Re: [RFC] configfs_unregister_group() API

[Christoph Hellwig <hch@lst.de>]

On Tue, Jul 30, 2019 at 10:13:55PM +0100, Al Viro wrote:
> 	AFAICS, it (and configfs_unregister_default_group())
> will break if called with group non-empty (i.e. when rmdir(2)
> would've failed with -ENOTEMPTY); configfs_detach_prep()
> is called, but return value is completely ignored.
> 
> 	Similar breakage happens in configfs_unregister_subsystem(),
> but there it looks like the drivers are responsible for not calling
> it that way.  It yells if configfs_detach_prep() fails and AFAICS
> all callers do guarantee it never happens.
> 
> 	configfs_unregister_group() is quiet; from my reading of
> the callers, only pci-endpoint might end up calling it for group
> that is not guaranteed to be empty.  I'm not familiar with
> pci-endpoint guts, so I might very well be missing something there.
> 
> Questions to configfs API maintainers (that'd be Christoph, these
> days, AFAIK)
> 
> 1) should such a call be considered a driver bug?
> 2) should configfs_unregister_group() at least warn when that happens?

Yes, I'm patch monkeying these days.  From my POV expecting it to
act recursively seems like a bug, and we should at the very least warn.