documentation: Add lockless_dereference()
The recently added lockless_dereference() macro is not present in the
Documentation/ directory, so this commit fixes that.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index d336e4d..8e7cf9a 100644
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -1710,6 +1710,17 @@
operations" subsection for information on where to use these.
+ (*) lockless_dereference();
+ This can be thought of as a pointer-fetch wrapper around the
+ smp_read_barrier_depends() data-dependency barrier.
+
+ This is also similar to rcu_dereference(), but in cases where
+ object lifetime is handled by some mechanism other than RCU, for
+ example, when the objects removed only when the system goes down.
+ In addition, lockless_dereference() is used in some data structures
+ that can be used both with and without RCU.
+
+
(*) dma_wmb();
(*) dma_rmb();
