task_work_stress.c

 1// SPDX-License-Identifier: GPL-2.0
 2/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
 3
 4#include <vmlinux.h>
 5#include <string.h>
 6#include <stdbool.h>
 7#include <bpf/bpf_helpers.h>
 8#include <bpf/bpf_tracing.h>
 9#include "bpf_misc.h"
10
11#define ENTRIES 128
12
13char _license[] SEC("license") = "GPL";
14
15__u64 callback_scheduled = 0;
16__u64 callback_success = 0;
17__u64 schedule_error = 0;
18__u64 delete_success = 0;
19
20struct elem {
21	__u32 count;
22	struct bpf_task_work tw;
23};
24
25struct {
26	__uint(type, BPF_MAP_TYPE_HASH);
27	__uint(map_flags, BPF_F_NO_PREALLOC);
28	__uint(max_entries, ENTRIES);
29	__type(key, int);
30	__type(value, struct elem);
31} hmap SEC(".maps");
32
33static int process_work(struct bpf_map *map, void *key, void *value)
34{
35	__sync_fetch_and_add(&callback_success, 1);
36	return 0;
37}
38
39SEC("syscall")
40int schedule_task_work(void *ctx)
41{
42	struct elem empty_work = {.count = 0};
43	struct elem *work;
44	int key = 0, err;
45
46	key = bpf_ktime_get_ns() % ENTRIES;
47	work = bpf_map_lookup_elem(&hmap, &key);
48	if (!work) {
49		bpf_map_update_elem(&hmap, &key, &empty_work, BPF_NOEXIST);
50		work = bpf_map_lookup_elem(&hmap, &key);
51		if (!work)
52			return 0;
53	}
54	err = bpf_task_work_schedule_signal_impl(bpf_get_current_task_btf(), &work->tw, &hmap,
55						 process_work, NULL);
56	if (err)
57		__sync_fetch_and_add(&schedule_error, 1);
58	else
59		__sync_fetch_and_add(&callback_scheduled, 1);
60	return 0;
61}
62
63SEC("syscall")
64int delete_task_work(void *ctx)
65{
66	int key = 0, err;
67
68	key = bpf_get_prandom_u32() % ENTRIES;
69	err = bpf_map_delete_elem(&hmap, &key);
70	if (!err)
71		__sync_fetch_and_add(&delete_success, 1);
72	return 0;
73}