Module Name: src
Committed By: riastradh
Date: Sat Apr 9 23:46:10 UTC 2022
Modified Files:
src/sys/kern: kern_mutex.c
Log Message:
mutex(9): Convert to membar_acquire/release.
Except for setting the waiters bit -- not sure if this is actually
required to be store-before-load/store. Seems unlikely -- surely
we'd have seen some serious bug by now if not, because membar_enter
has failed to guarantee that on x86! -- but I'm leaving it for now
until I have time to think enough about it to be sure one way or
another.
To generate a diff of this commit:
cvs rdiff -u -r1.98 -r1.99 src/sys/kern/kern_mutex.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/kern_mutex.c
diff -u src/sys/kern/kern_mutex.c:1.98 src/sys/kern/kern_mutex.c:1.99
--- src/sys/kern/kern_mutex.c:1.98 Wed Aug 25 04:13:42 2021
+++ src/sys/kern/kern_mutex.c Sat Apr 9 23:46:10 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_mutex.c,v 1.98 2021/08/25 04:13:42 thorpej Exp $ */
+/* $NetBSD: kern_mutex.c,v 1.99 2022/04/09 23:46:10 riastradh Exp $ */
/*-
* Copyright (c) 2002, 2006, 2007, 2008, 2019 The NetBSD Foundation, Inc.
@@ -40,7 +40,7 @@
#define __MUTEX_PRIVATE
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_mutex.c,v 1.98 2021/08/25 04:13:42 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_mutex.c,v 1.99 2022/04/09 23:46:10 riastradh Exp $");
#include <sys/param.h>
#include <sys/atomic.h>
@@ -169,10 +169,12 @@ do { \
*/
#ifdef __HAVE_ATOMIC_AS_MEMBAR
#define MUTEX_MEMBAR_ENTER()
-#define MUTEX_MEMBAR_EXIT()
+#define MUTEX_MEMBAR_ACQUIRE()
+#define MUTEX_MEMBAR_RELEASE()
#else
#define MUTEX_MEMBAR_ENTER() membar_enter()
-#define MUTEX_MEMBAR_EXIT() membar_exit()
+#define MUTEX_MEMBAR_ACQUIRE() membar_acquire()
+#define MUTEX_MEMBAR_RELEASE() membar_release()
#endif
/*
@@ -238,7 +240,7 @@ MUTEX_ACQUIRE(kmutex_t *mtx, uintptr_t c
MUTEX_INHERITDEBUG(oldown, mtx->mtx_owner);
MUTEX_INHERITDEBUG(newown, oldown);
rv = MUTEX_CAS(&mtx->mtx_owner, oldown, newown);
- MUTEX_MEMBAR_ENTER();
+ MUTEX_MEMBAR_ACQUIRE();
return rv;
}
@@ -256,7 +258,7 @@ MUTEX_RELEASE(kmutex_t *mtx)
{
uintptr_t newown;
- MUTEX_MEMBAR_EXIT();
+ MUTEX_MEMBAR_RELEASE();
newown = 0;
MUTEX_INHERITDEBUG(newown, mtx->mtx_owner);
mtx->mtx_owner = newown;
