Re: patch usb-serial-straighten-out-serial_open.patch added to 2.6.31-stable tree

[Stefan Lippers-Hollmann]

Hi

On Friday 02 October 2009, gregkh@xxxxxxx wrote:
> 
> This is a note to let you know that we have just queued up the patch titled
> 
>     Subject: usb-serial: straighten out serial_open
> 
> to the 2.6.31-stable tree.  Its filename is
> 
>     usb-serial-straighten-out-serial_open.patch

This patch breaks compilation of the current 2.6.31 -stable queue:
[...]
  LD [M]  drivers/usb/mon/usbmon.o                                                               
  LD      drivers/usb/serial/built-in.o                                                          
  CC [M]  drivers/usb/serial/usb-serial.o                                                        
drivers/usb/serial/usb-serial.c: In function 'serial_open':                                      
drivers/usb/serial/usb-serial.c:272: error: 'flip' undeclared (first use in this function)       
drivers/usb/serial/usb-serial.c:272: error: (Each undeclared identifier is reported only once    
drivers/usb/serial/usb-serial.c:272: error: for each function it appears in.)                    
make[6]: *** [drivers/usb/serial/usb-serial.o] Error 1                                           
make[5]: *** [drivers/usb/serial] Error 2                                                        
make[4]: *** [drivers/usb] Error 2                                                               
make[3]: *** [drivers] Error 2                                                                   
[...]

> From 320348c8d5c9b591282633ddb8959b42f7fc7a1c Mon Sep 17 00:00:00 2001
> From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> Date: Tue, 1 Sep 2009 11:39:59 -0400
> Subject: usb-serial: straighten out serial_open
> 
> From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> 
> 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@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
> 
> ---
>  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);

s/flip/filp/

>  		mutex_unlock(&serial->disc_mutex);
> +		mutex_unlock(&port->mutex);
> +		if (retval)
> +			return retval;
>  		set_bit(ASYNCB_INITIALIZED, &port->port.flags);
>  	}
[...]

Regards
	Stefan Lippers-Hollmann
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