once: Fix race causing pa_once to sometimes run twice

There was a race in the existing code that could cause the pa_once code
to be run twice, see:
http://lists.freedesktop.org/archives/pulseaudio-discuss/2012-April/013354.html

Therefore the existing implementation was rewritten to instead look like
the reference implementation here:
http://www.hpl.hp.com/research/linux/atomic_ops/example.php4

Signed-off-by: David Henningsson <david.henningsson@canonical.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/src/pulsecore/once.h b/src/pulsecore/once.h
index edc81881..a478d1ff 100644
--- a/src/pulsecore/once.h
+++ b/src/pulsecore/once.h
@@ -23,16 +23,16 @@
 ***/
 
 #include <pulsecore/atomic.h>
+#include <pulsecore/mutex.h>
 
 typedef struct pa_once {
-    pa_atomic_ptr_t mutex;
-    pa_atomic_t ref, done;
+    pa_static_mutex mutex;
+    pa_atomic_t done;
 } pa_once;
 
 #define PA_ONCE_INIT                                                    \
     {                                                                   \
-        .mutex = PA_ATOMIC_PTR_INIT(NULL),                              \
-        .ref = PA_ATOMIC_INIT(0),                                       \
+        .mutex = PA_STATIC_MUTEX_INIT,                                  \
         .done = PA_ATOMIC_INIT(0)                                       \
     }