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tty: Convert termios_mutex to termios_rwsem

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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>
tirimbino
Peter Hurley 12 years ago committed by Greg Kroah-Hartman
parent a2f73be8ee
commit 6a1c0680cf
8 changed files with 70 additions and 69 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 8
      drivers/net/irda/irtty-sir.c
  2. 2
      drivers/tty/n_tty.c
  3. 4
      drivers/tty/pty.c
  4. 14
      drivers/tty/tty_io.c
  5. 90
      drivers/tty/tty_ioctl.c
  6. 10
      drivers/tty/tty_ldisc.c
  7. 4
      drivers/tty/vt/vt.c
  8. 7
      include/linux/tty.h

8
drivers/net/irda/irtty-sir.c
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@ -123,14 +123,14 @@ static int irtty_change_speed(struct sir_dev *dev, unsigned speed)
tty = priv->tty;
mutex_lock(&tty->termios_mutex);
down_write(&tty->termios_rwsem);
old_termios = tty->termios;
cflag = tty->termios.c_cflag;
tty_encode_baud_rate(tty, speed, speed);
if (tty->ops->set_termios)
tty->ops->set_termios(tty, &old_termios);
priv->io.speed = speed;
mutex_unlock(&tty->termios_mutex);
up_write(&tty->termios_rwsem);
return 0;
}
@ -280,7 +280,7 @@ static inline void irtty_stop_receiver(struct tty_struct *tty, int stop)
struct ktermios old_termios;
int cflag;
mutex_lock(&tty->termios_mutex);
down_write(&tty->termios_rwsem);
old_termios = tty->termios;
cflag = tty->termios.c_cflag;
@ -292,7 +292,7 @@ static inline void irtty_stop_receiver(struct tty_struct *tty, int stop)
tty->termios.c_cflag = cflag;
if (tty->ops->set_termios)
tty->ops->set_termios(tty, &old_termios);
mutex_unlock(&tty->termios_mutex);
up_write(&tty->termios_rwsem);
}
/*****************************************************************/

2
drivers/tty/n_tty.c
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@ -1539,7 +1539,7 @@ int is_ignored(int sig)
* guaranteed that this function will not be re-entered or in progress
* when the ldisc is closed.
*
* Locking: Caller holds tty->termios_mutex
* Locking: Caller holds tty->termios_rwsem
*/
static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)

4
drivers/tty/pty.c
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@ -287,7 +287,7 @@ static int pty_resize(struct tty_struct *tty, struct winsize *ws)
struct tty_struct *pty = tty->link;
/* For a PTY we need to lock the tty side */
mutex_lock(&tty->termios_mutex);
down_write(&tty->termios_rwsem);
if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
goto done;
@ -314,7 +314,7 @@ static int pty_resize(struct tty_struct *tty, struct winsize *ws)
tty->winsize = *ws;
pty->winsize = *ws; /* Never used so will go away soon */
done:
mutex_unlock(&tty->termios_mutex);
up_write(&tty->termios_rwsem);
return 0;
}

14
drivers/tty/tty_io.c
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@ -604,7 +604,7 @@ static int tty_signal_session_leader(struct tty_struct *tty, int exit_session)
* redirect lock for undoing redirection
* file list lock for manipulating list of ttys
* tty_ldiscs_lock from called functions
* termios_mutex resetting termios data
* termios_rwsem resetting termios data
* tasklist_lock to walk task list for hangup event
* ->siglock to protect ->signal/->sighand
*/
@ -2230,7 +2230,7 @@ static int tiocsti(struct tty_struct *tty, char __user *p)
*
* Copies the kernel idea of the window size into the user buffer.
*
* Locking: tty->termios_mutex is taken to ensure the winsize data
* Locking: tty->termios_rwsem is taken to ensure the winsize data
* is consistent.
*/
@ -2238,9 +2238,9 @@ static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
{
int err;
mutex_lock(&tty->termios_mutex);
down_read(&tty->termios_rwsem);
err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
mutex_unlock(&tty->termios_mutex);
up_read(&tty->termios_rwsem);
return err ? -EFAULT: 0;
}
@ -2261,7 +2261,7 @@ int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
unsigned long flags;
/* Lock the tty */
mutex_lock(&tty->termios_mutex);
down_write(&tty->termios_rwsem);
if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
goto done;
/* Get the PID values and reference them so we can
@ -2276,7 +2276,7 @@ int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
tty->winsize = *ws;
done:
mutex_unlock(&tty->termios_mutex);
up_write(&tty->termios_rwsem);
return 0;
}
EXPORT_SYMBOL(tty_do_resize);
@ -3015,7 +3015,7 @@ void initialize_tty_struct(struct tty_struct *tty,
tty->session = NULL;
tty->pgrp = NULL;
mutex_init(&tty->legacy_mutex);
mutex_init(&tty->termios_mutex);
init_rwsem(&tty->termios_rwsem);
init_ldsem(&tty->ldisc_sem);
init_waitqueue_head(&tty->write_wait);
init_waitqueue_head(&tty->read_wait);

