Fix case where watch callback unregisters itself: do not try to ack it

Signed-off-by: Rusty Russel <rusty@rustcorp.com.au>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>

diff --git a/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_xs.c b/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_xs.c
index ccb64f84cc15f79bcd1d80a6d3216830cde8bed9..118069237b5ecfbc4dcb43cb631ebd4e480d9bd1 100644 (file)
--- a/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_xs.c
+++ b/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_xs.c
@@ -485,6 +485,8 @@ int register_xenbus_watch(struct xenbus_watch *watch)
        return err;
 }
 
+static struct xenbus_watch *watch_callback;
+
 void unregister_xenbus_watch(struct xenbus_watch *watch)
 {
        char token[sizeof(watch) * 2 + 1];
@@ -496,6 +498,10 @@ void unregister_xenbus_watch(struct xenbus_watch *watch)
        err = xs_unwatch(watch->node, token);
        list_del(&watch->list);
 
+       /* Make sure watch thread knows we unwatched, so don't ack. */
+       if (watch_callback == watch)
+               watch_callback = NULL;
+
        if (err)
                printk(KERN_WARNING "XENBUS Failed to release watch %s: %i\n",
                       watch->node, err);
@@ -523,13 +529,16 @@ static int watch_thread(void *unused)
 
                        w = find_watch(token);
                        BUG_ON(!w);
+                       watch_callback = w;
                        w->callback(w, node);
-                       /* FIXME: Only ack if it wasn't deleted. */
-                       err = xs_acknowledge_watch(token);
-                       if (err)
-                               printk(KERN_WARNING
-                                      "XENBUS acknowledge %s failed %i\n",
-                                      node, err);
+
+                       if (watch_callback) {
+                               err = xs_acknowledge_watch(token);
+                               if (err)
+                                       printk(KERN_WARNING
+                                              "XENBUS ack %s fail %i\n",
+                                              node, err);
+                       }
                        kfree(node);
                } else
                        printk(KERN_WARNING "XENBUS xs_read_watch: %li\n",