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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204// SPDX-License-Identifier: GPL-2.0-only/* * Sample dynamic sized record fifo implementation * * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net> */
#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_access);
/* lock for procfs write access */static DEFINE_MUTEX(write_access);
/* * 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 DYNAMICstruct kfifo_rec_ptr_1 test;
#elsetypedef 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;}
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_access)) return -ERESTARTSYS;
ret = kfifo_from_user(&test, buf, count, &copied);
mutex_unlock(&write_access); if (ret) return ret;
return copied;}
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_access)) return -ERESTARTSYS;
ret = kfifo_to_user(&test, buf, count, &copied);
mutex_unlock(&read_access); if (ret) return ret;
return copied;}
static const struct proc_ops fifo_proc_ops = { .proc_read = fifo_read, .proc_write = fifo_write, .proc_lseek = 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_proc_ops) == NULL) {#ifdef DYNAMIC kfifo_free(&test);#endif return -ENOMEM; } return 0;}
static void __exit example_exit(void){ remove_proc_entry(PROC_FIFO, NULL);#ifdef DYNAMIC kfifo_free(&test);#endif}
module_init(example_init);module_exit(example_exit);MODULE_DESCRIPTION("Sample dynamic sized record fifo implementation");MODULE_LICENSE("GPL");MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");