On Fri, 15 Nov 2019 13:48:23 +0000 Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > > BTW, what do you mean by "can debugfs_remove_recursive() rely upon the > > lack of attempts to create new entries inside the subtree it's trying > > to kill?" > > Is it possible for something to call e.g. debugfs_create_dir() (or any > similar primitive) with parent inside the subtree that has been > passed to debugfs_remove_recursive() call that is still in progress? > > If debugfs needs to cope with that, debugfs_remove_recursive() needs > considerably heavier locking, to start with. I don't know about debugfs, but at least tracefs (which cut and pasted from debugfs) does not allow that. At least in theory it doesn't allow that (and if it does, it's a bug in the locking at the higher levels). And perhaps debugfs shouldn't allow that either. As it is only suppose to be a light weight way to interact with the kernel, hence the name "debugfs". Yu, do you have a test case for the "infinite loop" case? -- Steve
