tty: Convert termios_mutex to termios_rwsem
termios is commonly accessed unsafely (especially by N_TTY)
because the existing mutex forces exclusive access.
Convert existing usage.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index 3500d41..9ce20df 100644
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -94,20 +94,20 @@
* @tty: terminal
*
* Indicate that a tty should stop transmitting data down the stack.
- * Takes the termios mutex to protect against parallel throttle/unthrottle
+ * Takes the termios rwsem to protect against parallel throttle/unthrottle
* and also to ensure the driver can consistently reference its own
* termios data at this point when implementing software flow control.
*/
void tty_throttle(struct tty_struct *tty)
{
- mutex_lock(&tty->termios_mutex);
+ down_write(&tty->termios_rwsem);
/* check TTY_THROTTLED first so it indicates our state */
if (!test_and_set_bit(TTY_THROTTLED, &tty->flags) &&
tty->ops->throttle)
tty->ops->throttle(tty);
tty->flow_change = 0;
- mutex_unlock(&tty->termios_mutex);
+ up_write(&tty->termios_rwsem);
}
EXPORT_SYMBOL(tty_throttle);
@@ -116,7 +116,7 @@
* @tty: terminal
*
* Indicate that a tty may continue transmitting data down the stack.
- * Takes the termios mutex to protect against parallel throttle/unthrottle
+ * Takes the termios rwsem to protect against parallel throttle/unthrottle
* and also to ensure the driver can consistently reference its own
* termios data at this point when implementing software flow control.
*
@@ -126,12 +126,12 @@
void tty_unthrottle(struct tty_struct *tty)
{
- mutex_lock(&tty->termios_mutex);
+ down_write(&tty->termios_rwsem);
if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
tty->ops->unthrottle)
tty->ops->unthrottle(tty);
tty->flow_change = 0;
- mutex_unlock(&tty->termios_mutex);
+ up_write(&tty->termios_rwsem);
}
EXPORT_SYMBOL(tty_unthrottle);
@@ -151,7 +151,7 @@
{
int ret = 0;
- mutex_lock(&tty->termios_mutex);
+ down_write(&tty->termios_rwsem);
if (!test_bit(TTY_THROTTLED, &tty->flags)) {
if (tty->flow_change != TTY_THROTTLE_SAFE)
ret = 1;
@@ -161,7 +161,7 @@
tty->ops->throttle(tty);
}
}
- mutex_unlock(&tty->termios_mutex);
+ up_write(&tty->termios_rwsem);
return ret;
}
@@ -182,7 +182,7 @@
{
int ret = 0;
- mutex_lock(&tty->termios_mutex);
+ down_write(&tty->termios_rwsem);
if (test_bit(TTY_THROTTLED, &tty->flags)) {
if (tty->flow_change != TTY_UNTHROTTLE_SAFE)
ret = 1;
@@ -192,7 +192,7 @@
tty->ops->unthrottle(tty);
}
}
- mutex_unlock(&tty->termios_mutex);
+ up_write(&tty->termios_rwsem);
return ret;
}
@@ -468,7 +468,7 @@
* @obad: output baud rate
*
* Update the current termios data for the tty with the new speed
- * settings. The caller must hold the termios_mutex for the tty in
+ * settings. The caller must hold the termios_rwsem for the tty in
* question.
*/
@@ -528,7 +528,7 @@
* is a bit of layering violation here with n_tty in terms of the
* internal knowledge of this function.
*
- * Locking: termios_mutex
+ * Locking: termios_rwsem
*/
int tty_set_termios(struct tty_struct *tty, struct ktermios *new_termios)
@@ -544,7 +544,7 @@
/* FIXME: we need to decide on some locking/ordering semantics
for the set_termios notification eventually */
- mutex_lock(&tty->termios_mutex);
+ down_write(&tty->termios_rwsem);
old_termios = tty->termios;
tty->termios = *new_termios;
unset_locked_termios(&tty->termios, &old_termios, &tty->termios_locked);
@@ -586,7 +586,7 @@
(ld->ops->set_termios)(tty, &old_termios);
tty_ldisc_deref(ld);
}
- mutex_unlock(&tty->termios_mutex);
+ up_write(&tty->termios_rwsem);
return 0;
}
EXPORT_SYMBOL_GPL(tty_set_termios);
@@ -601,7 +601,7 @@
* functions before using tty_set_termios to do the actual changes.
