[PATCH 5/8] serdev: ttyport: fix tty locking in close

[Johan Hovold]

Make sure to hold the tty lock as required when calling tty-driver
close() (e.g. to avoid racing with hangup()).

Note that the serport active flag is currently set under the lock at
controller open, but really isn't protected by it.

Fixes: cd6484e1830b ("serdev: Introduce new bus for serial attached devices")
Signed-off-by: Johan Hovold <jo...@kernel.org>
---
 drivers/tty/serdev/serdev-ttyport.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/tty/serdev/serdev-ttyport.c 
b/drivers/tty/serdev/serdev-ttyport.c
index 31c05665a0e6..334bce00364f 100644
--- a/drivers/tty/serdev/serdev-ttyport.c
+++ b/drivers/tty/serdev/serdev-ttyport.c
@@ -162,8 +162,10 @@ static void ttyport_close(struct serdev_controller *ctrl)
 
        clear_bit(SERPORT_ACTIVE, &serport->flags);
 
+       tty_lock(tty);
        if (tty->ops->close)
                tty->ops->close(tty, NULL);
+       tty_unlock(tty);
 
        tty_release_struct(tty, serport->tty_idx);
 }
-- 
2.15.0