Re: [PATCH] usb-serial regression fix

Mark Lord
2007-03-13T01:55:26Z

Jim Radford wrote:
> On Mon, Mar 12, 2007 at 05:18:19PM -0700, Greg KH wrote:
>> On Mon, Mar 12, 2007 at 03:59:22PM -0700, Jim Radford wrote:
>>> On Mon, Mar 12, 2007 at 03:42:35PM -0700, Jim Radford wrote:
>>>> On Mon, Mar 12, 2007 at 01:33:31PM -0700, Greg KH wrote:
>>>>> On Mon, Mar 12, 2007 at 04:22:22PM -0400, Mark Lord wrote:
>>>>>> Oliver Neukum wrote:
>>>>>>>> Mark Lord wrote:
>>>>>>>>> Okay, from that part (above), the problem is obvious:
>>>>>>>>> in that the "MCT U232 converter now disconnected"
>>>>>>>>> appears, and then we continue to try and call the
>>>>>>>>> driver's method.. Oops!
>
>>>>>>> IMHO shutdown() is using serial->port[] and bombs.
>>>>>>> Could you reverse the order here?
>
>>> Do not NULL serial->port[i] since it is used in ->shutdown().
>>> This wasn't an issue until the order or ->shutdown() and
>>> device_unregister was corrected.
>
>>> for (i = 0; i < serial->num_ports; ++i)
>>> if (serial->port[i]->dev.parent != NULL) {
>>> device_unregister(&serial->port[i]->dev);
>>> - serial->port[i] = NULL;
>>> }
>
>> But shouldn't you null it out somewhere? It will be an "empty"
>> pointer at some point in time...
>
> Not as far as I can see. The serial structure that ->port[i] is in
> gets kfree()ed soon after, in the same function, and nothing in
> between, other than ->shutdown(), uses ->port[]. I assume it was
> someone being overly cautious.

So where does the memory get freed -- the structure pointed at
by the serial->port[i] thingie ? It's not a leak, is it?

???