Re: [PATCH v8 08/11] xl/libxl: implement QDISK libxl_device_disk_local_attach

[Roger Pau Monne <roger.pau@citrix.com>]

Stefano Stabellini wrote:
>   int libxl__device_disk_local_detach(libxl__gc *gc, libxl_device_disk *disk)
>   {
> -    /* Nothing to do for PHYSTYPE_PHY. */
> +    int rc = 0;
>
> -    /*
> -     * For other device types assume that the blktap2 process is
> -     * needed by the soon to be started domain and do nothing.
> -     */
> +    switch (disk->backend) {
> +        case LIBXL_DISK_BACKEND_QDISK:
> +            if (disk->vdev != NULL) {
> +                libxl_device_disk_remove(gc->owner, LIBXL_TOOLSTACK_DOMID,
> +                        disk, 0);

I was just looking at this code, and I have the feeling this could be 
dangerous, since you call libxl__device_disk_local_detach from an 
already running ao (the bootloader ao), and libxl_device_disk_remove 
will initiate another ao, and set it to completed inside of an already 
running ao.

> +                rc = libxl_device_disk_destroy(gc->owner,
> +                        LIBXL_TOOLSTACK_DOMID, disk);
> +            }
> +            break;
> +        default:
> +            /*
> +             * Nothing to do for PHYSTYPE_PHY.
> +             * For other device types assume that the blktap2 process is
> +             * needed by the soon to be started domain and do nothing.
> +             */
> +            break;
> +    }
>
>       free(disk->pdev_path);
>       free(disk->script);
> -    return 0;
> +
> +    return rc;
>   }
>
>   /******************************************************************************/