[PATCH 06/11] xen/hvm kexec: unregister shutdown+sysrq watches during reboot

[Olaf Hering <olaf@aepfle.de>]

[-- Attachment #1: xen.syscore_ops.unregister_watch.shutdown_event.patch --]
[-- Type: text/plain, Size: 1433 bytes --]

Unregister the shutdown and sysrq watch during kexec.  The watches can
not be re-registered in the kexec kernel because they are still seen as
busy by xenstore.

v2:
 use kexec_is_loaded() function

Signed-off-by: Olaf Hering <olaf@aepfle.de>

---
 drivers/xen/manage.c |   17 +++++++++++++++++
 1 file changed, 17 insertions(+)

Index: linux-3.0/drivers/xen/manage.c
===================================================================
--- linux-3.0.orig/drivers/xen/manage.c
+++ linux-3.0/drivers/xen/manage.c
@@ -8,6 +8,7 @@
 #include <linux/sysrq.h>
 #include <linux/stop_machine.h>
 #include <linux/freezer.h>
+#include <linux/kexec.h>
 #include <linux/syscore_ops.h>
 
 #include <xen/xen.h>
@@ -320,6 +321,21 @@ static int shutdown_event(struct notifie
 	return NOTIFY_DONE;
 }
 
+static void xenbus_manage_shutdown_watcher(void)
+{
+	if (!kexec_is_loaded())
+		return;
+
+	unregister_xenbus_watch(&shutdown_watch);
+#ifdef CONFIG_MAGIC_SYSRQ
+	unregister_xenbus_watch(&sysrq_watch);
+#endif
+}
+
+static struct syscore_ops xenbus_manage_watcher_syscore_ops = {
+	.shutdown = xenbus_manage_shutdown_watcher,
+};
+
 int xen_setup_shutdown_event(void)
 {
 	static struct notifier_block xenstore_notifier = {
@@ -329,6 +345,7 @@ int xen_setup_shutdown_event(void)
 	if (!xen_domain())
 		return -ENODEV;
 	register_xenstore_notifier(&xenstore_notifier);
+	register_syscore_ops(&xenbus_manage_watcher_syscore_ops);
 
 	return 0;
 }