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Differential D22202 Diff 63818 sys/fs/devfs/devfs_vnops.c

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sys/fs/devfs/devfs_vnops.c

Show First 20 Lines • Show All 475 Lines • ▼ Show 20 Lines if (de->de_dirent->d_type == DT_CHR) {
vp->v_type = VCHR; vp->v_type = VCHR;
VI_LOCK(vp); VI_LOCK(vp);
dev_lock(); dev_lock();
dev_refl(dev); dev_refl(dev);
/* XXX: v_rdev should be protect by vnode lock */ /* XXX: v_rdev should be protect by vnode lock */
vp->v_rdev = dev; vp->v_rdev = dev;
KASSERT(vp->v_usecount == 1, KASSERT(vp->v_usecount == 1,
("%s %d (%d)\n", __func__, __LINE__, vp->v_usecount)); ("%s %d (%d)\n", __func__, __LINE__, vp->v_usecount));
dev->si_usecount += vp->v_usecount; dev->si_usecount++;
/* Special casing of ttys for deadfs. Probably redundant. */ /* Special casing of ttys for deadfs. Probably redundant. */
dsw = dev->si_devsw; dsw = dev->si_devsw;
if (dsw != NULL && (dsw->d_flags & D_TTY) != 0) if (dsw != NULL && (dsw->d_flags & D_TTY) != 0)
vp->v_vflag |= VV_ISTTY; vp->v_vflag |= VV_ISTTY;
dev_unlock(); dev_unlock();
VI_UNLOCK(vp); VI_UNLOCK(vp);
if ((dev->si_flags & SI_ETERNAL) != 0) if ((dev->si_flags & SI_ETERNAL) != 0)
vp->v_vflag |= VV_ETERNALDEV; vp->v_vflag |= VV_ETERNALDEV;
▲ Show 20 Lines • Show All 83 Lines • ▼ Show 20 Linesdevfs_close(struct vop_close_args *ap)
* Hack: a tty device that is a controlling terminal * Hack: a tty device that is a controlling terminal
* has a reference from the session structure. * has a reference from the session structure.
* We cannot easily tell that a character device is * We cannot easily tell that a character device is
* a controlling terminal, unless it is the closing * a controlling terminal, unless it is the closing
* process' controlling terminal. In that case, * process' controlling terminal. In that case,
* if the reference count is 2 (this last descriptor * if the reference count is 2 (this last descriptor
* plus the session), release the reference from the session. * plus the session), release the reference from the session.
*/ */
if (td != NULL) { if (vp->v_usecount == 2 && td != NULL) {
p = td->td_proc; p = td->td_proc;
PROC_LOCK(p); PROC_LOCK(p);
if (vp == p->p_session->s_ttyvp) { if (vp == p->p_session->s_ttyvp) {
PROC_UNLOCK(p); PROC_UNLOCK(p);
oldvp = NULL; oldvp = NULL;
sx_xlock(&proctree_lock); sx_xlock(&proctree_lock);
if (vp == p->p_session->s_ttyvp) { if (vp == p->p_session->s_ttyvp) {
SESS_LOCK(p->p_session); SESS_LOCK(p->p_session);
VI_LOCK(vp); VI_LOCK(vp);
if (count_dev(dev) == 2 && if (vp->v_usecount == 2 && vcount(vp) == 1 &&
kibUnsubmitted
Not Done
Inline Actions

These two checks for v_usecount == 2 are optimizations and can be committed separately.

