs_path);
> +                event_type = VIR_NODE_DEVICE_EVENT_STOPPED;
> +                break;
> +            }
> +        }
> +        cap = cap->next;
> +    }
> +

...which would simplify ^this while loop to a mere:
if (obj->persitent) {
    VIR_FREE(def->sysfs_path);
    virNodeDeviceObjSetActive(obj, false);
}

>      event = virNodeDeviceEventLifecycleNew(def->name,
> -                                           VIR_NODE_DEVICE_EVENT_DELETED,
> +                                           event_type,
>                                             0);
>  
>      VIR_DEBUG("Removing device '%s' with sysfs path '%s'",
>                def->name, path);
> -    virNodeDeviceObjListRemove(driver->devs, obj);
> +
> +    if (event_type == VIR_NODE_DEVICE_EVENT_DELETED)
> +        virNodeDeviceObjListRemove(driver->devs, obj);
> +    else
> +        virNodeDeviceObjSetActive(obj, false);

...and this 'else' branch would be unnecessary then.

>      virNodeDeviceObjEndAPI(&obj);
>  
>      virObjectEventStateQueue(driver->nodeDeviceEventState, event);

Regards,
Erik