tty: Remove ASYNC_CLOSING checks in open()/hangup() methods

Since at least before 2.6.30, tty drivers that do not drop the tty lock
while closing cannot observe ASYNC_CLOSING set while holding the
tty lock; this includes the tty driver's open() and hangup() methods,
since the tty core calls these methods holding the tty lock.

For these drivers, waiting for ASYNC_CLOSING to clear while opening
is not required, since this condition cannot occur. Similarly, even
when the open() method drops and reacquires the tty lock after
blocking, ASYNC_CLOSING cannot be set (again, for drivers that
do not drop the tty lock while closing).

Now that tty port drivers no longer drop the tty lock while closing
(since 'tty: Remove tty_wait_until_sent_from_close()'), the same
conditions apply: waiting for ASYNC_CLOSING to clear while opening
is not required, nor is re-checking ASYNC_CLOSING after dropping and
reacquiring the tty lock while blocking (eg., in *_block_til_ready()).

Note: The ASYNC_CLOSING flag state is still maintained since several
bitrotting drivers use it for (dubious) other purposes.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 0 insertions, 12 deletions

diff --git a/drivers/tty/rocket.c b/drivers/tty/rocket.c
index c8dd8dc31086..69c72d1aa627 100644
--- a/drivers/tty/rocket.c
+++ b/drivers/tty/rocket.c
@@ -895,14 +895,6 @@ static int rp_open(struct tty_struct *tty, struct file *filp)
 	if (!page)
 		return -ENOMEM;
 
-	if (port->flags & ASYNC_CLOSING) {
-		retval = wait_for_completion_interruptible(&info->close_wait);
-		free_page(page);
-		if (retval)
-			return retval;
-		return ((port->flags & ASYNC_HUP_NOTIFY) ? -EAGAIN : -ERESTARTSYS);
-	}
-
 	/*
 	 * We must not sleep from here until the port is marked fully in use.
 	 */
@@ -1511,10 +1503,6 @@ static void rp_hangup(struct tty_struct *tty)
 #endif
 	rp_flush_buffer(tty);
 	spin_lock_irqsave(&info->port.lock, flags);
-	if (info->port.flags & ASYNC_CLOSING) {
-		spin_unlock_irqrestore(&info->port.lock, flags);
-		return;
-	}
 	if (info->port.count)
 		atomic_dec(&rp_num_ports_open);
 	clear_bit((info->aiop * 8) + info->chan, (void *) &xmit_flags[info->board]);