*
* Locking:
- * Called functions take ldisc and termios_mutex locks
+ * Called functions take ldisc and termios_rwsem locks
*/
static int set_termios(struct tty_struct *tty, void __user *arg, int opt)
@@ -613,9 +613,9 @@
if (retval)
return retval;
- mutex_lock(&tty->termios_mutex);
+ down_read(&tty->termios_rwsem);
tmp_termios = tty->termios;
- mutex_unlock(&tty->termios_mutex);
+ up_read(&tty->termios_rwsem);
if (opt & TERMIOS_TERMIO) {
if (user_termio_to_kernel_termios(&tmp_termios,
@@ -667,16 +667,16 @@
static void copy_termios(struct tty_struct *tty, struct ktermios *kterm)
{
- mutex_lock(&tty->termios_mutex);
+ down_read(&tty->termios_rwsem);
*kterm = tty->termios;
- mutex_unlock(&tty->termios_mutex);
+ up_read(&tty->termios_rwsem);
}
static void copy_termios_locked(struct tty_struct *tty, struct ktermios *kterm)
{
- mutex_lock(&tty->termios_mutex);
+ down_read(&tty->termios_rwsem);
*kterm = tty->termios_locked;
- mutex_unlock(&tty->termios_mutex);
+ up_read(&tty->termios_rwsem);
}
static int get_termio(struct tty_struct *tty, struct termio __user *termio)
@@ -723,10 +723,10 @@
return -ERESTARTSYS;
}
- mutex_lock(&tty->termios_mutex);
+ down_write(&tty->termios_rwsem);
if (tty->ops->set_termiox)
tty->ops->set_termiox(tty, &tnew);
- mutex_unlock(&tty->termios_mutex);
+ up_write(&tty->termios_rwsem);
return 0;
}
@@ -761,13 +761,13 @@
{
struct sgttyb tmp;
- mutex_lock(&tty->termios_mutex);
+ down_read(&tty->termios_rwsem);
tmp.sg_ispeed = tty->termios.c_ispeed;
tmp.sg_ospeed = tty->termios.c_ospeed;
tmp.sg_erase = tty->termios.c_cc[VERASE];
tmp.sg_kill = tty->termios.c_cc[VKILL];
tmp.sg_flags = get_sgflags(tty);
- mutex_unlock(&tty->termios_mutex);
+ up_read(&tty->termios_rwsem);
return copy_to_user(sgttyb, &tmp, sizeof(tmp)) ? -EFAULT : 0;
}
@@ -806,7 +806,7 @@
* Updates a terminal from the legacy BSD style terminal information
* structure.
*
- * Locking: termios_mutex
+ * Locking: termios_rwsem
*/
static int set_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)
@@ -822,7 +822,7 @@
if (copy_from_user(&tmp, sgttyb, sizeof(tmp)))
return -EFAULT;
- mutex_lock(&tty->termios_mutex);
+ down_write(&tty->termios_rwsem);
termios = tty->termios;
termios.c_cc[VERASE] = tmp.sg_erase;
termios.c_cc[VKILL] = tmp.sg_kill;
@@ -832,7 +832,7 @@
tty_termios_encode_baud_rate(&termios, termios.c_ispeed,
termios.c_ospeed);
#endif
- mutex_unlock(&tty->termios_mutex);
+ up_write(&tty->termios_rwsem);
tty_set_termios(tty, &termios);
return 0;
}
@@ -843,14 +843,14 @@
{
struct tchars tmp;
- mutex_lock(&tty->termios_mutex);
+ down_read(&tty->termios_rwsem);
tmp.t_intrc = tty->termios.c_cc[VINTR];
tmp.t_quitc = tty->termios.c_cc[VQUIT];
tmp.t_startc = tty->termios.c_cc[VSTART];
tmp.t_stopc = tty->termios.c_cc[VSTOP];
tmp.t_eofc = tty->termios.c_cc[VEOF];
tmp.t_brkc = tty->termios.c_cc[VEOL2]; /* what is brkc anyway? */
- mutex_unlock(&tty->termios_mutex);
+ up_read(&tty->termios_rwsem);
return copy_to_user(tchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
}
@@ -860,14 +860,14 @@
if (copy_from_user(&tmp, tchars, sizeof(tmp)))
return -EFAULT;
- mutex_lock(&tty->termios_mutex);
+ down_write(&tty->termios_rwsem);
