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5bf2b193 SS |
1 | /* |
2 | * Sample dynamic sized record fifo 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 variable sized record fifo. | |
18 | */ | |
19 | ||
20 | /* fifo size in elements (bytes) */ | |
21 | #define FIFO_SIZE 128 | |
22 | ||
23 | /* name of the proc entry */ | |
24 | #define PROC_FIFO "record-fifo" | |
25 | ||
26 | /* lock for procfs read access */ | |
27 | static DEFINE_MUTEX(read_lock); | |
28 | ||
29 | /* lock for procfs write access */ | |
30 | static 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 | /* | |
42 | * struct kfifo_rec_ptr_1 and STRUCT_KFIFO_REC_1 can handle records of a | |
43 | * length between 0 and 255 bytes. | |
44 | * | |
45 | * struct kfifo_rec_ptr_2 and STRUCT_KFIFO_REC_2 can handle records of a | |
46 | * length between 0 and 65535 bytes. | |
47 | */ | |
48 | ||
49 | #ifdef DYNAMIC | |
50 | struct kfifo_rec_ptr_1 test; | |
51 | ||
52 | #else | |
53 | typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest; | |
54 | ||
55 | static mytest test; | |
56 | #endif | |
57 | ||
a25effa4 AR |
58 | static const char *expected_result[] = { |
59 | "a", | |
60 | "bb", | |
61 | "ccc", | |
62 | "dddd", | |
63 | "eeeee", | |
64 | "ffffff", | |
65 | "ggggggg", | |
66 | "hhhhhhhh", | |
67 | "iiiiiiiii", | |
68 | "jjjjjjjjjj", | |
69 | }; | |
70 | ||
5bf2b193 SS |
71 | static int __init testfunc(void) |
72 | { | |
73 | char buf[100]; | |
74 | unsigned int i; | |
75 | unsigned int ret; | |
76 | struct { unsigned char buf[6]; } hello = { "hello" }; | |
77 | ||
78 | printk(KERN_INFO "record fifo test start\n"); | |
79 | ||
80 | kfifo_in(&test, &hello, sizeof(hello)); | |
81 | ||
82 | /* show the size of the next record in the fifo */ | |
83 | printk(KERN_INFO "fifo peek len: %u\n", kfifo_peek_len(&test)); | |
84 | ||
85 | /* put in variable length data */ | |
86 | for (i = 0; i < 10; i++) { | |
87 | memset(buf, 'a' + i, i + 1); | |
88 | kfifo_in(&test, buf, i + 1); | |
89 | } | |
90 | ||
a25effa4 AR |
91 | /* skip first element of the fifo */ |
92 | printk(KERN_INFO "skip 1st element\n"); | |
93 | kfifo_skip(&test); | |
94 | ||
5bf2b193 SS |
95 | printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test)); |
96 | ||
97 | /* show the first record without removing from the fifo */ | |
98 | ret = kfifo_out_peek(&test, buf, sizeof(buf)); | |
99 | if (ret) | |
100 | printk(KERN_INFO "%.*s\n", ret, buf); | |
101 | ||
a25effa4 AR |
102 | /* check the correctness of all values in the fifo */ |
103 | i = 0; | |
5bf2b193 SS |
104 | while (!kfifo_is_empty(&test)) { |
105 | ret = kfifo_out(&test, buf, sizeof(buf)); | |
a25effa4 AR |
106 | buf[ret] = '\0'; |
107 | printk(KERN_INFO "item = %.*s\n", ret, buf); | |
108 | if (strcmp(buf, expected_result[i++])) { | |
109 | printk(KERN_WARNING "value mismatch: test failed\n"); | |
110 | return -EIO; | |
111 | } | |
112 | } | |
113 | if (i != ARRAY_SIZE(expected_result)) { | |
114 | printk(KERN_WARNING "size mismatch: test failed\n"); | |
115 | return -EIO; | |
5bf2b193 | 116 | } |
a25effa4 | 117 | printk(KERN_INFO "test passed\n"); |
5bf2b193 SS |
118 | |
119 | return 0; | |
120 | } | |
121 | ||
122 | static ssize_t fifo_write(struct file *file, const char __user *buf, | |
123 | size_t count, loff_t *ppos) | |
124 | { | |
125 | int ret; | |
126 | unsigned int copied; | |
127 | ||
128 | if (mutex_lock_interruptible(&write_lock)) | |
129 | return -ERESTARTSYS; | |
130 | ||
131 | ret = kfifo_from_user(&test, buf, count, &copied); | |
132 | ||
133 | mutex_unlock(&write_lock); | |
134 | ||
135 | return ret ? ret : copied; | |
136 | } | |
137 | ||
138 | static ssize_t fifo_read(struct file *file, char __user *buf, | |
139 | size_t count, loff_t *ppos) | |
140 | { | |
141 | int ret; | |
142 | unsigned int copied; | |
143 | ||
144 | if (mutex_lock_interruptible(&read_lock)) | |
145 | return -ERESTARTSYS; | |
146 | ||
147 | ret = kfifo_to_user(&test, buf, count, &copied); | |
148 | ||
149 | mutex_unlock(&read_lock); | |
150 | ||
151 | return ret ? ret : copied; | |
152 | } | |
153 | ||
154 | static const struct file_operations fifo_fops = { | |
155 | .owner = THIS_MODULE, | |
156 | .read = fifo_read, | |
157 | .write = fifo_write, | |
6038f373 | 158 | .llseek = noop_llseek, |
5bf2b193 SS |
159 | }; |
160 | ||
161 | static int __init example_init(void) | |
162 | { | |
163 | #ifdef DYNAMIC | |
164 | int ret; | |
165 | ||
166 | ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL); | |
167 | if (ret) { | |
168 | printk(KERN_ERR "error kfifo_alloc\n"); | |
169 | return ret; | |
170 | } | |
171 | #else | |
172 | INIT_KFIFO(test); | |
173 | #endif | |
a25effa4 AR |
174 | if (testfunc() < 0) { |
175 | #ifdef DYNAMIC | |
176 | kfifo_free(&test); | |
177 | #endif | |
178 | return -EIO; | |
179 | } | |
5bf2b193 SS |
180 | |
181 | if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) { | |
182 | #ifdef DYNAMIC | |
183 | kfifo_free(&test); | |
184 | #endif | |
185 | return -ENOMEM; | |
186 | } | |
187 | return 0; | |
188 | } | |
189 | ||
190 | static void __exit example_exit(void) | |
191 | { | |
192 | remove_proc_entry(PROC_FIFO, NULL); | |
193 | #ifdef DYNAMIC | |
194 | kfifo_free(&test); | |
195 | #endif | |
196 | } | |
197 | ||
198 | module_init(example_init); | |
199 | module_exit(example_exit); | |
200 | MODULE_LICENSE("GPL"); | |
201 | MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>"); |