Driver not unset properly after kldunload

[John Baldwin]

On Wednesday 29 November 2006 18:18, Iasen Kostoff wrote:
>   Hi,
> It seems that after I load and then unload a driver its name stays
> linked to the device e.g:
> 
> nfe0 at pci0:10:0: class=0x068000 card=0x81411043 chip=0x005710de rev=0xa3
> hdr=0x00
> 
> but of course if_nfe is neither compiled in kernel nor is loaded as
> module anymore.
>   I digged around in kernel and saw this in device_detach():
> 
> 	if (!(dev->flags & DF_FIXEDCLASS))
> 		devclass_delete_device(dev->devclass, dev);
> 
> 	dev->state = DS_NOTPRESENT;
> 	device_set_driver(dev, NULL);
> 	device_set_desc(dev, NULL);
> 	device_sysctl_fini(dev);
> 
> I've put some device_printf()s around and then looked at
> devclass_delete_device(). It destroys (frees) a lot of the info about
> the device and so the device_printf() prints device name as
> "unknown" (NULL). That seems to be a problem for at least
> device_set_driver(dev, NULL) - it doesn't unset the driver. I'm not so
> sure about the other 2 but I guess it's same there. So when I changed the
> order of this funcs everything worked fine (at least it looks like it
> worked fine :) I'm not absolutely sure that this won't broke something
> else). I've attached a patch for review.

I don't see why this patch changes things.  devclass_delete_device() only 
clears dev->unit, dev->devclass, and dev->nameunit.  device_set_driver() 
doesn't check or clear any of those.  In fact, your change does make 
device_set_driver() not work at all since the device state will still be 
DS_ATTACHED when you call device_set_driver() now.  So, I guess your patch 
actually makes the device _not_ be detached from the driver.

-- 
John Baldwin