实现自己的系统调用针对linux-2.6.34【转】

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <asm/uaccess.h>
#include <linux/slab.h>
#define TASK_COMM_LEN 16
#define TMP_DATA_LEN 50
typedef struct my_task_struct {
    volatile long state;
    int prio, static_prio, normal_prio;
    pid_t pid;
    pid_t tgid;
    char comm[TASK_COMM_LEN];
    struct my_task_struct *next;
}my_struct_t, *my_struct_p;
my_struct_p get_data (void)
{
    my_struct_p p, head, h;
    struct task_struct *task = NULL;
    head = (my_struct_p)kmalloc(sizeof(my_struct_t), GFP_ATOMIC);
    head->next = NULL;
    h = head;
    for_each_process (task) {
        p = (my_struct_p)kmalloc(sizeof(my_struct_t), GFP_ATOMIC);
        p ->state = task->state;
        p->prio = task->prio;
        p->static_prio = task->static_prio;
        p->normal_prio = task->normal_prio;
        p->pid = task->pid;
        p->tgid = task->tgid;
         memset(p->comm, '\0', sizeof(p->comm));
        strncpy(p->comm, task->comm, TASK_COMM_LEN-1);
        p ->next = h->next;
        h->next = p;
        h = p;
    }
    return head;
}
int filewrite(const char * filename, my_struct_p head)
{
    struct file *filp;
    mm_segment_t fs;
    my_struct_p data;
    char *change_line = "\t";
    char *menu_line = "state\tprio\tstatic_prio\tnormal_prio\tpid\ttgid\tcomm\n"; 
    char tmpdata[TMP_DATA_LEN];
    data = head->next;
    filp = filp_open(filename, O_RDWR|O_APPEND|O_CREAT, 0644);
    if(IS_ERR(filp)) {
        printk("open error!\n");
        return 1;
    }
    fs = get_fs();
    set_fs(KERNEL_DS);
    filp->f_op->write(filp, menu_line, strlen(menu_line), &filp->f_pos);
     while(NULL != data) {
        memset(tmpdata, '\0', TMP_DATA_LEN);
        snprintf(tmpdata, sizeof(data->state), "%ld", data->state); 
        strcat(tmpdata, change_line);
        filp->f_op->write(filp, tmpdata, strlen(tmpdata), &filp->f_pos);
         memset(tmpdata, '\0', TMP_DATA_LEN);
        snprintf(tmpdata, sizeof(data->prio), "%d", data->prio); 
        strcat(tmpdata, change_line);
        filp->f_op->write(filp, tmpdata, strlen(tmpdata), &filp->f_pos);
         memset(tmpdata, '\0', TMP_DATA_LEN);
        snprintf(tmpdata, sizeof(data->static_prio), "%d", data->static_prio); 
        strcat(tmpdata, change_line);
        filp->f_op->write(filp, tmpdata, strlen(tmpdata), &filp->f_pos);
         memset(tmpdata, '\0', TMP_DATA_LEN);
        snprintf(tmpdata, sizeof(data->normal_prio), "%d", data->normal_prio); 
        strcat(tmpdata, change_line);
        filp->f_op->write(filp, tmpdata, strlen(tmpdata), &filp->f_pos);
         memset(tmpdata, '\0', TMP_DATA_LEN);
        snprintf(tmpdata, sizeof(data->pid), "%d", data->pid); 
        strcat(tmpdata, change_line);
        filp->f_op->write(filp, tmpdata, strlen(tmpdata), &filp->f_pos);
         memset(tmpdata, '\0', TMP_DATA_LEN);
        snprintf(tmpdata, sizeof(data->tgid), "%d", data->tgid); 
        strcat(tmpdata, change_line);
        filp->f_op->write(filp, tmpdata, strlen(tmpdata), &filp->f_pos);
         memset(tmpdata, '\0', TMP_DATA_LEN);
        snprintf(tmpdata, sizeof(data->comm), "%s", data->comm); 
        strcat(tmpdata, change_line);
        filp->f_op->write(filp, tmpdata, strlen(tmpdata), &filp->f_pos);
        
        memset(tmpdata, '\0', TMP_DATA_LEN);
        strcpy(tmpdata, "\n");
        filp->f_op->write(filp, tmpdata, strlen(tmpdata), &filp->f_pos);
        data = data->next;
    }
    set_fs(fs);
    filp_close(filp, NULL);
    return 0;
}
int data_flush(my_struct_p head)
{
    my_struct_p data;
    data = head;
    while(NULL != data) {
        head = head->next;
        kfree(data);
        data = head;
    }
    return 0;
}
asmlinkage my_struct_p sys_getdata (void)
{
    my_struct_p res;
    res = get_data();
    return res;
}
asmlinkage int sys_datawrite(const char *filename, my_struct_p head)
{
    return filewrite(filename, head);
}
asmlinkage int sys_dataflush(my_struct_p head)
{
    return data_flush(head);
}

#include <asm/unistd.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/syscall.h>
#include <stdlib.h>
#include <string.h>
#define SYS_SAYHELLO 338
#define SYS_GETDATA 339
#define SYS_FILEWRITE 340
#define SYS_DATAFLUSH 341
struct my_struct {
     volatile long state;
    int prio, static_prio, normal_prio;
    pid_t pid;
    pid_t tgid;
    char comm[16];
    struct my_struct *next;
};
int main(void)
{
    struct my_struct * data;
    
    data = syscall(SYS_GETDATA);
    syscall(SYS_FILEWRITE, "file", data);
    syscall(SYS_DATAFLUSH, data)
    return 0;
}