device_detach() never clears devclasses

[Warner Losh]

This looks good to me.  I think I should have had != here anyway. :)

Warner

On Feb 27, 2012, at 10:08 AM, John Baldwin wrote:

> I haven't reproduced this, I just have a hunch based on code-reading while 
> fixing another bug.  Ah, looking in SVN history it looks like this was broken 
> in 129711 when device_attach() was split out of device_probe_and_attach().  
> Specifically, if DEVICE_ATTACH() fails then this:
> 
> 		/* Unset the class; set in device_probe_child */
> 		if (dev->devclass == NULL)
> 			(void)device_set_devclass(dev, NULL);
> 
> is wrong.  dev->devclass is always non-NULL at this point.  However, we should 
> be clearing the devclass for any device that doesn't have a fixed device 
> class.  And in fact that is what device_detach() does:
> 
> 	if (!(dev->flags & DF_FIXEDCLASS))
> 		devclass_delete_device(dev->devclass, dev);
> 
> The patch below fixes this:
> 
> Index: subr_bus.c
> ===================================================================
> --- subr_bus.c	(revision 232218)
> +++ subr_bus.c	(working copy)
> @@ -2732,9 +2732,8 @@ device_attach(device_t dev)
> 	if ((error = DEVICE_ATTACH(dev)) != 0) {
> 		printf("device_attach: %s%d attach returned %d\n",
> 		    dev->driver->name, dev->unit, error);
> -		/* Unset the class; set in device_probe_child */
> -		if (dev->devclass == NULL)
> -			(void)device_set_devclass(dev, NULL);
> +		if (!(dev->flags & DF_FIXEDCLASS))
> +			devclass_delete_device(dev->devclass, dev);
> 		(void)device_set_driver(dev, NULL);
> 		device_sysctl_fini(dev);
> 		dev->state = DS_NOTPRESENT;
> 
> 
> -- 
> John Baldwin
> 
>