Module Name: src
Committed By: pgoyette
Date: Sat Aug 21 13:17:32 UTC 2010
Modified Files:
src/share/man/man9: module.9
src/sys/conf: files
src/sys/kern: init_main.c kern_module.c
src/sys/sys: module.h param.h systm.h
Added Files:
src/sys/kern: kern_cfglock.c
Log Message:
Define a set of new kernel locking primitives to implement the recursive
kernconfig_mutex. Update module subsystem to use this mutex rather than
its own internal (non-recursive) mutex. Make module_autoload() do its
own locking to be consistent with the rest of the module_xxx() calls.
Update module(9) man page appropriately.
As discussed on tech-kern over the last few weeks.
Welcome to NetBSD 5.99.39 !
To generate a diff of this commit:
cvs rdiff -u -r1.17 -r1.18 src/share/man/man9/module.9
cvs rdiff -u -r1.992 -r1.993 src/sys/conf/files
cvs rdiff -u -r1.422 -r1.423 src/sys/kern/init_main.c
cvs rdiff -u -r0 -r1.1 src/sys/kern/kern_cfglock.c
cvs rdiff -u -r1.71 -r1.72 src/sys/kern/kern_module.c
cvs rdiff -u -r1.24 -r1.25 src/sys/sys/module.h
cvs rdiff -u -r1.373 -r1.374 src/sys/sys/param.h
cvs rdiff -u -r1.239 -r1.240 src/sys/sys/systm.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/share/man/man9/module.9
diff -u src/share/man/man9/module.9:1.17 src/share/man/man9/module.9:1.18
--- src/share/man/man9/module.9:1.17 Wed Aug 18 01:56:45 2010
+++ src/share/man/man9/module.9 Sat Aug 21 13:17:32 2010
@@ -1,4 +1,4 @@
-.\" $NetBSD: module.9,v 1.17 2010/08/18 01:56:45 pgoyette Exp $
+.\" $NetBSD: module.9,v 1.18 2010/08/21 13:17:32 pgoyette Exp $
.\"
.\" Copyright (c) 2010 The NetBSD Foundation, Inc.
.\" All rights reserved.
@@ -27,7 +27,7 @@
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.Dd August 17, 2010
+.Dd August XXX, 2010
.Dt MODULE 9
.Os
.Sh NAME
@@ -86,6 +86,8 @@
.Vt modinfo_t
type resides within the module itself, and contains module header info.
.El
+.Pp
+The module subsystem is protected by the global kernconfig_mutex.
.Sh FUNCTIONS
.Bl -tag -width abcd
.It Fn MODULE "class" "name" "required"
@@ -362,21 +364,37 @@
Until this routine is called, modules can only be loaded if they were
built-in to the kernel image or provided by the boot loader.
.El
-.Sh LOCK PROTOCOL
-The
-.Nm
-subsystem is protected with the global
-.Vt module_mutex .
-This
-.Xr mutex 9
-must be acquired before calling any of these routines.
-As an exception, the
+.Sh PROGRAMMING CONSIDERATIONS
+The module subsystem is designed to be called recursively, but only within
+a single lwp.
+This permits one module's
+.Fn modcmd
+routine to load or unload other modules.
+.Pp
+A module is not permitted to load or unload itself.
+Attempts to load or unload a module from within its own
+.Fn modcmd
+routine will fail with
+.Er EEXIST
+or
+.Er EBUSY
+respectively.
+.Pp
+Although a module can be loaded by either
.Fn module_load
-routine acquires the mutex itself, so one does not need to acquire it
-before calling
-.Fn module_load .
-Loading of a module and its required modules occurs as an atomic
-operation, and either completely succeeds or completely fails.
+or
+.Fn module_autoload
+it is not possible for the module's
+.Fn modcmd
+routine to distinguish between the two methods.
+Any module which needs to ensure that it does not get auto-unloaded must
+either handle the
+.Dv MODULE_CMD_AUTOUNLOAD
+command in its
+.Fn modcmd
+routine, or use
+.Fn module_hold
+to increment its reference count.
