drivers/usb/serial/aircable.c: inconsequent NULL checking

drivers/usb/serial/aircable.c: inconsequent NULL checking

[Adrian Bunk]

The Coverity checker spotted the following in 
drivers/usb/serial/aircable.c:

<--  snip  -->

...
static void aircable_read(void *params)
{
        struct usb_serial_port *port = params;
        struct aircable_private *priv = usb_get_serial_port_data(port);
        struct tty_struct *tty;
        unsigned char *data;
        int count;
        if (priv->rx_flags & THROTTLED){
                if (priv->rx_flags & ACTUALLY_THROTTLED)
                        schedule_work(&priv->rx_work);
                return;
        }

        /* By now I will flush data to the tty in packages of no more than
         * 64 bytes, to ensure I do not get throttled.
         * Ask USB mailing list for better aproach.
         */
        tty = port->tty;

        if (!tty)
                schedule_work(&priv->rx_work);

        count = min(64, serial_buf_data_avail(priv->rx_buf));

        if (count <= 0)
                return; //We have finished sending everything.

        tty_prepare_flip_string(tty, &data, count);
...

<--  snip  -->

"tty" is first checked for being !NULL, but later it's unconditionally 
dereferenced.

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

Re: drivers/usb/serial/aircable.c: inconsequent NULL checking

[Naranjo Manuel Francisco]

> 2006/11/11, Adrian Bunk <bunk@stusta.de>:
> > The Coverity checker spotted the following in
> > drivers/usb/serial/aircable.c:
> >
> > <--  snip  -->
> >
> > ...
> > static void aircable_read(void *params)
> > {
> > ...


Hi everyone,
Sorry for the long time response but here is the patch, I think this way should work, if anyone has any suggestion let me know. What I do now is, in case I don't have the tty available I reschedule the work, I have tried it and it works with no problem, I even tried removing the device, and didn't find anything strange.

Manuel Naranjo

Signed-off-by: Naranjo Manuel <naranjo.manuel@gmail.com>

----

--- linux2/drivers/usb/serial/aircable.c.orig	2006-11-15 15:03:40.000000000 -0300
+++ linux2/drivers/usb/serial/aircable.c	2006-11-12 21:59:05.000000000 -0300
@@ -270,8 +270,11 @@ static void aircable_read(void *params)
 	 */
 	tty = port->tty;
 
-	if (!tty)
+	if (!tty){
 		schedule_work(&priv->rx_work);
+		err("%s - No tty available", __FUNCTION__);
+		return ;
+	}
 
 	count = min(64, serial_buf_data_avail(priv->rx_buf));