[src/trunk]: src/sys/kern - Add nsems_total and track the use of all semaphor...

[rmind <rmind%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/2ba77575aa6e
branches:  trunk
changeset: 764330:2ba77575aa6e
user:      rmind <rmind%NetBSD.org@localhost>
date:      Sat Apr 16 20:39:18 2011 +0000

description:
- Add nsems_total and track the use of all semaphores (not only named ones).
  Prevents ksem module from unloading while anonymous semaphore(s) are in use.
- ksem_free: add few asserts.

diffstat:

 sys/kern/uipc_sem.c |  23 ++++++++++++++++++-----
 1 files changed, 18 insertions(+), 5 deletions(-)

diffs (84 lines):

diff -r f36c6a8bc10c -r 2ba77575aa6e sys/kern/uipc_sem.c
--- a/sys/kern/uipc_sem.c       Sat Apr 16 18:41:58 2011 +0000
+++ b/sys/kern/uipc_sem.c       Sat Apr 16 20:39:18 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uipc_sem.c,v 1.33 2011/04/15 00:01:48 rmind Exp $      */
+/*     $NetBSD: uipc_sem.c,v 1.34 2011/04/16 20:39:18 rmind Exp $      */
 
 /*-
  * Copyright (c) 2011 The NetBSD Foundation, Inc.
@@ -60,11 +60,12 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uipc_sem.c,v 1.33 2011/04/15 00:01:48 rmind Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uipc_sem.c,v 1.34 2011/04/16 20:39:18 rmind Exp $");
 
 #include <sys/param.h>
-#include <sys/systm.h>
 #include <sys/kernel.h>
+
+#include <sys/atomic.h>
 #include <sys/proc.h>
 #include <sys/ksem.h>
 #include <sys/syscall.h>
@@ -104,6 +105,7 @@
 
 static kmutex_t                ksem_lock       __cacheline_aligned;
 static LIST_HEAD(,ksem)        ksem_head       __cacheline_aligned;
+static u_int           nsems_total     __cacheline_aligned;
 static u_int           nsems           __cacheline_aligned;
 
 static int             ksem_sysinit(void);
@@ -141,9 +143,10 @@
 {
        int error;
 
-       nsems = 0;
        mutex_init(&ksem_lock, MUTEX_DEFAULT, IPL_NONE);
        LIST_INIT(&ksem_head);
+       nsems_total = 0;
+       nsems = 0;
 
        error = syscall_establish(NULL, ksem_syscalls);
        if (error) {
@@ -162,7 +165,11 @@
                if (error != 0) {
                        return error;
                }
-               if (nsems != 0) {
+               /*
+                * Make sure that no semaphores are in use.  Note: semops
+                * must be unused at this point.
+                */
+               if (nsems_total) {
                        error = syscall_establish(NULL, ksem_syscalls);
                        KASSERT(error == 0);
                        return EBUSY;
@@ -296,6 +303,7 @@
        ks->ks_uid = kauth_cred_geteuid(uc);
        ks->ks_gid = kauth_cred_getegid(uc);
 
+       atomic_inc_uint(&nsems_total);
        *ksret = ks;
        return 0;
 }
@@ -304,6 +312,9 @@
 ksem_free(ksem_t *ks)
 {
 
+       KASSERT(ks->ks_ref == 0);
+       KASSERT(!cv_has_waiters(&ks->ks_cv));
+
        if (ks->ks_name) {
                KASSERT(ks->ks_namelen > 0);
                kmem_free(ks->ks_name, ks->ks_namelen);
@@ -311,6 +322,8 @@
        mutex_destroy(&ks->ks_lock);
        cv_destroy(&ks->ks_cv);
        kmem_free(ks, sizeof(ksem_t));
+
+       atomic_dec_uint(&nsems_total);
 }
 
 int