Re: [PATCH net-next v3 2/2] tcp: Free TCP-AO/TCP-MD5 info/keys without RCU

[Jakub Kicinski]

On Thu, 4 Sep 2025 00:17:34 +0100 Dmitry Safonov wrote:
> > > Right. I'll remove tcp_ao_info::rcu in v4.
> > > For tcp_ao_key it's needed for the regular key rotation, as well as
> > > for tcp_md5sig_key.  
> >
> > Hm, maybe I missed something. I did a test allmodconfig build yesterday
> > and while the md5sig_key rcu was still needed, removing the ao_key
> > didn't cause issues. But it was just a quick test I didn't even config
> > kconfig is sane.  
> 
> Hmm, probably CONFIG_TCP_AO was off?
> tcp_ao_delete_key() does call_rcu(&key->rcu, tcp_ao_key_free_rcu).
> 
> Looking at the code now, I guess what I could have done even more is
> migrating tcp_sock::ao_info (and tcp_timewait_sock::ao_info) from
> rcu_*() helpers to acquire/release ones. Somewhat feeling uneasy about
> going that far just yet. Should I do it with another cleanup on the
> top, what do you think?

No preference :)