.Sh CODE REFERENCES
This section describes places within the
.Nx
Index: src/sys/conf/files
diff -u src/sys/conf/files:1.992 src/sys/conf/files:1.993
--- src/sys/conf/files:1.992 Wed Jul 7 01:09:39 2010
+++ src/sys/conf/files Sat Aug 21 13:17:32 2010
@@ -1,4 +1,4 @@
-# $NetBSD: files,v 1.992 2010/07/07 01:09:39 chs Exp $
+# $NetBSD: files,v 1.993 2010/08/21 13:17:32 pgoyette Exp $
# @(#)files.newconf 7.5 (Berkeley) 5/10/93
version 20100430
@@ -1434,6 +1434,7 @@
file kern/init_sysent.c
file kern/kern_acct.c
file kern/kern_auth.c
+file kern/kern_cfglock.c
file kern/kern_clock.c
file kern/kern_condvar.c
file kern/kern_core.c coredump
Index: src/sys/kern/init_main.c
diff -u src/sys/kern/init_main.c:1.422 src/sys/kern/init_main.c:1.423
--- src/sys/kern/init_main.c:1.422 Sat Jun 26 07:23:57 2010
+++ src/sys/kern/init_main.c Sat Aug 21 13:17:31 2010
@@ -1,4 +1,4 @@
-/* $NetBSD: init_main.c,v 1.422 2010/06/26 07:23:57 pgoyette Exp $ */
+/* $NetBSD: init_main.c,v 1.423 2010/08/21 13:17:31 pgoyette Exp $ */
/*-
* Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
@@ -97,7 +97,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: init_main.c,v 1.422 2010/06/26 07:23:57 pgoyette Exp $");
+__KERNEL_RCSID(0, "$NetBSD: init_main.c,v 1.423 2010/08/21 13:17:31 pgoyette Exp $");
#include "opt_ddb.h"
#include "opt_ipsec.h"
@@ -303,6 +303,7 @@
kernel_lock_init();
once_init();
mutex_init(&cpu_lock, MUTEX_DEFAULT, IPL_NONE);
+ kernconfig_lock_init();
/* Initialize the device switch tables. */
devsw_init();
Index: src/sys/kern/kern_module.c
diff -u src/sys/kern/kern_module.c:1.71 src/sys/kern/kern_module.c:1.72
--- src/sys/kern/kern_module.c:1.71 Wed Aug 11 12:04:49 2010
+++ src/sys/kern/kern_module.c Sat Aug 21 13:17:31 2010
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_module.c,v 1.71 2010/08/11 12:04:49 pgoyette Exp $ */
+/* $NetBSD: kern_module.c,v 1.72 2010/08/21 13:17:31 pgoyette Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -34,7 +34,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_module.c,v 1.71 2010/08/11 12:04:49 pgoyette Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_module.c,v 1.72 2010/08/21 13:17:31 pgoyette Exp $");
#define _MODULE_INTERNAL
@@ -72,7 +72,6 @@
static int module_autoload_on = 1;
u_int module_count;
u_int module_builtinlist;
-kmutex_t module_lock;
u_int module_autotime = 10;
u_int module_gen = 1;
static kcondvar_t module_thread_cv;
@@ -223,7 +222,7 @@
modp[i] = module_newmodule(MODULE_SOURCE_KERNEL);
modp[i]->mod_info = mip[i+mipskip];
}
- mutex_enter(&module_lock);
+ kernconfig_lock();
/* do this in three stages for error recovery and atomicity */
@@ -263,7 +262,7 @@
}
out:
- mutex_exit(&module_lock);
+ kernconfig_unlock();
if (rv != 0) {
for (i = 0; i < nmodinfo; i++) {
if (modp[i])
@@ -291,13 +290,13 @@
if (rv)
return rv;
- mutex_enter(&module_lock);
+ kernconfig_lock();
rv = module_do_unload(mi->mi_name, true);
if (rv) {
goto out;
}
} else {
- mutex_enter(&module_lock);
+ kernconfig_lock();
}
TAILQ_FOREACH(mod, &module_builtins, mod_chain) {
if (strcmp(mod->mod_info->mi_name, mi->mi_name) == 0)
@@ -312,7 +311,7 @@
}
out:
- mutex_exit(&module_lock);
+ kernconfig_unlock();
return rv;
}
@@ -332,7 +331,6 @@
if (module_map == NULL) {
module_map = kernel_map;
}
- mutex_init(&module_lock, MUTEX_DEFAULT, IPL_NONE);
cv_init(&module_thread_cv, "mod_unld");
mutex_init(&module_thread_lock, MUTEX_DEFAULT, IPL_NONE);
@@ -388,11 +386,11 @@
{
module_t *mod;
- mutex_enter(&module_lock);
+ kernconfig_lock();
TAILQ_FOREACH(mod, &module_builtins, mod_chain) {
module_require_force(mod);
}
- mutex_exit(&module_lock);
+ kernconfig_unlock();
}
static struct sysctllog *module_sysctllog;
@@ -444,7 +442,7 @@
module_t *mod;
modinfo_t *mi;
- mutex_enter(&module_lock);
+ kernconfig_lock();
/*
* Builtins first. These will not depend on pre-loaded modules
* (because the kernel would not link).
