Commit f49843af authored by Chuyi Zhou's avatar Chuyi Zhou Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add tests for css_task iter combining with cgroup iter 



This patch adds a test which demonstrates how css_task iter can be combined
with cgroup iter and it won't cause deadlock, though cgroup iter is not
sleepable.

Signed-off-by: default avatarChuyi Zhou <zhouchuyi@bytedance.com>
Acked-by: default avatarYonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20231031050438.93297-3-zhouchuyi@bytedance.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 3091b667

tools/testing/selftests/bpf/prog_tests/cgroup_iter.c

+33 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
#include <test_progs.h>

#include <bpf/libbpf.h>

#include <bpf/btf.h>

#include "iters_css_task.skel.h"

#include "cgroup_iter.skel.h"

#include "cgroup_helpers.h"
@@ -263,6 +264,35 @@ static void test_walk_dead_self_only(struct cgroup_iter *skel) 
	close(cgrp_fd);

}



static void test_walk_self_only_css_task(void)

{

	struct iters_css_task *skel;

	int err;



	skel = iters_css_task__open();

	if (!ASSERT_OK_PTR(skel, "skel_open"))

		return;



	bpf_program__set_autoload(skel->progs.cgroup_id_printer, true);



	err = iters_css_task__load(skel);

	if (!ASSERT_OK(err, "skel_load"))

		goto cleanup;



	err = join_cgroup(cg_path[CHILD2]);

	if (!ASSERT_OK(err, "join_cgroup"))

		goto cleanup;



	skel->bss->target_pid = getpid();

	snprintf(expected_output, sizeof(expected_output),

		PROLOGUE "%8llu\n" EPILOGUE, cg_id[CHILD2]);

	read_from_cgroup_iter(skel->progs.cgroup_id_printer, cg_fd[CHILD2],

		BPF_CGROUP_ITER_SELF_ONLY, "test_walk_self_only_css_task");

	ASSERT_EQ(skel->bss->css_task_cnt, 1, "css_task_cnt");

cleanup:

	iters_css_task__destroy(skel);

}



void test_cgroup_iter(void)

{

	struct cgroup_iter *skel = NULL;
@@ -293,6 +323,9 @@ void test_cgroup_iter(void) 
		test_walk_self_only(skel);

	if (test__start_subtest("cgroup_iter__dead_self_only"))

		test_walk_dead_self_only(skel);

	if (test__start_subtest("cgroup_iter__self_only_css_task"))

		test_walk_self_only_css_task();



out:

	cgroup_iter__destroy(skel);

	cleanup_cgroups();

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

+44 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 


char _license[] SEC("license") = "GPL";



struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym;

struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;

void bpf_cgroup_release(struct cgroup *p) __ksym;
@@ -45,3 +46,46 @@ int BPF_PROG(iter_css_task_for_each, struct vm_area_struct *vma, 


	return -EPERM;

}



static inline u64 cgroup_id(struct cgroup *cgrp)

{

	return cgrp->kn->id;

}



SEC("?iter/cgroup")

int cgroup_id_printer(struct bpf_iter__cgroup *ctx)

{

	struct seq_file *seq = ctx->meta->seq;

	struct cgroup *cgrp, *acquired;

	struct cgroup_subsys_state *css;

	struct task_struct *task;

	u64 cgrp_id;



	cgrp = ctx->cgroup;



	/* epilogue */

	if (cgrp == NULL) {

		BPF_SEQ_PRINTF(seq, "epilogue\n");

		return 0;

	}



	/* prologue */

	if (ctx->meta->seq_num == 0)

		BPF_SEQ_PRINTF(seq, "prologue\n");



	cgrp_id = cgroup_id(cgrp);



	BPF_SEQ_PRINTF(seq, "%8llu\n", cgrp_id);



	acquired = bpf_cgroup_from_id(cgrp_id);

	if (!acquired)

		return 0;

	css = &acquired->self;

	css_task_cnt = 0;

	bpf_for_each(css_task, task, css, CSS_TASK_ITER_PROCS) {

		if (task->pid == target_pid)

			css_task_cnt++;

	}

	bpf_cgroup_release(acquired);

	return 0;

}