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SubjectRe: [PATCH v3 02/11] xenbus: add freeze/thaw/restore callbacks support
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On Sun, Sep 13, 2020 at 12:11:47PM -0400, boris.ostrovsky@oracle.com wrote:
> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe.
>
>
>
> On 8/21/20 6:26 PM, Anchal Agarwal wrote:
> > From: Munehisa Kamata <kamatam@amazon.com>
> >
> > 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.
>
The message is trying to say that that freeze/thaw/restore callbacks will be
used for both PM SUSPEND and PM HIBERNATION. Since, we are only focussing on PM
hibernation, I will remove all wordings of PM suspend from this message to avoid
confusion. I left it there in case someone wants to pick it up in future knowing
framework is already present.
>
> And please be consistent with "PM suspend" vs. "PM hibernation".
>
I should remove PM suspend from everywhere since the mode is not tested
for.
>
> > 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)?
>
>
Nope, they should be same. We can use dev here too. I should probably just use
dev.
> > "%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.
>
Yes this I left unchanged, it should be consistent with xdev.
>
> > + bool xen_suspend = is_xen_suspend();
>
>
> No need for this, you use it only once anyway.
>
>
> -boris
>
Thanks,
Anchal
>

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