[PATCH] tty: BKL pushdown

From: Alan Cox
Date: Fri Feb 08 2008 - 10:48:58 EST

- Push the BKL down into the line disciplines
- Switch the tty layer to unlocked_ioctl
- Introduce a new ctrl_lock spin lock for the control bits
- Eliminate much of the lock_kernel use in n_tty
- Prepare to (but don't yet) call the drivers with the lock dropped
on the paths that historically held the lock

BKL now primarily protects open/close/ldisc change in the tty layer

I'm sure this will break something so it wants to stew in -mm for a
little while.

Signed-off-by: Alan Cox <alan@xxxxxxxxxx>

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.24-mm1/drivers/char/n_hdlc.c linux-2.6.24-mm1/drivers/char/n_hdlc.c
--- linux.vanilla-2.6.24-mm1/drivers/char/n_hdlc.c 2008-02-06 14:13:24.000000000 +0000
+++ linux-2.6.24-mm1/drivers/char/n_hdlc.c 2008-02-06 14:33:00.000000000 +0000
@@ -578,26 +578,36 @@
return -EFAULT;
}

+ lock_kernel();
+
for (;;) {
- if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
+ if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
+ unlock_kernel();
return -EIO;
+ }

n_hdlc = tty2n_hdlc (tty);
if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC ||
- tty != n_hdlc->tty)
+ tty != n_hdlc->tty) {
+ unlock_kernel();
return 0;
+ }

rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list);
if (rbuf)
break;

/* no data */
- if (file->f_flags & O_NONBLOCK)
+ if (file->f_flags & O_NONBLOCK) {
+ unlock_kernel();
return -EAGAIN;
+ }

interruptible_sleep_on (&tty->read_wait);
- if (signal_pending(current))
+ if (signal_pending(current)) {
+ unlock_kernel();
return -EINTR;
+ }
}

if (rbuf->count > nr)
@@ -618,7 +628,7 @@
kfree(rbuf);
else
n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,rbuf);
-
+ unlock_kernel();
return ret;

} /* end of n_hdlc_tty_read() */
@@ -661,6 +671,8 @@
count = maxframe;
}

+ lock_kernel();
+
add_wait_queue(&tty->write_wait, &wait);
set_current_state(TASK_INTERRUPTIBLE);

@@ -695,7 +707,7 @@
n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf);
n_hdlc_send_frames(n_hdlc,tty);
}
-
+ unlock_kernel();
return error;

} /* end of n_hdlc_tty_write() */
diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.24-mm1/drivers/char/n_r3964.c linux-2.6.24-mm1/drivers/char/n_r3964.c
--- linux.vanilla-2.6.24-mm1/drivers/char/n_r3964.c 2008-02-06 14:13:23.000000000 +0000
+++ linux-2.6.24-mm1/drivers/char/n_r3964.c 2008-02-06 14:33:00.000000000 +0000
@@ -1074,6 +1074,8 @@
int count;

TRACE_L("read()");
+
+ lock_kernel();

pClient = findClient(pInfo, task_pid(current));
if (pClient) {
@@ -1081,6 +1083,7 @@
if (pMsg == NULL) {
/* no messages available. */
if (file->f_flags & O_NONBLOCK) {
+ unlock_kernel();
return -EAGAIN;
}
/* block until there is a message: */
@@ -1090,8 +1093,10 @@

/* If we still haven't got a message, we must have been signalled */

- if (!pMsg)
+ if (!pMsg) {
+ unlock_kernel();
return -EINTR;
+ }

/* deliver msg to client process: */
theMsg.msg_id = pMsg->msg_id;
@@ -1102,12 +1107,15 @@
kfree(pMsg);
TRACE_M("r3964_read - msg kfree %p", pMsg);

- if (copy_to_user(buf, &theMsg, count))
+ if (copy_to_user(buf, &theMsg, count)) {
+ unlock_kernel();
return -EFAULT;
+ }

TRACE_PS("read - return %d", count);
return count;
}
+ unlock_kernel();
return -EPERM;
}

@@ -1156,6 +1164,8 @@
pHeader->locks = 0;
pHeader->owner = NULL;

