Re: [PATCH v3 02/11] xenbus: add freeze/thaw/restore callbacks support

[boris.ostrovsky@xxxxxxxxxx]

On 8/21/20 6:26 PM, Anchal Agarwal wrote:
> From: Munehisa Kamata <kamatam@xxxxxxxxxx> 
>
> Since commit b3e96c0c7562 ("xen: use freeze/restore/thaw PM events for
> suspend/resume/chkpt"), xenbus uses PMSG_FREEZE, PMSG_THAW and
> PMSG_RESTORE events for Xen suspend. However, they're actually assigned
> to xenbus_dev_suspend(), xenbus_dev_cancel() and xenbus_dev_resume()
> respectively, and only suspend and resume callbacks are supported at
> driver level. To support PM suspend and PM hibernation, modify the bus
> level PM callbacks to invoke not only device driver's suspend/resume but
> also freeze/thaw/restore.
>
> Note that we'll use freeze/restore callbacks even for PM suspend whereas
> suspend/resume callbacks are normally used in the case, becausae the
> existing xenbus device drivers already have suspend/resume callbacks
> specifically designed for Xen suspend.


Something is wrong with this sentence. Or with my brain --- I can't
quite parse this.


And please be consistent with "PM suspend" vs. "PM hibernation".


>  So we can allow the device
> drivers to keep the existing callbacks wihtout modification.
>


> @@ -599,16 +600,33 @@ int xenbus_dev_suspend(struct device *dev)
>       struct xenbus_driver *drv;
>       struct xenbus_device *xdev
>               = container_of(dev, struct xenbus_device, dev);
> +     bool xen_suspend = is_xen_suspend();
>  
>       DPRINTK("%s", xdev->nodename);
>  
>       if (dev->driver == NULL)
>               return 0;
>       drv = to_xenbus_driver(dev->driver);
> -     if (drv->suspend)
> -             err = drv->suspend(xdev);
> -     if (err)
> -             dev_warn(dev, "suspend failed: %i\n", err);
> +     if (xen_suspend) {
> +             if (drv->suspend)
> +                     err = drv->suspend(xdev);
> +     } else {
> +             if (drv->freeze) {


'else if' (to avoid extra indent level).  In xenbus_dev_resume() too.


> +                     err = drv->freeze(xdev);
> +                     if (!err) {
> +                             free_otherend_watch(xdev);
> +                             free_otherend_details(xdev);
> +                             return 0;
> +                     }
> +             }
> +     }
> +
> +     if (err) {
> +             dev_warn(&xdev->dev,


Is there a reason why you replaced dev with xdev->dev (here and elsewhere)?


>  "%s %s failed: %d\n", xen_suspend ?
> +                             "suspend" : "freeze", xdev->nodename, err);
> +             return err;
> +     }
> +
>       

> @@ -653,8 +683,44 @@ EXPORT_SYMBOL_GPL(xenbus_dev_resume);
>  
>  int xenbus_dev_cancel(struct device *dev)
>  {
> -     /* Do nothing */
> -     DPRINTK("cancel");
> +     int err;
> +     struct xenbus_driver *drv;
> +     struct xenbus_device *xendev = to_xenbus_device(dev);


xdev for consistency please.


> +     bool xen_suspend = is_xen_suspend();


No need for this, you use it only once anyway.


-boris