Module Name: src
Committed By: riastradh
Date: Mon Jul 29 02:34:27 UTC 2024
Modified Files:
src/sys/net: if_wg.c
Log Message:
wg(4): Fix memory ordering in detach.
PR kern/58510: experimental wg(4) lacks memory ordering between
wg_count_dec and module unload
To generate a diff of this commit:
cvs rdiff -u -r1.117 -r1.118 src/sys/net/if_wg.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/net/if_wg.c
diff -u src/sys/net/if_wg.c:1.117 src/sys/net/if_wg.c:1.118
--- src/sys/net/if_wg.c:1.117 Mon Jul 29 02:33:58 2024
+++ src/sys/net/if_wg.c Mon Jul 29 02:34:27 2024
@@ -1,4 +1,4 @@
-/* $NetBSD: if_wg.c,v 1.117 2024/07/29 02:33:58 riastradh Exp $ */
+/* $NetBSD: if_wg.c,v 1.118 2024/07/29 02:34:27 riastradh Exp $ */
/*
* Copyright (C) Ryota Ozaki <[email protected]>
@@ -41,7 +41,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_wg.c,v 1.117 2024/07/29 02:33:58 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_wg.c,v 1.118 2024/07/29 02:34:27 riastradh Exp $");
#ifdef _KERNEL_OPT
#include "opt_altq_enabled.h"
@@ -923,6 +923,7 @@ wg_count_dec(void)
{
unsigned c __diagused;
+ membar_release(); /* match atomic_load_acquire in wgdetach */
c = atomic_dec_uint_nv(&wg_count);
KASSERT(c != UINT_MAX);
}
@@ -934,8 +935,11 @@ wgdetach(void)
/* Prevent new interface creation. */
if_clone_detach(&wg_cloner);
- /* Check whether there are any existing interfaces. */
- if (atomic_load_relaxed(&wg_count)) {
+ /*
+ * Check whether there are any existing interfaces. Matches
+ * membar_release and atomic_dec_uint_nv in wg_count_dec.
+ */
+ if (atomic_load_acquire(&wg_count)) {
/* Back out -- reattach the cloner. */
if_clone_attach(&wg_cloner);
return EBUSY;
