Re: [PATCH bpf-next v4 1/2] bpf: Only enforce 8 frame call stack limit for all-static stacks

[bot+bpf-ci@kernel.org]

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> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 8e4f69918693..ccd4efec179d 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -6733,9 +6733,11 @@ static int check_max_stack_depth_subprog(struct bpf_verifier_env *env, int idx,
>  	struct bpf_insn *insn = env->prog->insnsi;
>  	int depth = 0, frame = 0, i, subprog_end, subprog_depth;
>  	bool tail_call_reachable = false;
> -	int ret_insn[MAX_CALL_FRAMES];
> -	int ret_prog[MAX_CALL_FRAMES];
> -	int j;
> +	int total;
> +	int tmp;
> +
> +	/* no caller idx */
> +	subprog[idx].dinfo.caller = -1;

The function header comment above this hunk still reads:

    Since recursion is prevented by check_cfg() this algorithm
    only needs a local stack of MAX_CALL_FRAMES to remember callsites

The local stack arrays (ret_insn[] and ret_prog[]) have been removed
in favor of per-subprog dinfo fields. Should this comment be updated
to reflect the new approach?

This was also noted during the v3 review:
https://lore.kernel.org/bpf/ad397307a9cd76c9739ee05f4642c7b6a881b7dfb8a2facefa6b2062ffe328ea@mail.kernel.org/


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