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| -rw-r--r-- | Documentation/memory-barriers.txt | 15 |
1 files changed, 0 insertions, 15 deletions
diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index c90922b9b294..6bee0a2c43ab 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 |