Stefani Seibold | 5bf2b19 | 2010-08-10 18:03:39 -0700 | [diff] [blame] | 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 */ |
| 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 | #ifdef DYNAMIC |
| 42 | static DECLARE_KFIFO_PTR(test, int); |
| 43 | #else |
| 44 | static DEFINE_KFIFO(test, int, FIFO_SIZE); |
| 45 | #endif |
| 46 | |
Andrea Righi | a25effa | 2010-08-19 14:13:30 -0700 | [diff] [blame] | 47 | static 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 | |
Stefani Seibold | 5bf2b19 | 2010-08-10 18:03:39 -0700 | [diff] [blame] | 54 | static int __init testfunc(void) |
| 55 | { |
| 56 | int buf[6]; |
Andrea Righi | a25effa | 2010-08-19 14:13:30 -0700 | [diff] [blame] | 57 | int i, j; |
Stefani Seibold | 5bf2b19 | 2010-08-10 18:03:39 -0700 | [diff] [blame] | 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 | |
Andrea Righi | a25effa | 2010-08-19 14:13:30 -0700 | [diff] [blame] | 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 | ; |
Stefani Seibold | 5bf2b19 | 2010-08-10 18:03:39 -0700 | [diff] [blame] | 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 | |
Andrea Righi | a25effa | 2010-08-19 14:13:30 -0700 | [diff] [blame] | 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"); |
Stefani Seibold | 5bf2b19 | 2010-08-10 18:03:39 -0700 | [diff] [blame] | 104 | |
| 105 | return 0; |
| 106 | } |
| 107 | |
| 108 | static 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 | |
| 124 | static 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 | |
| 140 | static const struct file_operations fifo_fops = { |
| 141 | .owner = THIS_MODULE, |
| 142 | .read = fifo_read, |
| 143 | .write = fifo_write, |
Arnd Bergmann | 6038f37 | 2010-08-15 18:52:59 +0200 | [diff] [blame] | 144 | .llseek = noop_llseek, |
Stefani Seibold | 5bf2b19 | 2010-08-10 18:03:39 -0700 | [diff] [blame] | 145 | }; |
| 146 | |
| 147 | static 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 |
Andrea Righi | a25effa | 2010-08-19 14:13:30 -0700 | [diff] [blame] | 158 | if (testfunc() < 0) { |
| 159 | #ifdef DYNAMIC |
| 160 | kfifo_free(&test); |
| 161 | #endif |
| 162 | return -EIO; |
| 163 | } |
Stefani Seibold | 5bf2b19 | 2010-08-10 18:03:39 -0700 | [diff] [blame] | 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 | |
| 174 | static void __exit example_exit(void) |
| 175 | { |
| 176 | remove_proc_entry(PROC_FIFO, NULL); |
| 177 | #ifdef DYNAMIC |
| 178 | kfifo_free(&test); |
| 179 | #endif |
| 180 | } |
| 181 | |
| 182 | module_init(example_init); |
| 183 | module_exit(example_exit); |
| 184 | MODULE_LICENSE("GPL"); |
| 185 | MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>"); |