netdev - Re: [RFC -next 1/2] lib: add reference counting infrastructure

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Message-ID: <CACT4Y+Z21Z8wXgMd=DhyL6TViSVVA4mbSXeAsR1qbKLY9HrfcQ@mail.gmail.com>
Date:   Wed, 1 Dec 2021 08:23:14 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     eric.dumazet@...il.com, davem@...emloft.net, kuba@...nel.org,
        netdev@...r.kernel.org
Subject: Re: [RFC -next 1/2] lib: add reference counting infrastructure

On Tue, 30 Nov 2021 at 16:08, Eric Dumazet <edumazet@...gle.com> wrote:
> > Hi Eric, Jakub,
> >
> > How strongly do you want to make this work w/o KASAN?
> > I am asking because KASAN will already memorize alloc/free stacks for every
> > heap object (+ pids + 2 aux stacks with kasan_record_aux_stack()).
> > So basically we just need to alloc struct list_head and won't need
> > quarantine/quarantine_avail in ref_tracker_dir.
> > If there are some refcount bugs, it may be due to a previous use-after-free,
> > so debugging a refcount bug w/o KASAN may be waste of time.
> >
>
> No strong opinion, we could have the quarantine stuff enabled only if
> KASAN is not compiled in.
> I was trying to make something that could be used even in a production
> environment, for seldom modified refcounts.
> As this tracking is optional, we do not have to use it in very small
> sections of code, where the inc/dec are happening in obviously correct
> and not long living pairs.

If it won't be used on very frequent paths, then it probably does not
matter much for syzbot as well. And additional ifdefs are not worth
it. Then try to go with your current version.