[src/trunk]: src/sys/arch/mips/include mips: Redefine LLSCSYNC as empty on no...

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

details:   https://anonhg.NetBSD.org/src/rev/14b2f76e7abe
branches:  trunk
changeset: 362457:14b2f76e7abe
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sun Feb 27 19:22:20 2022 +0000

description:
mips: Redefine LLSCSYNC as empty on non-Octeon MP.

This change deletes memory barriers on non-Octeon MP.  However, all
the appropriate acquire and release barriers are already used in
mutex stubs, and no barriers are needed in atomic_* unless we set
__HAVE_ATOMIC_AS_MEMBAR which we don't on MIPS.  So this should be
safe.

Unclear whether we need this even on Octeon -- don't have a clear
reference on why it's here.

diffstat:

 sys/arch/mips/include/asm.h |  4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diffs (18 lines):

diff -r 1b391c129697 -r 14b2f76e7abe sys/arch/mips/include/asm.h
--- a/sys/arch/mips/include/asm.h       Sun Feb 27 19:22:12 2022 +0000
+++ b/sys/arch/mips/include/asm.h       Sun Feb 27 19:22:20 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: asm.h,v 1.68 2022/02/27 19:22:12 riastradh Exp $       */
+/*     $NetBSD: asm.h,v 1.69 2022/02/27 19:22:20 riastradh Exp $       */
 
 /*
  * Copyright (c) 1992, 1993
@@ -581,7 +581,7 @@
 #define        BDSYNC_PLUNGER  sync 4
 #define        SYNC_PLUNGER    sync 4
 #elif __mips >= 3 || !defined(__mips_o32)
-#define        LLSCSYNC        sync
+#define        LLSCSYNC        /* nothing */
 #define        BDSYNC          sync
 #define        BDSYNC_ACQ      sync
 #define        SYNC_ACQ        sync