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author | Chris Metcalf <cmetcalf@ezchip.com> | 2015-11-24 01:04:17 +0300 |
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committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-12-05 23:34:54 +0300 |
commit | f84cfbb0ff269b427a0db591e22ac6948c554ab4 (patch) | |
tree | a80a07771c60c0de8b62b306dc409356e2608617 /Documentation/memory-barriers.txt | |
parent | c64c4b0f9a183e4c73abff848378afa6edf796c5 (diff) | |
download | linux-f84cfbb0ff269b427a0db591e22ac6948c554ab4.tar.xz |
Documentation/memory-barriers.txt: Fix ACCESS_ONCE thinko
In commit 2ecf810121c7 ("Documentation/memory-barriers.txt: Add
needed ACCESS_ONCE() calls to memory-barriers.txt") the statement
"Q = P" was converted to "ACCESS_ONCE(Q) = P". This should have
been "Q = ACCESS_ONCE(P)". It later became "WRITE_ONCE(Q, P)".
This doesn't match the following text, which is "Q = LOAD P".
Change the statement to be "Q = READ_ONCE(P)".
Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'Documentation/memory-barriers.txt')
-rw-r--r-- | Documentation/memory-barriers.txt | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index aef9487303d0..85304ebd187c 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -194,7 +194,7 @@ There are some minimal guarantees that may be expected of a CPU: (*) On any given CPU, dependent memory accesses will be issued in order, with respect to itself. This means that for: - WRITE_ONCE(Q, P); smp_read_barrier_depends(); D = READ_ONCE(*Q); + Q = READ_ONCE(P); smp_read_barrier_depends(); D = READ_ONCE(*Q); the CPU will issue the following memory operations: @@ -202,9 +202,9 @@ There are some minimal guarantees that may be expected of a CPU: and always in that order. On most systems, smp_read_barrier_depends() does nothing, but it is required for DEC Alpha. The READ_ONCE() - and WRITE_ONCE() are required to prevent compiler mischief. Please - note that you should normally use something like rcu_dereference() - instead of open-coding smp_read_barrier_depends(). + is required to prevent compiler mischief. Please note that you + should normally use something like rcu_dereference() instead of + open-coding smp_read_barrier_depends(). (*) Overlapping loads and stores within a particular CPU will appear to be ordered within that CPU. This means that for: |