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-rw-r--r--include/linux/rcupdate.h12
1 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 01f71e1d2e94..6ade6a52d9d4 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -1161,5 +1161,17 @@ do { \
ftrace_dump(oops_dump_mode); \
} while (0)
+/*
+ * Place this after a lock-acquisition primitive to guarantee that
+ * an UNLOCK+LOCK pair acts as a full barrier. This guarantee applies
+ * if the UNLOCK and LOCK are executed by the same CPU or if the
+ * UNLOCK and LOCK operate on the same lock variable.
+ */
+#ifdef CONFIG_PPC
+#define smp_mb__after_unlock_lock() smp_mb() /* Full ordering for lock. */
+#else /* #ifdef CONFIG_PPC */
+#define smp_mb__after_unlock_lock() do { } while (0)
+#endif /* #else #ifdef CONFIG_PPC */
+
#endif /* __LINUX_RCUPDATE_H */