1// SPDX-License-Identifier: GPL-2.0
 2/* Copyright (c) 2022 Google */
 3#include <vmlinux.h>
 4#include <bpf/bpf_helpers.h>
 5#include <bpf/bpf_tracing.h>
 6
 7char _license[] SEC("license") = "GPL";
 8int terminate_early = 0;
 9u64 terminal_cgroup = 0;
10
11static inline u64 cgroup_id(struct cgroup *cgrp)
12{
13	return cgrp->kn->id;
14}
15
16SEC("iter/cgroup")
17int cgroup_id_printer(struct bpf_iter__cgroup *ctx)
18{
19	struct seq_file *seq = ctx->meta->seq;
20	struct cgroup *cgrp = ctx->cgroup;
21
22	/* epilogue */
23	if (cgrp == NULL) {
24		BPF_SEQ_PRINTF(seq, "epilogue\n");
25		return 0;
26	}
27
28	/* prologue */
29	if (ctx->meta->seq_num == 0)
30		BPF_SEQ_PRINTF(seq, "prologue\n");
31
32	BPF_SEQ_PRINTF(seq, "%8llu\n", cgroup_id(cgrp));
33
34	if (terminal_cgroup == cgroup_id(cgrp))
35		return 1;
36
37	return terminate_early ? 1 : 0;
38}