device_detach() never clears devclasses

[John Baldwin]

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