netdev - Re: [PATCH bpf] bpf: allow clearing all sock

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Date:   Mon, 15 Apr 2019 22:46:15 +0000
From:   Martin Lau <kafai@...com>
To:     Viet Hoang Tran <hoang.tran@...ouvain.be>
CC:     "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        "Daniel Borkmann" <daniel@...earbox.net>,
        "David S. Miller" <davem@...emloft.net>,
        Lawrence Brakmo <brakmo@...com>,
        Quentin Monnet <quentin.monnet@...ronome.com>,
        "tranviethoang.vn@...il.com" <tranviethoang.vn@...il.com>
Subject: Re: [PATCH bpf] bpf: allow clearing all sock_ops callback flags

On Mon, Apr 15, 2019 at 09:54:55AM +0000, Viet Hoang Tran wrote:
> The helper function bpf_sock_ops_cb_flags_set() can be used to both
> set and clear the sock_ops callback flags. However, its current
> behavior is not consistent. BPF program may clear a flag if more than
> one were set, or replace a flag with another one, but cannot clear all
> flags.
> 
> This patch also updates the documentation to clarify the ability to
> clear flags of this helper function.
>

[ ... ]

> diff --git a/net/core/filter.c b/net/core/filter.c
> index fc92ebc4e200..0c4cdfbb2fc7 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -4355,8 +4355,7 @@ BPF_CALL_2(bpf_sock_ops_cb_flags_set, struct bpf_sock_ops_kern *, bpf_sock,
>  	if (!IS_ENABLED(CONFIG_INET) || !sk_fullsock(sk))
>  		return -EINVAL;
>  
> -	if (val)
> -		tcp_sk(sk)->bpf_sock_ops_cb_flags = val;
> +	tcp_sk(sk)->bpf_sock_ops_cb_flags = val;
Acked-by: Martin KaFai Lau <kafai@...com>

>  
>  	return argval & (~BPF_SOCK_OPS_ALL_CB_FLAGS);
>  }
> -- 
> 2.17.1
>