xen: use freeze/restore/thaw PM events for suspend/resume/chkpt

Use PM_FREEZE, PM_THAW and PM_RESTORE power events for
suspend/resume/checkpoint functionality, instead of PM_SUSPEND
and PM_RESUME. Use of these pm events fixes the Xen Guest hangup
when taking checkpoints. When a suspend event is cancelled
(while taking checkpoints once/continuously), we use PM_THAW
instead of PM_RESUME. PM_RESTORE is used when suspend is not
cancelled. See Documentation/power/devices.txt and linux/pm.h
for more info about freeze, thaw and restore. The sequence of
pm events in a suspend-resume scenario is shown below.

        dpm_suspend_start(PMSG_FREEZE);

                dpm_suspend_noirq(PMSG_FREEZE);

                       sysdev_suspend(PMSG_FREEZE);
                       cancelled = suspend_hypercall()
                       sysdev_resume();

               dpm_resume_noirq(cancelled ? PMSG_THAW : PMSG_RESTORE);

       dpm_resume_end(cancelled ? PMSG_THAW : PMSG_RESTORE);

Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Shriram Rajagopalan <rshriram@cs.ubc.ca>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
index ea83999c02f3..b6a2690c9d49 100644
--- a/drivers/xen/xenbus/xenbus_probe_frontend.c
+++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
@@ -86,9 +86,11 @@ static struct device_attribute xenbus_frontend_dev_attrs[] = {
 };
 
 static const struct dev_pm_ops xenbus_pm_ops = {
-        .suspend = xenbus_dev_suspend,
-        .resume  = xenbus_dev_resume,
-        .thaw  = xenbus_dev_cancel,
+        .suspend        = xenbus_dev_suspend,
+        .resume         = xenbus_dev_resume,
+        .freeze         = xenbus_dev_suspend,
+        .thaw           = xenbus_dev_cancel,
+        .restore        = xenbus_dev_resume,
 };
 
 static struct xen_bus_type xenbus_frontend = {