[Xen-devel] [PATCH] xen: use freeze/restore/thaw PM events for suspend/resume/chkpt

[Shriram Rajagopalan <rshriram@xxxxxxxxx>]

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);

Signed-off-by: Shriram Rajagopalan <rshriram@xxxxxxxxx>
---
 drivers/xen/manage.c                       |   12 ++++++------
 drivers/xen/xenbus/xenbus_probe.c          |    2 +-
 drivers/xen/xenbus/xenbus_probe_frontend.c |    8 +++++---
 3 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index db8c4c4..3f76dcf 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -63,7 +63,7 @@ static int xen_suspend(void *data)
 
        BUG_ON(!irqs_disabled());
 
-       err = sysdev_suspend(PMSG_SUSPEND);
+       err = sysdev_suspend(PMSG_FREEZE);
        if (err) {
                printk(KERN_ERR "xen_suspend: sysdev_suspend failed: %d\n",
                        err);
@@ -114,16 +114,16 @@ static void do_suspend(void)
        }
 #endif
 
-       err = dpm_suspend_start(PMSG_SUSPEND);
+       err = dpm_suspend_start(PMSG_FREEZE);
        if (err) {
                printk(KERN_ERR "xen suspend: dpm_suspend_start %d\n", err);
                goto out_thaw;
        }
 
-       printk(KERN_DEBUG "suspending xenstore...\n");
+       /* printk(KERN_DEBUG "suspending xenstore...\n"); */
        xs_suspend();
 
-       err = dpm_suspend_noirq(PMSG_SUSPEND);
+       err = dpm_suspend_noirq(PMSG_FREEZE);
        if (err) {
                printk(KERN_ERR "dpm_suspend_noirq failed: %d\n", err);
                goto out_resume;
@@ -134,7 +134,7 @@ static void do_suspend(void)
        else
                err = stop_machine(xen_suspend, &cancelled, cpumask_of(0));
 
-       dpm_resume_noirq(PMSG_RESUME);
+       dpm_resume_noirq(cancelled ? PMSG_THAW : PMSG_RESTORE);
 
        if (err) {
                printk(KERN_ERR "failed to start xen_suspend: %d\n", err);
@@ -148,7 +148,7 @@ out_resume:
        } else
                xs_suspend_cancel();
 
-       dpm_resume_end(PMSG_RESUME);
+       dpm_resume_end(cancelled ? PMSG_THAW : PMSG_RESTORE);
 
        /* Make sure timer events get retriggered on all CPUs */
        clock_was_set();
diff --git a/drivers/xen/xenbus/xenbus_probe.c 
b/drivers/xen/xenbus/xenbus_probe.c
index 7397695..471ca48 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -645,7 +645,7 @@ EXPORT_SYMBOL_GPL(xenbus_dev_resume);
 int xenbus_dev_cancel(struct device *dev)
 {
        /* Do nothing */
-       DPRINTK("cancel");
+       /* DPRINTK("cancel"); */
        return 0;
 }
 EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c 
b/drivers/xen/xenbus/xenbus_probe_frontend.c
index 9ad8868..d6e5f0d 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 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 = {
-- 
1.7.0.4


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