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"); }