[src/trunk]: src/sys/kern vfs(9): Add XXX comment about unclear membar_enter.

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

details:   https://anonhg.NetBSD.org/src/rev/b8af0509e482
branches:  trunk
changeset: 365168:b8af0509e482
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sat Apr 09 23:45:45 2022 +0000

description:
vfs(9): Add XXX comment about unclear membar_enter.

diffstat:

 sys/kern/vfs_vnode.c |  6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diffs (27 lines):

diff -r 8f0730f151ce -r b8af0509e482 sys/kern/vfs_vnode.c
--- a/sys/kern/vfs_vnode.c      Sat Apr 09 23:45:36 2022 +0000
+++ b/sys/kern/vfs_vnode.c      Sat Apr 09 23:45:45 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_vnode.c,v 1.142 2022/04/09 23:38:33 riastradh Exp $        */
+/*     $NetBSD: vfs_vnode.c,v 1.143 2022/04/09 23:45:45 riastradh Exp $        */
 
 /*-
  * Copyright (c) 1997-2011, 2019, 2020 The NetBSD Foundation, Inc.
@@ -148,7 +148,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.142 2022/04/09 23:38:33 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.143 2022/04/09 23:45:45 riastradh Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_pax.h"
@@ -273,6 +273,8 @@
                /*
                 * Prevent predictive loads from the CPU, but check the state
                 * without loooking first.
+                *
+                * XXX what does this pair with?
                 */
                membar_enter();
                if (state == VS_ACTIVE && refcnt > 0 &&