cancellable: Use more atomic exchanges operations

We used to do get and set atomic operations pair, but these may be
unsafe in some cases as threads may rely on data that is changed in
in between them, however this is not a problem if we do exchange the
pointers.

So just use exchange ops, in this way we can avoid lock/unlock mutex
dances

1 files changed, 2 insertions, 5 deletions

diff --git a/gio/gcancellable.c b/gio/gcancellable.c
index 64755206b..13a891a69 100644
--- a/gio/gcancellable.c
+++ b/gio/gcancellable.c
@@ -273,12 +273,10 @@ g_cancellable_reset (GCancellable *cancellable)
       g_cond_wait (&cancellable_cond, &cancellable_mutex);
     }
 
-  if (g_atomic_int_get (&priv->cancelled))
+  if (g_atomic_int_exchange (&priv->cancelled, FALSE))
     {
       if (priv->wakeup)
         GLIB_PRIVATE_CALL (g_wakeup_acknowledge) (priv->wakeup);
-
-      g_atomic_int_set (&priv->cancelled, FALSE);
     }
 
   g_mutex_unlock (&cancellable_mutex);
@@ -497,13 +495,12 @@ g_cancellable_cancel (GCancellable *cancellable)
 
   g_mutex_lock (&cancellable_mutex);
 
-  if (g_atomic_int_get (&priv->cancelled))
+  if (g_atomic_int_exchange (&priv->cancelled, TRUE))
     {
       g_mutex_unlock (&cancellable_mutex);
       return;
     }
 
-  g_atomic_int_set (&priv->cancelled, TRUE);
   priv->cancelled_running = TRUE;
 
   if (priv->wakeup)