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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, SeongJae Park <sjpark@amazon.de>,
        Michael Kurth <mku@amazon.de>,
        Pawel Wieczorkiewicz <wipawel@amazon.de>,
        Juergen Gross <jgross@suse.com>
Subject: [PATCH 4.14 238/242] xen/xenbus/xen_bus_type: Support will_handle watch callback
Date:   Mon, 28 Dec 2020 13:50:43 +0100
Message-Id: <20201228124916.402987167@linuxfoundation.org>
In-Reply-To: <20201228124904.654293249@linuxfoundation.org>
References: <20201228124904.654293249@linuxfoundation.org>
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From: SeongJae Park <sjpark@amazon.de>

commit be987200fbaceaef340872841d4f7af2c5ee8dc3 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/xen/xenbus/xenbus.h       |    2 ++
 drivers/xen/xenbus/xenbus_probe.c |    3 ++-
 2 files changed, 4 insertions(+), 1 deletion(-)

--- 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;
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -136,7 +136,8 @@ static int watch_otherend(struct xenbus_
 		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");
 }