[PATCH v19 01/12] libxl: introduce libxl__multidev_prepare_with_aodev

[Yang Hongyang <yanghy@cn.fujitsu.com>]

libxl__multidev_prepare_with_aodev is similar to libxl__multidev_prepare,
but takes a libxl__ao_device as an extra argument.
libxl__multidev_prepare is now a wrapper around
libxl__multidev_prepare_with_aodev.

This new internal API will be used by the Remus device abstract layer
for handling various Remus devices.

Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
Signed-off-by: Shriram Rajagopalan <rshriram@cs.ubc.ca>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
---
 tools/libxl/libxl_device.c   | 13 ++++++++++---
 tools/libxl/libxl_internal.h | 14 +++++++++++---
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
index f8a2e1b..9180732 100644
--- a/tools/libxl/libxl_device.c
+++ b/tools/libxl/libxl_device.c
@@ -463,11 +463,10 @@ void libxl__multidev_begin(libxl__ao *ao, libxl__multidev *multidev)
 
 static void multidev_one_callback(libxl__egc *egc, libxl__ao_device *aodev);
 
-libxl__ao_device *libxl__multidev_prepare(libxl__multidev *multidev) {
+void libxl__multidev_prepare_with_aodev(libxl__multidev *multidev,
+                                        libxl__ao_device *aodev) {
     STATE_AO_GC(multidev->ao);
-    libxl__ao_device *aodev;
 
-    GCNEW(aodev);
     aodev->multidev = multidev;
     aodev->callback = multidev_one_callback;
     libxl__prepare_ao_device(ao, aodev);
@@ -477,6 +476,14 @@ libxl__ao_device *libxl__multidev_prepare(libxl__multidev *multidev) {
         GCREALLOC_ARRAY(multidev->array, multidev->allocd);
     }
     multidev->array[multidev->used++] = aodev;
+}
+
+libxl__ao_device *libxl__multidev_prepare(libxl__multidev *multidev) {
+    STATE_AO_GC(multidev->ao);
+    libxl__ao_device *aodev;
+
+    GCNEW(aodev);
+    libxl__multidev_prepare_with_aodev(multidev, aodev);
 
     return aodev;
 }
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index beb052e..611b9fb 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -2148,9 +2148,17 @@ struct libxl__ao_device {
 /* Starts preparing to add/remove a bunch of devices. */
 _hidden void libxl__multidev_begin(libxl__ao *ao, libxl__multidev*);
 
-/* Prepares to add/remove one of many devices.  Returns a libxl__ao_device
- * which has had libxl__prepare_ao_device called, and which has also
- * had ->callback set.  The user should not mess with aodev->callback. */
+/* Prepares to add/remove one of many devices.
+ * Calls libxl__prepare_ao_device on libxl__ao_device argument provided and
+ * also sets the ->callback. The user should not mess with aodev->callback.
+ */
+_hidden void libxl__multidev_prepare_with_aodev(libxl__multidev*,
+                                                libxl__ao_device*);
+
+/* A wrapper function around libxl__multidev_prepare_with_aodev.
+ * Allocates a libxl__ao_device and prepares it for addition/removal.
+ * Returns the newly allocated libxl__ao_dev.
+ */
 _hidden libxl__ao_device *libxl__multidev_prepare(libxl__multidev*);
 
 /* Notifies the multidev machinery that we have now finished preparing
-- 
1.9.1