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From: Edward Tomasz Napierala <trasz@FreeBSD.org>
Date: Fri, 6 Feb 2009 18:16:01 +0000 (UTC)
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Subject: svn commit: r188243 - in head/sys: kern sys
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Author: trasz
Date: Fri Feb  6 18:16:01 2009
New Revision: 188243
URL: http://svn.freebsd.org/changeset/base/188243

Log:
  Add KASSERTs to make it easier to debug problems like the one fixed
  in r188141.
  
  Reviewed by:	kib,attilio
  Approved by:	rwatson (mentor)
  Tested by:	pho
  Sponsored by:	FreeBSD Foundation

Modified:
  head/sys/kern/vfs_subr.c
  head/sys/sys/mount.h

Modified: head/sys/kern/vfs_subr.c
==============================================================================
--- head/sys/kern/vfs_subr.c	Fri Feb  6 17:21:41 2009	(r188242)
+++ head/sys/kern/vfs_subr.c	Fri Feb  6 18:16:01 2009	(r188243)
@@ -381,6 +381,7 @@ vfs_unbusy(struct mount *mp)
 	CTR2(KTR_VFS, "%s: mp %p", __func__, mp);
 	MNT_ILOCK(mp);
 	MNT_REL(mp);
+	KASSERT(mp->mnt_lockref > 0, ("negative mnt_lockref"));
 	mp->mnt_lockref--;
 	if (mp->mnt_lockref == 0 && (mp->mnt_kern_flag & MNTK_DRAINING) != 0) {
 		MPASS(mp->mnt_kern_flag & MNTK_UNMOUNT);

Modified: head/sys/sys/mount.h
==============================================================================
--- head/sys/sys/mount.h	Fri Feb  6 17:21:41 2009	(r188242)
+++ head/sys/sys/mount.h	Fri Feb  6 18:16:01 2009	(r188243)
@@ -206,6 +206,7 @@ void          __mnt_vnode_markerfree(str
 #define	MNT_MTX(mp)	(&(mp)->mnt_mtx)
 #define	MNT_REF(mp)	(mp)->mnt_ref++
 #define	MNT_REL(mp)	do {						\
+	KASSERT((mp)->mnt_ref > 0, ("negative mnt_ref"));			\
 	(mp)->mnt_ref--;						\
 	if ((mp)->mnt_ref == 0)						\
 		wakeup((mp));						\