[ofa-general] CM sysfs-related oops on device driver reload

[Roland Dreier]

OK, the smaller patch below seems to fix things to, so that's what
I'll merge.  I think the real issue was that I left the code as

	ret = kobject_init_and_add(&cm_dev->dev_obj, &cm_dev_obj_type,
				   &cm_class.subsys.kobj, "%s", device->name);

without doing kobject_get() on subsys.kobj, which meant on unload, we
did an extra put of that subsys.kobj, which left the infiniband_cm
class in a messed-up state.  But there's no reason to do an extra get
of the parents (kobject_init_and_add() already gets the parent once
for us), so we can just simplify everything as below:

diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
index 435e276..b10ade9 100644
--- a/drivers/infiniband/core/cm.c
+++ b/drivers/infiniband/core/cm.c
@@ -3612,18 +3612,12 @@ struct class cm_class = {
 };
 EXPORT_SYMBOL(cm_class);
 
-static void cm_remove_fs_obj(struct kobject *obj)
-{
-	kobject_put(obj->parent);
-	kobject_put(obj);
-}
-
 static int cm_create_port_fs(struct cm_port *port)
 {
 	int i, ret;
 
 	ret = kobject_init_and_add(&port->port_obj, &cm_port_obj_type,
-				   kobject_get(&port->cm_dev->dev_obj),
+				   &port->cm_dev->dev_obj,
 				   "%d", port->port_num);
 	if (ret) {
 		kfree(port);
@@ -3633,7 +3627,7 @@ static int cm_create_port_fs(struct cm_port *port)
 	for (i = 0; i < CM_COUNTER_GROUPS; i++) {
 		ret = kobject_init_and_add(&port->counter_group[i].obj,
 					   &cm_counter_obj_type,
-					   kobject_get(&port->port_obj),
+					   &port->port_obj,
 					   "%s", counter_group_names[i]);
 		if (ret)
 			goto error;
@@ -3643,8 +3637,8 @@ static int cm_create_port_fs(struct cm_port *port)
 
 error:
 	while (i--)
-		cm_remove_fs_obj(&port->counter_group[i].obj);
-	cm_remove_fs_obj(&port->port_obj);
+		kobject_put(&port->counter_group[i].obj);
+	kobject_put(&port->port_obj);
 	return ret;
 
 }
@@ -3654,9 +3648,9 @@ static void cm_remove_port_fs(struct cm_port *port)
 	int i;
 
 	for (i = 0; i < CM_COUNTER_GROUPS; i++)
-		cm_remove_fs_obj(&port->counter_group[i].obj);
+		kobject_put(&port->counter_group[i].obj);
 
-	cm_remove_fs_obj(&port->port_obj);
+	kobject_put(&port->port_obj);
 }
 
 static void cm_add_one(struct ib_device *device)
@@ -3740,7 +3734,7 @@ error1:
 		ib_unregister_mad_agent(port->mad_agent);
 		cm_remove_port_fs(port);
 	}
-	cm_remove_fs_obj(&cm_dev->dev_obj);
+	kobject_put(&cm_dev->dev_obj);
 }
 
 static void cm_remove_one(struct ib_device *device)
@@ -3767,7 +3761,7 @@ static void cm_remove_one(struct ib_device *device)
 		ib_unregister_mad_agent(port->mad_agent);
 		cm_remove_port_fs(port);
 	}
-	cm_remove_fs_obj(&cm_dev->dev_obj);
+	kobject_put(&cm_dev->dev_obj);
 }
 
 static int __init ib_cm_init(void)