+ lock_kernel();
+
pClient = findClient(pInfo, task_pid(current));
if (pClient) {
pHeader->owner = pClient;
@@ -1172,6 +1182,8 @@
*/
add_tx_queue(pInfo, pHeader);
trigger_transmit(pInfo);
+
+ unlock_kernel();

return 0;
}
diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.24-mm1/drivers/char/n_tty.c linux-2.6.24-mm1/drivers/char/n_tty.c
--- linux.vanilla-2.6.24-mm1/drivers/char/n_tty.c 2008-02-06 14:14:39.000000000 +0000
+++ linux-2.6.24-mm1/drivers/char/n_tty.c 2008-02-06 14:33:00.000000000 +0000
@@ -183,22 +183,24 @@
* at hangup) or when the N_TTY line discipline internally has to
* clean the pending queue (for example some signals).
*
- * FIXME: tty->ctrl_status is not spinlocked and relies on
- * lock_kernel() still.
+ * Locking: ctrl_lock
*/

static void n_tty_flush_buffer(struct tty_struct *tty)
{
+ unsigned long flags;
/* clear everything and unthrottle the driver */
reset_buffer_flags(tty);

if (!tty->link)
return;

+ spin_lock_irqsave(&tty->ctrl_lock, flags);
if (tty->link->packet) {
tty->ctrl_status |= TIOCPKT_FLUSHREAD;
wake_up_interruptible(&tty->link->read_wait);
}
+ spin_unlock_irqrestore(&tty->ctrl_lock, flags);
}

/**
@@ -264,7 +266,7 @@
* relevant in the world today. If you ever need them, add them here.
*
* Called from both the receive and transmit sides and can be called
- * re-entrantly. Relies on lock_kernel() still.
+ * re-entrantly. Relies on lock_kernel() for tty->column state.
*/

static int opost(unsigned char c, struct tty_struct *tty)
@@ -275,6 +277,7 @@
if (!space)
return -1;

+ lock_kernel();
if (O_OPOST(tty)) {
switch (c) {
case '\n':
@@ -323,6 +326,7 @@
}
}
tty->driver->put_char(tty, c);
+ unlock_kernel();
return 0;
}

@@ -337,7 +341,8 @@
* the simple cases normally found and helps to generate blocks of
* symbols for the console driver and thus improve performance.
*
- * Called from write_chan under the tty layer write lock.
+ * Called from write_chan under the tty layer write lock. Relies
+ * on lock_kernel for the tty->column state.
*/

static ssize_t opost_block(struct tty_struct *tty,
@@ -353,6 +358,7 @@
if (nr > space)
nr = space;

+ lock_kernel();
for (i = 0, cp = buf; i < nr; i++, cp++) {
switch (*cp) {
case '\n':
@@ -387,6 +393,7 @@
if (tty->driver->flush_chars)
tty->driver->flush_chars(tty);
i = tty->driver->write(tty, buf, i);
+ unlock_kernel();
return i;
}

@@ -1194,6 +1201,11 @@
* Perform job control management checks on this file/tty descriptor
* and if appropriate send any needed signals and return a negative
* error code if action should be taken.
+ *
+ * FIXME:
+ * Locking: None - redirected write test is safe, testing
+ * current->signal should possibly lock current->sighand
+ * pgrp locking ?
*/

static int job_control(struct tty_struct *tty, struct file *file)
@@ -1246,6 +1258,7 @@
ssize_t size;
long timeout;
unsigned long flags;
+ int packet;

do_it_again:

@@ -1289,16 +1302,19 @@
if (mutex_lock_interruptible(&tty->atomic_read_lock))
return -ERESTARTSYS;
}
-
+ packet = tty->packet;
+
add_wait_queue(&tty->read_wait, &wait);
while (nr) {
/* First test for status change. */
- if (tty->packet && tty->link->ctrl_status) {
+ if (packet && tty->link->ctrl_status) {
unsigned char cs;
if (b != buf)
break;
+ spin_lock_irqsave(&tty->link->ctrl_lock, flags);
cs = tty->link->ctrl_status;
tty->link->ctrl_status = 0;
+ spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
if (tty_put_user(tty, cs, b++)) {
retval = -EFAULT;
b--;
@@ -1333,6 +1349,7 @@
retval = -ERESTARTSYS;
break;
}
+ /* FIXME: does n_tty_set_room need locking ? */
n_tty_set_room(tty);
timeout = schedule_timeout(timeout);
continue;
@@ -1340,7 +1357,7 @@
__set_current_state(TASK_RUNNING);

