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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.c120
1 files changed, 83 insertions, 37 deletions
diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index d58b92cc187c..3500d4114147 100644
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -106,6 +106,7 @@ void tty_throttle(struct tty_struct *tty)
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);
}
EXPORT_SYMBOL(tty_throttle);
@@ -129,11 +130,74 @@ void tty_unthrottle(struct tty_struct *tty)
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);
}
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->termios_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->termios_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->termios_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->termios_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
@@ -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
@@ -1086,14 +1122,12 @@ 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) {
@@ -1111,12 +1145,24 @@ int tty_perform_flush(struct tty_struct *tty, unsigned long arg)
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,
@@ -1155,7 +1201,7 @@ int n_tty_ioctl_helper(struct tty_struct *tty, struct file *file,
}
return 0;
case TCFLSH:
- return tty_perform_flush(tty, arg);
+ return __tty_perform_flush(tty, arg);
default:
/* Try the mode commands */
return tty_mode_ioctl(tty, file, cmd, arg);
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