[PATCH V5 30/32] libxl: consider force removal of device successful

[Wei Liu <wei.liu2@citrix.com>]

The current behavior of libxl to remove a device is, if the backend
times out, libxl will initiate a force removal (destroy) of that device.
However, libxl still returns failure in that case, even if the force
removal was successful.

If a device is force removed and the force removal succeeds, from
guest's PoV this device is gone. Libxl should consider this a
successful case as well.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
 tools/libxl/libxl_device.c   |   12 ++++++++++--
 tools/libxl/libxl_internal.h |    4 ++++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
index fa99f77..ce0b358 100644
--- a/tools/libxl/libxl_device.c
+++ b/tools/libxl/libxl_device.c
@@ -845,6 +845,11 @@ void libxl__initiate_device_remove(libxl__egc *egc,
         if (rc < 0) goto out;
     }
 
+    /* At this point the XS transaction is committed. So check if we were
+     * force removing the device.
+     */
+    aodev->force_removed = aodev->force;
+
     rc = libxl__ev_devstate_wait(gc, &aodev->backend_ds,
                                  device_backend_callback,
                                  state_path, XenbusStateClosed,
@@ -928,7 +933,7 @@ static void device_backend_callback(libxl__egc *egc, libxl__ev_devstate *ds,
         return;
     }
 
-    if (rc) {
+    if (rc && !aodev->force_removed) {
         LOG(ERROR, "unable to %s device with path %s",
                    libxl__device_action_to_string(aodev->action),
                    libxl__device_backend_path(gc, aodev->dev));
@@ -939,7 +944,10 @@ static void device_backend_callback(libxl__egc *egc, libxl__ev_devstate *ds,
     return;
 
 out:
-    aodev->rc = rc;
+    /* If force removal is successful, the device is gone from guest's
+     * PoV. Libxl should return success, too.
+     */
+    aodev->rc = aodev->force_removed ? 0 : rc;
     device_hotplug_done(egc, aodev);
     return;
 }
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 89bbf7d..21bb774 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -2086,6 +2086,10 @@ struct libxl__ao_device {
     libxl__device_action action;
     libxl__device *dev;
     int force;
+    /* If force removal is successful, force_removed=1. The device is
+     * gone from guest's PoV
+     */
+    int force_removed;
     libxl__device_callback *callback;
     /* return value, zeroed by user on entry, is valid on callback */
     int rc;
-- 
1.7.10.4