tty_port: add "tty_port_open" helper
For the moment this just moves the USB logic over and fixes the 'what if
we open and hangup at the same time' race noticed by Oliver Neukum.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/char/tty_port.c b/drivers/char/tty_port.c
index c63f3d3..b22a61a 100644
--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -99,10 +99,11 @@
static void tty_port_shutdown(struct tty_port *port)
{
+ mutex_lock(&port->mutex);
if (port->ops->shutdown &&
test_and_clear_bit(ASYNCB_INITIALIZED, &port->flags))
port->ops->shutdown(port);
-
+ mutex_unlock(&port->mutex);
}
/**
@@ -381,3 +382,36 @@
tty_port_tty_set(port, NULL);
}
EXPORT_SYMBOL(tty_port_close);
+
+int tty_port_open(struct tty_port *port, struct tty_struct *tty,
+ struct file *filp)
+{
+ spin_lock_irq(&port->lock);
+ if (!tty_hung_up_p(filp))
+ ++port->count;
+ spin_unlock_irq(&port->lock);
+ tty_port_tty_set(port, tty);
+
+ /*
+ * Do the device-specific open only if the hardware isn't
+ * already initialized. Serialize open and shutdown using the
+ * port mutex.
+ */
+
+ mutex_lock(&port->mutex);
+
+ if (!test_bit(ASYNCB_INITIALIZED, &port->flags)) {
+ if (port->ops->activate) {
+ int retval = port->ops->activate(port, tty);
+ if (retval) {
+ mutex_unlock(&port->mutex);
+ return retval;
+ }
+ }
+ set_bit(ASYNCB_INITIALIZED, &port->flags);
+ }
+ mutex_unlock(&port->mutex);
+ return tty_port_block_til_ready(port, tty, filp);
+}
+
+EXPORT_SYMBOL(tty_port_open);