tty_port: add "tty_port_open" helper

For the moment this just moves the USB logic over and fixes the 'what if
we open and hangup at the same time' race noticed by Oliver Neukum.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 9 insertions, 1 deletions

diff --git a/include/linux/tty.h b/include/linux/tty.h
index f0f43d08d8b8..6352ac257fcb 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -190,9 +190,15 @@ struct tty_port_operations {
         /* Control the DTR line */
         void (*dtr_rts)(struct tty_port *port, int raise);
         /* Called when the last close completes or a hangup finishes
-           IFF the port was initialized. Do not use to free resources */
+           IFF the port was initialized. Do not use to free resources. Called
+           under the port mutex to serialize against activate/shutdowns */
         void (*shutdown)(struct tty_port *port);
         void (*drop)(struct tty_port *port);
+        /* Called under the port mutex from tty_port_open, serialized using
+           the port mutex */
+        /* FIXME: long term getting the tty argument *out* of this would be
+           good for consoles */
+        int (*activate)(struct tty_port *port, struct tty_struct *tty);
 };
         
 struct tty_port {
@@ -467,6 +473,8 @@ extern int tty_port_close_start(struct tty_port *port,
 extern void tty_port_close_end(struct tty_port *port, struct tty_struct *tty);
 extern void tty_port_close(struct tty_port *port,
                                 struct tty_struct *tty, struct file *filp);
+extern int tty_port_open(struct tty_port *port,
+                                struct tty_struct *tty, struct file *filp);
 extern inline int tty_port_users(struct tty_port *port)
 {
         return port->count + port->blocked_open;