f5baf8d66b
Lock cdev mutex too to close the race with tty being freed. Relock clone_drain_lock to prevent the LOR with proctree lock, thus add #include <fs/devfs/devfs_int.h>. Suggested by: tegge Debugging help and testing by: Peter Holm Approved by: re (kensmith)
97 lines
2.8 KiB
C
97 lines
2.8 KiB
C
/*-
|
|
* Copyright (c) 2003 Poul-Henning Kamp. All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
__FBSDID("$FreeBSD$");
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/conf.h>
|
|
#include <sys/kernel.h>
|
|
#include <sys/proc.h>
|
|
#include <sys/sx.h>
|
|
#include <sys/vnode.h>
|
|
|
|
#include <fs/devfs/devfs.h>
|
|
#include <fs/devfs/devfs_int.h>
|
|
|
|
static d_open_t cttyopen;
|
|
|
|
static struct cdevsw ctty_cdevsw = {
|
|
.d_version = D_VERSION,
|
|
.d_open = cttyopen,
|
|
.d_name = "ctty",
|
|
.d_flags = D_TTY | D_NEEDGIANT,
|
|
};
|
|
|
|
static struct cdev *ctty;
|
|
|
|
static int
|
|
cttyopen(struct cdev *dev, int flag, int mode, struct thread *td)
|
|
{
|
|
|
|
return (ENXIO);
|
|
}
|
|
|
|
static void
|
|
ctty_clone(void *arg, struct ucred *cred, char *name, int namelen,
|
|
struct cdev **dev)
|
|
{
|
|
|
|
if (*dev != NULL)
|
|
return;
|
|
if (strcmp(name, "tty"))
|
|
return;
|
|
sx_sunlock(&clone_drain_lock);
|
|
mtx_lock(&Giant);
|
|
sx_slock(&proctree_lock);
|
|
sx_slock(&clone_drain_lock);
|
|
dev_lock();
|
|
if (!(curthread->td_proc->p_flag & P_CONTROLT))
|
|
*dev = ctty;
|
|
else if (curthread->td_proc->p_session->s_ttyvp == NULL)
|
|
*dev = ctty;
|
|
else if (curthread->td_proc->p_session->s_ttyvp->v_type == VBAD ||
|
|
curthread->td_proc->p_session->s_ttyvp->v_rdev == NULL) {
|
|
/* e.g. s_ttyvp was revoked */
|
|
*dev = ctty;
|
|
} else
|
|
*dev = curthread->td_proc->p_session->s_ttyvp->v_rdev;
|
|
dev_refl(*dev);
|
|
dev_unlock();
|
|
sx_sunlock(&proctree_lock);
|
|
mtx_unlock(&Giant);
|
|
}
|
|
|
|
static void
|
|
ctty_drvinit(void *unused)
|
|
{
|
|
|
|
EVENTHANDLER_REGISTER(dev_clone, ctty_clone, 0, 1000);
|
|
ctty = make_dev(&ctty_cdevsw, 0, 0, 0, 0666, "ctty");
|
|
}
|
|
|
|
SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,ctty_drvinit,NULL)
|