tty->termios.c_cc[VINTR] = tmp.t_intrc;
tty->termios.c_cc[VQUIT] = tmp.t_quitc;
tty->termios.c_cc[VSTART] = tmp.t_startc;
tty->termios.c_cc[VSTOP] = tmp.t_stopc;
tty->termios.c_cc[VEOF] = tmp.t_eofc;
tty->termios.c_cc[VEOL2] = tmp.t_brkc; /* what is brkc anyway? */
- mutex_unlock(&tty->termios_mutex);
+ up_write(&tty->termios_rwsem);
return 0;
}
#endif
@@ -877,7 +877,7 @@
{
struct ltchars tmp;
- mutex_lock(&tty->termios_mutex);
+ down_read(&tty->termios_rwsem);
tmp.t_suspc = tty->termios.c_cc[VSUSP];
/* what is dsuspc anyway? */
tmp.t_dsuspc = tty->termios.c_cc[VSUSP];
@@ -886,7 +886,7 @@
tmp.t_flushc = tty->termios.c_cc[VEOL2];
tmp.t_werasc = tty->termios.c_cc[VWERASE];
tmp.t_lnextc = tty->termios.c_cc[VLNEXT];
- mutex_unlock(&tty->termios_mutex);
+ up_read(&tty->termios_rwsem);
return copy_to_user(ltchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
}
@@ -897,7 +897,7 @@
if (copy_from_user(&tmp, ltchars, sizeof(tmp)))
return -EFAULT;
- mutex_lock(&tty->termios_mutex);
+ down_write(&tty->termios_rwsem);
tty->termios.c_cc[VSUSP] = tmp.t_suspc;
/* what is dsuspc anyway? */
tty->termios.c_cc[VEOL2] = tmp.t_dsuspc;
@@ -906,7 +906,7 @@
tty->termios.c_cc[VEOL2] = tmp.t_flushc;
tty->termios.c_cc[VWERASE] = tmp.t_werasc;
tty->termios.c_cc[VLNEXT] = tmp.t_lnextc;
- mutex_unlock(&tty->termios_mutex);
+ up_write(&tty->termios_rwsem);
return 0;
}
#endif
@@ -946,7 +946,7 @@
* @arg: enable/disable CLOCAL
*
* Perform a change to the CLOCAL state and call into the driver
- * layer to make it visible. All done with the termios mutex
+ * layer to make it visible. All done with the termios rwsem
*/
static int tty_change_softcar(struct tty_struct *tty, int arg)
@@ -955,7 +955,7 @@
int bit = arg ? CLOCAL : 0;
struct ktermios old;
- mutex_lock(&tty->termios_mutex);
+ down_write(&tty->termios_rwsem);
old = tty->termios;
tty->termios.c_cflag &= ~CLOCAL;
tty->termios.c_cflag |= bit;
@@ -963,7 +963,7 @@
tty->ops->set_termios(tty, &old);
if ((tty->termios.c_cflag & CLOCAL) != bit)
ret = -EINVAL;
- mutex_unlock(&tty->termios_mutex);
+ up_write(&tty->termios_rwsem);
return ret;
}
@@ -1066,9 +1066,9 @@
if (user_termios_to_kernel_termios(&kterm,
(struct termios __user *) arg))
return -EFAULT;
- mutex_lock(&real_tty->termios_mutex);
+ down_write(&real_tty->termios_rwsem);
real_tty->termios_locked = kterm;
- mutex_unlock(&real_tty->termios_mutex);
+ up_write(&real_tty->termios_rwsem);
return 0;
#else
case TIOCGLCKTRMIOS:
@@ -1083,9 +1083,9 @@
if (user_termios_to_kernel_termios_1(&kterm,
(struct termios __user *) arg))
return -EFAULT;
- mutex_lock(&real_tty->termios_mutex);
+ down_write(&real_tty->termios_rwsem);
real_tty->termios_locked = kterm;
- mutex_unlock(&real_tty->termios_mutex);
+ up_write(&real_tty->termios_rwsem);
return ret;
#endif
#ifdef TCGETX
@@ -1093,9 +1093,9 @@
struct termiox ktermx;
if (real_tty->termiox == NULL)
return -EINVAL;
- mutex_lock(&real_tty->termios_mutex);
+ down_read(&real_tty->termios_rwsem);
memcpy(&ktermx, real_tty->termiox, sizeof(struct termiox));
- mutex_unlock(&real_tty->termios_mutex);
+ up_read(&real_tty->termios_rwsem);
if (copy_to_user(p, &ktermx, sizeof(struct termiox)))
ret = -EFAULT;
return ret;