On Tue, Oct 20, 2020 at 11:52:56PM +0100, Dan Scally wrote: > On 20/10/2020 11:05, Sakari Ailus wrote: > > On Mon, Oct 19, 2020 at 11:58:55PM +0100, Daniel Scally wrote: > >> Software nodes that are children of another software node should be > >> unregistered before their parent. To allow easy unregistering of an array > >> of software_nodes ordered parent to child, add a helper function to loop > >> over and unregister nodes in such an array in reverse order. ... > >> + * software_node_unregister_nodes_reverse - Unregister an array of software > >> + * nodes in reverse order. > >> + * @nodes: Array of software nodes to be unregistered. > >> + * > >> + * NOTE: The same warning applies as with software_node_unregister_nodes. > >> + * Unless you are _sure_ that the array of nodes is ordered parent to child > >> + * it is wiser to remove them individually in the correct order. > > Could the default order in software_node_unregister_nodes() be reversed > > instead? There are no users so this should be easy to change. > > > > Doing this only one way may require enforcing the registration order in > > software_node_register_nodes(), but the end result would be safer. > > > > What do you think? > > Yeah fine by me. We can just use software_node_to_swnode(node->parent) > within software_node_unregister_nodes() to check that children come > after their parents have already been processed. I'll add a patch to do > that in the next version of this series, and another changing the > ordering of software_node_unregister_node_group() as Andy suggests for > consistency. I remember it was a big discussion between Rafael, Heikki and Greg KH about child-parent release in kobjects. That ended up with few patches to device object handling along with one that reversed the order of swnode unregistering in test_printf.c. So here is the question who is maintaining the order: a kref (via kobject) or a caller? -- With Best Regards, Andy Shevchenko