@@ -493,7 +491,7 @@
TAILQ_INSERT_TAIL(&module_builtins, mod, mod_chain);
}
- mutex_exit(&module_lock);
+ kernconfig_unlock();
}
/*
@@ -534,10 +532,10 @@
return error;
}
- mutex_enter(&module_lock);
+ kernconfig_lock();
error = module_do_load(filename, false, flags, props, NULL, class,
false);
- mutex_exit(&module_lock);
+ kernconfig_unlock();
return error;
}
@@ -552,27 +550,31 @@
{
int error;
- KASSERT(mutex_owned(&module_lock));
+ kernconfig_lock();
/* Nothing if the user has disabled it. */
if (!module_autoload_on) {
+ kernconfig_unlock();
return EPERM;
}
/* Disallow path separators and magic symlinks. */
if (strchr(filename, '/') != NULL || strchr(filename, '@') != NULL ||
strchr(filename, '.') != NULL) {
+ kernconfig_unlock();
return EPERM;
}
/* Authorize. */
error = kauth_authorize_system(kauth_cred_get(), KAUTH_SYSTEM_MODULE,
0, (void *)(uintptr_t)MODCTL_LOAD, (void *)(uintptr_t)1, NULL);
- if (error != 0) {
- return error;
- }
- return module_do_load(filename, false, 0, NULL, NULL, class, true);
+ if (error == 0)
+ error = module_do_load(filename, false, 0, NULL, NULL, class,
+ true);
+
+ kernconfig_unlock();
+ return error;
}
/*
@@ -592,9 +594,9 @@
return error;
}
- mutex_enter(&module_lock);
+ kernconfig_lock();
error = module_do_unload(name, true);
- mutex_exit(&module_lock);
+ kernconfig_unlock();
return error;
}
@@ -609,7 +611,7 @@
{
module_t *mod;
- KASSERT(mutex_owned(&module_lock));
+ KASSERT(kernconfig_is_held());
TAILQ_FOREACH(mod, &module_list, mod_chain) {
if (strcmp(mod->mod_info->mi_name, name) == 0) {
@@ -632,14 +634,14 @@
{
module_t *mod;
- mutex_enter(&module_lock);
+ kernconfig_lock();
mod = module_lookup(name);
if (mod == NULL) {
- mutex_exit(&module_lock);
+ kernconfig_unlock();
return ENOENT;
}
mod->mod_refcnt++;
- mutex_exit(&module_lock);
+ kernconfig_unlock();
return 0;
}
@@ -654,14 +656,14 @@
{
module_t *mod;
- mutex_enter(&module_lock);
+ kernconfig_lock();
mod = module_lookup(name);
if (mod == NULL) {
- mutex_exit(&module_lock);
+ kernconfig_unlock();
panic("module_rele: gone");
}
mod->mod_refcnt--;
- mutex_exit(&module_lock);
+ kernconfig_unlock();
}
/*
@@ -674,7 +676,7 @@
{
int i;
- KASSERT(mutex_owned(&module_lock));
+ KASSERT(kernconfig_is_held());
/*
* If there are requisite modules, put at the head of the queue.
