1 files changed, 44 insertions, 12 deletions

diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 84f7b1526e..70b21e9d51 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -1552,10 +1552,50 @@ bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file)
     return true;
 }
 
-int postcopy_preempt_setup(MigrationState *s, Error **errp)
+static void
+postcopy_preempt_send_channel_new(QIOTask *task, gpointer opaque)
 {
-    QIOChannel *ioc;
+    MigrationState *s = opaque;
+    QIOChannel *ioc = QIO_CHANNEL(qio_task_get_source(task));
+    Error *local_err = NULL;
+
+    if (qio_task_propagate_error(task, &local_err)) {
+        /* Something wrong happened.. */
+        migrate_set_error(s, local_err);
+        error_free(local_err);
+    } else {
+        migration_ioc_register_yank(ioc);
+        s->postcopy_qemufile_src = qemu_file_new_output(ioc);
+        trace_postcopy_preempt_new_channel();
+    }
+
+    /*
+     * Kick the waiter in all cases.  The waiter should check upon
+     * postcopy_qemufile_src to know whether it failed or not.
+     */
+    qemu_sem_post(&s->postcopy_qemufile_src_sem);
+    object_unref(OBJECT(ioc));
+}
 
+/* Returns 0 if channel established, -1 for error. */
+int postcopy_preempt_wait_channel(MigrationState *s)
+{
+    /* If preempt not enabled, no need to wait */
+    if (!migrate_postcopy_preempt()) {
+        return 0;
+    }
+
+    /*
+     * We need the postcopy preempt channel to be established before
+     * starting doing anything.
+     */
+    qemu_sem_wait(&s->postcopy_qemufile_src_sem);
+
+    return s->postcopy_qemufile_src ? 0 : -1;
+}
+
+int postcopy_preempt_setup(MigrationState *s, Error **errp)
+{
     if (!migrate_postcopy_preempt()) {
         return 0;
     }
@@ -1566,16 +1606,8 @@ int postcopy_preempt_setup(MigrationState *s, Error **errp)
         return -1;
     }
 
-    ioc = socket_send_channel_create_sync(errp);
-
-    if (ioc == NULL) {
-        return -1;
-    }
-
-    migration_ioc_register_yank(ioc);
-    s->postcopy_qemufile_src = qemu_file_new_output(ioc);
-
-    trace_postcopy_preempt_new_channel();
+    /* Kick an async task to connect */
+    socket_send_channel_create(postcopy_preempt_send_channel_new, s);
 
     return 0;
 }