[glib: 3/6] gmain: Make GUnixSignalWatchSource pending field atomic

[Philip Withnall <pwithnall src gnome org>]

commit 9e652f94d285b1722ea82a0465c6724eee346738
Author: Tomasz Miąsko <tomasz miasko gmail com>
Date:   Thu Nov 1 00:00:00 2018 +0000

    gmain: Make GUnixSignalWatchSource pending field atomic
    
    Ensure synchronization between prepare / check /dispatch of
    GUnixSignalWatchSource and UNIX signal dispatcher by making operations
    on `pending` field atomic.
    
    Issue #1312.

 glib/gmain.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)
---
diff --git a/glib/gmain.c b/glib/gmain.c
index ad57b4927..07ec867bc 100644
--- a/glib/gmain.c
+++ b/glib/gmain.c
@@ -5138,14 +5138,10 @@ dispatch_unix_signals_unlocked (void)
     {
       GUnixSignalWatchSource *source = node->data;
 
-      if (!source->pending)
+      if (pending[source->signum] &&
+          g_atomic_int_compare_and_exchange (&source->pending, FALSE, TRUE))
         {
-          if (pending[source->signum])
-            {
-              source->pending = TRUE;
-
-              wake_source ((GSource *) source);
-            }
+          wake_source ((GSource *) source);
         }
     }
 
@@ -5188,7 +5184,7 @@ g_unix_signal_watch_prepare (GSource *source,
 
   unix_signal_source = (GUnixSignalWatchSource *) source;
 
-  return unix_signal_source->pending;
+  return g_atomic_int_get (&unix_signal_source->pending);
 }
 
 static gboolean
@@ -5198,7 +5194,7 @@ g_unix_signal_watch_check (GSource  *source)
 
   unix_signal_source = (GUnixSignalWatchSource *) source;
 
-  return unix_signal_source->pending;
+  return g_atomic_int_get (&unix_signal_source->pending);
 }
 
 static gboolean
@@ -5220,7 +5216,7 @@ g_unix_signal_watch_dispatch (GSource    *source,
 
   again = (callback) (user_data);
 
-  unix_signal_source->pending = FALSE;
+  g_atomic_int_set (&unix_signal_source->pending, FALSE);
 
   return again;
 }