Subject: [merged] doc-fix-important-typo-re-memory-barriers.patch removed from -mm tree
To: adobriyan@xxxxxxxxx,dhowells@xxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Mon, 09 Jun 2014 12:33:22 -0700
The patch titled
Subject: Documentation/memory-barriers.txt: fix important typo re memory barriers
has been removed from the -mm tree. Its filename was
doc-fix-important-typo-re-memory-barriers.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Subject: Documentation/memory-barriers.txt: fix important typo re memory barriers
Examples introducing neccesity of RMB+WMP pair reads as
A=3 READ B
www rrrrrr
B=4 READ A
Note the opposite order of reads vs writes.
But the first example without barriers reads as
A=3 READ A
B=4 READ B
There are 4 outcomes in the first example.
But if someone new to the concept tries to insert barriers like this:
A=3 READ A
www rrrrrr
B=4 READ B
he will still get all 4 possible outcomes, because "READ A" is first.
All this can be utterly confusing because barrier pair seems to be
superfluous. In short, fixup first example to match latter examples with
barriers.
Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/memory-barriers.txt | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff -puN Documentation/memory-barriers.txt~doc-fix-important-typo-re-memory-barriers Documentation/memory-barriers.txt
--- a/Documentation/memory-barriers.txt~doc-fix-important-typo-re-memory-barriers
+++ a/Documentation/memory-barriers.txt
@@ -115,8 +115,8 @@ For example, consider the following sequ
CPU 1 CPU 2
=============== ===============
{ A == 1; B == 2 }
- A = 3; x = A;
- B = 4; y = B;
+ A = 3; x = B;
+ B = 4; y = A;
The set of accesses as seen by the memory system in the middle can be arranged
in 24 different combinations:
_
Patches currently in -mm which might be from adobriyan@xxxxxxxxx are
origin.patch
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