Re: [Xen-devel] [PATCH 2/2] xenbus: bypass xenbus frontend resume if xenstored is not running

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2013-05-01 at 13:57 +0100, Aurelien Chartier wrote:
> If the xenbus frontend is running in a domain running xenstored or in dom0,
> the device resume is hanging because it is happening before the process
> resume. This patch adds extra logic to the resume code to check if we are
> the domain running xenstored or dom0.
> 
> The frontend will be reconnected later, when the backend resumes from S3.
> This logic is working when xenstored is running in dom0, but has not been
> tested with a xenstore stub domain.
> ---
>  drivers/xen/xenbus/xenbus_probe_frontend.c |   15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c 
> b/drivers/xen/xenbus/xenbus_probe_frontend.c
> index 3159a37..8583afe 100644
> --- a/drivers/xen/xenbus/xenbus_probe_frontend.c
> +++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
> @@ -89,9 +89,22 @@ static void backend_changed(struct xenbus_watch *watch,
>       xenbus_otherend_changed(watch, vec, len, 1);
>  }
>  
> +static int xenbus_frontend_dev_resume(struct device *dev)
> +{
> +     /* 
> +      * If xenstored is running in that domain, we cannot access the backend
> +      * state at the moment. If we are running in dom0, the domain running
> +      * xenstored is still suspended at that point
> +      */
> +     if (xen_initial_domain() || (xen_store_domain == XS_LOCAL))
> +             return 0;
> +
> +     return xenbus_dev_resume(dev);

When or where does this eventually get called for the init domain or
XS_LOCAL cases?

> +}
> +
>  static const struct dev_pm_ops xenbus_pm_ops = {
>       .suspend        = xenbus_dev_suspend,
> -     .resume         = xenbus_dev_resume,
> +     .resume         = xenbus_frontend_dev_resume,
>       .freeze         = xenbus_dev_suspend,
>       .thaw           = xenbus_dev_cancel,
>       .restore        = xenbus_dev_resume,



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