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path: root/drivers/tty/tty_ioctl.c
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Diffstat (limited to 'drivers/tty/tty_ioctl.c')
-rw-r--r--drivers/tty/tty_ioctl.c217
1 files changed, 135 insertions, 82 deletions
diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index 8481b29d5b3..6fd60fece6b 100644
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -94,19 +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);
- mutex_unlock(&tty->termios_mutex);
+ tty->flow_change = 0;
+ up_write(&tty->termios_rwsem);
}
EXPORT_SYMBOL(tty_throttle);
@@ -115,7 +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.
*
@@ -125,15 +126,78 @@ 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);
- mutex_unlock(&tty->termios_mutex);
+ tty->flow_change = 0;
+ up_write(&tty->termios_rwsem);
}
EXPORT_SYMBOL(tty_unthrottle);
/**
+ * tty_throttle_safe - flow control
+ * @tty: terminal
+ *
+ * Similar to tty_throttle() but will only attempt throttle
+ * if tty->flow_change is TTY_THROTTLE_SAFE. Prevents an accidental
+ * throttle due to race conditions when throttling is conditional
+ * on factors evaluated prior to throttling.
+ *
+ * Returns 0 if tty is throttled (or was already throttled)
+ */
+
+int tty_throttle_safe(struct tty_struct *tty)
+{
+ int ret = 0;
+
+ mutex_lock(&tty->throttle_mutex);
+ if (!test_bit(TTY_THROTTLED, &tty->flags)) {
+ if (tty->flow_change != TTY_THROTTLE_SAFE)
+ ret = 1;
+ else {
+ set_bit(TTY_THROTTLED, &tty->flags);
+ if (tty->ops->throttle)
+ tty->ops->throttle(tty);
+ }
+ }
+ mutex_unlock(&tty->throttle_mutex);
+
+ return ret;
+}
+
+/**
+ * tty_unthrottle_safe - flow control
+ * @tty: terminal
+ *
+ * Similar to tty_unthrottle() but will only attempt unthrottle
+ * if tty->flow_change is TTY_UNTHROTTLE_SAFE. Prevents an accidental
+ * unthrottle due to race conditions when unthrottling is conditional
+ * on factors evaluated prior to unthrottling.
+ *
+ * Returns 0 if tty is unthrottled (or was already unthrottled)
+ */
+
+int tty_unthrottle_safe(struct tty_struct *tty)
+{
+ int ret = 0;
+
+ mutex_lock(&tty->throttle_mutex);
+ if (test_bit(TTY_THROTTLED, &tty->flags)) {
+ if (tty->flow_change != TTY_UNTHROTTLE_SAFE)
+ ret = 1;
+ else {
+ clear_bit(TTY_THROTTLED, &tty->flags);
+ if (tty->ops->unthrottle)
+ tty->ops->unthrottle(tty);
+ }
+ }
+ mutex_unlock(&tty->throttle_mutex);
+
+ return ret;
+}
+
+/**
* tty_wait_until_sent - wait for I/O to finish
* @tty: tty we are waiting for
* @timeout: how long we will wait
@@ -404,7 +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.
*/
@@ -415,34 +479,6 @@ void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud, speed_t obaud)
EXPORT_SYMBOL_GPL(tty_encode_baud_rate);
/**
- * tty_get_baud_rate - get tty bit rates
- * @tty: tty to query
- *
- * Returns the baud rate as an integer for this terminal. The
- * termios lock must be held by the caller and the terminal bit
- * flags may be updated.
