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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: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210225234319.336131-5-songliubraving@fb.com
This commit is contained in:
Song Liu 2021-02-25 15:43:17 -08:00 committed by Alexei Starovoitov
parent 1f87dcf116
commit c540957a4d
2 changed files with 93 additions and 0 deletions
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23
tools/testing/selftests/bpf/prog_tests/task_local_storage.c
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@ -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();
}

70
tools/testing/selftests/bpf/progs/task_ls_recursion.c Normal file
View File

@ -0,0 +1,70 @@
// 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;
}