Module Name: src
Committed By: hannken
Date: Fri Nov 29 14:58:55 UTC 2013
Modified Files:
src/sys/kern: vfs_vnode.c
Log Message:
Change vrelel() to mark the vnode as changing after it has aquired
the vnode lock but before it calls VOP_INACTIVE().
Should fix the race between layer_node_find() trying to vget(, LK_NOWAIT)
a locked vnode when vrelel() marked it as changing and wants its lock.
PR kern/48411 (repeatable SMP crashes in amd64-current)
To generate a diff of this commit:
cvs rdiff -u -r1.26 -r1.27 src/sys/kern/vfs_vnode.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/vfs_vnode.c
diff -u src/sys/kern/vfs_vnode.c:1.26 src/sys/kern/vfs_vnode.c:1.27
--- src/sys/kern/vfs_vnode.c:1.26 Sat Nov 23 13:46:22 2013
+++ src/sys/kern/vfs_vnode.c Fri Nov 29 14:58:55 2013
@@ -1,4 +1,4 @@
-/* $NetBSD: vfs_vnode.c,v 1.26 2013/11/23 13:46:22 hannken Exp $ */
+/* $NetBSD: vfs_vnode.c,v 1.27 2013/11/29 14:58:55 hannken Exp $ */
/*-
* Copyright (c) 1997-2011 The NetBSD Foundation, Inc.
@@ -116,7 +116,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.26 2013/11/23 13:46:22 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.27 2013/11/29 14:58:55 hannken Exp $");
#define _VFS_VNODE_PRIVATE
@@ -606,10 +606,6 @@ vrelel(vnode_t *vp, int flags)
}
KASSERT((vp->v_iflag & VI_XLOCK) == 0);
- if ((flags & VRELEL_CHANGING_SET) == 0) {
- KASSERT((vp->v_iflag & VI_CHANGING) == 0);
- vp->v_iflag |= VI_CHANGING;
- }
#ifdef DIAGNOSTIC
if ((vp->v_type == VBLK || vp->v_type == VCHR) &&
@@ -654,13 +650,14 @@ vrelel(vnode_t *vp, int flags)
*/
if (__predict_false(vtryrele(vp))) {
VOP_UNLOCK(vp);
- KASSERT((vp->v_iflag & VI_CHANGING) != 0);
- vp->v_iflag &= ~VI_CHANGING;
- cv_broadcast(&vp->v_cv);
+ if ((flags & VRELEL_CHANGING_SET) != 0) {
+ KASSERT((vp->v_iflag & VI_CHANGING) != 0);
+ vp->v_iflag &= ~VI_CHANGING;
+ cv_broadcast(&vp->v_cv);
+ }
mutex_exit(vp->v_interlock);
return;
}
- mutex_exit(vp->v_interlock);
defer = false;
} else if ((vp->v_iflag & VI_LAYER) != 0) {
/*
@@ -675,10 +672,10 @@ vrelel(vnode_t *vp, int flags)
error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
if (error != 0) {
defer = true;
- mutex_enter(vp->v_interlock);
} else {
defer = false;
}
+ mutex_enter(vp->v_interlock);
}
if (defer) {
@@ -687,18 +684,26 @@ vrelel(vnode_t *vp, int flags)
* clean it here. We donate it our last reference.
*/
KASSERT(mutex_owned(vp->v_interlock));
- KASSERT((vp->v_iflag & VI_CHANGING) != 0);
- vp->v_iflag &= ~VI_CHANGING;
+ if ((flags & VRELEL_CHANGING_SET) != 0) {
+ KASSERT((vp->v_iflag & VI_CHANGING) != 0);
+ vp->v_iflag &= ~VI_CHANGING;
+ cv_broadcast(&vp->v_cv);
+ }
mutex_enter(&vrele_lock);
TAILQ_INSERT_TAIL(&vrele_list, vp, v_freelist);
if (++vrele_pending > (desiredvnodes >> 8))
cv_signal(&vrele_cv);
mutex_exit(&vrele_lock);
- cv_broadcast(&vp->v_cv);
mutex_exit(vp->v_interlock);
return;
}
+ if ((flags & VRELEL_CHANGING_SET) == 0) {
+ KASSERT((vp->v_iflag & VI_CHANGING) == 0);
+ vp->v_iflag |= VI_CHANGING;
+ }
+ mutex_exit(vp->v_interlock);
+
/*
* The vnode can gain another reference while being
* deactivated. If VOP_INACTIVE() indicates that
@@ -739,6 +744,11 @@ vrelel(vnode_t *vp, int flags)
vclean(vp);
}
KASSERT(vp->v_usecount > 0);
+ } else { /* vnode was already clean */
+ if ((flags & VRELEL_CHANGING_SET) == 0) {
+ KASSERT((vp->v_iflag & VI_CHANGING) == 0);
+ vp->v_iflag |= VI_CHANGING;
+ }
}
if (atomic_dec_uint_nv(&vp->v_usecount) != 0) {
