[PATCH tip/core/rcu 14/14] documentation: Clarify compiler store-fusion example

From: Paul E. McKenney
Date: Wed Feb 24 2016 - 00:08:40 EST


From: SeongJae Park <sj38.park@xxxxxxxxx>

The compiler store-fusion example in memory-barriers.txt uses a C
comment to represent arbitrary code that does not update a given
variable. Unfortunately, someone could reasonably interpret the
comment as instead referring to the following line of code. This
commit therefore replaces the comment with a string that more
clearly represents the arbitrary code.

Signed-off-by: SeongJae Park <sj38.park@xxxxxxxxx>
Acked-by: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
Documentation/memory-barriers.txt | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index 8367d393cba2..3729cbe60e41 100644
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -1550,7 +1550,7 @@ of optimizations:
the following:

a = 0;
- /* Code that does not store to variable a. */
+ ... Code that does not store to variable a ...
a = 0;

The compiler sees that the value of variable 'a' is already zero, so
@@ -1562,7 +1562,7 @@ of optimizations:
wrong guess:

WRITE_ONCE(a, 0);
- /* Code that does not store to variable a. */
+ ... Code that does not store to variable a ...
WRITE_ONCE(a, 0);

(*) The compiler is within its rights to reorder memory accesses unless
--
2.5.2