Fix race condition when locking/unlocking pixels.

src/core/SkBitmap.cpp

 
 /*
  * Copyright 2008 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkBitmap.h"
@@ skipping 322 matching lines @@
         }
         fPixelRefOffset = offset;
         this->updatePixelsFromRef();
     }
 
     SkDEBUGCODE(this->validate();)
     return pr;
 }
 
 void SkBitmap::lockPixels() const {
-    if (NULL != fPixelRef && 1 == ++fPixelLockCount) {
+    if (NULL != fPixelRef && 0 == sk_atomic_inc(&fPixelLockCount)) {
         fPixelRef->lockPixels();
         this->updatePixelsFromRef();
     }
     SkDEBUGCODE(this->validate();)
 }
 
 void SkBitmap::unlockPixels() const {
     SkASSERT(NULL == fPixelRef || fPixelLockCount > 0);
 
-    if (NULL != fPixelRef && 0 == --fPixelLockCount) {
+    if (NULL != fPixelRef && 1 == sk_atomic_dec(&fPixelLockCount)) {
         fPixelRef->unlockPixels();
         this->updatePixelsFromRef();
     }
     SkDEBUGCODE(this->validate();)
 }
 
 bool SkBitmap::lockPixelsAreWritable() const {
     return (fPixelRef) ? fPixelRef->lockPixelsAreWritable() : false;
 }
 
@@ skipping 1322 matching lines @@
         if (NULL != uri) {
             str->appendf(" uri:\"%s\"", uri);
         } else {
             str->appendf(" pixelref:%p", pr);
         }
     }
 
     str->append(")");
 }
 #endif