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1/*
2 * Sample kfifo int type implementation
3 *
4 * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
5 *
6 * Released under the GPL version 2 only.
7 *
8 */
9
10#include <linux/init.h>
11#include <linux/module.h>
12#include <linux/proc_fs.h>
13#include <linux/mutex.h>
14#include <linux/kfifo.h>
15
16/*
17 * This module shows how to create a int type fifo.
18 */
19
20/* fifo size in elements (ints) */
21#define FIFO_SIZE 32
22
23/* name of the proc entry */
24#define PROC_FIFO "int-fifo"
25
26/* lock for procfs read access */
27static DEFINE_MUTEX(read_lock);
28
29/* lock for procfs write access */
30static DEFINE_MUTEX(write_lock);
31
32/*
33 * define DYNAMIC in this example for a dynamically allocated fifo.
34 *
35 * Otherwise the fifo storage will be a part of the fifo structure.
36 */
37#if 0
38#define DYNAMIC
39#endif
40
41#ifdef DYNAMIC
42static DECLARE_KFIFO_PTR(test, int);
43#else
44static DEFINE_KFIFO(test, int, FIFO_SIZE);
45#endif
46
47static const int expected_result[FIFO_SIZE] = {
48 3, 4, 5, 6, 7, 8, 9, 0,
49 1, 20, 21, 22, 23, 24, 25, 26,
50 27, 28, 29, 30, 31, 32, 33, 34,
51 35, 36, 37, 38, 39, 40, 41, 42,
52};
53
54static int __init testfunc(void)
55{
56 int buf[6];
57 int i, j;
58 unsigned int ret;
59
60 printk(KERN_INFO "int fifo test start\n");
61
62 /* put values into the fifo */
63 for (i = 0; i != 10; i++)
64 kfifo_put(&test, i);
65
66 /* show the number of used elements */
67 printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
68
69 /* get max of 2 elements from the fifo */
70 ret = kfifo_out(&test, buf, 2);
71 printk(KERN_INFO "ret: %d\n", ret);
72 /* and put it back to the end of the fifo */
73 ret = kfifo_in(&test, buf, ret);
74 printk(KERN_INFO "ret: %d\n", ret);
75
76 /* skip first element of the fifo */
77 printk(KERN_INFO "skip 1st element\n");
78 kfifo_skip(&test);
79
80 /* put values into the fifo until is full */
81 for (i = 20; kfifo_put(&test, i); i++)
82 ;
83
84 printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
85
86 /* show the first value without removing from the fifo */
87 if (kfifo_peek(&test, &i))
88 printk(KERN_INFO "%d\n", i);
89
90 /* check the correctness of all values in the fifo */
91 j = 0;
92 while (kfifo_get(&test, &i)) {
93 printk(KERN_INFO "item = %d\n", i);
94 if (i != expected_result[j++]) {
95 printk(KERN_WARNING "value mismatch: test failed\n");
96 return -EIO;
97 }
98 }
99 if (j != ARRAY_SIZE(expected_result)) {
100 printk(KERN_WARNING "size mismatch: test failed\n");
101 return -EIO;
102 }
103 printk(KERN_INFO "test passed\n");
104
105 return 0;
106}
107
108static ssize_t fifo_write(struct file *file, const char __user *buf,
109 size_t count, loff_t *ppos)
110{
111 int ret;
112 unsigned int copied;
113
114 if (mutex_lock_interruptible(&write_lock))
115 return -ERESTARTSYS;
116
117 ret = kfifo_from_user(&test, buf, count, &copied);
118
119 mutex_unlock(&write_lock);
120
121 return ret ? ret : copied;
122}
123
124static ssize_t fifo_read(struct file *file, char __user *buf,
125 size_t count, loff_t *ppos)
126{
127 int ret;
128 unsigned int copied;
129
130 if (mutex_lock_interruptible(&read_lock))
131 return -ERESTARTSYS;
132
133 ret = kfifo_to_user(&test, buf, count, &copied);
134
135 mutex_unlock(&read_lock);
136
137 return ret ? ret : copied;
138}
139
140static const struct file_operations fifo_fops = {
141 .owner = THIS_MODULE,
142 .read = fifo_read,
143 .write = fifo_write,
144 .llseek = noop_llseek,
145};
146
147static int __init example_init(void)
148{
149#ifdef DYNAMIC
150 int ret;
151
152 ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
153 if (ret) {
154 printk(KERN_ERR "error kfifo_alloc\n");
155 return ret;
156 }
157#endif
158 if (testfunc() < 0) {
159#ifdef DYNAMIC
160 kfifo_free(&test);
161#endif
162 return -EIO;
163 }
164
165 if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
166#ifdef DYNAMIC
167 kfifo_free(&test);
168#endif
169 return -ENOMEM;
170 }
171 return 0;
172}
173
174static void __exit example_exit(void)
175{
176 remove_proc_entry(PROC_FIFO, NULL);
177#ifdef DYNAMIC
178 kfifo_free(&test);
179#endif
180}
181
182module_init(example_init);
183module_exit(example_exit);
184MODULE_LICENSE("GPL");
185MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
1/*
2 * Sample kfifo int type implementation
3 *
4 * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
5 *
6 * Released under the GPL version 2 only.
