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186 lines
3.7 KiB
186 lines
3.7 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Sample kfifo int type implementation |
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* |
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* Copyright (C) 2010 Stefani Seibold <[email protected]> |
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*/ |
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#include <linux/init.h> |
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#include <linux/module.h> |
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#include <linux/proc_fs.h> |
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#include <linux/mutex.h> |
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#include <linux/kfifo.h> |
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/* |
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* This module shows how to create a int type fifo. |
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*/ |
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/* fifo size in elements (ints) */ |
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#define FIFO_SIZE 32 |
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/* name of the proc entry */ |
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#define PROC_FIFO "int-fifo" |
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/* lock for procfs read access */ |
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static DEFINE_MUTEX(read_lock); |
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/* lock for procfs write access */ |
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static DEFINE_MUTEX(write_lock); |
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/* |
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* define DYNAMIC in this example for a dynamically allocated fifo. |
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* |
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* Otherwise the fifo storage will be a part of the fifo structure. |
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*/ |
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#if 0 |
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#define DYNAMIC |
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#endif |
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#ifdef DYNAMIC |
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static DECLARE_KFIFO_PTR(test, int); |
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#else |
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static DEFINE_KFIFO(test, int, FIFO_SIZE); |
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#endif |
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static const int expected_result[FIFO_SIZE] = { |
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3, 4, 5, 6, 7, 8, 9, 0, |
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1, 20, 21, 22, 23, 24, 25, 26, |
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27, 28, 29, 30, 31, 32, 33, 34, |
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35, 36, 37, 38, 39, 40, 41, 42, |
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}; |
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static int __init testfunc(void) |
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{ |
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int buf[6]; |
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int i, j; |
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unsigned int ret; |
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printk(KERN_INFO "int fifo test start\n"); |
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/* put values into the fifo */ |
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for (i = 0; i != 10; i++) |
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kfifo_put(&test, i); |
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/* show the number of used elements */ |
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printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test)); |
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/* get max of 2 elements from the fifo */ |
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ret = kfifo_out(&test, buf, 2); |
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printk(KERN_INFO "ret: %d\n", ret); |
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/* and put it back to the end of the fifo */ |
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ret = kfifo_in(&test, buf, ret); |
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printk(KERN_INFO "ret: %d\n", ret); |
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/* skip first element of the fifo */ |
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printk(KERN_INFO "skip 1st element\n"); |
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kfifo_skip(&test); |
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/* put values into the fifo until is full */ |
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for (i = 20; kfifo_put(&test, i); i++) |
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; |
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printk(KERN_INFO "queue len: %u\n", kfifo_len(&test)); |
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/* show the first value without removing from the fifo */ |
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if (kfifo_peek(&test, &i)) |
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printk(KERN_INFO "%d\n", i); |
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/* check the correctness of all values in the fifo */ |
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j = 0; |
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while (kfifo_get(&test, &i)) { |
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printk(KERN_INFO "item = %d\n", i); |
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if (i != expected_result[j++]) { |
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printk(KERN_WARNING "value mismatch: test failed\n"); |
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return -EIO; |
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} |
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} |
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if (j != ARRAY_SIZE(expected_result)) { |
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printk(KERN_WARNING "size mismatch: test failed\n"); |
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return -EIO; |
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} |
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printk(KERN_INFO "test passed\n"); |
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return 0; |
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} |
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static ssize_t fifo_write(struct file *file, const char __user *buf, |
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size_t count, loff_t *ppos) |
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{ |
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int ret; |
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unsigned int copied; |
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if (mutex_lock_interruptible(&write_lock)) |
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return -ERESTARTSYS; |
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ret = kfifo_from_user(&test, buf, count, &copied); |
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mutex_unlock(&write_lock); |
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if (ret) |
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return ret; |
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return copied; |
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} |
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static ssize_t fifo_read(struct file *file, char __user *buf, |
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size_t count, loff_t *ppos) |
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{ |
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int ret; |
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unsigned int copied; |
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if (mutex_lock_interruptible(&read_lock)) |
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return -ERESTARTSYS; |
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ret = kfifo_to_user(&test, buf, count, &copied); |
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mutex_unlock(&read_lock); |
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if (ret) |
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return ret; |
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return copied; |
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} |
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static const struct proc_ops fifo_proc_ops = { |
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.proc_read = fifo_read, |
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.proc_write = fifo_write, |
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.proc_lseek = noop_llseek, |
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}; |
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static int __init example_init(void) |
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{ |
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#ifdef DYNAMIC |
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int ret; |
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ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL); |
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if (ret) { |
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printk(KERN_ERR "error kfifo_alloc\n"); |
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return ret; |
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} |
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#endif |
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if (testfunc() < 0) { |
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#ifdef DYNAMIC |
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kfifo_free(&test); |
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#endif |
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return -EIO; |
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} |
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if (proc_create(PROC_FIFO, 0, NULL, &fifo_proc_ops) == NULL) { |
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#ifdef DYNAMIC |
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kfifo_free(&test); |
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#endif |
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return -ENOMEM; |
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} |
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return 0; |
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} |
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static void __exit example_exit(void) |
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{ |
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remove_proc_entry(PROC_FIFO, NULL); |
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#ifdef DYNAMIC |
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kfifo_free(&test); |
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#endif |
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} |
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module_init(example_init); |
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module_exit(example_exit); |
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MODULE_LICENSE("GPL"); |
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MODULE_AUTHOR("Stefani Seibold <[email protected]>");
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