tty: Replace ASYNC_NORMAL_ACTIVE bit and update atomically

Replace ASYNC_NORMAL_ACTIVE bit in the tty_port::flags field with
TTY_PORT_ACTIVE bit in the tty_port::iflags field. Introduce helpers
tty_port_set_active() and tty_port_active() to abstract atomic bit ops.

Extract state changes from port lock sections, as this usage is
broken and confused; the state transitions are protected by the
tty lock (which mutually excludes parallel open/close/hangup),
and no user tests the active state while holding the port lock.

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

1 files changed, 6 insertions, 6 deletions

diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index 9127c54b803e..130c8cf520cb 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -236,12 +236,12 @@ void tty_port_hangup(struct tty_port *port)
 
 	spin_lock_irqsave(&port->lock, flags);
 	port->count = 0;
-	port->flags &= ~ASYNC_NORMAL_ACTIVE;
 	tty = port->tty;
 	if (tty)
 		set_bit(TTY_IO_ERROR, &tty->flags);
 	port->tty = NULL;
 	spin_unlock_irqrestore(&port->lock, flags);
+	tty_port_set_active(port, 0);
 	tty_port_shutdown(port, tty);
 	tty_kref_put(tty);
 	wake_up_interruptible(&port->open_wait);
@@ -365,14 +365,14 @@ int tty_port_block_til_ready(struct tty_port *port,
 	/* if non-blocking mode is set we can pass directly to open unless
 	   the port has just hung up or is in another error state */
 	if (tty_io_error(tty)) {
-		port->flags |= ASYNC_NORMAL_ACTIVE;
+		tty_port_set_active(port, 1);
 		return 0;
 	}
 	if (filp->f_flags & O_NONBLOCK) {
 		/* Indicate we are open */
 		if (C_BAUD(tty))
 			tty_port_raise_dtr_rts(port);
-		port->flags |= ASYNC_NORMAL_ACTIVE;
+		tty_port_set_active(port, 1);
 		return 0;
 	}
 
@@ -430,9 +430,9 @@ int tty_port_block_til_ready(struct tty_port *port,
 	if (!tty_hung_up_p(filp))
 		port->count++;
 	port->blocked_open--;
-	if (retval == 0)
-		port->flags |= ASYNC_NORMAL_ACTIVE;
 	spin_unlock_irqrestore(&port->lock, flags);
+	if (retval == 0)
+		tty_port_set_active(port, 1);
 	return retval;
 }
 EXPORT_SYMBOL(tty_port_block_til_ready);
@@ -514,8 +514,8 @@ void tty_port_close_end(struct tty_port *port, struct tty_struct *tty)
 		spin_lock_irqsave(&port->lock, flags);
 		wake_up_interruptible(&port->open_wait);
 	}
-	port->flags &= ~ASYNC_NORMAL_ACTIVE;
 	spin_unlock_irqrestore(&port->lock, flags);
+	tty_port_set_active(port, 0);
 }
 EXPORT_SYMBOL(tty_port_close_end);