OTOH I should note that changing v_usecount updates to atomic make these checks racy.

kib: These two checks for v_usecount == 2 are optimizations and can be committed separately. OTOH I…
mjgAuthorUnsubmitted
Done
Inline Actions

I think the code was racy even beforehand. Moreover, I suspect there is a different bug here as well: if the target device gets a ref from another devfs mount point, this code will decline clearing it which probably was not intended. At least dragonfly only checks the current vnode and changing this would be a noop for typical use cases. That said, I consider the patch to maintain to be bug compatible.

mjg: I think the code was racy even beforehand. Moreover, I suspect there is a different bug here as…
(vp->v_iflag & VI_DOOMED) == 0) { (vp->v_iflag & VI_DOOMED) == 0) {
p->p_session->s_ttyvp = NULL; p->p_session->s_ttyvp = NULL;
p->p_session->s_ttydp = NULL; p->p_session->s_ttydp = NULL;
oldvp = vp; oldvp = vp;
} }
VI_UNLOCK(vp); VI_UNLOCK(vp);
SESS_UNLOCK(p->p_session); SESS_UNLOCK(p->p_session);
} }
Show All 12 Linesdevfs_close(struct vop_close_args *ap)
* sum of the reference counts on all the aliased * sum of the reference counts on all the aliased
* vnodes descends to one, we are on last close. * vnodes descends to one, we are on last close.
*/ */
dsw = dev_refthread(dev, &ref); dsw = dev_refthread(dev, &ref);
if (dsw == NULL) if (dsw == NULL)
return (ENXIO); return (ENXIO);
dflags = 0; dflags = 0;
VI_LOCK(vp); VI_LOCK(vp);
if (vp->v_usecount == 1 && vcount(vp) == 1)
dflags |= FLASTCLOSE;
if (vp->v_iflag & VI_DOOMED) { if (vp->v_iflag & VI_DOOMED) {
/* Forced close. */ /* Forced close. */
dflags |= FREVOKE | FNONBLOCK; dflags |= FREVOKE | FNONBLOCK;
} else if (dsw->d_flags & D_TRACKCLOSE) { } else if (dsw->d_flags & D_TRACKCLOSE) {
/* Keep device updated on status. */ /* Keep device updated on status. */
} else if (count_dev(dev) > 1) { } else if ((dflags & FLASTCLOSE) == 0) {
VI_UNLOCK(vp); VI_UNLOCK(vp);
dev_relthread(dev, ref); dev_relthread(dev, ref);
return (0); return (0);
} }
if (count_dev(dev) == 1) vholdnz(vp);
dflags |= FLASTCLOSE;
vholdl(vp);
VI_UNLOCK(vp); VI_UNLOCK(vp);
vp_locked = VOP_ISLOCKED(vp); vp_locked = VOP_ISLOCKED(vp);
VOP_UNLOCK(vp, 0); VOP_UNLOCK(vp, 0);
KASSERT(dev->si_refcount > 0, KASSERT(dev->si_refcount > 0,
("devfs_close() on un-referenced struct cdev *(%s)", devtoname(dev))); ("devfs_close() on un-referenced struct cdev *(%s)", devtoname(dev)));
error = dsw->d_close(dev, ap->a_fflag | dflags, S_IFCHR, td); error = dsw->d_close(dev, ap->a_fflag | dflags, S_IFCHR, td);
dev_relthread(dev, ref); dev_relthread(dev, ref);
vn_lock(vp, vp_locked | LK_RETRY); vn_lock(vp, vp_locked | LK_RETRY);
▲ Show 20 Lines • Show All 776 Lines • ▼ Show 20 Linesdevfs_reclaim_vchr(struct vop_reclaim_args *ap)
devfs_reclaim(ap); devfs_reclaim(ap);
VI_LOCK(vp); VI_LOCK(vp);
dev_lock(); dev_lock();
dev = vp->v_rdev; dev = vp->v_rdev;
vp->v_rdev = NULL; vp->v_rdev = NULL;
if (dev != NULL) if (dev != NULL)
dev->si_usecount -= vp->v_usecount; dev->si_usecount -= (vp->v_usecount > 0);
dev_unlock(); dev_unlock();
VI_UNLOCK(vp); VI_UNLOCK(vp);
if (dev != NULL) if (dev != NULL)
dev_rel(dev); dev_rel(dev);
return (0); return (0);
} }
static int static int
▲ Show 20 Lines • Show All 537 Lines • Show Last 20 Lines