Re: [PATCH] xen/blkfront: allow xenbus state transition to Closing->Closed when not Connected.

[Jeremy Fitzhardinge <jeremy@goop.org>]

Ian Campbell wrote:
> This situation can occur when attempting to attach a block device whose backend
> is an empty physical CD-ROM driver. The backend in this case will go directly
> from the Initialising state to Closing->Closed. Previously this would result in
> a NULL pointer deref on info->gd (xenbus_dev_fatal does not return as a1a15ac5
> seems to expect)
>
> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> Cc: Jeremy Fitzhardinge <jeremy@goop.org>
>   

Jens, does this look OK to you?

Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Thanks,
    J
> ---
>  drivers/block/xen-blkfront.c |    6 ++++--
>  1 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> index aa0c94b..a6cbf7b 100644
> --- a/drivers/block/xen-blkfront.c
> +++ b/drivers/block/xen-blkfront.c
> @@ -977,8 +977,10 @@ static void backend_changed(struct xenbus_device *dev,
>  		break;
>  
>  	case XenbusStateClosing:
> -		if (info->gd == NULL)
> -			xenbus_dev_fatal(dev, -ENODEV, "gd is NULL");
> +		if (info->gd == NULL) {
> +			xenbus_frontend_closed(dev);
> +			break;
> +		}
>  		bd = bdget_disk(info->gd, 0);
>  		if (bd == NULL)
>  			xenbus_dev_fatal(dev, -ENODEV, "bdget failed");
>