1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (c) 2019 Facebook
3 #include <linux/bpf.h>
4 #include <linux/version.h>
5 #include <bpf/bpf_helpers.h>
6 
7 struct hmap_elem {
8 	volatile int cnt;
9 	struct bpf_spin_lock lock;
10 	int test_padding;
11 };
12 
13 struct {
14 	__uint(type, BPF_MAP_TYPE_HASH);
15 	__uint(max_entries, 1);
16 	__type(key, int);
17 	__type(value, struct hmap_elem);
18 } hmap SEC(".maps");
19 
20 struct cls_elem {
21 	struct bpf_spin_lock lock;
22 	volatile int cnt;
23 };
24 
25 struct {
26 	__uint(type, BPF_MAP_TYPE_CGROUP_STORAGE);
27 	__type(key, struct bpf_cgroup_storage_key);
28 	__type(value, struct cls_elem);
29 } cls_map SEC(".maps");
30 
31 struct bpf_vqueue {
32 	struct bpf_spin_lock lock;
33 	/* 4 byte hole */
34 	unsigned long long lasttime;
35 	int credit;
36 	unsigned int rate;
37 };
38 
39 struct {
40 	__uint(type, BPF_MAP_TYPE_ARRAY);
41 	__uint(max_entries, 1);
42 	__type(key, int);
43 	__type(value, struct bpf_vqueue);
44 } vqueue SEC(".maps");
45 
46 #define CREDIT_PER_NS(delta, rate) (((delta) * rate) >> 20)
47 
48 SEC("spin_lock_demo")
49 int bpf_sping_lock_test(struct __sk_buff *skb)
50 {
51 	volatile int credit = 0, max_credit = 100, pkt_len = 64;
52 	struct hmap_elem zero = {}, *val;
53 	unsigned long long curtime;
54 	struct bpf_vqueue *q;
55 	struct cls_elem *cls;
56 	int key = 0;
57 	int err = 0;
58 
59 	val = bpf_map_lookup_elem(&hmap, &key);
60 	if (!val) {
61 		bpf_map_update_elem(&hmap, &key, &zero, 0);
62 		val = bpf_map_lookup_elem(&hmap, &key);
63 		if (!val) {
64 			err = 1;
65 			goto err;
66 		}
67 	}
68 	/* spin_lock in hash map run time test */
69 	bpf_spin_lock(&val->lock);
70 	if (val->cnt)
71 		val->cnt--;
72 	else
73 		val->cnt++;
74 	if (val->cnt != 0 && val->cnt != 1)
75 		err = 1;
76 	bpf_spin_unlock(&val->lock);
77 
78 	/* spin_lock in array. virtual queue demo */
79 	q = bpf_map_lookup_elem(&vqueue, &key);
80 	if (!q)
81 		goto err;
82 	curtime = bpf_ktime_get_ns();
83 	bpf_spin_lock(&q->lock);
84 	q->credit += CREDIT_PER_NS(curtime - q->lasttime, q->rate);
85 	q->lasttime = curtime;
86 	if (q->credit > max_credit)
87 		q->credit = max_credit;
88 	q->credit -= pkt_len;
89 	credit = q->credit;
90 	bpf_spin_unlock(&q->lock);
91 
92 	/* spin_lock in cgroup local storage */
93 	cls = bpf_get_local_storage(&cls_map, 0);
94 	bpf_spin_lock(&cls->lock);
95 	cls->cnt++;
96 	bpf_spin_unlock(&cls->lock);
97 
98 err:
99 	return err;
100 }
101 char _license[] SEC("license") = "GPL";
102