diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index d336e4d42029..8e7cf9ad3db1 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -1710,6 +1710,17 @@ There are some more advanced barrier functions: 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();