2009/9/1 Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>:
> 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@xxxxxxxxxxxxxxxxxxx>
>
> ---
>
> Index: usb-2.6/drivers/usb/serial/usb-serial.c
> ===================================================================
> --- usb-2.6.orig/drivers/usb/serial/usb-serial.c
> +++ usb-2.6/drivers/usb/serial/usb-serial.c
> @@ -246,55 +246,40 @@ 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);
The lock is still needed in usb_console_setup() to protect port->port.count,
isn't it?
Thanks.
--
Lei Ming
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