srcu: API for barrier after srcu read unlock

[~andy/linux] / include / linux / srcu.h

diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index c114614ed172fdbb02b70fde61d6838f4734bfb4..9b058eecd40390b914d705809a1aabac3eff132b 100644 (file)
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -237,4 +237,18 @@ static inline void srcu_read_unlock(struct srcu_struct *sp, int idx)
        __srcu_read_unlock(sp, idx);
 }
 
+/**
+ * smp_mb__after_srcu_read_unlock - ensure full ordering after srcu_read_unlock
+ *
+ * Converts the preceding srcu_read_unlock into a two-way memory barrier.
+ *
+ * Call this after srcu_read_unlock, to guarantee that all memory operations
+ * that occur after smp_mb__after_srcu_read_unlock will appear to happen after
+ * the preceding srcu_read_unlock.
+ */
+static inline void smp_mb__after_srcu_read_unlock(void)
+{
+       /* __srcu_read_unlock has smp_mb() internally so nothing to do here. */
+}
+
 #endif