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>
OraBug: 25497392

(cherry picked from commit c251f15c7dbf2cb72e7b2b282020b41f4e4d3665)
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
index 611a231196757abdb040615acf2a80244360a6a2..6d40a972ffb24585c7e386d5817f53672841e0fc 100644 (file)
--- 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);