[glib] gmain: Close race condition in _g_main_wake_up_all_contexts()

[Colin Walters <walters src gnome org>]

commit c9f883f133bc83942484cb8a1349b58ada46b4bc
Author: Colin Walters <walters verbum org>
Date:   Tue Jun 14 18:46:06 2011 -0400

    gmain: Close race condition in _g_main_wake_up_all_contexts()
    
    Running gthread/tests/spawn-multithreaded in a loop, I very easily hit:
    
    GLib-CRITICAL **: g_main_context_wakeup: assertion `g_atomic_int_get (&context->ref_count) > 0' failed
    
    Testing the refcount still left a window where we would fall into the
    assertion.  Fix this by just locking the context.

 glib/gmain.c |   17 +++++------------
 1 files changed, 5 insertions(+), 12 deletions(-)
---
diff --git a/glib/gmain.c b/glib/gmain.c
index c84d7b9..47b26cc 100644
--- a/glib/gmain.c
+++ b/glib/gmain.c
@@ -3774,16 +3774,11 @@ _g_main_wake_up_all_contexts (void)
   G_LOCK (main_context_list);
   for (list = main_context_list; list; list = list->next)
     {
-      GMainContext *context;
-
-      context = list->data;
-      if (g_atomic_int_get (&context->ref_count) > 0)
-	/* Due to racing conditions we can find ref_count == 0, in
-	 * that case, however, the context is still not destroyed
-	 * and no poll can be active, otherwise the ref_count
-	 * wouldn't be 0
-	 */
-	g_main_context_wakeup (context);
+      GMainContext *context = list->data;
+
+      LOCK_CONTEXT (context);
+      g_main_context_wakeup_unlocked (context);
+      UNLOCK_CONTEXT (context);
     }
   G_UNLOCK (main_context_list);
 }
@@ -4635,8 +4630,6 @@ unix_signal_helper_thread (gpointer data)
 	deliver_unix_signal (SIGINT);
       if (sighup_received)
 	deliver_unix_signal (SIGHUP);
-      if (sigchld_received)
-	deliver_sigchld ();
       _g_main_wake_up_all_contexts ();
     }
 }