commit 82d90705fe203cc6e150c10bd61f0dbe6979e8f4
author Peter Xu <peterx@redhat.com> Thu Sep 28 10:59:56 2017 +0800
committer Stefan Hajnoczi <stefanha@redhat.com> Tue Oct 03 14:36:16 2017 -0400
tree 5787f080ae09a751e55075ca15e44da122b52653
parent 0173e21b617d3de1fcfa917e329bb9194ab332a4

iothread: export iothread_stop()

So that internal iothread users can explicitly stop one iothread without
destroying it.

Since at it, fix iothread_stop() to allow it to be called multiple
times.  Before this patch we may call iothread_stop() more than once on
single iothread, while that may not be correct since qemu_thread_join()
is not allowed to run twice.  From manual of pthread_join():

  Joining with a thread that has previously been joined results in
  undefined behavior.

Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-id: 20170928025958.1420-4-peterx@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

iothread.c

diff --git a/iothread.c b/iothread.c
index 0672a91..b3c092b 100644
--- a/iothread.c
+++ b/iothread.c
@@ -80,13 +80,10 @@
     return NULL;
 }
 
-static int iothread_stop(Object *object, void *opaque)
+void iothread_stop(IOThread *iothread)
 {
-    IOThread *iothread;
-
-    iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
-    if (!iothread || !iothread->ctx || iothread->stopping) {
-        return 0;
+    if (!iothread->ctx || iothread->stopping) {
+        return;
     }
     iothread->stopping = true;
     aio_notify(iothread->ctx);
@@ -94,6 +91,17 @@
         g_main_loop_quit(iothread->main_loop);
     }
     qemu_thread_join(&iothread->thread);
+}
+
+static int iothread_stop_iter(Object *object, void *opaque)
+{
+    IOThread *iothread;
+
+    iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
+    if (!iothread) {
+        return 0;
+    }
+    iothread_stop(iothread);
     return 0;
 }
 
@@ -108,7 +116,7 @@
 {
     IOThread *iothread = IOTHREAD(obj);
 
-    iothread_stop(obj, NULL);
+    iothread_stop(iothread);
     qemu_cond_destroy(&iothread->init_done_cond);
     qemu_mutex_destroy(&iothread->init_done_lock);
     if (!iothread->ctx) {
@@ -328,7 +336,7 @@
         aio_context_release(ctx);
     }
 
-    object_child_foreach(container, iothread_stop, NULL);
+    object_child_foreach(container, iothread_stop_iter, NULL);
 }
 
 static gpointer iothread_g_main_context_init(gpointer opaque)