Work around C11 const atomic restrictions.
Cast away the const qualifier in BBinder::findObject. C11, unlike C++11,
does not allow loads from const atomics. This is widely regarded as
a bug (see WG14 DR 459). This is a hack to work around it until it's
officially fixed in the spec.
load_const_atomic was adapted from commit
1e8587a479fd8b1ce9b594298a93f517816e8f15
I don't think we want to dignify this by putting it into a header file.
Bug:17067219
Change-Id: Icbfcbda2722e6f80d2bb065a0bb3ec7634bcacb2
diff --git a/libs/binder/Binder.cpp b/libs/binder/Binder.cpp
index 2554351..296a98b 100644
--- a/libs/binder/Binder.cpp
+++ b/libs/binder/Binder.cpp
@@ -160,10 +160,18 @@
e->mObjects.attach(objectID, object, cleanupCookie, func);
}
+// The C11 standard doesn't allow atomic loads from const fields,
+// though C++11 does. Fudge it until standards get straightened out.
+static inline uintptr_t load_const_atomic(const atomic_uintptr_t* p,
+ memory_order mo) {
+ atomic_uintptr_t* non_const_p = const_cast<atomic_uintptr_t*>(p);
+ return atomic_load_explicit(non_const_p, mo);
+}
+
void* BBinder::findObject(const void* objectID) const
{
Extras* e = reinterpret_cast<Extras*>(
- atomic_load_explicit(&mExtras, memory_order_acquire));
+ load_const_atomic(&mExtras, memory_order_acquire));
if (!e) return NULL;
AutoMutex _l(e->mLock);