PM: Add missing syscore_suspend() and syscore_resume() calls

Device suspend/resume infrastructure is used not only by the suspend
and hibernate code in kernel/power, but also by APM, Xen and the
kexec jump feature.  However, commit 40dc166cb5dddbd36aa4ad11c03915ea
(PM / Core: Introduce struct syscore_ops for core subsystems PM)
failed to add syscore_suspend() and syscore_resume() calls to that
code, which generally leads to breakage when the features in question
are used.

To fix this problem, add the missing syscore_suspend() and
syscore_resume() calls to arch/x86/kernel/apm_32.c, kernel/kexec.c
and drivers/xen/manage.c.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
diff --git a/drivers/base/syscore.c b/drivers/base/syscore.c
index 90af294..c126db3 100644
--- a/drivers/base/syscore.c
+++ b/drivers/base/syscore.c
@@ -73,6 +73,7 @@
 
 	return ret;
 }
+EXPORT_SYMBOL_GPL(syscore_suspend);
 
 /**
  * syscore_resume - Execute all the registered system core resume callbacks.
@@ -95,6 +96,7 @@
 				"Interrupts enabled after %pF\n", ops->resume);
 		}
 }
+EXPORT_SYMBOL_GPL(syscore_resume);
 #endif /* CONFIG_PM_SLEEP */
 
 /**
diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index 1ac9412..a2eee57 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -8,6 +8,7 @@
 #include <linux/sysrq.h>
 #include <linux/stop_machine.h>
 #include <linux/freezer.h>
+#include <linux/syscore_ops.h>
 
 #include <xen/xen.h>
 #include <xen/xenbus.h>
@@ -70,8 +71,13 @@
 	BUG_ON(!irqs_disabled());
 
 	err = sysdev_suspend(PMSG_FREEZE);
+	if (!err) {
+		err = syscore_suspend();
+		if (err)
+			sysdev_resume();
+	}
 	if (err) {
-		printk(KERN_ERR "xen_suspend: sysdev_suspend failed: %d\n",
+		printk(KERN_ERR "xen_suspend: system core suspend failed: %d\n",
 			err);
 		return err;
 	}
@@ -95,6 +101,7 @@
 		xen_timer_resume();
 	}
 
+	syscore_resume();
 	sysdev_resume();
 
 	return 0;