am ae66946b: Merge "fix a race in SF buffer management" into gingerbread
Merge commit 'ae66946bd9e9f1168241c75196d2379b43e3ca30' into gingerbread-plus-aosp
* commit 'ae66946bd9e9f1168241c75196d2379b43e3ca30':
fix a race in SF buffer management
diff --git a/include/private/surfaceflinger/SharedBufferStack.h b/include/private/surfaceflinger/SharedBufferStack.h
index d016dfa..d689667 100644
--- a/include/private/surfaceflinger/SharedBufferStack.h
+++ b/include/private/surfaceflinger/SharedBufferStack.h
@@ -151,7 +151,6 @@
~SharedBufferBase();
status_t getStatus() const;
int32_t getIdentity() const;
- size_t getFrontBuffer() const;
String8 dump(char const* prefix) const;
protected:
@@ -226,6 +225,11 @@
inline ssize_t operator()();
};
+ struct DequeueUpdate : public UpdateBase {
+ inline DequeueUpdate(SharedBufferBase* sbb);
+ inline ssize_t operator()();
+ };
+
struct UndoDequeueUpdate : public UpdateBase {
inline UndoDequeueUpdate(SharedBufferBase* sbb);
inline ssize_t operator()();
diff --git a/libs/surfaceflinger_client/SharedBufferStack.cpp b/libs/surfaceflinger_client/SharedBufferStack.cpp
index 4ad9f86..38b2fae 100644
--- a/libs/surfaceflinger_client/SharedBufferStack.cpp
+++ b/libs/surfaceflinger_client/SharedBufferStack.cpp
@@ -191,12 +191,6 @@
return stack.identity;
}
-size_t SharedBufferBase::getFrontBuffer() const
-{
- SharedBufferStack& stack( *mSharedStack );
- return size_t( stack.head );
-}
-
String8 SharedBufferBase::dump(char const* prefix) const
{
const size_t SIZE = 1024;
@@ -281,6 +275,16 @@
return NO_ERROR;
}
+SharedBufferClient::DequeueUpdate::DequeueUpdate(SharedBufferBase* sbb)
+ : UpdateBase(sbb) {
+}
+ssize_t SharedBufferClient::DequeueUpdate::operator()() {
+ if (android_atomic_dec(&stack.available) == 0) {
+ LOGW("dequeue probably called from multiple threads!");
+ }
+ return NO_ERROR;
+}
+
SharedBufferClient::UndoDequeueUpdate::UndoDequeueUpdate(SharedBufferBase* sbb)
: UpdateBase(sbb) {
}
@@ -388,12 +392,8 @@
if (err != NO_ERROR)
return ssize_t(err);
- // NOTE: 'stack.available' is part of the conditions, however
- // decrementing it, never changes any conditions, so we don't need
- // to do this as part of an update.
- if (android_atomic_dec(&stack.available) == 0) {
- LOGW("dequeue probably called from multiple threads!");
- }
+ DequeueUpdate update(this);
+ updateCondition( update );
undoDequeueTail = tail;
int dequeued = stack.index[tail];