/* Deal with packet mode. */
- if (tty->packet && b == buf) {
+ if (packet && b == buf) {
if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
retval = -EFAULT;
b--;
@@ -1388,6 +1405,8 @@
break;
} else {
int uncopied;
+ /* The copy function takes the read lock and handles
+ locking internally for this case */
uncopied = copy_from_read_buf(tty, &b, &nr);
uncopied += copy_from_read_buf(tty, &b, &nr);
if (uncopied) {
@@ -1429,7 +1448,6 @@
goto do_it_again;

n_tty_set_room(tty);
-
return retval;
}

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.24-mm1/drivers/char/pty.c linux-2.6.24-mm1/drivers/char/pty.c
--- linux.vanilla-2.6.24-mm1/drivers/char/pty.c 2008-02-06 14:13:22.000000000 +0000
+++ linux-2.6.24-mm1/drivers/char/pty.c 2008-02-06 14:33:29.000000000 +0000
@@ -181,6 +181,7 @@
static void pty_flush_buffer(struct tty_struct *tty)
{
struct tty_struct *to = tty->link;
+ unsigned long flags;

if (!to)
return;
@@ -189,8 +190,10 @@
to->ldisc.flush_buffer(to);

if (to->packet) {
+ spin_lock_irqsave(&tty->ctrl_lock, flags);
tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
wake_up_interruptible(&to->read_wait);
+ spin_unlock_irqrestore(&tty->ctrl_lock, flags);
}
}

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.24-mm1/drivers/char/tty_io.c linux-2.6.24-mm1/drivers/char/tty_io.c
--- linux.vanilla-2.6.24-mm1/drivers/char/tty_io.c 2008-02-06 14:14:39.000000000 +0000
+++ linux-2.6.24-mm1/drivers/char/tty_io.c 2008-02-06 14:33:29.000000000 +0000
@@ -152,8 +152,7 @@
static unsigned int tty_poll(struct file *, poll_table *);
static int tty_open(struct inode *, struct file *);
static int tty_release(struct inode *, struct file *);
-int tty_ioctl(struct inode *inode, struct file *file,
- unsigned int cmd, unsigned long arg);
+long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
#ifdef CONFIG_COMPAT
static long tty_compat_ioctl(struct file *file, unsigned int cmd,
unsigned long arg);
@@ -1163,7 +1163,7 @@
* not in the foreground, send a SIGTTOU. If the signal is blocked or
* ignored, go ahead and perform the operation. (POSIX 7.2)
*
- * Locking: none
+ * Locking: none - FIXME: review this
*/

int tty_check_change(struct tty_struct *tty)
@@ -1205,7 +1205,7 @@
return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
}

-static int hung_up_tty_ioctl(struct inode *inode, struct file *file,
+static long hung_up_tty_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
@@ -1222,7 +1222,7 @@
.read = tty_read,
.write = tty_write,
.poll = tty_poll,
- .ioctl = tty_ioctl,
+ .unlocked_ioctl = tty_ioctl,
.compat_ioctl = tty_compat_ioctl,
.open = tty_open,
.release = tty_release,
@@ -1235,7 +1235,7 @@
.read = tty_read,
.write = tty_write,
.poll = tty_poll,
- .ioctl = tty_ioctl,
+ .unlocked_ioctl = tty_ioctl,
.compat_ioctl = tty_compat_ioctl,
.open = ptmx_open,
.release = tty_release,
@@ -1248,7 +1248,7 @@
.read = tty_read,
.write = redirected_tty_write,
.poll = tty_poll,
- .ioctl = tty_ioctl,
+ .unlocked_ioctl = tty_ioctl,
.compat_ioctl = tty_compat_ioctl,
.open = tty_open,
.release = tty_release,
@@ -1584,16 +1584,17 @@
struct tty_struct *tty;
struct pid *tty_pgrp = NULL;

