Merge git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6

[karo-tx-linux.git] / drivers / xen / xenbus / xenbus_client.c

diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index 7b3e973a1aee8ca5525ae334efba433d6bd3e12a..7e49527189b6c4fdad40ec817c9086a22c6175ed 100644 (file)
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -133,17 +133,12 @@ int xenbus_watch_pathfmt(struct xenbus_device *dev,
 }
 EXPORT_SYMBOL_GPL(xenbus_watch_pathfmt);
 
+static void xenbus_switch_fatal(struct xenbus_device *, int, int,
+                               const char *, ...);
 
-/**
- * xenbus_switch_state
- * @dev: xenbus device
- * @state: new state
- *
- * Advertise in the store a change of the given driver to the given new_state.
- * Return 0 on success, or -errno on error.  On error, the device will switch
- * to XenbusStateClosing, and the error will be saved in the store.
- */
-int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state state)
+static int
+__xenbus_switch_state(struct xenbus_device *dev,
+                     enum xenbus_state state, int depth)
 {
        /* We check whether the state is currently set to the given value, and
           if not, then the state is set.  We don't want to unconditionally
@@ -152,35 +147,65 @@ int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state state)
           to it, as the device will be tearing down, and we don't want to
           resurrect that directory.
 
-          Note that, because of this cached value of our state, this function
-          will not work inside a Xenstore transaction (something it was
-          trying to in the past) because dev->state would not get reset if
-          the transaction was aborted.
-
+          Note that, because of this cached value of our state, this
+          function will not take a caller's Xenstore transaction
+          (something it was trying to in the past) because dev->state
+          would not get reset if the transaction was aborted.
         */
 
+       struct xenbus_transaction xbt;
        int current_state;
-       int err;
+       int err, abort;
 
        if (state == dev->state)
                return 0;
 
-       err = xenbus_scanf(XBT_NIL, dev->nodename, "state", "%d",
-                          &current_state);
-       if (err != 1)
+again:
+       abort = 1;
+
+       err = xenbus_transaction_start(&xbt);
+       if (err) {
+               xenbus_switch_fatal(dev, depth, err, "starting transaction");
                return 0;
+       }
+
+       err = xenbus_scanf(xbt, dev->nodename, "state", "%d", &current_state);
+       if (err != 1)
+               goto abort;
 
-       err = xenbus_printf(XBT_NIL, dev->nodename, "state", "%d", state);
+       err = xenbus_printf(xbt, dev->nodename, "state", "%d", state);
        if (err) {
-               if (state != XenbusStateClosing) /* Avoid looping */
-                       xenbus_dev_fatal(dev, err, "writing new state");
-               return err;
+               xenbus_switch_fatal(dev, depth, err, "writing new state");
+               goto abort;
        }
 
-       dev->state = state;
+       abort = 0;
+abort:
+       err = xenbus_transaction_end(xbt, abort);
+       if (err) {
+               if (err == -EAGAIN && !abort)
+                       goto again;
+               xenbus_switch_fatal(dev, depth, err, "ending transaction");
+       } else
+               dev->state = state;
 
        return 0;
 }
+
+/**
+ * xenbus_switch_state
+ * @dev: xenbus device
+ * @state: new state
+ *
+ * Advertise in the store a change of the given driver to the given new_state.
+ * Return 0 on success, or -errno on error.  On error, the device will switch
+ * to XenbusStateClosing, and the error will be saved in the store.
+ */
+int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state state)
+{
+       return __xenbus_switch_state(dev, state, 0);
+}
+
 EXPORT_SYMBOL_GPL(xenbus_switch_state);
 
 int xenbus_frontend_closed(struct xenbus_device *dev)
@@ -283,6 +308,23 @@ void xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt, ...)
 }
 EXPORT_SYMBOL_GPL(xenbus_dev_fatal);
 
+/**
+ * Equivalent to xenbus_dev_fatal(dev, err, fmt, args), but helps
+ * avoiding recursion within xenbus_switch_state.
+ */
+static void xenbus_switch_fatal(struct xenbus_device *dev, int depth, int err,
+                               const char *fmt, ...)
+{
+       va_list ap;
+
+       va_start(ap, fmt);
+       xenbus_va_dev_error(dev, err, fmt, ap);
+       va_end(ap);
+
+       if (!depth)
+               __xenbus_switch_state(dev, XenbusStateClosing, 1);
+}
+
 /**
  * xenbus_grant_ring
  * @dev: xenbus device