Re: [PATCH v7 bpf-next 06/11] tcp: Migrate TCP_NEW_SYN_RECV requests at retransmitting SYN+ACKs.

From: Kuniyuki Iwashima
Date: Thu Jun 10 2021 - 18:53:13 EST


From: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Date: Thu, 10 Jun 2021 22:21:00 +0200
> On 5/21/21 8:20 PM, Kuniyuki Iwashima wrote:
> > As with the preceding patch, this patch changes reqsk_timer_handler() to
> > call reuseport_migrate_sock() and inet_reqsk_clone() to migrate in-flight
> > requests at retransmitting SYN+ACKs. If we can select a new listener and
> > clone the request, we resume setting the SYN+ACK timer for the new req. If
> > we can set the timer, we call inet_ehash_insert() to unhash the old req and
> > put the new req into ehash.
> >
>
> ...
>
> > static void reqsk_migrate_reset(struct request_sock *req)
> > {
> > + req->saved_syn = NULL;
> > + inet_rsk(req)->ireq_opt = NULL;
> > #if IS_ENABLED(CONFIG_IPV6)
> > - inet_rsk(req)->ipv6_opt = NULL;
> > + inet_rsk(req)->pktopts = NULL;
> > #endif
> > }
>
> This is fragile.
>
> Maybe instead :
>
> #if IS_ENABLED(CONFIG_IPV6)
> inet_rsk(req)->ipv6_opt = NULL;
> inet_rsk(req)->pktopts = NULL;
> #else
> inet_rsk(req)->ireq_opt = NULL;
> #endif

I will fix this, thank you.

Also I will send a follow-up patch later to fix the same style in
inet_reqsk_alloc().