- lock_kernel();

mutex_lock(&tty_mutex);
tty = get_current_tty();
if (tty) {
tty_pgrp = get_pid(tty->pgrp);
mutex_unlock(&tty_mutex);
+ lock_kernel();
/* XXX: here we race, there is nothing protecting tty */
if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
tty_vhangup(tty);
+ unlock_kernel();
} else if (on_exit) {
struct pid *old_pgrp;
spin_lock_irq(&current->sighand->siglock);
@@ -1606,7 +1607,6 @@
put_pid(old_pgrp);
}
mutex_unlock(&tty_mutex);
- unlock_kernel();
return;
}
if (tty_pgrp) {
@@ -1641,7 +1641,6 @@
read_lock(&tasklist_lock);
session_clear_tty(task_session(current));
read_unlock(&tasklist_lock);
- unlock_kernel();
}

/**
@@ -1651,8 +1650,10 @@
void no_tty(void)
{
struct task_struct *tsk = current;
+ lock_kernel();
if (tsk->signal->leader)
disassociate_ctty(0);
+ unlock_kernel();
proc_clear_tty(tsk);
}

@@ -1672,19 +1673,24 @@
* but not always.
*
* Locking:
- * Broken. Relies on BKL which is unsafe here.
+ * Uses the tty control lock internally
*/

void stop_tty(struct tty_struct *tty)
{
- if (tty->stopped)
+ unsigned long flags;
+ spin_lock_irqsave(&tty->ctrl_lock, flags);
+ if (tty->stopped) {
+ spin_unlock_irqrestore(&tty->ctrl_lock, flags);
return;
+ }
tty->stopped = 1;
if (tty->link && tty->link->packet) {
tty->ctrl_status &= ~TIOCPKT_START;
tty->ctrl_status |= TIOCPKT_STOP;
wake_up_interruptible(&tty->link->read_wait);
}
+ spin_unlock_irqrestore(&tty->ctrl_lock, flags);
if (tty->driver->stop)
(tty->driver->stop)(tty);
}
@@ -1701,19 +1707,24 @@
* driver start method is invoked and the line discipline woken.
*
* Locking:
- * Broken. Relies on BKL which is unsafe here.
+ * ctrl_lock
*/

void start_tty(struct tty_struct *tty)
{
- if (!tty->stopped || tty->flow_stopped)
+ unsigned long flags;
+ spin_lock_irqsave(&tty->ctrl_lock, flags);
+ if (!tty->stopped || tty->flow_stopped) {
+ spin_unlock_irqrestore(&tty->ctrl_lock, flags);
return;
+ }
tty->stopped = 0;
if (tty->link && tty->link->packet) {
tty->ctrl_status &= ~TIOCPKT_STOP;
tty->ctrl_status |= TIOCPKT_START;
wake_up_interruptible(&tty->link->read_wait);
}
+ spin_unlock_irqrestore(&tty->ctrl_lock, flags);
if (tty->driver->start)
(tty->driver->start)(tty);
/* If we have a running line discipline it may need kicking */
@@ -1757,13 +1768,11 @@
/* We want to wait for the line discipline to sort out in this
situation */
ld = tty_ldisc_ref_wait(tty);
- lock_kernel();
if (ld->read)
i = (ld->read)(tty, file, buf, count);
else
i = -EIO;
tty_ldisc_deref(ld);
- unlock_kernel();
if (i > 0)
inode->i_atime = current_fs_time(inode->i_sb);
return i;
@@ -1851,9 +1860,7 @@
ret = -EFAULT;
if (copy_from_user(tty->write_buf, buf, size))
break;
- lock_kernel();
ret = write(tty, file, tty->write_buf, size);
- unlock_kernel();
if (ret <= 0)
break;
written += ret;
@@ -3028,10 +3165,13 @@
if (get_user(nonblock, p))
return -EFAULT;

+ /* file->f_flags is still BKL protected in the fs layer - vomit */
+ lock_kernel();
if (nonblock)
file->f_flags |= O_NONBLOCK;
else
file->f_flags &= ~O_NONBLOCK;
+ unlock_kernel();
return 0;
}

