netdev - Re: [PATCH/RFC bpf-next 02/16] bpf: refactor propagate

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Date:   Tue, 26 Mar 2019 19:26:59 +0100
From:   Jann Horn <jannh@...gle.com>
To:     Jiong Wang <jiong.wang@...ronome.com>
Cc:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>, bpf@...r.kernel.org,
        Network Development <netdev@...r.kernel.org>,
        oss-drivers@...ronome.com
Subject: Re: [PATCH/RFC bpf-next 02/16] bpf: refactor propagate_live implementation

On Tue, Mar 26, 2019 at 7:07 PM Jiong Wang <jiong.wang@...ronome.com> wrote:
> Some code inside current implementation of "propagate_liveness" is a little
> bit verbose.
>
> This patch refactor them so the code looks more simple and more clear.
>
> The redundant usage of "vparent->frame[vstate->curframe]" is removed as we
> are here. It is safe to do this because "state_equal" has guaranteed that
> vstate->curframe must be equal with vparent->curframe.
[...]
> @@ -6050,6 +6050,22 @@ static bool states_equal(struct bpf_verifier_env *env,
>         return true;
>  }
>
> +static int propagate_liveness_reg(struct bpf_verifier_env *env,
> +                                 struct bpf_reg_state *reg,
> +                                 struct bpf_reg_state *parent_reg, u8 flag)

This function takes four arguments...

[...]
> @@ -6071,16 +6088,13 @@ static int propagate_liveness(struct bpf_verifier_env *env,
[...]
> +               err = propagate_liveness_reg(env, &regs[i], &parent_regs[i]);

.. but both here...

[...]
> @@ -6089,11 +6103,13 @@ static int propagate_liveness(struct bpf_verifier_env *env,
[...]
> +                       err = propagate_liveness_reg(env, reg, parent_reg);

... and here you only pass in three arguments? Does this compile?