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, 2 insertions, 0 deletions

diff --git a/drivers/char/synclink_gt.c b/drivers/char/synclink_gt.c
index 5a602eb7cd2d..fef80cfcab5c 100644
--- a/drivers/char/synclink_gt.c
+++ b/drivers/char/synclink_gt.c
@@ -3244,7 +3244,9 @@ static int block_til_ready(struct tty_struct *tty, struct file *filp,
                 }
 
                 DBGINFO(("%s block_til_ready wait\n", tty->driver->name));
+                tty_unlock();
                 schedule();
+                tty_lock();
         }
 
         set_current_state(TASK_RUNNING);