netdev - Re: [PATCH bpf-next v4 1/2] bpf: add CHECKSUM

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Date: Wed, 12 Jun 2024 07:49:17 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Vadim Fedorenko <vadfed@...a.com>
Cc: Vadim Fedorenko <vadim.fedorenko@...ux.dev>, Daniel Borkmann
 <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, "Alexei
 Starovoitov" <ast@...nel.org>, Mykola Lysenko <mykolal@...com>, Martin
 KaFai Lau <martin.lau@...ux.dev>, <bpf@...r.kernel.org>,
 <netdev@...r.kernel.org>
Subject: Re: [PATCH bpf-next v4 1/2] bpf: add CHECKSUM_COMPLETE to bpf test
 progs

On Thu, 6 Jun 2024 07:58:50 -0700 Vadim Fedorenko wrote:
> @@ -1060,9 +1062,19 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
>  		__skb_push(skb, hh_len);
>  	if (is_direct_pkt_access)
>  		bpf_compute_data_pointers(skb);
> +
>  	ret = convert___skb_to_skb(skb, ctx);
>  	if (ret)
>  		goto out;
> +
> +	if (kattr->test.flags & BPF_F_TEST_SKB_CHECKSUM_COMPLETE) {
> +		const int off = skb_network_offset(skb);
> +		int len = skb->len - off;
> +
> +		skb->csum = skb_checksum(skb, off, len, 0);
> +		skb->ip_summed = CHECKSUM_COMPLETE;
> +	}

Looks good, overall, although I'd be tempted to place this before 
the L2 is pushed, a few lines up, so that we don't need to worry
about network offset. Then again, with you approach there is a nice
symmetry between the pre- and post- if blocks so either way is fine:

Reviewed-by: Jakub Kicinski <kuba@...nel.org>