[tip:locking/core] locking/x86: Tweak the comment about use of wmb() for IO

[tip-bot for Michael S. Tsirkin]

Commit-ID:  57d9b1b43433a6ba7267c80b87d8e8f6e86edceb
Gitweb:     http://git.kernel.org/tip/57d9b1b43433a6ba7267c80b87d8e8f6e86edceb
Author:     Michael S. Tsirkin <mst@xxxxxxxxxx>
AuthorDate: Thu, 28 Jan 2016 19:02:44 +0200
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 29 Jan 2016 09:40:10 +0100

locking/x86: Tweak the comment about use of wmb() for IO

On x86, we *do* still use the non-NOP rmb()/wmb() for IO barriers,
but even that is generally questionable.

Leave them around as historial unless somebody can point to a
case where they care about the performance, but tweak the
comment so people don't think they are strictly required in all
cases.

Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: virtualization <virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1453921746-16178-4-git-send-email-mst@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/include/asm/barrier.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
index a291745..bfb28ca 100644
--- a/arch/x86/include/asm/barrier.h
+++ b/arch/x86/include/asm/barrier.h
@@ -6,7 +6,7 @@
 
 /*
  * Force strict CPU ordering.
- * And yes, this is required on UP too when we're talking
+ * And yes, this might be required on UP too when we're talking
  * to devices.
  */