@@ -708,11 +710,11 @@
const char *p, *s;
char buf[MAXMODNAME];
modinfo_t *mi = NULL;
- module_t *mod, *mod2, *mod_loaded;
+ module_t *mod, *mod2, *mod_loaded, *prev_active;
size_t len;
int error;
- KASSERT(mutex_owned(&module_lock));
+ KASSERT(kernconfig_is_held());
/*
* Search the list to see if we have a module by this name.
@@ -775,10 +777,10 @@
/*
* Try to initialize the module.
*/
- KASSERT(module_active == NULL);
+ prev_active = module_active;
module_active = mod;
error = (*mi->mi_modcmd)(MODULE_CMD_INIT, NULL);
- module_active = NULL;
+ module_active = prev_active;
if (error != 0) {
module_error("builtin module `%s' "
"failed to init", mi->mi_name);
@@ -809,18 +811,22 @@
prop_dictionary_t props, module_t **modp, modclass_t class,
bool autoload)
{
- static TAILQ_HEAD(,module) pending = TAILQ_HEAD_INITIALIZER(pending);
- static int depth;
- const int maxdepth = 6;
+#define MODULE_MAX_DEPTH 6
+
+ TAILQ_HEAD(pending_t, module);
+ static int depth = 0;
+ static struct pending_t *pending_lists[MODULE_MAX_DEPTH];
+ struct pending_t *pending;
+ struct pending_t new_pending = TAILQ_HEAD_INITIALIZER(new_pending);
modinfo_t *mi;
- module_t *mod, *mod2;
+ module_t *mod, *mod2, *prev_active;
prop_dictionary_t filedict;
char buf[MAXMODNAME];
const char *s, *p;
int error;
size_t len;
- KASSERT(mutex_owned(&module_lock));
+ KASSERT(kernconfig_is_held());
filedict = NULL;
error = 0;
@@ -828,13 +834,26 @@
/*
* Avoid recursing too far.
*/
- if (++depth > maxdepth) {
- module_error("too many required modules");
+ if (++depth > MODULE_MAX_DEPTH) {
+ module_error("recursion too deep");
depth--;
return EMLINK;
}
/*
+ * Set up the pending list for this depth. If this is a
+ * recursive entry, then use same list as for outer call,
+ * else use the locally allocated list. In either case,
+ * remember which one we're using.
+ */
+ if (isdep) {
+ KASSERT(depth > 1);
+ pending = pending_lists[depth - 2];
+ } else
+ pending = &new_pending;
+ pending_lists[depth - 1] = pending;
+
+ /*
* Search the list of disabled builtins first.
*/
TAILQ_FOREACH(mod, &module_builtins, mod_chain) {
@@ -869,18 +888,14 @@
}
}
if (mod != NULL) {
- TAILQ_INSERT_TAIL(&pending, mod, mod_chain);
+ TAILQ_INSERT_TAIL(pending, mod, mod_chain);
} else {
/*
* If a requisite module, check to see if it is
* already present.
*/
if (isdep) {
- TAILQ_FOREACH(mod, &module_list, mod_chain) {
- if (strcmp(mod->mod_info->mi_name, name) == 0) {
- break;
- }
- }
+ mod = module_lookup(name);
if (mod != NULL) {
if (modp != NULL) {
*modp = mod;
@@ -903,7 +918,7 @@
depth--;
return error;
}
- TAILQ_INSERT_TAIL(&pending, mod, mod_chain);
+ TAILQ_INSERT_TAIL(pending, mod, mod_chain);
error = module_fetch_info(mod);
if (error != 0) {
@@ -971,7 +986,7 @@
/*
* Block circular dependencies.
*/
- TAILQ_FOREACH(mod2, &pending, mod_chain) {
+ TAILQ_FOREACH(mod2, pending, mod_chain) {
if (mod == mod2) {
continue;
}
@@ -1041,10 +1056,10 @@
goto fail;
}
}
- KASSERT(module_active == NULL);
+ prev_active = module_active;
module_active = mod;
error = (*mi->mi_modcmd)(MODULE_CMD_INIT, filedict ? filedict : props);
- module_active = NULL;
+ module_active = prev_active;
if (filedict) {
prop_object_release(filedict);
filedict = NULL;
@@ -1062,7 +1077,7 @@
* Good, the module loaded successfully. Put it onto the
* list and add references to its requisite modules.
