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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-09-17 08:18:32 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-10-06 11:22:57 -0700
commitad2ad5d31f90fc6fb269e9be244224cecfc8b400 (patch)
tree514da7f8d0ff06b41f1e0c553c10188ce9cc5814 /Documentation/memory-barriers.txt
parentb672adf8cfb822781ab904343e5de0297ee117ed (diff)
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>
Diffstat (limited to 'Documentation/memory-barriers.txt')
-rw-r--r--Documentation/memory-barriers.txt11
1 files changed, 11 insertions, 0 deletions
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();