libxl: convert libxl_domain_destroy to an async op

This change introduces some new structures, and breaks the mutual
dependency that libxl_domain_destroy and libxl__destroy_device_model
had. This is done by checking if the domid passed to
libxl_domain_destroy has a stubdom, and then having the bulk of the
destroy machinery in a separate function (libxl__destroy_domid) that
doesn't check for stubdom presence, since we check for it in the upper
level function. The reason behind this change is the need to use
structures for ao operations, and it was impossible to have two
different self-referencing structs.

All uses of libxl_domain_destroy have been changed, and either
replaced by the new libxl_domain_destroy ao function or by the
internal libxl__domain_destroy that can be used inside an already
running ao.

Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Campbell <ian.campbell@citrix.com>

1 files changed, 25 insertions, 4 deletions

diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 0bfa8babee..137659f993 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -571,6 +571,12 @@ static void domcreate_complete(libxl__egc *egc,
                                libxl__domain_create_state *dcs,
                                int rc);
 
+/* If creation is not successful, this callback will be executed
+ * when domain destruction is finished */
+static void domcreate_destruction_cb(libxl__egc *egc,
+                                     libxl__domain_destroy_state *dds,
+                                     int rc);
+
 static void initiate_domain_create(libxl__egc *egc,
                                    libxl__domain_create_state *dcs)
 {
@@ -999,16 +1005,31 @@ static void domcreate_complete(libxl__egc *egc,
 
     if (rc) {
         if (dcs->guest_domid) {
-            int rc2 = libxl_domain_destroy(CTX, dcs->guest_domid);
-            if (rc2)
-                LOG(ERROR, "unable to destroy domain %d following"
-                    " failed creation", dcs->guest_domid);
+            dcs->dds.ao = ao;
+            dcs->dds.domid = dcs->guest_domid;
+            dcs->dds.callback = domcreate_destruction_cb;
+            libxl__domain_destroy(egc, &dcs->dds);
+            return;
         }
         dcs->guest_domid = -1;
     }
     dcs->callback(egc, dcs, rc, dcs->guest_domid);
 }
 
+static void domcreate_destruction_cb(libxl__egc *egc,
+                                     libxl__domain_destroy_state *dds,
+                                     int rc)
+{
+    STATE_AO_GC(dds->ao);
+    libxl__domain_create_state *dcs = CONTAINER_OF(dds, *dcs, dds);
+
+    if (rc)
+        LOG(ERROR, "unable to destroy domain %u following failed creation",
+                   dds->domid);
+
+    dcs->callback(egc, dcs, ERROR_FAIL, dcs->guest_domid);
+}
+
 /*----- application-facing domain creation interface -----*/
 
 typedef struct {