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Subject[100/136] usb-serial: straighten out serial_open
2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Alan Stern <stern@rowland.harvard.edu>

commit 320348c8d5c9b591282633ddb8959b42f7fc7a1c upstream.

This patch (as1291) removes a bunch of code from serial_open(), things
that were rendered unnecessary by earlier patches. A missing spinlock
is added to protect port->port.count, which needs to be incremented
even if the open fails but not if the tty has gotten a hangup. The
test for whether the hardware has been initialized, based on the use
count, is replaced by a more transparent test of the
ASYNCB_INITIALIZED bit in the port flags.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/usb/serial/usb-serial.c | 59 ++++++++++++++--------------------------
1 file changed, 22 insertions(+), 37 deletions(-)

--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -245,55 +245,40 @@ static int serial_install(struct tty_dri
return retval;
}

-static int serial_open (struct tty_struct *tty, struct file *filp)
+static int serial_open(struct tty_struct *tty, struct file *filp)
{
- struct usb_serial *serial;
- struct usb_serial_port *port;
- int retval = 0;
- int first = 0;
-
- port = tty->driver_data;
- serial = port->serial;
+ struct usb_serial_port *port = tty->driver_data;
+ struct usb_serial *serial = port->serial;
+ int retval;

dbg("%s - port %d", __func__, port->number);

- if (mutex_lock_interruptible(&port->mutex))
- return -ERESTARTSYS;
-
- ++port->port.count;
+ spin_lock_irq(&port->port.lock);
+ if (!tty_hung_up_p(filp))
+ ++port->port.count;
+ spin_unlock_irq(&port->port.lock);
tty_port_tty_set(&port->port, tty);

- /* If the console is attached, the device is already open */
- if (port->port.count == 1 && !port->console) {
- first = 1;
+ /* Do the device-specific open only if the hardware isn't
+ * already initialized.
+ */
+ if (!test_bit(ASYNCB_INITIALIZED, &port->port.flags)) {
+ if (mutex_lock_interruptible(&port->mutex))
+ return -ERESTARTSYS;
mutex_lock(&serial->disc_mutex);
-
- /* only call the device specific open if this
- * is the first time the port is opened */
- retval = serial->type->open(tty, port, filp);
- if (retval)
- goto bailout_module_put;
+ if (serial->disconnected)
+ retval = -ENODEV;
+ else
+ retval = port->serial->type->open(tty, port, flip);
mutex_unlock(&serial->disc_mutex);
+ mutex_unlock(&port->mutex);
+ if (retval)
+ return retval;
set_bit(ASYNCB_INITIALIZED, &port->port.flags);
}
- mutex_unlock(&port->mutex);
+
/* Now do the correct tty layer semantics */
retval = tty_port_block_til_ready(&port->port, tty, filp);
- if (retval == 0) {
- if (!first)
- usb_serial_put(serial);
- return 0;
- }
- mutex_lock(&port->mutex);
- if (first == 0)
- goto bailout_mutex_unlock;
- /* Undo the initial port actions */
- mutex_lock(&serial->disc_mutex);
-bailout_module_put:
- mutex_unlock(&serial->disc_mutex);
-bailout_mutex_unlock:
- port->port.count = 0;
- mutex_unlock(&port->mutex);
return retval;
}




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