Re: [PATCH v5 bpf-next 05/11] tcp: Migrate TCP_ESTABLISHED/TCP_SYN_RECV sockets in accept queues.

From: Kuniyuki Iwashima
Date: Sat May 15 2021 - 00:18:01 EST


From: Martin KaFai Lau <kafai@xxxxxx>
Date: Fri, 14 May 2021 18:06:16 -0700
> On Mon, May 10, 2021 at 12:44:27PM +0900, Kuniyuki Iwashima wrote:
> > diff --git a/net/core/request_sock.c b/net/core/request_sock.c
> > index f35c2e998406..7879a3660c52 100644
> > --- a/net/core/request_sock.c
> > +++ b/net/core/request_sock.c
> > @@ -130,3 +130,42 @@ void reqsk_fastopen_remove(struct sock *sk, struct request_sock *req,
> > out:
> > spin_unlock_bh(&fastopenq->lock);
> > }
> > +
> > +struct request_sock *reqsk_clone(struct request_sock *req, struct sock *sk)
> > +{
> > + struct sock *req_sk, *nreq_sk;
> > + struct request_sock *nreq;
> > +
> > + nreq = kmem_cache_alloc(req->rsk_ops->slab, GFP_ATOMIC | __GFP_NOWARN);
> > + if (!nreq) {
> > + /* paired with refcount_inc_not_zero() in reuseport_migrate_sock() */
> > + sock_put(sk);
> > + return NULL;
> > + }
> > +
> > + req_sk = req_to_sk(req);
> > + nreq_sk = req_to_sk(nreq);
> > +
> > + memcpy(nreq_sk, req_sk,
> > + offsetof(struct sock, sk_dontcopy_begin));
> > + memcpy(&nreq_sk->sk_dontcopy_end, &req_sk->sk_dontcopy_end,
> > + req->rsk_ops->obj_size - offsetof(struct sock, sk_dontcopy_end));
> > +
> > + sk_node_init(&nreq_sk->sk_node);
> > + nreq_sk->sk_tx_queue_mapping = req_sk->sk_tx_queue_mapping;
> > +#ifdef CONFIG_XPS
> > + nreq_sk->sk_rx_queue_mapping = req_sk->sk_rx_queue_mapping;
> > +#endif
> > + nreq_sk->sk_incoming_cpu = req_sk->sk_incoming_cpu;
> > + refcount_set(&nreq_sk->sk_refcnt, 0);
> > +
> > + nreq->rsk_listener = sk;
> > +
> > + /* We need not acquire fastopenq->lock
> > + * because the child socket is locked in inet_csk_listen_stop().
> > + */
> > + if (tcp_rsk(nreq)->tfo_listener)
> Should IPPROTO_TCP be tested first like other similar situations
> in inet_connection_sock.c?

I've written this way because migration happens only in TCP for now, but I
agree that test of IPPROTO_TCP makes less error-prone in the future. So,
I'll test it first in the next spin.

Thank you!


>
> Also, reqsk_clone() is only used in inet_connection_sock.c.
> Can it be moved to inet_connection_sock.c instead and renamed to
> inet_reqsk_clone()?

I'll do that.