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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2013-07-02 15:24:09 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2013-08-19 21:39:42 -0700 |
| commit | 45c8a36a5519960638a4f331839bb99c1994fd04 (patch) | |
| tree | 58ddb29830df06a0a87524f4514c299bb22988c7 /Documentation | |
| parent | 6ae3771850910018c89b4ce063c52008bf2c8d6a (diff) | |
| download | lwn-45c8a36a5519960638a4f331839bb99c1994fd04.tar.gz lwn-45c8a36a5519960638a4f331839bb99c1994fd04.zip | |
doc: Fix memory-barrier control-dependency example
Each control-dependency example needs its barriers between the "if"
condition and the body of the "if" because a control dependency is
a dependency induced by a branch. This commit makes the needed
adjustment.
Reported-by: Yongming Shen <symingz@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/memory-barriers.txt | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index fa5d8a9ae205..c8c42e64e953 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -531,9 +531,10 @@ dependency barrier to make it work correctly. Consider the following bit of code: q = &a; - if (p) + if (p) { + <data dependency barrier> q = &b; - <data dependency barrier> + } x = *q; This will not have the desired effect because there is no actual data @@ -542,9 +543,10 @@ attempting to predict the outcome in advance. In such a case what's actually required is: q = &a; - if (p) + if (p) { + <read barrier> q = &b; - <read barrier> + } x = *q; |