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usb-serial: straighten out serial_open 

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>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2009-09-01 11:39:59 -04:00 committed by Live-CD User
parent ff8324df11
commit 320348c8d5
1 changed files with 22 additions and 37 deletions
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59
drivers/usb/serial/usb-serial.c
View File

@ -245,55 +245,40 @@ static int serial_install(struct tty_driver *driver, struct tty_struct *tty)
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);
if (retval)
goto bailout_module_put;
if (serial->disconnected)
retval = -ENODEV;
else
retval = port->serial->type->open(tty, port);
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;
}