Linux内核中kfifo使用

/* * Sample kfifo byte stream implementation * * Copyright (C) 2010 Stefani Seibold <[e-mail]> * * 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>#include <linux/kthread.h>#include <linux/time.h>#include <linux/delay.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 1#define DYNAMIC#endif#ifdef DYNAMICstatic struct kfifo test;#elsestatic DECLARE_KFIFO(test, unsigned char, FIFO_SIZE);#endifstatic 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[32]={'0'};    unsigned char   i, j;    unsigned int    ret;    printk(KERN_INFO "byte stream fifo test start\n");    if(!kfifo_is_empty(&test)){            printk(KERN_INFO"1111not empty \n!");    }else{            printk(KERN_INFO "empty ! \n");    }    /* put string into the fifo */    kfifo_in(&test, "hello",5);    /* get max of 2 elements from the fifo */    ret = kfifo_in(&test, "121212121212121212121212121212121212",36);    printk(KERN_INFO "ret: %d buf = %s\n" , ret,buf);    if(!kfifo_is_full(&test)){            printk(KERN_INFO"2222not kfifo_is_full \n!");    }else{            printk(KERN_INFO "kfifo_is_full ! \n");    }    /* and put it back to the end of the fifo */    ret = kfifo_out(&test,buf,9);    printk(KERN_INFO "ret: %d buf = %s\n", ret,buf);    if(!kfifo_is_empty(&test)){            printk(KERN_INFO"2222not empty ! \n");    }else{            printk(KERN_INFO "empty ! \n");    }  memset(buf,0,32);    ret = kfifo_out(&test,buf,8);    printk(KERN_INFO "test passed buf = %s\n",buf);  memset(buf,0,32);    ret = kfifo_out(&test,buf,8);    printk(KERN_INFO "test passed buf = %s\n",buf);    if(!kfifo_is_empty(&test)){            printk(KERN_INFO "3333333333not empty ! \n");    }else{            printk(KERN_INFO "empty ! \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_lock))        return -ERESTARTSYS;    ret = kfifo_from_user(&test, buf, count, &copied);    mutex_unlock(&write_lock);    return ret ? ret : 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_lock))        return -ERESTARTSYS;    ret = kfifo_to_user(&test, buf, count, &copied);    mutex_unlock(&read_lock);    return ret ? ret : copied;}static const struct file_operations fifo_fops = {    .owner      = THIS_MODULE,    .read       = fifo_read,    .write      = fifo_write,    .llseek     = noop_llseek,};static int productor_thread(void *p){    unsigned char mac[7]={0x00};    int i = 0;    unsigned int    ret;    while(i<100){        mac[0] = i;        mac[1] = i+1;        mac[2] = i+2;        mac[3] = i+3;        mac[4] = i+4;        mac[5] = i+5;        mac[6] = i+6;         ret = kfifo_in(&test,mac,7);     i++;    msleep(1000);  }    return 0;}static int consumer_thread(void *p){    unsigned char mac[7]={0x00};    unsigned int    ret;    int i = 0;    while(i<10){        ret = kfifo_out(&test,mac,7);        msleep(1000);        if(kfifo_is_empty(&test)){            i++;        }else{                printk(KERN_INFO "mac =0x%x:0x%x:0x%x:0x%x:0x%x:0x%x:0x%x \n",mac[0],mac[1],mac[2],mac[3],mac[4],mac[5],mac[6]);        }    }    printk("iiiiiiiiiiiiiiiiiiiiiiii=%d \n",i);    return 0;}static struct task_struct *ps_tsks1;static struct task_struct *ps_tsks2;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    ps_tsks1 = kthread_run(productor_thread,(void *)(unsigned long)NULL,"productor_thread");    ps_tsks2 = kthread_run(consumer_thread,(void *)(unsigned long)NULL,"consumer_thread");/*    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;}static void __exit example_exit(void){    //kthread_stop(ps_tsks1);    //kthread_stop(ps_tsks2);    remove_proc_entry(PROC_FIFO, NULL);#ifdef DYNAMIC    kfifo_free(&test);#endif}module_init(example_init);module_exit(example_exit);MODULE_LICENSE("GPL");MODULE_AUTHOR("Stefani Seibold <[e-mail]>");