tty: Add throttle/unthrottle helpers

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.25-mm1/drivers/char/tty_ioctl.c linux-2.6.25-mm1/drivers/char/tty_ioctl.c
@@ -67,6 +67,24 @@
 
 EXPORT_SYMBOL(tty_driver_flush_buffer);
 
+void tty_throttle(struct tty_struct *tty)
+{
+	/* 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);
+}
+
+EXPORT_SYMBOL(tty_throttle);
+
+void tty_unthrottle(struct tty_struct *tty)
+{
+	if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
+	    tty->ops->unthrottle)
+		tty->ops->unthrottle(tty);
+}
+
+EXPORT_SYMBOL(tty_unthrottle);
 
 /**
  *	tty_wait_until_sent	-	wait for I/O to finish

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.25-mm1/include/linux/tty_driver.h linux-2.6.25-mm1/include/linux/tty_driver.h
@@ -83,10 +83,10 @@
  * void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
  *
  * 	This routine allows the tty driver to be notified when
- * 	device's termios settings have changed.
+ * 	device's termios settings have changed.
  *
  *	Optional: Called under the termios lock
  *
  *
  * void (*set_ldisc)(struct tty_struct *tty);
  *

@@ -100,6 +100,8 @@
  * 	This routine notifies the tty driver that input buffers for
  * 	the line discipline are close to full, and it should somehow
  * 	signal that no more characters should be sent to the tty.
+ *
+ *	Optional: Always invoke via tty_throttle();
  * 
  * void (*unthrottle)(struct tty_struct * tty);
  *

@@ -107,12 +109,14 @@
  * 	that characters can now be sent to the tty without fear of
  * 	overrunning the input buffers of the line disciplines.
  * 
+ *	Optional: Always invoke via tty_unthrottle();
+ *
  * void (*stop)(struct tty_struct *tty);
  *
  * 	This routine notifies the tty driver that it should stop
  * 	outputting characters to the tty device.  
  *
- *	Optional:
+ *	Optional: 
  *
  *	Note: Call stop_tty not this method.
  * 

@@ -141,7 +145,7 @@
  *
  * 	If this routine is implemented, the high-level tty driver will
  * 	handle the following ioctls: TCSBRK, TCSBRKP, TIOCSBRK,
- * 	TIOCCBRK.
+ * 	TIOCCBRK. 
  *
  *	Optional: Required for TCSBRK/BRKP/etc handling.
  *

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.25-mm1/include/linux/tty.h linux-2.6.25-mm1/include/linux/tty.h
@@ -303,6 +321,8 @@
 extern int tty_chars_in_buffer(struct tty_struct *tty);
 extern int tty_write_room(struct tty_struct *tty);
 extern void tty_driver_flush_buffer(struct tty_struct *tty);
+extern void tty_throttle(struct tty_struct *tty);
+extern void tty_unthrottle(struct tty_struct *tty);
 
 extern int is_current_pgrp_orphaned(void);
 extern struct pid *tty_get_pgrp(struct tty_struct *tty);

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.25-mm1/drivers/bluetooth/hci_ldisc.c linux-2.6.25-mm1/drivers/bluetooth/hci_ldisc.c
@@ -370,9 +370,7 @@
 	hu->hdev->stat.byte_rx += count;
 	spin_unlock(&hu->rx_lock);
 
-	if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
-					tty->ops->unthrottle)
-		tty->ops->unthrottle(tty);
+	tty_unthrottle(tty);
 }
 
 static int hci_uart_register_dev(struct hci_uart *hu)

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.25-mm1/drivers/char/n_tty.c linux-2.6.25-mm1/drivers/char/n_tty.c
@@ -147,10 +147,8 @@
 
 static void check_unthrottle(struct tty_struct *tty)
 {
-	if (tty->count &&
-	    test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
-	    tty->ops->unthrottle)
-		tty->ops->unthrottle(tty);
+	if (tty->count)
+		tty_unthrottle(tty);
 }
 
 /**

@@ -982,12 +980,8 @@
 	 * mode.  We don't want to throttle the driver if we're in
 	 * canonical mode and don't have a newline yet!
 	 */
-	if (tty->receive_room < TTY_THRESHOLD_THROTTLE) {
-		/* 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);
-	}
+	if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
+		tty_throttle(tty);
 }
 
 int is_ignored(int sig)

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.25-mm1/drivers/net/hamradio/6pack.c linux-2.6.25-mm1/drivers/net/hamradio/6pack.c
@@ -491,9 +491,7 @@
 	sixpack_decode(sp, buf, count1);
 
 	sp_put(sp);
-	if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
-	    && tty->ops->unthrottle)
-		tty->ops->unthrottle(tty);
+	tty_unthrottle(tty);
 }
 
 /*

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.25-mm1/drivers/net/hamradio/mkiss.c linux-2.6.25-mm1/drivers/net/hamradio/mkiss.c
@@ -936,9 +936,7 @@
 	}
 
 	mkiss_put(ax);
-	if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
-	    && tty->ops->unthrottle)
-		tty->ops->unthrottle(tty);
+	tty_unthrottle(tty);
 }
 
 /*

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.25-mm1/drivers/net/ppp_async.c linux-2.6.25-mm1/drivers/net/ppp_async.c
@@ -361,9 +361,7 @@
 	if (!skb_queue_empty(&ap->rqueue))
 		tasklet_schedule(&ap->tsk);
 	ap_put(ap);
-	if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
-	    && tty->ops->unthrottle)
-		tty->ops->unthrottle(tty);
+	tty_unthrottle(tty);
 }
 
 static void

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.25-mm1/drivers/net/ppp_synctty.c linux-2.6.25-mm1/drivers/net/ppp_synctty.c
@@ -401,9 +401,7 @@
 	if (!skb_queue_empty(&ap->rqueue))
 		tasklet_schedule(&ap->tsk);
 	sp_put(ap);
-	if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
-	    && tty->ops->unthrottle)
-		tty->ops->unthrottle(tty);
+	tty_unthrottle(tty);
 }
 
 static void