Re: [PATCH v2 03/10] blktrace: fix debugfs use after free

[Christoph Hellwig]

On Mon, Apr 20, 2020 at 08:41:56PM +0000, Luis Chamberlain wrote:
> Its already there. And yes, after my changes it is technically possible
> to just re-use it directly. But this is complicated by a few things. One
> is that at this point in time, asynchronous request_queue removal is
> still possible, and so a race was exposed where a requeust_queue may be
> lingering but its old device is gone. That race is fixed by reverting us
> back to synchronous request_queue removal, therefore ensuring that the
> debugfs dir exists so long as the device does.
> 
> I can remove the debugfs_lookup() *after* we revert to synchronous
> request_queue removal, or we just re-order the patches so that the
> revert happens first. That should simplify this patch.

Yes, please move the synchronous removal first instead of working around
the current problems.