Date: Sat, 27 Nov 1999 15:14:34 +0100 (CET) From: assar@stacken.kth.se To: FreeBSD-gnats-submit@freebsd.org Cc: assar@stacken.kth.se Subject: kern/15117: vclean calls vrele leading to deadlock (if usecount > 0) Message-ID: <199911271414.PAA00823@mulet.e.kth.se>
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>Number: 15117
>Category: kern
>Synopsis: vclean calls vrele leading to deadlock (if usecount > 0)
>Confidential: no
>Severity: critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Sat Nov 27 06:20:00 PST 1999
>Closed-Date:
>Last-Modified:
>Originator: Assar Westerlund
>Release: FreeBSD 4.0-CURRENT i386
>Organization:
none
>Environment:
-current as of ~ today
>Description:
vclean() calls vrele() if v_usecount of the node was higher than one.
But before calling it, it sets the VXLOCK flag, which will make
vn_lock called from vrele dead-lock.
>How-To-Repeat:
>Fix:
[ largely based on the NetBSD - code ]
--- vfs_subr.c.orig Sat Nov 27 14:54:10 1999
+++ vfs_subr.c Sat Nov 27 15:11:47 1999
@@ -1693,8 +1693,23 @@
if (VOP_RECLAIM(vp, p))
panic("vclean: cannot reclaim");
- if (active)
- vrele(vp);
+ if (active) {
+ /*
+ * Inline copy of vrele() since VOP_INACTIVE
+ * has already been called.
+ */
+ simple_lock(&vp->v_interlock);
+ if (--vp->v_usecount <= 0) {
+#ifdef DIAGNOSTIC
+ if (vp->v_usecount < 0 || vp->v_writecount != 0) {
+ vprint("vclean: bad ref count", vp);
+ panic("vclean: ref cnt");
+ }
+#endif
+ vfree(vp);
+ }
+ simple_unlock(&vp->v_interlock);
+ }
cache_purge(vp);
if (vp->v_vnlock) {
>Release-Note:
>Audit-Trail:
>Unformatted:
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