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, 4 insertions, 0 deletions

diff --git a/drivers/char/ip2/ip2main.c b/drivers/char/ip2/ip2main.c
index 911e1da6def2..07f3ea38b582 100644
--- a/drivers/char/ip2/ip2main.c
+++ b/drivers/char/ip2/ip2main.c
@@ -1486,7 +1486,9 @@ ip2_open( PTTY tty, struct file *pFile )
 
         if ( tty_hung_up_p(pFile) || ( pCh->flags & ASYNC_CLOSING )) {
                 if ( pCh->flags & ASYNC_CLOSING ) {
+                        tty_unlock();
                         schedule();
+                        tty_lock();
                 }
                 if ( tty_hung_up_p(pFile) ) {
                         set_current_state( TASK_RUNNING );
@@ -1548,7 +1550,9 @@ ip2_open( PTTY tty, struct file *pFile )
                         rc = (( pCh->flags & ASYNC_HUP_NOTIFY ) ? -EAGAIN : -ERESTARTSYS);
                         break;
                 }
+                tty_unlock();
                 schedule();
+                tty_lock();
         }
         set_current_state( TASK_RUNNING );
         remove_wait_queue(&pCh->open_wait, &wait);