Linux-libre 4.8.2-gnupck-4.8.2-gnu

1 files changed, 5 insertions, 7 deletions

diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h
index 84f542df7..1c7eec09e 100644
--- a/include/linux/percpu-refcount.h
+++ b/include/linux/percpu-refcount.h
@@ -136,14 +136,12 @@ static inline bool __ref_is_percpu(struct percpu_ref *ref,
 	 * used as a pointer.  If the compiler generates a separate fetch
 	 * when using it as a pointer, __PERCPU_REF_ATOMIC may be set in
 	 * between contaminating the pointer value, meaning that
-	 * ACCESS_ONCE() is required when fetching it.
-	 *
-	 * Also, we need a data dependency barrier to be paired with
-	 * smp_store_release() in __percpu_ref_switch_to_percpu().
-	 *
-	 * Use lockless deref which contains both.
+	 * READ_ONCE() is required when fetching it.
 	 */
-	percpu_ptr = lockless_dereference(ref->percpu_count_ptr);
+	percpu_ptr = READ_ONCE(ref->percpu_count_ptr);
+
+	/* paired with smp_store_release() in __percpu_ref_switch_to_percpu() */
+	smp_read_barrier_depends();
 
 	/*
 	 * Theoretically, the following could test just ATOMIC; however,