130e0f7af9
This patch adds 4 subtests to demonstrate these patterns and validating correctness. subtest1: 1) We use task_iter to iterate all process in the system and search for the current process with a given pid. 2) We create some threads in current process context, and use BPF_TASK_ITER_PROC_THREADS to iterate all threads of current process. As expected, we would find all the threads of current process. 3) We create some threads and use BPF_TASK_ITER_ALL_THREADS to iterate all threads in the system. As expected, we would find all the threads which was created. subtest2: We create a cgroup and add the current task to the cgroup. In the BPF program, we would use bpf_for_each(css_task, task, css) to iterate all tasks under the cgroup. As expected, we would find the current process. subtest3: 1) We create a cgroup tree. In the BPF program, we use bpf_for_each(css, pos, root, XXX) to iterate all descendant under the root with pre and post order. As expected, we would find all descendant and the last iterating cgroup in post-order is root cgroup, the first iterating cgroup in pre-order is root cgroup. 2) We wse BPF_CGROUP_ITER_ANCESTORS_UP to traverse the cgroup tree starting from leaf and root separately, and record the height. The diff of the hights would be the total tree-high - 1. subtest4: Add some failure testcase when using css_task, task and css iters, e.g, unlock when using task-iters to iterate tasks. Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com> Link: https://lore.kernel.org/r/20231018061746.111364-9-zhouchuyi@bytedance.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
72 lines
1.8 KiB
C
72 lines
1.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/* Copyright (C) 2023 Chuyi Zhou <zhouchuyi@bytedance.com> */
|
|
|
|
#include "vmlinux.h"
|
|
#include <bpf/bpf_helpers.h>
|
|
#include <bpf/bpf_tracing.h>
|
|
#include "bpf_misc.h"
|
|
#include "bpf_experimental.h"
|
|
|
|
char _license[] SEC("license") = "GPL";
|
|
|
|
pid_t target_pid;
|
|
u64 root_cg_id, leaf_cg_id;
|
|
u64 first_cg_id, last_cg_id;
|
|
|
|
int pre_order_cnt, post_order_cnt, tree_high;
|
|
|
|
struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
|
|
void bpf_cgroup_release(struct cgroup *p) __ksym;
|
|
void bpf_rcu_read_lock(void) __ksym;
|
|
void bpf_rcu_read_unlock(void) __ksym;
|
|
|
|
SEC("fentry.s/" SYS_PREFIX "sys_getpgid")
|
|
int iter_css_for_each(const void *ctx)
|
|
{
|
|
struct task_struct *cur_task = bpf_get_current_task_btf();
|
|
struct cgroup_subsys_state *root_css, *leaf_css, *pos;
|
|
struct cgroup *root_cgrp, *leaf_cgrp, *cur_cgrp;
|
|
|
|
if (cur_task->pid != target_pid)
|
|
return 0;
|
|
|
|
root_cgrp = bpf_cgroup_from_id(root_cg_id);
|
|
|
|
if (!root_cgrp)
|
|
return 0;
|
|
|
|
leaf_cgrp = bpf_cgroup_from_id(leaf_cg_id);
|
|
|
|
if (!leaf_cgrp) {
|
|
bpf_cgroup_release(root_cgrp);
|
|
return 0;
|
|
}
|
|
root_css = &root_cgrp->self;
|
|
leaf_css = &leaf_cgrp->self;
|
|
pre_order_cnt = post_order_cnt = tree_high = 0;
|
|
first_cg_id = last_cg_id = 0;
|
|
|
|
bpf_rcu_read_lock();
|
|
bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_POST) {
|
|
cur_cgrp = pos->cgroup;
|
|
post_order_cnt++;
|
|
last_cg_id = cur_cgrp->kn->id;
|
|
}
|
|
|
|
bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_PRE) {
|
|
cur_cgrp = pos->cgroup;
|
|
pre_order_cnt++;
|
|
if (!first_cg_id)
|
|
first_cg_id = cur_cgrp->kn->id;
|
|
}
|
|
|
|
bpf_for_each(css, pos, leaf_css, BPF_CGROUP_ITER_ANCESTORS_UP)
|
|
tree_high++;
|
|
|
|
bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_ANCESTORS_UP)
|
|
tree_high--;
|
|
bpf_rcu_read_unlock();
|
|
bpf_cgroup_release(root_cgrp);
|
|
bpf_cgroup_release(leaf_cgrp);
|
|
return 0;
|
|
}
|