[PATCH 4.9 25/32] xen/xenbus: Add will_handle callback support in xenbus_watch_path()

Greg Kroah-Hartman
2021-01-07T14:17:39Z

From: SeongJae Park <sjpark@amazon.de>

commit 2e85d32b1c865bec703ce0c962221a5e955c52c2 upstream.

Some code does not directly make 'xenbus_watch' object and call
'register_xenbus_watch()' but use 'xenbus_watch_path()' instead. This
commit adds support of 'will_handle' callback in the
'xenbus_watch_path()' and it's wrapper, 'xenbus_watch_pathfmt()'.

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/block/xen-blkback/xenbus.c | 3 ++-
drivers/net/xen-netback/xenbus.c | 2 +-
drivers/xen/xen-pciback/xenbus.c | 2 +-
drivers/xen/xenbus/xenbus_client.c | 9 +++++++--
drivers/xen/xenbus/xenbus_probe.c | 2 +-
include/xen/xenbus.h | 6 +++++-
6 files changed, 17 insertions(+), 7 deletions(-)

--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -646,7 +646,8 @@ static int xen_blkbk_probe(struct xenbus
/* setup back pointer */
be->blkif->be = be;

- err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed,
+ err = xenbus_watch_pathfmt(dev, &be->backend_watch, NULL,
+ backend_changed,
"%s/%s", dev->nodename, "physical-device");
if (err)
goto fail;
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -1040,7 +1040,7 @@ static void connect(struct backend_info
xenvif_carrier_on(be->vif);

unregister_hotplug_status_watch(be);
- err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch,
+ err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch, NULL,
hotplug_status_changed,
"%s/%s", dev->nodename, "hotplug-status");
if (!err)
--- a/drivers/xen/xen-pciback/xenbus.c
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -689,7 +689,7 @@ static int xen_pcibk_xenbus_probe(struct

/* watch the backend node for backend configuration information */
err = xenbus_watch_path(dev, dev->nodename, &pdev->be_watch,
- xen_pcibk_be_watch);
+ NULL, xen_pcibk_be_watch);
if (err)
goto out;

--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -114,19 +114,22 @@ EXPORT_SYMBOL_GPL(xenbus_strstate);
*/
int xenbus_watch_path(struct xenbus_device *dev, const char *path,
struct xenbus_watch *watch,
+ bool (*will_handle)(struct xenbus_watch *,
+ const char **, unsigned int),
void (*callback)(struct xenbus_watch *,
const char **, unsigned int))
{
int err;

watch->node = path;
- watch->will_handle = NULL;
+ watch->will_handle = will_handle;
watch->callback = callback;

err = register_xenbus_watch(watch);

if (err) {
watch->node = NULL;
+ watch->will_handle = NULL;
watch->callback = NULL;
xenbus_dev_fatal(dev, err, "adding watch on %s", path);
}
@@ -153,6 +156,8 @@ EXPORT_SYMBOL_GPL(xenbus_watch_path);
*/
int xenbus_watch_pathfmt(struct xenbus_device *dev,
struct xenbus_watch *watch,
+ bool (*will_handle)(struct xenbus_watch *,
+ const char **, unsigned int),
void (*callback)(struct xenbus_watch *,
const char **, unsigned int),
const char *pathfmt, ...)
@@ -169,7 +174,7 @@ int xenbus_watch_pathfmt(struct xenbus_d
xenbus_dev_fatal(dev, -ENOMEM, "allocating path for watch");
return -ENOMEM;
}
- err = xenbus_watch_path(dev, path, watch, callback);
+ err = xenbus_watch_path(dev, path, watch, will_handle, callback);

if (err)
kfree(path);
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -137,7 +137,7 @@ static int watch_otherend(struct xenbus_
container_of(dev->dev.bus, struct xen_bus_type, bus);

return xenbus_watch_pathfmt(dev, &dev->otherend_watch,
- bus->otherend_changed,
+ NULL, bus->otherend_changed,
"%s/%s", dev->otherend, "state");
}

--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -201,10 +201,14 @@ void xenbus_suspend_cancel(void);

int xenbus_watch_path(struct xenbus_device *dev, const char *path,
struct xenbus_watch *watch,
+ bool (*will_handle)(struct xenbus_watch *,
+ const char **, unsigned int),
void (*callback)(struct xenbus_watch *,
const char **, unsigned int));
-__printf(4, 5)
+__printf(5, 6)
int xenbus_watch_pathfmt(struct xenbus_device *dev, struct xenbus_watch *watch,
+ bool (*will_handle)(struct xenbus_watch *,
+ const char **, unsigned int),
void (*callback)(struct xenbus_watch *,
const char **, unsigned int),
const char *pathfmt, ...);