Module Name: src
Committed By: riastradh
Date: Sun Feb 13 14:06:51 UTC 2022
Modified Files:
src/sys/arch/hppa/include: lock.h
Log Message:
hppa: __cpu_simple_lock membar audit.
ok skrll
To generate a diff of this commit:
cvs rdiff -u -r1.23 -r1.24 src/sys/arch/hppa/include/lock.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/hppa/include/lock.h
diff -u src/sys/arch/hppa/include/lock.h:1.23 src/sys/arch/hppa/include/lock.h:1.24
--- src/sys/arch/hppa/include/lock.h:1.23 Sat Feb 12 17:17:53 2022
+++ src/sys/arch/hppa/include/lock.h Sun Feb 13 14:06:51 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: lock.h,v 1.23 2022/02/12 17:17:53 riastradh Exp $ */
+/* $NetBSD: lock.h,v 1.24 2022/02/13 14:06:51 riastradh Exp $ */
/*-
* Copyright (c) 1998, 1999, 2000, 2001 The NetBSD Foundation, Inc.
@@ -91,6 +91,25 @@ __cpu_simple_lock_init(__cpu_simple_lock
__SIMPLELOCK_RAW_UNLOCKED;
}
+static __inline int
+__cpu_simple_lock_try(__cpu_simple_lock_t *alp)
+{
+ volatile unsigned long *__aptr = __SIMPLELOCK_ALIGN(alp);
+
+ if (__ldcw(__aptr) == __SIMPLELOCK_RAW_LOCKED)
+ return 0;
+
+ /*
+ * __cpu_simple_lock_try must be a load-acquire operation, but
+ * HPPA's LDCW does not appear to guarantee load-acquire
+ * semantics, so we have to do LDCW and then an explicit SYNC
+ * to make a load-acquire operation that pairs with a preceding
+ * store-release in __cpu_simple_unlock.
+ */
+ __sync();
+ return 1;
+}
+
static __inline void
__cpu_simple_lock(__cpu_simple_lock_t *alp)
{
@@ -103,24 +122,20 @@ __cpu_simple_lock(__cpu_simple_lock_t *a
* some work.
*/
- while (__ldcw(__aptr) == __SIMPLELOCK_RAW_LOCKED)
+ while (!__cpu_simple_lock_try(alp))
while (*__aptr == __SIMPLELOCK_RAW_LOCKED)
;
}
-static __inline int
-__cpu_simple_lock_try(__cpu_simple_lock_t *alp)
-{
- volatile unsigned long *__aptr = __SIMPLELOCK_ALIGN(alp);
-
- return (__ldcw(__aptr) != __SIMPLELOCK_RAW_LOCKED);
-}
-
static __inline void
__cpu_simple_unlock(__cpu_simple_lock_t *alp)
{
volatile unsigned long *__aptr = __SIMPLELOCK_ALIGN(alp);
+ /*
+ * SYNC and then store makes a store-release that pairs with
+ * the load-acquire in a subsequent __cpu_simple_lock_try.
+ */
__sync();
*__aptr = __SIMPLELOCK_RAW_UNLOCKED;
}
