[src/trunk]: src/sys/arch/xen/include xen: Fix sense of xen_rmb/wmb to make s...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c892267a6d86
branches:  trunk
changeset: 373710:c892267a6d86
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sat Feb 25 00:32:26 2023 +0000

description:
xen: Fix sense of xen_rmb/wmb to make sense.

Use membar_acquire and membar_release, not membar_consumer and
membar_producer, out of paranoia -- that better matches Linux's
rmb/wmb (at least for non-I/O loads and stores).

Proposed on port-xen:
https://mail-index.netbsd.org/port-xen/2022/07/13/msg010248.html

diffstat:

 sys/arch/xen/include/hypervisor.h |  6 +++---
 sys/arch/xen/include/xenring.h    |  6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diffs (40 lines):

diff -r ff17715d5fba -r c892267a6d86 sys/arch/xen/include/hypervisor.h
--- a/sys/arch/xen/include/hypervisor.h Sat Feb 25 00:32:13 2023 +0000
+++ b/sys/arch/xen/include/hypervisor.h Sat Feb 25 00:32:26 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: hypervisor.h,v 1.55 2022/09/07 00:40:19 knakahara Exp $        */
+/*     $NetBSD: hypervisor.h,v 1.56 2023/02/25 00:32:26 riastradh Exp $        */
 
 /*
  * Copyright (c) 2006 Manuel Bouyer.
@@ -111,8 +111,8 @@
 #undef xen_wmb
 
 #define xen_mb()  membar_sync()
-#define xen_rmb() membar_producer()
-#define xen_wmb() membar_consumer()
+#define xen_rmb() membar_acquire()
+#define xen_wmb() membar_release()
 #endif /* __XEN_INTERFACE_VERSION */
 
 #include <machine/xen/hypercalls.h>
diff -r ff17715d5fba -r c892267a6d86 sys/arch/xen/include/xenring.h
--- a/sys/arch/xen/include/xenring.h    Sat Feb 25 00:32:13 2023 +0000
+++ b/sys/arch/xen/include/xenring.h    Sat Feb 25 00:32:26 2023 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: xenring.h,v 1.6 2020/04/25 15:26:17 bouyer Exp $ */
+/* $NetBSD: xenring.h,v 1.7 2023/02/25 00:32:26 riastradh Exp $ */
 
 /*
  * Glue goop for xbd ring request/response protocol structures.
@@ -25,8 +25,8 @@
 #undef xen_wmb
 
 #define xen_mb()  membar_sync()
-#define xen_rmb() membar_producer()
-#define xen_wmb() membar_consumer()
+#define xen_rmb() membar_acquire()
+#define xen_wmb() membar_release()
 
 /*
  * Define ring types. These were previously part of the public API.