netdev - RE: [PATCH bpf-next v3 03/12] bpf: tcp: move assertions into tcp_bpf_get

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Date:   Fri, 06 Mar 2020 07:25:32 -0800
From:   John Fastabend <john.fastabend@...il.com>
To:     Lorenz Bauer <lmb@...udflare.com>, john.fastabend@...il.com,
        Eric Dumazet <edumazet@...gle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Lorenz Bauer <lmb@...udflare.com>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Alexei Starovoitov <ast@...nel.org>
Cc:     kernel-team@...udflare.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, bpf@...r.kernel.org
Subject: RE: [PATCH bpf-next v3 03/12] bpf: tcp: move assertions into
 tcp_bpf_get_proto

Lorenz Bauer wrote:
> We need to ensure that sk->sk_prot uses certain callbacks, so that
> code that directly calls e.g. tcp_sendmsg in certain corner cases
> works. To avoid spurious asserts, we must to do this only if
> sk_psock_update_proto has not yet been called. The same invariants
> apply for tcp_bpf_check_v6_needs_rebuild, so move the call as well.
> 
> Doing so allows us to merge tcp_bpf_init and tcp_bpf_reinit.
> 
> Signed-off-by: Lorenz Bauer <lmb@...udflare.com>

Small nit if you update it just carry the acks through.

Acked-by: John Fastabend <john.fastabend@...il.com>
 
>  	skb_verdict = READ_ONCE(progs->skb_verdict);
> @@ -191,18 +191,14 @@ static int sock_map_link(struct bpf_map *map, struct sk_psock_progs *progs,
>  			ret = -ENOMEM;
>  			goto out_progs;
>  		}
> -		sk_psock_is_new = true;
>  	}
>  
>  	if (msg_parser)
>  		psock_set_prog(&psock->progs.msg_parser, msg_parser);
> -	if (sk_psock_is_new) {
> -		ret = tcp_bpf_init(sk);
> -		if (ret < 0)
> -			goto out_drop;
> -	} else {
> -		tcp_bpf_reinit(sk);
> -	}
> +
> +	ret = tcp_bpf_init(sk);
> +	if (ret < 0)
> +		goto out_drop;
>  
>  	write_lock_bh(&sk->sk_callback_lock);
>  	if (skb_progs && !psock->parser.enabled) {
> @@ -239,12 +235,9 @@ static int sock_map_link_no_progs(struct bpf_map *map, struct sock *sk)
>  	if (IS_ERR(psock))
>  		return PTR_ERR(psock);
>  
> -	if (psock) {
> -		tcp_bpf_reinit(sk);
> -		return 0;
> -	}
> +	if (!psock)
> +		psock = sk_psock_init(sk, map->numa_node);
>  
> -	psock = sk_psock_init(sk, map->numa_node);
>  	if (!psock)
>  		return -ENOMEM;

also small nit this reads,

 if (!psock)
    psock = ...
 if (!psock)
    return -ENOMEM

how about,

 if (!psock) {
   psock = ...
   if (!psock) return -ENOMEM;
 }