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specfs: sn_gone cannot be set while we hold the vnode lock. 

Revoke runs with the vnode lock too, which is exclusive.  Add an
assertion to this effect in spec_node_revoke to make it clear.
This commit is contained in:
riastradh 2022-03-28 12:35:44 +00:00
parent ce78318abc
commit 4241b4d4c6
1 changed files with 8 additions and 15 deletions
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23
sys/miscfs/specfs/spec_vnops.c
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@ -1,4 +1,4 @@
/* $NetBSD: spec_vnops.c,v 1.194 2022/03/28 12:35:35 riastradh Exp $ */
/* $NetBSD: spec_vnops.c,v 1.195 2022/03/28 12:35:44 riastradh Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@ -58,7 +58,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: spec_vnops.c,v 1.194 2022/03/28 12:35:35 riastradh Exp $");
__KERNEL_RCSID(0, "$NetBSD: spec_vnops.c,v 1.195 2022/03/28 12:35:44 riastradh Exp $");
#include <sys/param.h>
#include <sys/proc.h>
@ -402,6 +402,8 @@ spec_node_revoke(vnode_t *vp)
specnode_t *sn;
specdev_t *sd;
KASSERT(VOP_ISLOCKED(vp) == LK_EXCLUSIVE);
sn = vp->v_specnode;
sd = sn->sn_dev;
@ -552,11 +554,8 @@ spec_open(void *v)
/*
* Acquire an open reference -- as long as we hold onto it, and
* the vnode isn't revoked, it can't be closed.
*
* But first check whether it has been revoked -- if so, we
* can't acquire more open references and we must fail
* immediately with EBADF.
* the vnode isn't revoked, it can't be closed, and the vnode
* can't be revoked until we release the vnode lock.
*/
mutex_enter(&device_lock);
switch (vp->v_type) {
@ -565,10 +564,7 @@ spec_open(void *v)
* Character devices can accept opens from multiple
* vnodes.
*/
if (sn->sn_gone) {
error = EBADF;
break;
}
KASSERT(!sn->sn_gone);
sd->sd_opencnt++;
sn->sn_opencnt++;
break;
@ -581,10 +577,7 @@ spec_open(void *v)
* Treat zero opencnt with non-NULL mountpoint as open.
* This may happen after forced detach of a mounted device.
*/
if (sn->sn_gone) {
error = EBADF;
break;
}
KASSERT(!sn->sn_gone);
if (sd->sd_opencnt != 0 || sd->sd_mountpoint != NULL) {
error = EBUSY;
break;