tty: release BTM while sleeping in block_til_ready

Most tty drivers may block while opening a device.
Since this possibly depends on another thread
closing it first and both threads may need the BTM,
we need to release it here.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/char/serial167.c b/drivers/char/serial167.c
index 90b3ec0aabdd..f646725bd567 100644
--- a/drivers/char/serial167.c
+++ b/drivers/char/serial167.c
@@ -1786,7 +1786,9 @@ block_til_ready(struct tty_struct *tty, struct file *filp,
                        tty->name, info->count);
                 /**/
 #endif
-                    schedule();
+                tty_unlock();
+                schedule();
+                tty_lock();
         }
         __set_current_state(TASK_RUNNING);
         remove_wait_queue(&info->open_wait, &wait);