cregit-Linux how code gets into the kernel

Release 4.16 samples/kfifo/record-example.c

Directory: samples/kfifo
/*
 * Sample dynamic sized record fifo 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 variable sized record fifo.
 */

/* fifo size in elements (bytes) */

#define FIFO_SIZE	128

/* name of the proc entry */

#define	PROC_FIFO	"record-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

/*
 * struct kfifo_rec_ptr_1 and  STRUCT_KFIFO_REC_1 can handle records of a
 * length between 0 and 255 bytes.
 *
 * struct kfifo_rec_ptr_2 and  STRUCT_KFIFO_REC_2 can handle records of a
 * length between 0 and 65535 bytes.
 */

#ifdef DYNAMIC

struct kfifo_rec_ptr_1 test;

#else

typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest;


static mytest test;
#endif


static const char *expected_result[] = {
	"a",
	"bb",
	"ccc",
	"dddd",
	"eeeee",
	"ffffff",
	"ggggggg",
	"hhhhhhhh",
	"iiiiiiiii",
	"jjjjjjjjjj",
};


static int __init testfunc(void) { char buf[100]; unsigned int i; unsigned int ret; struct { unsigned char buf[6]; } hello = { "hello" }; printk(KERN_INFO "record fifo test start\n"); kfifo_in(&test, &hello, sizeof(hello)); /* show the size of the next record in the fifo */ printk(KERN_INFO "fifo peek len: %u\n", kfifo_peek_len(&test)); /* put in variable length data */ for (i = 0; i < 10; i++) { memset(buf, 'a' + i, i + 1); kfifo_in(&test, buf, i + 1); } /* skip first element of the fifo */ printk(KERN_INFO "skip 1st element\n"); kfifo_skip(&test); printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test)); /* show the first record without removing from the fifo */ ret = kfifo_out_peek(&test, buf, sizeof(buf)); if (ret) printk(KERN_INFO "%.*s\n", ret, buf); /* check the correctness of all values in the fifo */ i = 0; while (!kfifo_is_empty(&test)) { ret = kfifo_out(&test, buf, sizeof(buf)); buf[ret] = '\0'; printk(KERN_INFO "item = %.*s\n", ret, buf); if (strcmp(buf, expected_result[i++])) { printk(KERN_WARNING "value mismatch: test failed\n"); return -EIO; } } if (i != ARRAY_SIZE(expected_result)) { printk(KERN_WARNING "size mismatch: test failed\n"); return -EIO; } printk(KERN_INFO "test passed\n"); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Stefani Seibold19371.22%150.00%
Andrea Righi7828.78%150.00%
Total271100.00%2100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Stefani Seibold71100.00%1100.00%
Total71100.00%1100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Stefani 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; }

Contributors

PersonTokensPropCommitsCommitProp
Stefani Seibold9081.08%150.00%
Andrea 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 }

Contributors

PersonTokensPropCommitsCommitProp
Stefani Seibold27100.00%1100.00%
Total27100.00%1100.00%

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

Overall Contributors

PersonTokensPropCommitsCommitProp
Stefani Seibold56781.00%133.33%
Andrea Righi12818.29%133.33%
Arnd Bergmann50.71%133.33%
Total700100.00%3100.00%
Directory: samples/kfifo
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