Re: [PATCH net-next v3 14/14] bpf: add simple bpf tests in the tx path for so_timstamping feature

[Martin KaFai Lau <martin.lau@linux.dev>]

On 10/28/24 4:05 AM, Jason Xing wrote:
> From: Jason Xing <kernelxing@tencent.com>
> 
> Only check if we pass those three key points after we enable the
> bpf extension for so_timestamping. During each point, we can choose
> whether to print the current timestamp.

The bpf prog usually does more than just print. The bpf prog aggregates data 
first before sending all raw data to the user space.

The selftests will be more useful for the reviewer and the future user if it can 
at least show how it can calculate the tx delay between [sendmsg, SCHED], 
[SCHED, SND], [SND, ACK].

[ ... ]

> +SEC("sockops")
> +int skops_sockopt(struct bpf_sock_ops *skops)
> +{
> +	struct bpf_sock *bpf_sk = skops->sk;
> +	struct sock *sk;
> +
> +	if (!bpf_sk)
> +		return 1;
> +
> +	sk = (struct sock *)bpf_skc_to_tcp_sock(bpf_sk);
> +	if (!sk)
> +		return 1;
> +
> +	switch (skops->op) {
> +	case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
> +		nr_active += !bpf_test_sockopt(skops, sk);
> +		break;
> +	case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
> +		nr_passive += !bpf_test_sockopt(skops, sk);
> +		break;
> +	case BPF_SOCK_OPS_TS_SCHED_OPT_CB:
> +		nr_sched += 1;
> +		break;
> +	case BPF_SOCK_OPS_TS_SW_OPT_CB:
> +		nr_txsw += 1;
> +		break;
> +	case BPF_SOCK_OPS_TS_ACK_OPT_CB:
> +		nr_ack += 1;

> +		break;
> +	}
> +
> +	return 1;
> +}
> +
> +char _license[] SEC("license") = "GPL";