tty: Document locking for tty driver methods

The tty core calls the tty driver's open, close and hangup
methods holding the tty lock.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index 756a60989294..e48c608a8fa8 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -35,14 +35,14 @@
  *      This routine is mandatory; if this routine is not filled in,
  *      the attempted open will fail with ENODEV.
  *
- *      Required method.
- *     
+ *      Required method. Called with tty lock held.
+ *
  * void (*close)(struct tty_struct * tty, struct file * filp);
  *
  *      This routine is called when a particular tty device is closed.
  *      Note: called even if the corresponding open() failed.
  *
- *      Required method.
+ *      Required method. Called with tty lock held.
  *
  * void (*shutdown)(struct tty_struct * tty);
  *
@@ -172,6 +172,8 @@
  *
  *      Optional:
  *
+ *      Called with tty lock held.
+ *
  * int (*break_ctl)(struct tty_struct *tty, int state);
  *
  *      This optional routine requests the tty driver to turn on or