- *
- * Locking: none
- */
-
-speed_t tty_get_baud_rate(struct tty_struct *tty)
-{
- speed_t baud = tty_termios_baud_rate(&tty->termios);
-
- if (baud == 38400 && tty->alt_speed) {
- if (!tty->warned) {
- printk(KERN_WARNING "Use of setserial/setrocket to "
- "set SPD_* flags is deprecated\n");
- tty->warned = 1;
- }
- baud = tty->alt_speed;
- }
-
- return baud;
-}
-EXPORT_SYMBOL(tty_get_baud_rate);
-
-/**
* tty_termios_copy_hw - copy hardware settings
* @new: New termios
* @old: Old termios
@@ -492,7 +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)
@@ -508,7 +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);
@@ -550,7 +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);
@@ -565,7 +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)
@@ -577,9 +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,
@@ -617,7 +653,7 @@ static int set_termios(struct tty_struct *tty, void __user *arg, int opt)
if (opt & TERMIOS_WAIT) {
tty_wait_until_sent(tty, 0);
if (signal_pending(current))
- return -EINTR;
+ return -ERESTARTSYS;
}
tty_set_termios(tty, &tmp_termios);
@@ -631,16 +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)
@@ -684,13 +720,13 @@ static int set_termiox(struct tty_struct *tty, void __user *arg, int opt)
if (opt & TERMIOS_WAIT) {
tty_wait_until_sent(tty, 0);
if (signal_pending(current))
- return -EINTR;
+ 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;
}
@@ -725,13 +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;
}
@@ -770,7 +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)
@@ -786,7 +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;
@@ -796,7 +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;
}
@@ -807,14 +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;
}
@@ -824,14 +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
@@ -841,7 +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];
@@ -850,7 +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;
}
@@ -861,7 +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;
@@ -870,7 +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
@@ -910,7 +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)
@@ -919,7 +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;
@@ -927,7 +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;
}
@@ -1030,9 +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:
@@ -1047,9 +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
@@ -1057,9 +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;
@@ -1086,33 +1122,47 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
}
EXPORT_SYMBOL_GPL(tty_mode_ioctl);
-int tty_perform_flush(struct tty_struct *tty, unsigned long arg)
+
+/* Caller guarantees ldisc reference is held */
+static int __tty_perform_flush(struct tty_struct *tty, unsigned long arg)
{
- struct tty_ldisc *ld;
- int retval = tty_check_change(tty);
- if (retval)
- return retval;
+ struct tty_ldisc *ld = tty->ldisc;
- ld = tty_ldisc_ref_wait(tty);
switch (arg) {
case TCIFLUSH:
- if (ld && ld->ops->flush_buffer)
+ if (ld && ld->ops->flush_buffer) {
ld->ops->flush_buffer(tty);
+ tty_unthrottle(tty);
+ }
break;
case TCIOFLUSH:
- if (ld && ld->ops->flush_buffer)
+ if (ld && ld->ops->flush_buffer) {
ld->ops->flush_buffer(tty);
+ tty_unthrottle(tty);
+ }
/* fall through */
case TCOFLUSH:
tty_driver_flush_buffer(tty);
break;
default:
- tty_ldisc_deref(ld);
return -EINVAL;
}
- tty_ldisc_deref(ld);
return 0;
}
+
+int tty_perform_flush(struct tty_struct *tty, unsigned long arg)
+{
+ struct tty_ldisc *ld;
+ int retval = tty_check_change(tty);
+ if (retval)
+ return retval;
+
+ ld = tty_ldisc_ref_wait(tty);
+ retval = __tty_perform_flush(tty, arg);
+ if (ld)
+ tty_ldisc_deref(ld);
+ return retval;
+}
EXPORT_SYMBOL_GPL(tty_perform_flush);
int n_tty_ioctl_helper(struct tty_struct *tty, struct file *file,
@@ -1151,7 +1201,10 @@ int n_tty_ioctl_helper(struct tty_struct *tty, struct file *file,
}
return 0;
case TCFLSH:
- return tty_perform_flush(tty, arg);
+ retval = tty_check_change(tty);
+ if (retval)
+ return retval;
+ return __tty_perform_flush(tty, arg);
default:
/* Try the mode commands */
return tty_mode_ioctl(tty, file, cmd, arg);
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-11-09 23:26:24 +0000