7 *
8 */
9
10#include <linux/init.h>
11#include <linux/module.h>
12#include <linux/proc_fs.h>
13#include <linux/mutex.h>
14#include <linux/kfifo.h>
15
16/*
17 * This module shows how to create a int type fifo.
18 */
19
20/* fifo size in elements (ints) */
21#define FIFO_SIZE 32
22
23/* name of the proc entry */
24#define PROC_FIFO "int-fifo"
25
26/* lock for procfs read access */
27static DEFINE_MUTEX(read_lock);
28
29/* lock for procfs write access */
30static DEFINE_MUTEX(write_lock);
31
32/*
33 * define DYNAMIC in this example for a dynamically allocated fifo.
34 *
35 * Otherwise the fifo storage will be a part of the fifo structure.
36 */
37#if 0
38#define DYNAMIC
39#endif
40
41#ifdef DYNAMIC
42static DECLARE_KFIFO_PTR(test, int);
43#else
44static DEFINE_KFIFO(test, int, FIFO_SIZE);
45#endif
46
47static const int expected_result[FIFO_SIZE] = {
48 3, 4, 5, 6, 7, 8, 9, 0,
49 1, 20, 21, 22, 23, 24, 25, 26,
50 27, 28, 29, 30, 31, 32, 33, 34,
51 35, 36, 37, 38, 39, 40, 41, 42,
52};
53
54static int __init testfunc(void)
55{
56 int buf[6];
57 int i, j;
58 unsigned int ret;
59
60 printk(KERN_INFO "int fifo test start\n");
61
62 /* put values into the fifo */
63 for (i = 0; i != 10; i++)
64 kfifo_put(&test, &i);
65
66 /* show the number of used elements */
67 printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
68
69 /* get max of 2 elements from the fifo */
70 ret = kfifo_out(&test, buf, 2);
71 printk(KERN_INFO "ret: %d\n", ret);
72 /* and put it back to the end of the fifo */
73 ret = kfifo_in(&test, buf, ret);
74 printk(KERN_INFO "ret: %d\n", ret);
75
76 /* skip first element of the fifo */
77 printk(KERN_INFO "skip 1st element\n");
78 kfifo_skip(&test);
79
80 /* put values into the fifo until is full */
81 for (i = 20; kfifo_put(&test, &i); i++)
82 ;
83
84 printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
85
86 /* show the first value without removing from the fifo */
87 if (kfifo_peek(&test, &i))
88 printk(KERN_INFO "%d\n", i);
89
90 /* check the correctness of all values in the fifo */
91 j = 0;
92 while (kfifo_get(&test, &i)) {
93 printk(KERN_INFO "item = %d\n", i);
94 if (i != expected_result[j++]) {
95 printk(KERN_WARNING "value mismatch: test failed\n");
96 return -EIO;
97 }
98 }
99 if (j != ARRAY_SIZE(expected_result)) {
100 printk(KERN_WARNING "size mismatch: test failed\n");
101 return -EIO;
102 }
103 printk(KERN_INFO "test passed\n");
104
105 return 0;
106}
107
108static ssize_t fifo_write(struct file *file, const char __user *buf,
109 size_t count, loff_t *ppos)
110{
111 int ret;
112 unsigned int copied;
113
114 if (mutex_lock_interruptible(&write_lock))
115 return -ERESTARTSYS;
116
117 ret = kfifo_from_user(&test, buf, count, &copied);
118
119 mutex_unlock(&write_lock);
120
121 return ret ? ret : copied;
122}
123
124static ssize_t fifo_read(struct file *file, char __user *buf,
125 size_t count, loff_t *ppos)
126{
127 int ret;
128 unsigned int copied;
129
130 if (mutex_lock_interruptible(&read_lock))
131 return -ERESTARTSYS;
132
133 ret = kfifo_to_user(&test, buf, count, &copied);
134
135 mutex_unlock(&read_lock);
136
137 return ret ? ret : copied;
138}
139
140static const struct file_operations fifo_fops = {
141 .owner = THIS_MODULE,
142 .read = fifo_read,
143 .write = fifo_write,
144 .llseek = noop_llseek,
145};
146
147static int __init example_init(void)
148{
149#ifdef DYNAMIC
150 int ret;
151
152 ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
153 if (ret) {
154 printk(KERN_ERR "error kfifo_alloc\n");
155 return ret;
156 }
157#endif
158 if (testfunc() < 0) {
159#ifdef DYNAMIC
160 kfifo_free(&test);
161#endif
162 return -EIO;
163 }
164
165 if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
166#ifdef DYNAMIC
167 kfifo_free(&test);
168#endif
169 return -ENOMEM;
170 }
171 return 0;
172}
173
174static void __exit example_exit(void)
175{
176 remove_proc_entry(PROC_FIFO, NULL);
177#ifdef DYNAMIC
178 kfifo_free(&test);
179#endif
180}
181
182module_init(example_init);
183module_exit(example_exit);
184MODULE_LICENSE("GPL");
185MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");