@@ -3120,7 +3260,7 @@
* Set the process group of the tty to the session passed. Only
* permitted where the tty session is our session.
*
- * Locking: None
+ * Locking: RCU
*/

static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
@@ -3195,10 +3335,14 @@
static int tiocsetd(struct tty_struct *tty, int __user *p)
{
int ldisc;
+ int ret;

if (get_user(ldisc, p))
return -EFAULT;
- return tty_set_ldisc(tty, ldisc);
+
+ lock_kernel();
+ ret = tty_set_ldisc(tty, ldisc);
+ unlock_kernel();
}

/**
@@ -3216,16 +3360,21 @@

static int send_break(struct tty_struct *tty, unsigned int duration)
{
+ int retval = -EINTR;
+
+ lock_kernel();
if (tty_write_lock(tty, 0) < 0)
- return -EINTR;
+ goto out;
tty->driver->break_ctl(tty, -1);
if (!signal_pending(current))
msleep_interruptible(duration);
tty->driver->break_ctl(tty, 0);
tty_write_unlock(tty);
- if (signal_pending(current))
- return -EINTR;
- return 0;
+ if (!signal_pending(current))
+ retval = 0;
+out:
+ unlock_kernel();
+ return retval;
}

/**
@@ -3245,7 +3394,9 @@
int retval = -EINVAL;

if (tty->driver->tiocmget) {
+ lock_kernel();
retval = tty->driver->tiocmget(tty, file);
+ unlock_kernel();

if (retval >= 0)
retval = put_user(retval, p);
@@ -3295,7 +3446,9 @@
set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;

+ lock_kernel();
retval = tty->driver->tiocmset(tty, file, set, clear);
+ unlock_kernel();
}
return retval;
}
@@ -3303,20 +3456,18 @@
/*
* Split this up, as gcc can choke on it otherwise..
*/
-int tty_ioctl(struct inode *inode, struct file *file,
- unsigned int cmd, unsigned long arg)
+long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct tty_struct *tty, *real_tty;
void __user *p = (void __user *)arg;
int retval;
struct tty_ldisc *ld;
+ struct inode *inode = file->f_dentry->d_inode;

tty = (struct tty_struct *)file->private_data;
if (tty_paranoia_check(tty, inode, "tty_ioctl"))
return -EINVAL;

- /* CHECKME: is this safe as one end closes ? */
-
real_tty = tty;
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
@@ -3325,13 +3476,19 @@
/*
* Break handling by driver
*/
+
+ retval = -EINVAL;
+
if (!tty->driver->break_ctl) {
switch (cmd) {
case TIOCSBRK:
case TIOCCBRK:
- if (tty->driver->ioctl)
- return tty->driver->ioctl(tty, file, cmd, arg);
- return -EINVAL;
+ if (tty->driver->ioctl) {
+ lock_kernel();
+ retval = tty->driver->ioctl(tty, file, cmd, arg);
+ unlock_kernel();
+ }
+ return retval;

/* These two ioctl's always return success; even if */
/* the driver doesn't support them. */
@@ -3339,7 +3496,9 @@
case TCSBRKP:
if (!tty->driver->ioctl)
return 0;
+ lock_kernel();
retval = tty->driver->ioctl(tty, file, cmd, arg);
+ unlock_kernel();
if (retval == -ENOIOCTLCMD)
retval = 0;
return retval;
@@ -3359,7 +3518,9 @@
if (retval)
return retval;
if (cmd != TIOCCBRK) {
+ lock_kernel();
tty_wait_until_sent(tty, 0);
+ unlock_kernel();
if (signal_pending(current))
return -EINTR;
}
@@ -3409,11 +3570,15 @@
* Break handling
*/
case TIOCSBRK: /* Turn break on, unconditionally */
+ lock_kernel();
tty->driver->break_ctl(tty, -1);
+ unlock_kernel();
return 0;

