On Thu, Jun 04, 2020 at 01:57:01PM -0700, Jordan Hand wrote: > On 6/4/20 1:15 PM, Greg Kroah-Hartman wrote: > > On Thu, Jun 04, 2020 at 12:36:23PM -0700, jorh...@linux.microsoft.com wrote: > > > From: Jordan Hand <jorh...@linux.microsoft.com> > > > > > > If a child swnode is unregistered after it's parent, it can lead to > > > undefined behavior. > > > > Crashing the system is not really "undefined" :) > > Fair point :) > > > > > > When a swnode is unregistered, recursively free it's children to avoid > > > this condition. > > > > Are you sure? Why would you be unregistering a child after it's parent? > > Why not just do not do that? > > > > The main motivation for doing this was to support > `software_node_unregister_nodes` so that the passed list of nodes does not > need to be ordered in any particular way. > > I suppose another way to do this would be to add a new function > `fwnode_remove_software_node_recursive` and just call that from > `software_node_unregister_nodes`. > > That said, I suppose just ordering the nodes so that children come before > parents would also be fine. My thinking was just that accepting any node > ordering is simpler.
Right now, the way the driver model and sysfs/kobjects work is that all objects must be removed in child-first order. The problem of your change where you want to try to remove the devices in parent-first order is that you do not really know if you still have a reference to a child device somewhere else, which would prevent this all from happening correctly, right? So if you "know" it is safe to drop a child, that's great, and expected. Don't work to make this one tiny user of the kobjects (which I'm still not quite sure why they are kobjects and not devices), do things in a different way from the rest of the kernel without a strong reason to do so. thanks, greg k-h
