Our current documentation claims that, when followed by an ACQUIRE,
smp_mb__before_spinlock() orders prior loads against subsequent loads
and stores, which isn't actually true.
Fix the documentation to state that this sequence orders only prior
stores against subsequent loads and stores.
Cc: Oleg Nesterov <o...@redhat.com>
Cc: "Paul E. McKenney" <paul...@linux.vnet.ibm.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Signed-off-by: Will Deacon <will.dea...@arm.com>
---
Could somebody pick this up please? I guess I could route it via the arm64
tree with an Ack, but I'd rather it went through Paul or -tip.
Documentation/memory-barriers.txt | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/Documentation/memory-barriers.txt
b/Documentation/memory-barriers.txt
index ca2387ef27ab..fa28a0c1e2b1 100644
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -1768,10 +1768,9 @@ for each construct. These operations all imply certain
barriers:
Memory operations issued before the ACQUIRE may be completed after
the ACQUIRE operation has completed. An smp_mb__before_spinlock(),
- combined with a following ACQUIRE, orders prior loads against
- subsequent loads and stores and also orders prior stores against
- subsequent stores. Note that this is weaker than smp_mb()! The
- smp_mb__before_spinlock() primitive is free on many architectures.
+ combined with a following ACQUIRE, orders prior stores against
+ subsequent loads and stores. Note that this is weaker than smp_mb()!
+ The smp_mb__before_spinlock() primitive is free on many architectures.
(2) RELEASE operation implication:
--
2.1.4
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