case TIOCCBRK: /* Turn break off, unconditionally */
+ lock_kernel();
tty->driver->break_ctl(tty, 0);
+ unlock_kernel();
return 0;
case TCSBRK: /* SVID version: non-zero arg --> no break */
/* non-zero arg means wait for all output data
@@ -3443,14 +3608,18 @@
break;
}
if (tty->driver->ioctl) {
+ lock_kernel();
retval = (tty->driver->ioctl)(tty, file, cmd, arg);
+ unlock_kernel();
if (retval != -ENOIOCTLCMD)
return retval;
}
ld = tty_ldisc_ref_wait(tty);
retval = -EINVAL;
if (ld->ioctl) {
+ lock_kernel();
retval = ld->ioctl(tty, file, cmd, arg);
+ unlock_kernel();
if (retval == -ENOIOCTLCMD)
retval = -EINVAL;
}
@@ -3728,6 +3897,7 @@
mutex_init(&tty->atomic_read_lock);
mutex_init(&tty->atomic_write_lock);
spin_lock_init(&tty->read_lock);
+ spin_lock_init(&tty->ctrl_lock);
INIT_LIST_HEAD(&tty->tty_files);
INIT_WORK(&tty->SAK_work, do_SAK_work);
}
diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.24-mm1/drivers/char/tty_ioctl.c linux-2.6.24-mm1/drivers/char/tty_ioctl.c
--- linux.vanilla-2.6.24-mm1/drivers/char/tty_ioctl.c 2008-02-06 14:14:39.000000000 +0000
+++ linux-2.6.24-mm1/drivers/char/tty_ioctl.c 2008-02-06 14:33:34.000000000 +0000
@@ -395,6 +395,7 @@
int canon_change;
struct ktermios old_termios = *tty->termios;
struct tty_ldisc *ld;
+ unsigned long flags;

/*
* Perform the actual termios internal changes under lock.
@@ -429,11 +430,13 @@
STOP_CHAR(tty) == '\023' &&
START_CHAR(tty) == '\021');
if (old_flow != new_flow) {
+ spin_lock_irqsave(&tty->ctrl_lock, flags);
tty->ctrl_status &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP);
if (new_flow)
tty->ctrl_status |= TIOCPKT_DOSTOP;
else
tty->ctrl_status |= TIOCPKT_NOSTOP;
+ spin_unlock_irqrestore(&tty->ctrl_lock, flags);
wake_up_interruptible(&tty->link->read_wait);
}
}
@@ -905,6 +908,7 @@
unsigned int cmd, unsigned long arg)
{
struct tty_struct *real_tty;
+ unsigned long flags;
int retval;

if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
@@ -963,6 +967,7 @@
return -ENOTTY;
if (get_user(pktmode, (int __user *) arg))
return -EFAULT;
+ spin_lock_irqsave(&tty->ctrl_lock, flags);
if (pktmode) {
if (!tty->packet) {
tty->packet = 1;
@@ -970,6 +975,7 @@
}
} else
tty->packet = 0;
+ spin_unlock_irqrestore(&tty->ctrl_lock, flags);
return 0;
}
default:
diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.24-mm1/drivers/char/vt.c linux-2.6.24-mm1/drivers/char/vt.c
--- linux.vanilla-2.6.24-mm1/drivers/char/vt.c 2008-02-06 14:14:39.000000000 +0000
+++ linux-2.6.24-mm1/drivers/char/vt.c 2008-02-06 14:33:40.000000000 +0000
@@ -2531,6 +2531,9 @@
if (get_user(type, p))
return -EFAULT;
ret = 0;
+
+ lock_kernel();
+
switch (type)
{
case TIOCL_SETSEL:
@@ -2605,6 +2608,7 @@
ret = -EINVAL;
break;
}
+ unlock_kernel();
return ret;
}

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.24-mm1/include/linux/tty.h linux-2.6.24-mm1/include/linux/tty.h
--- linux.vanilla-2.6.24-mm1/include/linux/tty.h 2008-02-06 14:14:42.000000000 +0000
+++ linux-2.6.24-mm1/include/linux/tty.h 2008-02-06 14:37:29.000000000 +0000
@@ -183,6 +200,7 @@
int index;
struct tty_ldisc ldisc;
struct mutex termios_mutex;
+ spinlock_t ctrl_lock;
struct ktermios *termios, *termios_locked;
char name[64];
struct pid *pgrp;
@@ -323,8 +342,7 @@
extern void tty_wakeup(struct tty_struct *tty);
extern void tty_ldisc_flush(struct tty_struct *tty);

-extern int tty_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
- unsigned long arg);
+extern long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
extern int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
unsigned int cmd, unsigned long arg);
extern int tty_perform_flush(struct tty_struct *tty, unsigned long arg);
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