Re: [PATCH 07 of 10] Add new shutdown mode for checkpoint

[Brendan Cully <brendan@cs.ubc.ca>]

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On Thursday, 28 December 2006 at 16:51, Keir Fraser wrote:
> On 15/12/06 6:38 am, "Brendan Cully" <brendan@cs.ubc.ca> wrote:
> 
> > Add new shutdown mode for checkpoint.
> > 
> > When control/shutdown = checkpoint, invoke an alternate suspend path
> > that doesn't disconnect from back ends, and only reconnects when the
> > image has been restored into a new domain.
> 
> I don't think a new type of 'checkpoint' handler is required in the guest
> OS. We are already most of the way there in terms of doing as little as
> possible on the suspend side of save/restore, so we should fix up what
> little else there is to be done. Looking at the differences versus your new
> checkpointing suspend:
>  1. Xenbus_suspend() needs to stay. Actually most drivers do not have a
> suspend handler anyway (only tpmfront does). We should provide a
> suspend_cancelled() hook callback so that drivers which *do* have a suspend
> handler can distinguish between proper resume and checkpoint return.

I guess this is what you had in mind? I don't have anything that uses
it at the moment though. It's just suspend_dev cut'n'pasted.

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# HG changeset patch
# User Brendan Cully <brendan@cs.ubc.ca>
# Date 1168646163 28800
# Node ID f6c3f5b0be95efeb0c47318bc6608310cd49c804
# Parent  4fc2fde1b3737554edd795e65701292d8320405d
Add unsuspend hook for resuming devices in the checkpoint parent.

Nothing uses it at the moment.

Signed-off-by: Brendan Cully <brendan@cs.ubc.ca>

diff -r 4fc2fde1b373 -r f6c3f5b0be95 linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c
--- a/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c	Fri Jan 12 15:02:24 2007 -0800
+++ b/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c	Fri Jan 12 15:56:03 2007 -0800
@@ -672,6 +672,26 @@ static int suspend_dev(struct device *de
 	return 0;
 }
 
+static int unsuspend_dev(struct device *dev, void *data)
+{
+	int err = 0;
+	struct xenbus_driver *drv;
+	struct xenbus_device *xdev;
+
+	DPRINTK("");
+
+	if (dev->driver == NULL)
+		return 0;
+	drv = to_xenbus_driver(dev->driver);
+	xdev = container_of(dev, struct xenbus_device, dev);
+	if (drv->unsuspend)
+		err = drv->unsuspend(xdev);
+	if (err)
+		printk(KERN_WARNING
+		       "xenbus: unsuspend %s failed: %i\n", dev->bus_id, err);
+	return 0;
+}
+
 static int resume_dev(struct device *dev, void *data)
 {
 	int err;
@@ -735,6 +755,9 @@ void xenbus_resume(int reconnect)
 
 	if (reconnect) {
 		bus_for_each_dev(&xenbus_frontend.bus, NULL, NULL, resume_dev);
+	} else {
+		bus_for_each_dev(&xenbus_frontend.bus, NULL, NULL,
+				 unsuspend_dev);
 	}
 	xenbus_backend_resume(resume_dev);
 }
diff -r 4fc2fde1b373 -r f6c3f5b0be95 linux-2.6-xen-sparse/include/xen/xenbus.h
--- a/linux-2.6-xen-sparse/include/xen/xenbus.h	Fri Jan 12 15:02:24 2007 -0800
+++ b/linux-2.6-xen-sparse/include/xen/xenbus.h	Fri Jan 12 15:56:03 2007 -0800
@@ -101,6 +101,7 @@ struct xenbus_driver {
 				 enum xenbus_state backend_state);
 	int (*remove)(struct xenbus_device *dev);
 	int (*suspend)(struct xenbus_device *dev);
+	int (*unsuspend)(struct xenbus_device *dev);
 	int (*resume)(struct xenbus_device *dev);
 	int (*uevent)(struct xenbus_device *, char **, int, char *, int);
 	struct device_driver driver;

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