90
drivers/tty/tty_ioctl.c
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@ -94,20 +94,20 @@ EXPORT_SYMBOL(tty_driver_flush_buffer);
* @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 @@ EXPORT_SYMBOL(tty_throttle);
* @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 @@ EXPORT_SYMBOL(tty_throttle);
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 tty_throttle_safe(struct tty_struct *tty)
{
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 @@ int tty_throttle_safe(struct tty_struct *tty)
tty->ops->throttle(tty);
}
}
mutex_unlock(&tty->termios_mutex);
up_write(&tty->termios_rwsem);
return ret;
}
@ -182,7 +182,7 @@ int tty_unthrottle_safe(struct tty_struct *tty)
{
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 @@ int tty_unthrottle_safe(struct tty_struct *tty)
tty->ops->unthrottle(tty);
}
}
mutex_unlock(&tty->termios_mutex);
up_write(&tty->termios_rwsem);
return ret;
}
@ -468,7 +468,7 @@ EXPORT_SYMBOL_GPL(tty_termios_encode_baud_rate);
* @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 @@ EXPORT_SYMBOL(tty_termios_hw_change);
* 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 @@ int tty_set_termios(struct tty_struct *tty, struct ktermios *new_termios)
/* 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 @@ int tty_set_termios(struct tty_struct *tty, struct ktermios *new_termios)
(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 @@ EXPORT_SYMBOL_GPL(tty_set_termios);
* 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 @@ static int set_termios(struct tty_struct *tty, void __user *arg, int opt)
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 int set_termios(struct tty_struct *tty, void __user *arg, int opt)
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 @@ static int set_termiox(struct tty_struct *tty, void __user *arg, int opt)
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 @@ static int get_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)
{
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 @@ static void set_sgflags(struct ktermios *termios, int flags)
* 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 @@ static int set_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)
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 @@ static int set_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)
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 @@ static int get_tchars(struct tty_struct *tty, struct tchars __user *tchars)
{
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 @@ static int set_tchars(struct tty_struct *tty, struct tchars __user *tchars)
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 @@ static int get_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
{
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 @@ static int get_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
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 @@ static int set_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
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 @@ static int set_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
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 @@ static int send_prio_char(struct tty_struct *tty, char ch)
* @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 @@ static int tty_change_softcar(struct tty_struct *tty, int arg)
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 @@ static int tty_change_softcar(struct tty_struct *tty, int arg)
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 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
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 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
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 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
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;

10
drivers/tty/tty_ldisc.c
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@ -415,14 +415,14 @@ EXPORT_SYMBOL_GPL(tty_ldisc_flush);
* they are not on hot paths so a little discipline won't do
* any harm.
*
* Locking: takes termios_mutex
* Locking: takes termios_rwsem
*/
static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
{
mutex_lock(&tty->termios_mutex);
down_write(&tty->termios_rwsem);
tty->termios.c_line = num;
mutex_unlock(&tty->termios_mutex);
up_write(&tty->termios_rwsem);
}
/**
@ -602,11 +602,11 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
static void tty_reset_termios(struct tty_struct *tty)
{
mutex_lock(&tty->termios_mutex);
down_write(&tty->termios_rwsem);
tty->termios = tty->driver->init_termios;
tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
mutex_unlock(&tty->termios_mutex);
up_write(&tty->termios_rwsem);
}

4
drivers/tty/vt/vt.c
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@ -828,7 +828,7 @@ static inline int resize_screen(struct vc_data *vc, int width, int height,
* If the caller passes a tty structure then update the termios winsize
* information and perform any necessary signal handling.
*
* Caller must hold the console semaphore. Takes the termios mutex and
* Caller must hold the console semaphore. Takes the termios rwsem and
* ctrl_lock of the tty IFF a tty is passed.
*/
@ -972,7 +972,7 @@ int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int rows)
* the actual work.
*
* Takes the console sem and the called methods then take the tty
* termios_mutex and the tty ctrl_lock in that order.
* termios_rwsem and the tty ctrl_lock in that order.
*/
static int vt_resize(struct tty_struct *tty, struct winsize *ws)
{

7
include/linux/tty.h
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@ -10,6 +10,7 @@
#include <linux/mutex.h>
#include <linux/tty_flags.h>
#include <uapi/linux/tty.h>
#include <linux/rwsem.h>
@ -243,9 +244,9 @@ struct tty_struct {
struct mutex atomic_write_lock;
struct mutex legacy_mutex;
struct mutex termios_mutex;
struct rw_semaphore termios_rwsem;
spinlock_t ctrl_lock;
/* Termios values are protected by the termios mutex */
/* Termios values are protected by the termios rwsem */
struct ktermios termios, termios_locked;
struct termiox *termiox; /* May be NULL for unsupported */
char name[64];
@ -253,7 +254,7 @@ struct tty_struct {
struct pid *session;
unsigned long flags;
int count;
struct winsize winsize; /* termios mutex */
struct winsize winsize; /* termios rwsem */
unsigned char stopped:1, hw_stopped:1, flow_stopped:1, packet:1;
unsigned char ctrl_status; /* ctrl_lock */
unsigned int receive_room; /* Bytes free for queue */

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