[pango/fix-deadlocks] Try to fix hands that people have observed

[Matthias Clasen <matthiasc src gnome org>]

commit 8485934c47abaf864f45d0c5b39463cbd1fcb90d
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Mar 31 16:21:55 2021 -0400

    Try to fix hands that people have observed
    
    Sadly, adding memory barriers by going all atomic
    on fc_initialized does not fix the hang of gnome-text-editor
    yet.

 pango/pangofc-fontmap.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
---
diff --git a/pango/pangofc-fontmap.c b/pango/pangofc-fontmap.c
index 813b6c78..45a81142 100644
--- a/pango/pangofc-fontmap.c
+++ b/pango/pangofc-fontmap.c
@@ -1357,7 +1357,7 @@ init_in_thread (GTask        *task,
   pango_trace_mark (before, "FcInit", NULL);
 
   g_mutex_lock (&fc_init_mutex);
-  fc_initialized = 2;
+  g_atomic_int_set (&fc_initialized, 2);
   g_cond_broadcast (&fc_init_cond);
   g_mutex_unlock (&fc_init_mutex);
 }
@@ -1367,17 +1367,17 @@ start_init_in_thread (PangoFcFontMap *fcfontmap)
 {
   g_mutex_lock (&fc_init_mutex);
 
-  if (fc_initialized == 0)
+  if (g_atomic_int_compare_and_exchange (&fc_initialized, 0, 1))
     {
       GTask *task;
 
-      fc_initialized = 1;
-
       task = g_task_new (fcfontmap, NULL, NULL, NULL);
       g_task_set_name (task, "[pango] FcInit");
       g_task_run_in_thread (task, init_in_thread);
       g_object_unref (task);
     }
+  else
+    g_cond_broadcast (&fc_init_cond);
 
   g_mutex_unlock (&fc_init_mutex);
 }
@@ -1389,7 +1389,7 @@ wait_for_fc_init (void)
   gboolean waited = FALSE;
 
   g_mutex_lock (&fc_init_mutex);
-  while (fc_initialized < 2)
+  while (g_atomic_int_get (&fc_initialized) < 2)
     {
       waited = TRUE;
       g_cond_wait (&fc_init_cond, &fc_init_mutex);