Commit fef062cb authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
Browse files

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: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 79c1faa4

drivers/char/pcmcia/synclink_cs.c

+0 −9
Original line number Diff line number Diff line
@@ -2507,15 +2507,6 @@ static int mgslpc_open(struct tty_struct *tty, struct file * filp) 
		printk("%s(%d):mgslpc_open(%s), old ref count = %d\n",

			 __FILE__, __LINE__, tty->driver->name, port->count);



	/* If port is closing, signal caller to try again */

	if (port->flags & ASYNC_CLOSING){

		wait_event_interruptible_tty(tty, port->close_wait,

					     !(port->flags & ASYNC_CLOSING));

		retval = ((port->flags & ASYNC_HUP_NOTIFY) ?

			-EAGAIN : -ERESTARTSYS);

		goto cleanup;

	}



	port->low_latency = (port->flags & ASYNC_LOW_LATENCY) ? 1 : 0;



	spin_lock_irqsave(&info->netlock, flags);

drivers/tty/cyclades.c

+0 −9
Original line number Diff line number Diff line
@@ -1576,15 +1576,6 @@ static int cy_open(struct tty_struct *tty, struct file *filp) 
		current->pid, info->port.count);

#endif



	/*

	 * If the port is the middle of closing, bail out now

	 */

	if (info->port.flags & ASYNC_CLOSING) {

		wait_event_interruptible_tty(tty, info->port.close_wait,

				!(info->port.flags & ASYNC_CLOSING));

		return (info->port.flags & ASYNC_HUP_NOTIFY) ? -EAGAIN: -ERESTARTSYS;

	}



	/*

	 * Start up serial port

	 */

drivers/tty/rocket.c

+0 −12
Original line number Diff line number Diff line
@@ -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]);

drivers/tty/serial/crisv10.c

+1 −32
Original line number Diff line number Diff line
@@ -3758,23 +3758,6 @@ block_til_ready(struct tty_struct *tty, struct file * filp, 
	int		retval;

	int		do_clocal = 0;



	/*

	 * If the device is in the middle of being closed, then block

	 * until it's done, and then try again.

	 */

	if (info->port.flags & ASYNC_CLOSING) {

		wait_event_interruptible_tty(tty, info->port.close_wait,

			!(info->port.flags & ASYNC_CLOSING));

#ifdef SERIAL_DO_RESTART

		if (info->port.flags & ASYNC_HUP_NOTIFY)

			return -EAGAIN;

		else

			return -ERESTARTSYS;

#else

		return -EAGAIN;

#endif

	}



	/*

	 * If non-blocking mode is set, or the port is not enabled,

	 * then make the check up front and then exit.
@@ -3825,7 +3808,7 @@ block_til_ready(struct tty_struct *tty, struct file * filp, 
#endif

			break;

		}

		if (!(info->port.flags & ASYNC_CLOSING) && do_clocal)

		if (do_clocal)

			/* && (do_clocal || DCD_IS_ASSERTED) */

			break;

		if (signal_pending(current)) {
@@ -3894,20 +3877,6 @@ rs_open(struct tty_struct *tty, struct file * filp) 


	info->port.low_latency = !!(info->port.flags & ASYNC_LOW_LATENCY);



	/*

	 * If the port is in the middle of closing, bail out now

	 */

	if (info->port.flags & ASYNC_CLOSING) {

		wait_event_interruptible_tty(tty, info->port.close_wait,

			!(info->port.flags & ASYNC_CLOSING));

#ifdef SERIAL_DO_RESTART

		return ((info->port.flags & ASYNC_HUP_NOTIFY) ?

			-EAGAIN : -ERESTARTSYS);

#else

		return -EAGAIN;

#endif

	}



	/*

	 * If DMA is enabled try to allocate the irq's.

	 */

drivers/tty/synclink.c

+4 −14
Original line number Diff line number Diff line
@@ -3316,8 +3316,7 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp, 
		}



		dcd = tty_port_carrier_raised(&info->port);

		

 		if (!(port->flags & ASYNC_CLOSING) && (do_clocal || dcd))

		if (do_clocal || dcd)

			break;



		if (signal_pending(current)) {
@@ -3398,15 +3397,6 @@ static int mgsl_open(struct tty_struct *tty, struct file * filp) 
		printk("%s(%d):mgsl_open(%s), old ref count = %d\n",

			 __FILE__,__LINE__,tty->driver->name, info->port.count);



	/* If port is closing, signal caller to try again */

	if (info->port.flags & ASYNC_CLOSING){

		wait_event_interruptible_tty(tty, info->port.close_wait,

				     !(info->port.flags & ASYNC_CLOSING));

		retval = ((info->port.flags & ASYNC_HUP_NOTIFY) ?

			-EAGAIN : -ERESTARTSYS);

		goto cleanup;

	}

	

	info->port.low_latency = (info->port.flags & ASYNC_LOW_LATENCY) ? 1 : 0;



	spin_lock_irqsave(&info->netlock, flags);

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