//hello.c#define __NO_VERSION__ #include <linux/module.h>
#include <linux/config.h>
#include <linux/version.h>
#include <asm/uaccess.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <asm/page.h>
#include <linux/poll.h>
#include <linux/kdev_t.h>
#include <asm/semaphore.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
unsigned int test_major = 0;
static int global_var=0;
static int globalvar_count = 0;
char *mystr="wodeshen" ;
static struct semaphore sem;
static spinlock_t spin = SPIN_LOCK_UNLOCKED; //宏定義 已經初始化static ssize_t read_test(struct file *file,char *buf,size_t count,loff_t *f_pos)
{
int left;
printk(KERN_INFO "read_test/n");
if (verify_area(VERIFY_WRITE,buf,count) == -EFAULT )
return -EFAULT; if (down_interruptible(&sem))
{
return - ERESTARTSYS;
}
printk("copy_to_user======2=======/n");
copy_to_user(buf, mystr, strlen(mystr));
/*
for(left = count ; left > 0 ; left--)
{
__put_user('1',buf);
buf++;
}
*/
up(&sem);
//return sizeof(int);
return strlen(mystr);
} static ssize_t write_test(struct file *file, const char *buf, size_t count, loff_t *f_pos)
{ if (down_interruptible(&sem))
{
return - ERESTARTSYS;
}
if (copy_from_user(&global_var, buf, sizeof(int)))
{
up(&sem);
return - EFAULT;
}
up(&sem);
printk(KERN_INFO "write_test/n");
return sizeof(int);
} static int open_test(struct inode *inode,struct file *file ) {
spin_lock(&spin);
printk("globalvar open/n");
//臨界資源訪問
if (globalvar_count)
{
spin_unlock(&spin);
return - EBUSY;
}
globalvar_count++;//釋放自選鎖
spin_unlock(&spin);
printk(KERN_INFO "open_test/n");
MOD_INC_USE_COUNT;
return 0;
} static int release_test(struct inode *inode,struct file *file )
{
printk(KERN_INFO "release_test/n");
MOD_DEC_USE_COUNT;
globalvar_count--;
return 0;
} struct file_operations test_fops = {
read:read_test,
write:write_test,
open: open_test,
release:release_test
}; int init_module(void)
{
int result;
result = register_chrdev(0, "test", &test_fops);
init_MUTEX(&sem);
if (result < 0) {
printk(KERN_INFO "test: can't get major number/n");
return result; } if (test_major == 0) test_major = result; /* dynamic */
return 0; } void cleanup_module(void) { unregister_chrdev(test_major, "test"); } MODULE_LICENSE("GPL");
MODULE_AUTHOR("BECKHAM"); //Makefile
CC=gcc
MODCFLAGS:=-Wall -DMODULE -D__KERNEL__ -DLINUX -I /usr/src/linux-2.4.20-8/include
test.o:hello.c
$(CC) $(MODCFLAGS) -c hello.c //test.c
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
main()
{
int testdev;
int i;
int j;
char *buf=malloc(150);
testdev = open("/dev/test",O_RDWR);
if ( testdev == -1 ) {
perror(open);
printf("Cann't open file /n");
exit(0);
} j=read(testdev,buf,10);
strcat(buf,"/0");
printf("%d===%s/n",j,buf);
while（1）;
close(testdev);
} 然後順序執行先刪除裝置rm /dev/test -f
卸載模組 rmmode testmakeinsmod test.omknod /dev/test c 254 0gcc -o test test.c./test再開啟一個終端，運行test，結果將失敗，顯示裝置處於忙的狀態 |
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