tools/testing/selftests/bpf/progs/iters_css.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (C) 2023 Chuyi Zhou <[email protected]> */
   3
   4 #include "vmlinux.h"
   5 #include <bpf/bpf_helpers.h>
   6 #include <bpf/bpf_tracing.h>
   7 #include "bpf_misc.h"
   8 #include "bpf_experimental.h"
   9
  10 char _license[] SEC("license") = "GPL";
  11
  12 pid_t target_pid;
  13 u64 root_cg_id, leaf_cg_id;
  14 u64 first_cg_id, last_cg_id;
  15
  16 int pre_order_cnt, post_order_cnt, tree_high;
  17
  18 struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
  19 void bpf_cgroup_release(struct cgroup *p) __ksym;
  20 void bpf_rcu_read_lock(void) __ksym;
  21 void bpf_rcu_read_unlock(void) __ksym;
  22
  23 SEC("fentry.s/" SYS_PREFIX "sys_getpgid")
  24 int iter_css_for_each(const void *ctx)
  25 {
  26         struct task_struct *cur_task = bpf_get_current_task_btf();
  27         struct cgroup_subsys_state *root_css, *leaf_css, *pos;
  28         struct cgroup *root_cgrp, *leaf_cgrp, *cur_cgrp;
  29
  30         if (cur_task->pid != target_pid)
  31                 return 0;
  32
  33         root_cgrp = bpf_cgroup_from_id(root_cg_id);
  34
  35         if (!root_cgrp)
  36                 return 0;
  37
  38         leaf_cgrp = bpf_cgroup_from_id(leaf_cg_id);
  39
  40         if (!leaf_cgrp) {
  41                 bpf_cgroup_release(root_cgrp);
  42                 return 0;
  43         }
  44         root_css = &root_cgrp->self;
  45         leaf_css = &leaf_cgrp->self;
  46         pre_order_cnt = post_order_cnt = tree_high = 0;
  47         first_cg_id = last_cg_id = 0;
  48
  49         bpf_rcu_read_lock();
  50         bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_POST) {
  51                 cur_cgrp = pos->cgroup;
  52                 post_order_cnt++;
  53                 last_cg_id = cur_cgrp->kn->id;
  54         }
  55
  56         bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_PRE) {
  57                 cur_cgrp = pos->cgroup;
  58                 pre_order_cnt++;
  59                 if (!first_cg_id)
  60                         first_cg_id = cur_cgrp->kn->id;
  61         }
  62
  63         bpf_for_each(css, pos, leaf_css, BPF_CGROUP_ITER_ANCESTORS_UP)
  64                 tree_high++;
  65
  66         bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_ANCESTORS_UP)
  67                 tree_high--;
  68         bpf_rcu_read_unlock();
  69         bpf_cgroup_release(root_cgrp);
  70         bpf_cgroup_release(leaf_cgrp);
  71         return 0;
  72 }