cregit-Linux how code gets into the kernel

Release 4.10 samples/kfifo/bytestream-example.c

Directory: samples/kfifo
/*
 * Sample kfifo byte stream implementation
 *
 * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
 *
 * Released under the GPL version 2 only.
 *
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/mutex.h>
#include <linux/kfifo.h>

/*
 * This module shows how to create a byte stream fifo.
 */

/* fifo size in elements (bytes) */

#define FIFO_SIZE	32

/* name of the proc entry */

#define	PROC_FIFO	"bytestream-fifo"

/* lock for procfs read access */
static DEFINE_MUTEX(read_lock);

/* lock for procfs write access */
static DEFINE_MUTEX(write_lock);

/*
 * define DYNAMIC in this example for a dynamically allocated fifo.
 *
 * Otherwise the fifo storage will be a part of the fifo structure.
 */
#if 0
#define DYNAMIC
#endif

#ifdef DYNAMIC

static struct kfifo test;
#else
static DECLARE_KFIFO(test, unsigned char, FIFO_SIZE);
#endif


static const unsigned char expected_result[FIFO_SIZE] = {
	 3,  4,  5,  6,  7,  8,  9,  0,
	 1, 20, 21, 22, 23, 24, 25, 26,
	27, 28, 29, 30, 31, 32, 33, 34,
	35, 36, 37, 38, 39, 40, 41, 42,
};


static int __init testfunc(void) { unsigned char buf[6]; unsigned char i, j; unsigned int ret; printk(KERN_INFO "byte stream fifo test start\n"); /* put string into the fifo */ kfifo_in(&test, "hello", 5); /* put values into the fifo */ for (i = 0; i != 10; i++) kfifo_put(&test, i); /* show the number of used elements */ printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test)); /* get max of 5 bytes from the fifo */ i = kfifo_out(&test, buf, 5); printk(KERN_INFO "buf: %.*s\n", i, buf); /* get max of 2 elements from the fifo */ ret = kfifo_out(&test, buf, 2); printk(KERN_INFO "ret: %d\n", ret); /* and put it back to the end of the fifo */ ret = kfifo_in(&test, buf, ret); printk(KERN_INFO "ret: %d\n", ret); /* skip first element of the fifo */ printk(KERN_INFO "skip 1st element\n"); kfifo_skip(&test); /* put values into the fifo until is full */ for (i = 20; kfifo_put(&test, i); i++) ; printk(KERN_INFO "queue len: %u\n", kfifo_len(&test)); /* show the first value without removing from the fifo */ if (kfifo_peek(&test, &i)) printk(KERN_INFO "%d\n", i); /* check the correctness of all values in the fifo */ j = 0; while (kfifo_get(&test, &i)) { printk(KERN_INFO "item = %d\n", i); if (i != expected_result[j++]) { printk(KERN_WARNING "value mismatch: test failed\n"); return -EIO; } } if (j != ARRAY_SIZE(expected_result)) { printk(KERN_WARNING "size mismatch: test failed\n"); return -EIO; } printk(KERN_INFO "test passed\n"); return 0; }

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stefani seiboldstefani seibold19468.07%125.00%
andrea righiandrea righi9131.93%375.00%
Total285100.00%4100.00%


static ssize_t fifo_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { int ret; unsigned int copied; if (mutex_lock_interruptible(&write_lock)) return -ERESTARTSYS; ret = kfifo_from_user(&test, buf, count, &copied); mutex_unlock(&write_lock); return ret ? ret : copied; }

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stefani seiboldstefani seibold71100.00%1100.00%
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static ssize_t fifo_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { int ret; unsigned int copied; if (mutex_lock_interruptible(&read_lock)) return -ERESTARTSYS; ret = kfifo_to_user(&test, buf, count, &copied); mutex_unlock(&read_lock); return ret ? ret : copied; }

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stefani seiboldstefani seibold70100.00%1100.00%
Total70100.00%1100.00%

static const struct file_operations fifo_fops = { .owner = THIS_MODULE, .read = fifo_read, .write = fifo_write, .llseek = noop_llseek, };
static int __init example_init(void) { #ifdef DYNAMIC int ret; ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL); if (ret) { printk(KERN_ERR "error kfifo_alloc\n"); return ret; } #else INIT_KFIFO(test); #endif if (testfunc() < 0) { #ifdef DYNAMIC kfifo_free(&test); #endif return -EIO; } if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) { #ifdef DYNAMIC kfifo_free(&test); #endif return -ENOMEM; } return 0; }

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stefani seiboldstefani seibold9081.08%150.00%
andrea righiandrea righi2118.92%150.00%
Total111100.00%2100.00%


static void __exit example_exit(void) { remove_proc_entry(PROC_FIFO, NULL); #ifdef DYNAMIC kfifo_free(&test); #endif }

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stefani seiboldstefani seibold27100.00%1100.00%
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module_init(example_init); module_exit(example_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");

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stefani seiboldstefani seibold56774.70%120.00%
andrea righiandrea righi18724.64%360.00%
arnd bergmannarnd bergmann50.66%120.00%
Total759100.00%5100.00%
Directory: samples/kfifo
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