[PATCH v3 3/5] xen/xenbus/xen_bus_type: Support will_handle watch callback

[SeongJae Park <sjpark@amazon.com>]

From: SeongJae Park <sjpark@amazon.de>

This commit adds support of the 'will_handle' watch callback for
'xen_bus_type' users.

This is part of XSA-349

This is upstream commit be987200fbaceaef340872841d4f7af2c5ee8dc3

Cc: stable@vger.kernel.org
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reported-by: Michael Kurth <mku@amazon.de>
Reported-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/xen/xenbus/xenbus_probe.c | 3 ++-
 drivers/xen/xenbus/xenbus_probe.h | 2 ++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index c560c1b8489a..ba7590d75985 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -137,7 +137,8 @@ static int watch_otherend(struct xenbus_device *dev)
 		container_of(dev->dev.bus, struct xen_bus_type, bus);
 
 	return xenbus_watch_pathfmt(dev, &dev->otherend_watch,
-				    NULL, bus->otherend_changed,
+				    bus->otherend_will_handle,
+				    bus->otherend_changed,
 				    "%s/%s", dev->otherend, "state");
 }
 
diff --git a/drivers/xen/xenbus/xenbus_probe.h b/drivers/xen/xenbus/xenbus_probe.h
index c9ec7ca1f7ab..2c394c6ba605 100644
--- a/drivers/xen/xenbus/xenbus_probe.h
+++ b/drivers/xen/xenbus/xenbus_probe.h
@@ -42,6 +42,8 @@ struct xen_bus_type {
 	int (*get_bus_id)(char bus_id[XEN_BUS_ID_SIZE], const char *nodename);
 	int (*probe)(struct xen_bus_type *bus, const char *type,
 		     const char *dir);
+	bool (*otherend_will_handle)(struct xenbus_watch *watch,
+				     const char **vec, unsigned int len);
 	void (*otherend_changed)(struct xenbus_watch *watch, const char **vec,
 				 unsigned int len);
 	struct bus_type bus;
-- 
2.17.1