Ensure memory ordering around libagl and EGL refcount operations
The android_atomic_inc/android_atomic_dec functions don't impose
sufficient memory ordering. Using them for object refcounting could
allow an object to be destroyed prior to writes by a different thread
being visible.
Bug: 28820690
Change-Id: Ie018091035174255a22ebc52852528cdaec2d648
diff --git a/opengl/libagl/egl.cpp b/opengl/libagl/egl.cpp
index 7560d8f..92139e9 100644
--- a/opengl/libagl/egl.cpp
+++ b/opengl/libagl/egl.cpp
@@ -16,6 +16,7 @@
*/
#include <assert.h>
+#include <atomic>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
@@ -27,7 +28,6 @@
#include <sys/mman.h>
#include <cutils/log.h>
-#include <cutils/atomic.h>
#include <utils/threads.h>
#include <ui/ANativeObjectBase.h>
@@ -107,8 +107,8 @@
return ((uintptr_t(dpy)-1U) >= NUM_DISPLAYS) ? EGL_FALSE : EGL_TRUE;
}
- NativeDisplayType type;
- volatile int32_t initialized;
+ NativeDisplayType type;
+ std::atomic_size_t initialized;
};
static egl_display_t gDisplays[NUM_DISPLAYS];
@@ -1429,7 +1429,7 @@
EGLBoolean res = EGL_TRUE;
egl_display_t& d = egl_display_t::get_display(dpy);
- if (android_atomic_inc(&d.initialized) == 0) {
+ if (d.initialized.fetch_add(1, std::memory_order_acquire) == 0) {
// initialize stuff here if needed
//pthread_mutex_lock(&gInitMutex);
//pthread_mutex_unlock(&gInitMutex);
@@ -1449,7 +1449,8 @@
EGLBoolean res = EGL_TRUE;
egl_display_t& d = egl_display_t::get_display(dpy);
- if (android_atomic_dec(&d.initialized) == 1) {
+ if (d.initialized.fetch_sub(1, std::memory_order_release) == 1) {
+ std::atomic_thread_fence(std::memory_order_acquire);
// TODO: destroy all resources (surfaces, contexts, etc...)
//pthread_mutex_lock(&gInitMutex);
//pthread_mutex_unlock(&gInitMutex);