Re: [PATCH v2 RFC 1/3] virtio: add notify() callback to virtio_driver

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

On Thu, Nov 21, 2013 at 03:45:31PM +0100, Heinz Graalfs wrote:
> Add an optional notify() callback to virtio_driver. A backend
> driver can provide this callback to perform actions for a lost
> device.
> 
> notify() event values are inherited from virtio_ccw's notify()
> callback. We might want to support even more of them lateron.
> 
> notify() return values are defined in include/linux/notifier.h.
> 
> Signed-off-by: Heinz Graalfs <graalfs@linux.vnet.ibm.com>
> ---
>  drivers/virtio/virtio.c |  9 +++++++++
>  include/linux/virtio.h  | 10 ++++++++++
>  2 files changed, 19 insertions(+)
> 
> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> index ee59b74..a7f4302 100644
> --- a/drivers/virtio/virtio.c
> +++ b/drivers/virtio/virtio.c
> @@ -3,6 +3,7 @@
>  #include <linux/virtio_config.h>
>  #include <linux/module.h>
>  #include <linux/idr.h>
> +#include <linux/notifier.h>
>  
>  /* Unique numbering for virtio devices. */
>  static DEFINE_IDA(virtio_index_ida);
> @@ -186,6 +187,14 @@ void unregister_virtio_driver(struct virtio_driver *driver)
>  }
>  EXPORT_SYMBOL_GPL(unregister_virtio_driver);
>  
> +int notify_virtio_device(struct virtio_device *vdev, int event)
> +{
> +	struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
> +
> +	return drv->notify ? drv->notify(vdev, event) : NOTIFY_DONE;
> +}
> +EXPORT_SYMBOL_GPL(notify_virtio_device);
> +
>  int register_virtio_device(struct virtio_device *dev)
>  {
>  	int err;
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index f15f6e7..da18e9a 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -110,6 +110,15 @@ int register_virtio_device(struct virtio_device *dev);
>  void unregister_virtio_device(struct virtio_device *dev);
>  
>  /**
> + * notify event values
> + * @VDEV_GONE: device gone
> + */
> +enum {
> +	VDEV_GONE		= 1,
> +};

OK after understanding what this does, I think a
better name would be

VIRTIO_DEV_SURPRIZE_REMOVAL

this is what happened here.


> +int notify_virtio_device(struct virtio_device *dev, int event);
> +
> +/**
>   * virtio_driver - operations for a virtio I/O driver
>   * @driver: underlying device driver (populate name and owner).
>   * @id_table: the ids serviced by this driver.
> @@ -129,6 +138,7 @@ struct virtio_driver {
>  	void (*scan)(struct virtio_device *dev);
>  	void (*remove)(struct virtio_device *dev);
>  	void (*config_changed)(struct virtio_device *dev);
> +	int (*notify)(struct virtio_device *dev, int event);
>  #ifdef CONFIG_PM
>  	int (*freeze)(struct virtio_device *dev);
>  	int (*restore)(struct virtio_device *dev);
> -- 
> 1.8.3.1