From e2f51e290061bb26be18fc2ecb1707dc2ae515b1 Mon Sep 17 00:00:00 2001
From: Matthew Dillon <dillon@dragonflybsd.org>
Date: Wed, 26 May 2004 01:14:36 +0000
Subject: [PATCH] Cleanup cdevsw and dev reference counting ops to fix a
 warning that occurs when a system is halted or rebooted.

---
 sys/dev/disk/vn/vn.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/sys/dev/disk/vn/vn.c b/sys/dev/disk/vn/vn.c
index dd3cd5995b..4ddd919ffb 100644
--- a/sys/dev/disk/vn/vn.c
+++ b/sys/dev/disk/vn/vn.c
@@ -39,7 +39,7 @@
  *
  *	from: @(#)vn.c	8.6 (Berkeley) 4/1/94
  * $FreeBSD: src/sys/dev/vn/vn.c,v 1.105.2.4 2001/11/18 07:11:00 dillon Exp $
- * $DragonFly: src/sys/dev/disk/vn/vn.c,v 1.10 2004/05/19 22:52:42 dillon Exp $
+ * $DragonFly: src/sys/dev/disk/vn/vn.c,v 1.11 2004/05/26 01:14:36 dillon Exp $
  */
 
 /*
@@ -173,6 +173,10 @@ vnclose(dev_t dev, int flags, int mode, struct thread *td)
 	return (0);
 }
 
+/*
+ * Called only when si_drv1 is NULL.  Locate the associated vn node and
+ * attach the device to it.
+ */
 static struct vn_softc *
 vnfindvn(dev_t dev)
 {
@@ -182,10 +186,10 @@ vnfindvn(dev_t dev)
 	unit = dkunit(dev);
 	SLIST_FOREACH(vn, &vn_list, sc_list) {
 		if (vn->sc_unit == unit) {
+			dev->si_drv1 = vn;
 			dev->si_drv2 = vn->sc_devlist;
 			vn->sc_devlist = dev;
 			reference_dev(dev);
-			dev->si_drv1 = vn;
 			break;
 		}
 	}
@@ -195,9 +199,11 @@ vnfindvn(dev_t dev)
 		dev->si_drv1 = vn;
 		vn->sc_devlist = make_dev(&vn_cdevsw, 0, UID_ROOT,
 					GID_OPERATOR, 0640, "vn%d", unit);
-		reference_dev(vn->sc_devlist);
-		vn->sc_devlist->si_drv1 = vn;
-		vn->sc_devlist->si_drv2 = NULL;
+		if (vn->sc_devlist->si_drv1 == NULL) {
+			reference_dev(vn->sc_devlist);
+			vn->sc_devlist->si_drv1 = vn;
+			vn->sc_devlist->si_drv2 = NULL;
+		}
 		if (vn->sc_devlist != dev) {
 			dev->si_drv1 = vn;
 			dev->si_drv2 = vn->sc_devlist;
@@ -774,10 +780,7 @@ vn_modevent(module_t mod, int type, void *data)
 	case MOD_UNLOAD:
 		/* fall through */
 	case MOD_SHUTDOWN:
-		for (;;) {
-			vn = SLIST_FIRST(&vn_list);
-			if (!vn)
-				break;
+		while ((vn = SLIST_FIRST(&vn_list)) != NULL) {
 			SLIST_REMOVE_HEAD(&vn_list, sc_list);
 			if (vn->sc_flags & VNF_INITED)
 				vnclear(vn);
@@ -789,7 +792,7 @@ vn_modevent(module_t mod, int type, void *data)
 			}
 			free(vn, M_DEVBUF);
 		}
-		cdevsw_remove(&vn_cdevsw, -1, 0);
+		cdevsw_remove(&vn_cdevsw, 0, 0);
 		break;
 	default:
 		break;
-- 
2.32.0