netdev - Re: [PATCH v6 bpf-next 03/11] tcp: Keep TCP_CLOSE sockets in the reuseport group.

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Message-ID: <20210520062648.ejqufb6m5wr6z7k2@kafai-mbp.dhcp.thefacebook.com>
Date:   Wed, 19 May 2021 23:26:48 -0700
From:   Martin KaFai Lau <kafai@...com>
To:     Kuniyuki Iwashima <kuniyu@...zon.co.jp>
CC:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Benjamin Herrenschmidt <benh@...zon.com>,
        Kuniyuki Iwashima <kuni1840@...il.com>, <bpf@...r.kernel.org>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 bpf-next 03/11] tcp: Keep TCP_CLOSE sockets in the
 reuseport group.

On Mon, May 17, 2021 at 09:22:50AM +0900, Kuniyuki Iwashima wrote:

> +static int reuseport_resurrect(struct sock *sk, struct sock_reuseport *old_reuse,
> +			       struct sock_reuseport *reuse, bool bind_inany)
> +{
> +	if (old_reuse == reuse) {
> +		/* If sk was in the same reuseport group, just pop sk out of
> +		 * the closed section and push sk into the listening section.
> +		 */
> +		__reuseport_detach_closed_sock(sk, old_reuse);
> +		__reuseport_add_sock(sk, old_reuse);
> +		return 0;
> +	}
> +
> +	if (!reuse) {
> +		/* In bind()/listen() path, we cannot carry over the eBPF prog
> +		 * for the shutdown()ed socket. In setsockopt() path, we should
> +		 * not change the eBPF prog of listening sockets by attaching a
> +		 * prog to the shutdown()ed socket. Thus, we will allocate a new
> +		 * reuseport group and detach sk from the old group.
> +		 */
For the reuseport_attach_prog() path, I think it needs to consider
the reuse->num_closed_socks != 0 case also and that should belong
to the resurrect case.  For example, when
sk_unhashed(sk) but sk->sk_reuseport == 0.