FAILED: patch "[PATCH] xen/xenbus/xen_bus_type: Support will_handle watch callback" failed to apply to 4.9-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From be987200fbaceaef340872841d4f7af2c5ee8dc3 Mon Sep 17 00:00:00 2001
From: SeongJae Park <sjpark@amazon.de>
Date: Mon, 14 Dec 2020 10:05:47 +0100
Subject: [PATCH] xen/xenbus/xen_bus_type: Support will_handle watch callback

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

This is part of XSA-349

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>

diff --git a/drivers/xen/xenbus/xenbus.h b/drivers/xen/xenbus/xenbus.h
index 5f5b8a7d5b80..2a93b7c9c159 100644
--- a/drivers/xen/xenbus/xenbus.h
+++ b/drivers/xen/xenbus/xenbus.h
@@ -44,6 +44,8 @@ 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 *path, const char *token);
 	void (*otherend_changed)(struct xenbus_watch *watch, const char *path,
 				 const char *token);
 	struct bus_type bus;
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index 4c3d1b84aa0a..44634d970a5c 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -136,7 +136,8 @@ 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");
 }