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_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")
bpf_sping_lock_test(struct __sk_buff * skb)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