Fix DiscardableMemoryPool::free race condition

BUG=skia:3596

Review URL: https://codereview.chromium.org/1017943003

diff --git a/src/lazy/SkDiscardableMemoryPool.cpp b/src/lazy/SkDiscardableMemoryPool.cpp
index 1f48366..5b9d87f 100644 (file)
--- a/src/lazy/SkDiscardableMemoryPool.cpp
+++ b/src/lazy/SkDiscardableMemoryPool.cpp
@@ -188,9 +188,9 @@ SkDiscardableMemory* DiscardableMemoryPool::create(size_t bytes) {
 }
 
 void DiscardableMemoryPool::free(PoolDiscardableMemory* dm) {
+    SkAutoMutexAcquire autoMutexAcquire(fMutex);
     // This is called by dm's destructor.
     if (dm->fPointer != NULL) {
-        SkAutoMutexAcquire autoMutexAcquire(fMutex);
         sk_free(dm->fPointer);
         dm->fPointer = NULL;
         SkASSERT(fUsed >= dm->fBytes);