[PATCH 3/6] nvme-auth: use xarray instead of linked list

[Christoph Hellwig]

On Wed, Nov 02, 2022 at 09:52:24AM +0100, Hannes Reinecke wrote:
> The control flow.
> Entries are only deallocated in nvme_auth_free(), which is called from 
> nvme_free_ctrl().
> By that time all processing has stopped, all workqueue entries are flushed, 
> and no further commands are accepted.
> Entries are allocated from two call sites; one via ops->create_ctrl(), and 
> the other one via the workqueue function nvme_dhchap_auth_work().
> 'create_ctrl' is synchronous, so the controller will only be deallocated on 
> the final put() of the create_ctrl() control flow. So we should be good 
> there.
> The workqueue function is flushed during nvme_free_ctrl(), so we're good 
> there, too.
>
> Hence I felt additional protection is not required.
> Do correct me if I'm wrong.

I'm not up to speed on the auth code.  But something like this
needs to be clearly documented in the commit log, and preferably
in the code as well.