tty: add throttle/unthrottle helpers

Something Arjan suggested which allows us to clean up the code nicely

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 16 insertions, 0 deletions

diff --git a/drivers/char/tty_ioctl.c b/drivers/char/tty_ioctl.c
index c10d40c4c5ca..b1a757a5ee27 100644
--- a/drivers/char/tty_ioctl.c
+++ b/drivers/char/tty_ioctl.c
@@ -67,6 +67,22 @@ void tty_driver_flush_buffer(struct tty_struct *tty)
 
 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