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Commit 45c8a36a authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

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: default avatarYongming Shen <symingz@gmail.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent 6ae37718

Documentation/memory-barriers.txt

+6 −4
Original line number Diff line number Diff line
@@ -531,9 +531,10 @@ dependency barrier to make it work correctly. Consider the following bit of 
code:



	q = &a;

	if (p)

		q = &b;

	if (p) {

		<data dependency barrier>

		q = &b;

	}

	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)

		q = &b;

	if (p) {

		<read barrier>

		q = &b;

	}

	x = *q;