Linux-libre 4.6.2-gnu

1 files changed, 31 insertions, 0 deletions

diff --git a/include/linux/atomic.h b/include/linux/atomic.h
index 301de78d6..506c35318 100644
--- a/include/linux/atomic.h
+++ b/include/linux/atomic.h
@@ -34,20 +34,29 @@
  * The idea here is to build acquire/release variants by adding explicit
  * barriers on top of the relaxed variant. In the case where the relaxed
  * variant is already fully ordered, no additional barriers are needed.
+ *
+ * Besides, if an arch has a special barrier for acquire/release, it could
+ * implement its own __atomic_op_* and use the same framework for building
+ * variants
  */
+#ifndef __atomic_op_acquire
 #define __atomic_op_acquire(op, args...)				\
 ({									\
 	typeof(op##_relaxed(args)) __ret  = op##_relaxed(args);		\
 	smp_mb__after_atomic();						\
 	__ret;								\
 })
+#endif
 
+#ifndef __atomic_op_release
 #define __atomic_op_release(op, args...)				\
 ({									\
 	smp_mb__before_atomic();					\
 	op##_relaxed(args);						\
 })
+#endif
 
+#ifndef __atomic_op_fence
 #define __atomic_op_fence(op, args...)					\
 ({									\
 	typeof(op##_relaxed(args)) __ret;				\
@@ -56,6 +65,7 @@
 	smp_mb__after_atomic();						\
 	__ret;								\
 })
+#endif
 
 /* atomic_add_return_relaxed */
 #ifndef atomic_add_return_relaxed
@@ -548,6 +558,27 @@ static inline int atomic_dec_if_positive(atomic_t *v)
 }
 #endif
 
+/**
+ * atomic_fetch_or - perform *p |= mask and return old value of *p
+ * @p: pointer to atomic_t
+ * @mask: mask to OR on the atomic_t
+ */
+#ifndef atomic_fetch_or
+static inline int atomic_fetch_or(atomic_t *p, int mask)
+{
+	int old, val = atomic_read(p);
+
+	for (;;) {
+		old = atomic_cmpxchg(p, val, val | mask);
+		if (old == val)
+			break;
+		val = old;
+	}
+
+	return old;
+}
+#endif
+
 #ifdef CONFIG_GENERIC_ATOMIC64
 #include <asm-generic/atomic64.h>
 #endif