*/
- TAILQ_REMOVE(&pending, mod, mod_chain);
+ TAILQ_REMOVE(pending, mod, mod_chain);
module_enqueue(mod);
if (modp != NULL) {
*modp = mod;
@@ -1085,7 +1100,7 @@
prop_object_release(filedict);
filedict = NULL;
}
- TAILQ_REMOVE(&pending, mod, mod_chain);
+ TAILQ_REMOVE(pending, mod, mod_chain);
kmem_free(mod, sizeof(*mod));
depth--;
return error;
@@ -1099,11 +1114,11 @@
static int
module_do_unload(const char *name, bool load_requires_force)
{
- module_t *mod;
+ module_t *mod, *prev_active;
int error;
u_int i;
- KASSERT(mutex_owned(&module_lock));
+ KASSERT(kernconfig_is_held());
mod = module_lookup(name);
if (mod == NULL) {
@@ -1114,10 +1129,10 @@
module_print("module `%s' busy", name);
return EBUSY;
}
- KASSERT(module_active == NULL);
+ prev_active = module_active;
module_active = mod;
error = (*mod->mod_info->mi_modcmd)(MODULE_CMD_FINI, NULL);
- module_active = NULL;
+ module_active = prev_active;
if (error != 0) {
module_print("cannot unload module `%s' error=%d", name,
error);
@@ -1223,7 +1238,7 @@
module_find_section(const char *name, void **addr, size_t *size)
{
- KASSERT(mutex_owned(&module_lock));
+ KASSERT(kernconfig_is_held());
KASSERT(module_active != NULL);
return kobj_find_section(module_active->mod_kobj, name, addr, size);
@@ -1244,7 +1259,7 @@
int error;
for (;;) {
- mutex_enter(&module_lock);
+ kernconfig_lock();
for (mod = TAILQ_FIRST(&module_list); mod != NULL; mod = next) {
next = TAILQ_NEXT(mod, mod_chain);
if (mod->mod_source == MODULE_SOURCE_KERNEL)
@@ -1271,7 +1286,7 @@
(void)module_do_unload(mi->mi_name, false);
}
}
- mutex_exit(&module_lock);
+ kernconfig_unlock();
mutex_enter(&module_thread_lock);
(void)cv_timedwait(&module_thread_cv, &module_thread_lock,
Index: src/sys/sys/module.h
diff -u src/sys/sys/module.h:1.24 src/sys/sys/module.h:1.25
--- src/sys/sys/module.h:1.24 Sat Jun 26 07:23:57 2010
+++ src/sys/sys/module.h Sat Aug 21 13:17:32 2010
@@ -1,4 +1,4 @@
-/* $NetBSD: module.h,v 1.24 2010/06/26 07:23:57 pgoyette Exp $ */
+/* $NetBSD: module.h,v 1.25 2010/08/21 13:17:32 pgoyette Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -115,7 +115,6 @@
TAILQ_HEAD(modlist, module);
extern struct vm_map *module_map;
-extern kmutex_t module_lock;
extern u_int module_count;
extern u_int module_builtinlist;
extern struct modlist module_list;
Index: src/sys/sys/param.h
diff -u src/sys/sys/param.h:1.373 src/sys/sys/param.h:1.374
--- src/sys/sys/param.h:1.373 Wed Jul 28 11:03:47 2010
+++ src/sys/sys/param.h Sat Aug 21 13:17:32 2010
@@ -1,4 +1,4 @@
-/* $NetBSD: param.h,v 1.373 2010/07/28 11:03:47 hannken Exp $ */
+/* $NetBSD: param.h,v 1.374 2010/08/21 13:17:32 pgoyette Exp $ */
/*-
* Copyright (c) 1982, 1986, 1989, 1993
@@ -63,7 +63,7 @@
* 2.99.9 (299000900)
*/
-#define __NetBSD_Version__ 599003800 /* NetBSD 5.99.38 */
