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From: John Fastabend <john.fastabend@gmail.com>
To: Cong Wang <xiyou.wangcong@gmail.com>,
	John Fastabend <john.fastabend@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Alexei Starovoitov <ast@fb.com>, bpf <bpf@vger.kernel.org>,
	Linux Kernel Network Developers <netdev@vger.kernel.org>,
	Lorenz Bauer <lmb@cloudflare.com>
Subject: Re: [bpf PATCH 1/2] bpf, sockmap: fix sk->prot unhash op reset
Date: Wed, 24 Mar 2021 19:28:35 -0700	[thread overview]
Message-ID: <605bf553d16f_64fde2081@john-XPS-13-9370.notmuch> (raw)
In-Reply-To: <CAM_iQpUNUE8cmyNaALG1dZtCfJGah2pggDNk-eVbyxexnA4o_g@mail.gmail.com>

Cong Wang wrote:
> On Wed, Mar 24, 2021 at 1:59 PM John Fastabend <john.fastabend@gmail.com> wrote:
> > diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
> > index 47b7c5334c34..ecb5634b4c4a 100644
> > --- a/net/tls/tls_main.c
> > +++ b/net/tls/tls_main.c
> > @@ -754,6 +754,12 @@ static void tls_update(struct sock *sk, struct proto *p,
> >
> >         ctx = tls_get_ctx(sk);
> >         if (likely(ctx)) {
> > +               /* TLS does not have an unhash proto in SW cases, but we need
> > +                * to ensure we stop using the sock_map unhash routine because
> > +                * the associated psock is being removed. So use the original
> > +                * unhash handler.
> > +                */
> > +               WRITE_ONCE(sk->sk_prot->unhash, p->unhash);
> >                 ctx->sk_write_space = write_space;
> >                 ctx->sk_proto = p;
> 
> It looks awkward to update sk->sk_proto inside tls_update(),
> at least when ctx!=NULL.

hmm. It doesn't strike me as paticularly awkward but OK.

> 
> What is wrong with updating it in sk_psock_restore_proto()
> when inet_csk_has_ulp() is true? It looks better to me.

It could be wrong if inet_csk_has_ulp has an unhash callback
already assigned. But, because we know inet_csk_has_ulp()
really means is_tls_attached() it would be fine.

> 
> diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
> index 6c09d94be2e9..da5dc3ef0ee3 100644
> --- a/include/linux/skmsg.h
> +++ b/include/linux/skmsg.h
> @@ -360,8 +360,8 @@ static inline void sk_psock_update_proto(struct sock *sk,
>  static inline void sk_psock_restore_proto(struct sock *sk,
>                                           struct sk_psock *psock)
>  {
> -       sk->sk_prot->unhash = psock->saved_unhash;
>         if (inet_csk_has_ulp(sk)) {
> +               sk->sk_prot->unhash = psock->sk_proto->unhash;
>                 tcp_update_ulp(sk, psock->sk_proto, psock->saved_write_space);
>         } else {
>                 sk->sk_write_space = psock->saved_write_space;
> 
> 
> sk_psock_restore_proto() is the only caller of tcp_update_ulp()
> so should be equivalent.

Agree it is equivalent. I don't mind moving the assignment around
if folks think its nicer.

> 
> Thanks.

  reply	other threads:[~2021-03-25  2:29 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-24 20:59 [bpf PATCH 0/2] bpf, sockmap fixes John Fastabend
2021-03-24 20:59 ` [bpf PATCH 1/2] bpf, sockmap: fix sk->prot unhash op reset John Fastabend
2021-03-25  0:11   ` Cong Wang
2021-03-25  2:28     ` John Fastabend [this message]
2021-03-25 18:57       ` Cong Wang
2021-03-26  0:57         ` John Fastabend
2021-03-24 20:59 ` [bpf PATCH 2/2] bpf, sockmap: fix incorrect fwd_alloc accounting John Fastabend
2021-03-25  0:44   ` Cong Wang
2021-03-25  2:46     ` John Fastabend
2021-03-25 19:27       ` Cong Wang
2021-03-26  0:58         ` John Fastabend

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