1#include <linux/init.h>
2#include <linux/kthread.h>
3#include <linux/hrtimer.h>
4#include <linux/fs.h>
5#include <linux/debugfs.h>
6#include <linux/export.h>
7#include <linux/spinlock.h>
8
9
10static int ss_get(void *data, u64 *val)
11{
12	ktime_t start, finish;
13	int loops;
14	int cont;
15	DEFINE_RAW_SPINLOCK(ss_spin);
16
17	loops = 1000000;
18	cont = 1;
19
20	start = ktime_get();
21
22	while (cont) {
23		raw_spin_lock(&ss_spin);
24		loops--;
25		if (loops == 0)
26			cont = 0;
27		raw_spin_unlock(&ss_spin);
28	}
29
30	finish = ktime_get();
31
32	*val = ktime_us_delta(finish, start);
33
34	return 0;
35}
36
37DEFINE_SIMPLE_ATTRIBUTE(fops_ss, ss_get, NULL, "%llu\n");
38
39
40
41struct spin_multi_state {
42	raw_spinlock_t lock;
43	atomic_t start_wait;
44	atomic_t enter_wait;
45	atomic_t exit_wait;
46	int loops;
47};
48
49struct spin_multi_per_thread {
50	struct spin_multi_state *state;
51	ktime_t start;
52};
53
54static int multi_other(void *data)
55{
56	int loops;
57	int cont;
58	struct spin_multi_per_thread *pt = data;
59	struct spin_multi_state *s = pt->state;
60
61	loops = s->loops;
62	cont = 1;
63
64	atomic_dec(&s->enter_wait);
65
66	while (atomic_read(&s->enter_wait))
67		; /* spin */
68
69	pt->start = ktime_get();
70
71	atomic_dec(&s->start_wait);
72
73	while (atomic_read(&s->start_wait))
74		; /* spin */
75
76	while (cont) {
77		raw_spin_lock(&s->lock);
78		loops--;
79		if (loops == 0)
80			cont = 0;
81		raw_spin_unlock(&s->lock);
82	}
83
84	atomic_dec(&s->exit_wait);
85	while (atomic_read(&s->exit_wait))
86		; /* spin */
87	return 0;
88}
89
90static int multi_get(void *data, u64 *val)
91{
92	ktime_t finish;
93	struct spin_multi_state ms;
94	struct spin_multi_per_thread t1, t2;
95
96	ms.lock = __RAW_SPIN_LOCK_UNLOCKED("multi_get");
97	ms.loops = 1000000;
98
99	atomic_set(&ms.start_wait, 2);
100	atomic_set(&ms.enter_wait, 2);
101	atomic_set(&ms.exit_wait, 2);
102	t1.state = &ms;
103	t2.state = &ms;
104
105	kthread_run(multi_other, &t2, "multi_get");
106
107	multi_other(&t1);
108
109	finish = ktime_get();
110
111	*val = ktime_us_delta(finish, t1.start);
112
113	return 0;
114}
115
116DEFINE_SIMPLE_ATTRIBUTE(fops_multi, multi_get, NULL, "%llu\n");
117
118
119extern struct dentry *mips_debugfs_dir;
120static int __init spinlock_test(void)
121{
122	struct dentry *d;
123
124	if (!mips_debugfs_dir)
125		return -ENODEV;
126
127	d = debugfs_create_file("spin_single", S_IRUGO,
128				mips_debugfs_dir, NULL,
129				&fops_ss);
130	if (!d)
131		return -ENOMEM;
132
133	d = debugfs_create_file("spin_multi", S_IRUGO,
134				mips_debugfs_dir, NULL,
135				&fops_multi);
136	if (!d)
137		return -ENOMEM;
138
139	return 0;
140}
141device_initcall(spinlock_test);
142