Commit c540957a authored by Song Liu's avatar Song Liu Committed by Alexei Starovoitov
Browse files

selftests/bpf: Test deadlock from recursive bpf_task_storage_[get|delete] 



Add a test with recursive bpf_task_storage_[get|delete] from fentry
programs on bpf_local_storage_lookup and bpf_local_storage_update. Without
proper deadlock prevent mechanism, this test would cause deadlock.

Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210225234319.336131-5-songliubraving@fb.com
parent 1f87dcf1

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

+23 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#include <test_progs.h>

#include "task_local_storage.skel.h"

#include "task_local_storage_exit_creds.skel.h"

#include "task_ls_recursion.skel.h"



static void test_sys_enter_exit(void)

{
@@ -60,10 +61,32 @@ static void test_exit_creds(void) 
	task_local_storage_exit_creds__destroy(skel);

}



static void test_recursion(void)

{

	struct task_ls_recursion *skel;

	int err;



	skel = task_ls_recursion__open_and_load();

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

		return;



	err = task_ls_recursion__attach(skel);

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

		goto out;



	/* trigger sys_enter, make sure it does not cause deadlock */

	syscall(SYS_gettid);



out:

	task_ls_recursion__destroy(skel);

}



void test_task_local_storage(void)

{

	if (test__start_subtest("sys_enter_exit"))

		test_sys_enter_exit();

	if (test__start_subtest("exit_creds"))

		test_exit_creds();

	if (test__start_subtest("recursion"))

		test_recursion();

}

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

0 → 100644
+70 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2021 Facebook */



#include "vmlinux.h"

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>



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



struct {

	__uint(type, BPF_MAP_TYPE_TASK_STORAGE);

	__uint(map_flags, BPF_F_NO_PREALLOC);

	__type(key, int);

	__type(value, long);

} map_a SEC(".maps");



struct {

	__uint(type, BPF_MAP_TYPE_TASK_STORAGE);

	__uint(map_flags, BPF_F_NO_PREALLOC);

	__type(key, int);

	__type(value, long);

} map_b SEC(".maps");



SEC("fentry/bpf_local_storage_lookup")

int BPF_PROG(on_lookup)

{

	struct task_struct *task = bpf_get_current_task_btf();



	bpf_task_storage_delete(&map_a, task);

	bpf_task_storage_delete(&map_b, task);

	return 0;

}



SEC("fentry/bpf_local_storage_update")

int BPF_PROG(on_update)

{

	struct task_struct *task = bpf_get_current_task_btf();

	long *ptr;



	ptr = bpf_task_storage_get(&map_a, task, 0,

				   BPF_LOCAL_STORAGE_GET_F_CREATE);

	if (ptr)

		*ptr += 1;



	ptr = bpf_task_storage_get(&map_b, task, 0,

				   BPF_LOCAL_STORAGE_GET_F_CREATE);

	if (ptr)

		*ptr += 1;



	return 0;

}



SEC("tp_btf/sys_enter")

int BPF_PROG(on_enter, struct pt_regs *regs, long id)

{

	struct task_struct *task;

	long *ptr;



	task = bpf_get_current_task_btf();

	ptr = bpf_task_storage_get(&map_a, task, 0,

				   BPF_LOCAL_STORAGE_GET_F_CREATE);

	if (ptr)

		*ptr = 200;



	ptr = bpf_task_storage_get(&map_b, task, 0,

				   BPF_LOCAL_STORAGE_GET_F_CREATE);

	if (ptr)

		*ptr = 100;

	return 0;

}