+#define __NetBSD_Version__ 599003900 /* NetBSD 5.99.39 */
#define __NetBSD_Prereq__(M,m,p) (((((M) * 100000000) + \
(m) * 1000000) + (p) * 100) <= __NetBSD_Version__)
Index: src/sys/sys/systm.h
diff -u src/sys/sys/systm.h:1.239 src/sys/sys/systm.h:1.240
--- src/sys/sys/systm.h:1.239 Sun Jan 31 02:04:43 2010
+++ src/sys/sys/systm.h Sat Aug 21 13:17:32 2010
@@ -1,4 +1,4 @@
-/* $NetBSD: systm.h,v 1.239 2010/01/31 02:04:43 pooka Exp $ */
+/* $NetBSD: systm.h,v 1.240 2010/08/21 13:17:32 pgoyette Exp $ */
/*-
* Copyright (c) 1982, 1988, 1991, 1993
@@ -492,6 +492,11 @@
void _kernel_lock(int);
void _kernel_unlock(int, int *);
+void kernconfig_lock_init(void);
+void kernconfig_lock(void);
+void kernconfig_unlock(void);
+bool kernconfig_is_held(void);
+
#if defined(MULTIPROCESSOR) || defined(_MODULE)
#define KERNEL_LOCK(count, lwp) \
do { \
Added files:
Index: src/sys/kern/kern_cfglock.c
diff -u /dev/null src/sys/kern/kern_cfglock.c:1.1
--- /dev/null Sat Aug 21 13:17:33 2010
+++ src/sys/kern/kern_cfglock.c Sat Aug 21 13:17:31 2010
@@ -0,0 +1,101 @@
+/* $NetBSD: kern_cfglock.c,v 1.1 2010/08/21 13:17:31 pgoyette Exp $ */
+
+/*-
+ * Copyright (c) 2002, 2006, 2007, 2008, 2009 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
+ * NASA Ames Research Center, and by Andrew Doran.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__KERNEL_RCSID(0, "$NetBSD: kern_cfglock.c,v 1.1 2010/08/21 13:17:31 pgoyette Exp $");
+
+#include <sys/param.h>
+#include <sys/cpu.h>
+#include <sys/mutex.h>
+#include <sys/lwp.h>
+#include <sys/systm.h>
+
+static kmutex_t kernconfig_mutex;
+static lwp_t *kernconfig_lwp;
+static int kernconfig_recurse;
+
+/*
+ * Functions for manipulating the kernel configuration lock. This
+ * recursive lock should be used to protect all additions and removals
+ * of kernel functionality, such as device configuration and loading
+ * of modular kernel components.
+ */
+
+void
+kernconfig_lock_init(void)
+{
+
+ mutex_init(&kernconfig_mutex, MUTEX_DEFAULT, IPL_NONE);
+ kernconfig_lwp = NULL;
+ kernconfig_recurse = 0;
+}
+
+void
+kernconfig_lock(void)
+{
+ lwp_t *my_lwp;
+
+ /*
+ * It's OK to check this unlocked, since it could only be set to
+ * curlwp by the current thread itself, and not by an interrupt
+ * or any other LWP.
+ */
+ KASSERT(!cpu_intr_p());
+ my_lwp = curlwp;
+ if (kernconfig_lwp == my_lwp) {
+ kernconfig_recurse++;
+ KASSERT(kernconfig_recurse > 1);
+ } else {
+ mutex_enter(&kernconfig_mutex);
+ kernconfig_lwp = my_lwp;
+ kernconfig_recurse = 1;
+ }
+}
+
+void
+kernconfig_unlock(void)
+{
+
+ KASSERT(kernconfig_is_held());
+ KASSERT(kernconfig_recurse != 0);
+ if (--kernconfig_recurse == 0) {
+ kernconfig_lwp = NULL;
+ mutex_exit(&kernconfig_mutex);
+ }
+}
+
+bool
+kernconfig_is_held(void)
+{
+
+ return mutex_owned(&kernconfig_mutex);
+}
