[mpf70-devel] Re: MpMan driver

[Jeremy <jer...@po...>]

Hi!

I'm not sure what you describe is accurate, there would already be
problems in a single device situation upon disconnecting/reconnecting.
If you look at mpf70.h you'll see that currently, the "list of
devices" only allows for one device (MPF70_MAX =3D 1). If indeed I am
writing s->usbdev =3D NULL in the wrong place, reconnecting the device
work should cause a failure (mpf70_find_struct would not find an entry
with a NULL usbdev). This is not the observed behaviour!

Jeremy

-- =20
http://www.jerryweb.org/         : JerryWeb.org
http://sailcut.sourceforge.net/  : Sailcut CAD
http://mpf70.sourceforge.net/    : MPman MP-F70 support for Linux

On Sat, 18 Oct 2003 15:59:32 +0200 (CEST)
Kiss Karoly wrote:

> Hello,
>=20
> The mailing list is OK with me. I just subscribed to it.
> In my e-mail what I meant was that it's ok that you try to set the
> s->usbdev =3D NULL;
> but that never happens because you are in the wrong place in memory.
> So if later you try to view what devices you have attached in your
> static block of devices one of your pointers will not be NULL (
> which you intended it to be ) and you would violate the rule you
> described to me in your letter earlyer.
>=20
> > "After returning from the disconnect function the USB framework
> > completly deallocates all data structures associated with this
> > device. So especially the  usb_device structure must not be used
> > any longer by the usb driver."
>=20
> This means that you still have a pointer to the usb_device structure
> in your list of devices.
>=20
> Regards
> Kiss Karoly
>=20
> On Sat, 18 Oct 2003, Jeremy [ISO-8859-1] Lain=E9 wrote:
>=20
> > Hello Anthony,
> >
> > Kiss Karoly (cc of this email) has been looking throught the mpf70
> > driver code as he is interested in producing a kernel module for
> > the mpf50. I thought maybe you'd be interested in joining the
> > discussion:)
> >
> > If it's ok with both of you maybe we can switch to :
> > mpf...@li...
> >
> > .. so there is a trace of all this!
> >
> > Regards,
> > Jeremy
> >
> > --
> > http://www.jerryweb.org/         : JerryWeb.org
> > http://sailcut.sourceforge.net/  : Sailcut CAD
> > http://mpf70.sourceforge.net/    : MPman MP-F70 support for Linux
> >
> > ---
> > Date: Sat, 18 Oct 2003 12:15:10 +0200 (CEST)
> > From: Kiss Karoly
> > To: Jeremy Lain=E9
> > Subject: MpMan driver
> >
> >
> > Hello Jeremy,
> >
> > I noticed a little bug in your mpf70 driver, it's probably not a
> > big thing
> > but anyways I think you should know.
> > In your mpf70_disconnect function you typecast the void *ptr to
> > mpf70_t
> > type and set the usbdev in it to NULL. That is wrong because that
> > pointer
> > contains a pointer to an integer containing the address of the usb
> > device
> > on the bus.
> > It probably does nothing important but if you try to handle more
> > than one
> > device with your driver you will notice that it does not free the
> > appropriate resource. Not to mention that you could write a NULL
> > value somewhere you shouldn't.
> >
> > Regards
> > Kiss Karoly
> >