[PATCH 06/29] libxl: Use libxl__xswait* in libxl__ao_device

[Ian Jackson <ian.jackson@eu.citrix.com>]

Replace the separate timeout and xenstore watch with use of
libxl__xswait*.

Different control flow, but no ultimate functional change apart from
slight changes to the text of error messages.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
---
 tools/libxl/libxl_device.c   |   64 ++++++++++++------------------------------
 tools/libxl/libxl_internal.h |    2 +-
 2 files changed, 19 insertions(+), 47 deletions(-)

diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
index 0f50d04..64ee541 100644
--- a/tools/libxl/libxl_device.c
+++ b/tools/libxl/libxl_device.c
@@ -450,7 +450,7 @@ void libxl__prepare_ao_device(libxl__ao *ao, libxl__ao_device *aodev)
      * Initialize xs_watch, because it's not used on all possible
      * execution paths, but it's unconditionally destroyed when finished.
      */
-    libxl__ev_xswatch_init(&aodev->xs_watch);
+    libxl__xswait_init(&aodev->xswait);
     aodev->active = 1;
     /* We init this here because we might call device_hotplug_done
      * without actually calling any hotplug script */
@@ -731,13 +731,9 @@ static void device_hotplug_child_death_cb(libxl__egc *egc,
                                           libxl__async_exec_state *aes,
                                           int status);
 
-static void device_destroy_be_timeout_cb(libxl__egc *egc, libxl__ev_time *ev,
-                                         const struct timeval *requested_abs);
-
 static void device_destroy_be_watch_cb(libxl__egc *egc,
-                                       libxl__ev_xswatch *watch,
-                                       const char *watch_path,
-                                       const char *event_path);
+                                       libxl__xswait_state *xswait,
+                                       int rc, const char *data);
 
 static void device_hotplug_done(libxl__egc *egc, libxl__ao_device *aodev);
 
@@ -988,22 +984,14 @@ static void device_hotplug(libxl__egc *egc, libxl__ao_device *aodev)
         if (aodev->action != LIBXL__DEVICE_ACTION_REMOVE)
             goto out;
 
-        rc = libxl__ev_time_register_rel(gc, &aodev->timeout,
-                                         device_destroy_be_timeout_cb,
-                                         LIBXL_DESTROY_TIMEOUT * 1000);
-        if (rc) {
-            LOG(ERROR, "setup of xs watch timeout failed");
-            goto out;
-        }
-
-        rc = libxl__ev_xswatch_register(gc, &aodev->xs_watch,
-                                        device_destroy_be_watch_cb,
-                                        be_path);
-        if (rc) {
-            LOG(ERROR, "setup of xs watch for %s failed", be_path);
-            libxl__ev_time_deregister(gc, &aodev->timeout);
+        aodev->xswait.ao = ao;
+        aodev->xswait.what = "removal of backend path";
+        aodev->xswait.path = be_path;
+        aodev->xswait.timeout_ms = LIBXL_DESTROY_TIMEOUT * 1000;
+        aodev->xswait.callback = device_destroy_be_watch_cb;
+        rc = libxl__xswait_start(gc, &aodev->xswait);
+        if (rc)
             goto out;
-        }
         return;
     }
 
@@ -1101,37 +1089,21 @@ error:
     device_hotplug_done(egc, aodev);
 }
 
-static void device_destroy_be_timeout_cb(libxl__egc *egc, libxl__ev_time *ev,
-                                         const struct timeval *requested_abs)
-{
-    libxl__ao_device *aodev = CONTAINER_OF(ev, *aodev, timeout);
-    STATE_AO_GC(aodev->ao);
-
-    LOG(ERROR, "timed out while waiting for %s to be removed",
-               libxl__device_backend_path(gc, aodev->dev));
-
-    aodev->rc = ERROR_TIMEDOUT;
-
-    device_hotplug_done(egc, aodev);
-    return;
-}
-
 static void device_destroy_be_watch_cb(libxl__egc *egc,
-                                       libxl__ev_xswatch *watch,
-                                       const char *watch_path,
-                                       const char *event_path)
+                                       libxl__xswait_state *xswait,
+                                       int rc, const char *dir)
 {
-    libxl__ao_device *aodev = CONTAINER_OF(watch, *aodev, xs_watch);
+    libxl__ao_device *aodev = CONTAINER_OF(xswait, *aodev, xswait);
     STATE_AO_GC(aodev->ao);
-    const char *dir;
-    int rc;
 
-    rc = libxl__xs_read_checked(gc, XBT_NULL, watch_path, &dir);
     if (rc) {
-        LOG(ERROR, "unable to read backend path: %s", watch_path);
+        if (rc == ERROR_TIMEDOUT)
+            LOG(ERROR, "timed out while waiting for %s to be removed",
+                xswait->path);
         aodev->rc = rc;
         goto out;
     }
+
     if (dir) {
         /* backend path still exists, wait a little longer... */
         return;
@@ -1164,7 +1136,7 @@ static void device_hotplug_clean(libxl__gc *gc, libxl__ao_device *aodev)
 {
     /* Clean events and check reentrancy */
     libxl__ev_time_deregister(gc, &aodev->timeout);
-    libxl__ev_xswatch_deregister(gc, &aodev->xs_watch);
+    libxl__xswait_stop(gc, &aodev->xswait);
     assert(!libxl__async_exec_inuse(&aodev->aes));
 }
 
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 2862c69..5a76d51 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -2152,7 +2152,7 @@ struct libxl__ao_device {
     /* Bodge for Qemu devices */
     libxl__ev_time timeout;
     /* xenstore watch for backend path of driver domains */
-    libxl__ev_xswatch xs_watch;
+    libxl__xswait_state xswait;
     int num_exec;
     /* for calling hotplug scripts */
     libxl__async_exec_state aes;
-- 
1.7.10.4