xenbus: check return value of xenbus_scanf()

Don't ignore errors here: Set backend state to unknown when
unsuccessful.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
index 611a23119675..6d40a972ffb2 100644
--- a/drivers/xen/xenbus/xenbus_probe_frontend.c
+++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
@@ -335,7 +335,9 @@ static int backend_state;
 static void xenbus_reset_backend_state_changed(struct xenbus_watch *w,
                                         const char **v, unsigned int l)
 {
-        xenbus_scanf(XBT_NIL, v[XS_WATCH_PATH], "", "%i", &backend_state);
+        if (xenbus_scanf(XBT_NIL, v[XS_WATCH_PATH], "", "%i",
+                         &backend_state) != 1)
+                backend_state = XenbusStateUnknown;
         printk(KERN_DEBUG "XENBUS: backend %s %s\n",
                         v[XS_WATCH_PATH], xenbus_strstate(backend_state));
         wake_up(&backend_state_wq);