タイマーが刻々と切れたときに TimerExpire 関数が最終的に呼び出されると、意味不明な出力が出力されます。理由を知っている人はいますか？しかし、私の IOCTL_MAKE_TIMER の printk 関数は正しく出力されるので、データを間違って渡していることが原因だと思います。
setup_timer() は、最初の引数でタイマーを設定し、2 番目の引数で指定された関数を呼び出すように指示し、データ (3 番目の引数) をその関数に渡します。
私の場合は、TimerExpire(char* data) 関数を呼び出して、char* から kern_arg への final_arg を渡します。kern_arg を関数に直接渡そうとしたこともありました...また、意味不明になりました。
以前 (昨日)、char kern_arg[] の代わりに char* kern_arg があり、それは完全に機能しましたが、安全ではなかったと思います。
誰かが何らかの洞察を提供できれば、それは素晴らしいことです! ありがとう！
//Necessary Includes For Device Drivers.
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/proc_fs.h>
#include <asm/uaccess.h>
#include <linux/timer.h>
#include <linux/ioctl.h>
#define DEVICE_NAME "mytimer"
#define DEVICE_FILE_NAME "mytimer"
#define MAJOR_NUM 61
#define MINOR_NUM 0
#define SUCCESS 0
#define IOCTL_MAKE_TIMER _IOWR(MAJOR_NUM, 0, int)
#define IOCTL_SET_TIMER _IOWR(MAJOR_NUM, 1, int)
#define IOCTL_GET_TIMER _IOWR(MAJOR_NUM, 2, int)
//Module License
MODULE_LICENSE("Dual BSD/GPL");
//Initialize timer structure.
static struct timer_list my_timer;
//Forward Declarations for File Operation Functions and Other Functions.
static int mytimer_open(struct inode *inode, struct file *file);
static int mytimer_release(struct inode *inode, struct file *file);
int mytimer_ioctl(struct inode *inode, struct file *file, unsigned int ioctl_num, unsigned long args);
void TimerExpire(char* data);
//Syscall Operations for the module.
struct file_operations FileOps =
{
.owner = THIS_MODULE,
.open = mytimer_open,
.release = mytimer_release,
.ioctl = mytimer_ioctl
};
//Syscall function for opening the module.
static int mytimer_open(struct inode *inode, struct file *file)
{
try_module_get(THIS_MODULE);
return SUCCESS;
}
//Syscall function for releasing the module.
static int mytimer_release(struct inode *inode, struct file *file)
{
module_put(THIS_MODULE);
return SUCCESS;
}
//Syscall function for controlling the module through IOCTLs.
int mytimer_ioctl(struct inode *inode, struct file *file, unsigned int fcn, unsigned long args)
{
//Copies the function parameters from userspace to kernel space in order to use them in the kernel module.
char* user_arg = args;
char kern_arg[strlen_user(user_arg)];
copy_from_user(kern_arg, user_arg, strlen_user(user_arg));
char* final_arg = kern_arg;
//If there is a timer, and the command is to make a new one, the old timer will be removed so a new one can be setup.
if (timer_pending(&my_timer) && fcn == IOCTL_MAKE_TIMER)
{
del_timer_sync(&my_timer);
printk("Timer already exists. Deleting old timer and setting new timer.\n");
}
//Switch function that serves the function that is called.
//Note that the make and set timer functions are separate. This is because only 1 arg is passed via ioctl at a time, so I had to make two different ioctl calls.
switch (fcn)
{
//Make a new timer.
case IOCTL_MAKE_TIMER:
setup_timer(&my_timer, TimerExpire, final_arg);
printk("Made timer with message: %s\n", final_arg);
break;
//Set the timer made above.
case IOCTL_SET_TIMER:
mod_timer(&my_timer, jiffies + msecs_to_jiffies(args * 1000));
printk("Armed timer for %d seconds.\n", args);
break;
//Print the current timer, if any.
case IOCTL_GET_TIMER:
if (!timer_pending(&my_timer))
{
printk("No timer currently set.\n");
}
else
{
printk("Time left in timer: %u seconds\n", jiffies_to_msecs(my_timer.expires - jiffies)/1000);
printk("Message in timer is: %s\n", my_timer.data);
}
break;
}
return SUCCESS;
}
//Function to perform when timer expires.
void TimerExpire(char* data)
{
printk("%s\n", data);
}
//Module Init and Exit Functions.
int init_module(void)
{
printk("Loading MyTimer Kernel Module...\n");
//Register the device with the system to obtain the major number and register the file operations for syscall functionality.
int initResult = register_chrdev(MAJOR_NUM, "mytimer", &FileOps);
//If we couldn't register the device, print the error.
if (initResult < 0)
{
printk("Cannot obtain major number %d\n", MAJOR_NUM);
return initResult;
}
printk("Please create device file using:\n\tmknod /dev/mytimer c 61 0\n");
return SUCCESS;
}
void cleanup_module(void)
{
//Unregister the device with the system to free the major number.
printk("Unloading MyTimer Kernel Module...\n");
unregister_chrdev(MAJOR_NUM, "mytimer");
printk("MyTimer Kernel Module Unloaded.\n");
}