Module Name: src
Committed By: riastradh
Date: Sun Feb 13 19:20:33 UTC 2022
Modified Files:
src/sys/kern: subr_thmap.c
Log Message:
thmap(9): Omit needless fences and use membar_exit for release fence.
It is the caller's responsibility to arrange that thmap_create, and,
if THMAP_SETROOT is set, thmap_root, happen before any use of the
thmap. No need for them to issue fences internally.
To generate a diff of this commit:
cvs rdiff -u -r1.9 -r1.10 src/sys/kern/subr_thmap.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/subr_thmap.c
diff -u src/sys/kern/subr_thmap.c:1.9 src/sys/kern/subr_thmap.c:1.10
--- src/sys/kern/subr_thmap.c:1.9 Tue Feb 8 12:59:16 2022
+++ src/sys/kern/subr_thmap.c Sun Feb 13 19:20:33 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: subr_thmap.c,v 1.9 2022/02/08 12:59:16 riastradh Exp $ */
+/* $NetBSD: subr_thmap.c,v 1.10 2022/02/13 19:20:33 riastradh Exp $ */
/*-
* Copyright (c) 2018 Mindaugas Rasiukevicius <rmind at noxt eu>
@@ -112,7 +112,7 @@
#include "utils.h"
#endif
-THMAP_RCSID("$NetBSD: subr_thmap.c,v 1.9 2022/02/08 12:59:16 riastradh Exp $");
+THMAP_RCSID("$NetBSD: subr_thmap.c,v 1.10 2022/02/13 19:20:33 riastradh Exp $");
#include <crypto/blake2/blake2s.h>
@@ -121,7 +121,7 @@ THMAP_RCSID("$NetBSD: subr_thmap.c,v 1.9
*/
#ifdef _KERNEL
#define ASSERT KASSERT
-#define atomic_thread_fence(x) membar_sync()
+#define atomic_thread_fence(x) membar_exit() /* only used for release order */
#define atomic_compare_exchange_weak_explicit_32(p, e, n, m1, m2) \
(atomic_cas_32((p), *(e), (n)) == *(e))
#define atomic_compare_exchange_weak_explicit_ptr(p, e, n, m1, m2) \
@@ -986,7 +986,6 @@ thmap_create(uintptr_t baseptr, const th
return NULL;
}
memset(thmap->root, 0, THMAP_ROOT_LEN);
- atomic_thread_fence(memory_order_release); /* XXX */
}
cprng_strong(kern_cprng, thmap->seed, sizeof thmap->seed, 0);
@@ -1001,7 +1000,6 @@ thmap_setroot(thmap_t *thmap, uintptr_t
return -1;
}
thmap->root = THMAP_GETPTR(thmap, root_off);
- atomic_thread_fence(memory_order_release); /* XXX */
return 0;
}
