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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2016-01-14 14:01:34 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2016-03-14 15:52:17 -0700
commit0e4bd2aba3d0ae5caeb0d1a2b71f6fe6147c4d56 (patch)
tree939de81e0d6e72b5765fdb1587d3cc269976fb19 /Documentation/memory-barriers.txt
parent895f5542220eeea43b811a9b4cd73f244c5673d7 (diff)
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documentation: Remove obsolete reference to RCU-protected indexes
Commit #1ebee8017d84 (rcu: Eliminate array-index-based RCU primitives) eliminated the primitives supporting RCU-protected array indexes, but failed to update Documentation/memory-barriers.txt accordingly. This commit therefore removes the discussion of RCU-protected array indexes. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'Documentation/memory-barriers.txt')
-rw-r--r--Documentation/memory-barriers.txt15
1 files changed, 0 insertions, 15 deletions
diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index c90922b..6bee0a2 100644
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -565,21 +565,6 @@ odd-numbered bank is idle, one can see the new value of the pointer P (&B),
but the old value of the variable B (2).
-Another example of where data dependency barriers might be required is where a
-number is read from memory and then used to calculate the index for an array
-access:
-
- CPU 1 CPU 2
- =============== ===============
- { M[0] == 1, M[1] == 2, M[3] = 3, P == 0, Q == 3 }
- M[1] = 4;
- <write barrier>
- WRITE_ONCE(P, 1);
- Q = READ_ONCE(P);
- <data dependency barrier>
- D = M[Q];
-
-
The data dependency barrier is very important to the RCU system,
for example. See rcu_assign_pointer() and rcu_dereference() in
include/linux/rcupdate.h. This permits the current target of an RCU'd
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