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>

2 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/tty.h b/include/linux/tty.h
index c36a76da2ae2..7f7121f9c968 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -303,6 +303,8 @@ extern int tty_put_char(struct tty_struct *tty, unsigned char c);
 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 --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index f80d73b690f6..59f1c0bd8f9c 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -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);
  *
@@ -107,6 +109,8 @@
  *      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