用户空间跟内核空间沟通问题

shihyu

我代码作用是想从 用户空间 appln  process 透过 ioctl  传 用户空间 process 的 pid 到 内核 , 内核再透过 send_sig 函数不断发 SIGUSR2 给用户空间的  appln prcoess , 当我不想kernel 再发  SIGUSR2 signal 我再透过 ioctl 让 kernel 停止发 SIGUSR2

1. #include <linux/init.h>
   
2. #include <linux/module.h>
   
3. #include <linux/fs.h>
   
4. #include <linux/device.h>
   
5. #include <linux/kernel.h>
   
6. #include <linux/oom.h>
   
7. #include <linux/sched.h>
   
8. #include <linux/delay.h>
   
9. #include <linux/kthread.h>
   
10. #include "header.h"
    
11. 
    
12. MODULE_LICENSE("Dual BSD/GPL");
    
13. 
    
14. static int major_no;
    
15. static int vrmonitor_pid;
    
16. static int cccc = 100;
    
17. static int send_sig_flag = 1;
    
18. 
    
19. static struct task_struct* brook_tsk;
    
20. static int vrmonitor_sig_handler(void* arg);
    
21. 
    
22. static int vrmonitor_sig_handler(void* arg)
    
23. {
    
24.     struct task_struct* p;
    
25.     struct pid* pp;
    
26. 
    
27.     printk(KERN_EMERG "cccc addr=%p ,cccc=%d\n", &cccc, cccc++);
    
28. 
    
29.     pp = find_vpid(vrmonitor_pid);
    
30.     p = pid_task(pp, PIDTYPE_PID);
    
31. 
    
32.     while (send_sig_flag) {
    
33.         msleep(1000);
    
34.         send_sig(SIGUSR2, p, 0);
    
35.         printk(KERN_EMERG "vrmonitor_sig_handler current pid=%d send to PID=%d \n", current->pid, vrmonitor_pid);
    
36.     }
    
37. 
    
38.     send_sig_flag = 1;
    
39. 
    
40.     return 0;
    
41. }
    
42. 
    
43. static int device_open(struct inode* inode, struct file* file)
    
44. {
    
45.     printk(KERN_EMERG "pid=%d, Node Opened\n", current->pid);
    
46.     return 0;
    
47. }
    
48. 
    
49. int device_ioctl(struct file* filp,
    
50.                  unsigned int cmd,
    
51.                  unsigned long args)
    
52. {
    
53.     int ret;
    
54. 
    
55.     switch (cmd) {
    
56.     case IOCTL_CMD:
    
57.         printk(KERN_EMERG "IOCTL_CMD");
    
58.         break;
    
59. 
    
60.     case IOCTL_SEND_PID:
    
61.         printk(KERN_EMERG "appln PID=%u , current kernel pid=%d\n", (unsigned int)args, current->pid);
    
62.         vrmonitor_pid = (unsigned int)args;
    
63.         brook_tsk = kthread_create(vrmonitor_sig_handler, NULL, "brook");
    
64. 
    
65.         if (IS_ERR(brook_tsk)) {
    
66.             ret = PTR_ERR(brook_tsk);
    
67.             brook_tsk = NULL;
    
68.             goto out;
    
69.         }
    
70. 
    
71.         wake_up_process(brook_tsk);
    
72.         break;
    
73. 
    
74.     case IOCTL_STOP_SIG:
    
75.         send_sig_flag = 0;
    
76.         printk(KERN_EMERG "IOCTL_STOP_SIG send_sig_flag=%d\n", send_sig_flag);
    
77.         break;
    
78. 
    
79.     default:
    
80.         printk(KERN_EMERG "Illegal ioctl command word\n");
    
81.         break;
    
82.     }
    
83. 
    
84.     return 0;
    
85. 
    
86. out:
    
87.     return ret;
    
88. }
    
89. 
    
90. static int device_release(struct inode* inode, struct file* file)
    
91. {
    
92.     printk(KERN_EMERG "Module Released \n");
    
93.     return 0;
    
94. }
    
95. 
    
96. static struct class* my_class;
    
97. 
    
98. static struct file_operations fops = {
    
99.     .open = device_open,
    
100.     .release = device_release,
     
101.     .unlocked_ioctl = device_ioctl
     
102. };
     
103. 
     
104. static int hello_init(void)
     
105. {
     
106.     major_no = register_chrdev(0, DEVICE_NAME, &fops);
     
107.     printk(KERN_EMERG "Module Major No : %d\n", major_no);
     
108. 
     
109.     my_class = class_create(THIS_MODULE, DEVICE_NAME);
     
110.     device_create(my_class, NULL, MKDEV(major_no, 0), NULL, DEVICE_NAME);
     
111.     printk(KERN_EMERG "Module loaded in kernel\n");
     
112.     return 0;
     
113. }
     
114. 
     
115. static void hello_exit(void)
     
116. {
     
117.     printk(KERN_EMERG "Device is Released or closed \n");
     
118.     device_destroy(my_class, MKDEV(major_no, 0));
     
119.     class_unregister(my_class);
     
120.     class_destroy(my_class);
     
121.     unregister_chrdev(major_no, DEVICE_NAME);
     
122. }
     
123. 
     
124. module_init(hello_init);
     
125. module_exit(hello_exit);
     

复制代码

1. #include <stdio.h>
   
2. #include <stdlib.h>
   
3. #include <fcntl.h>
   
4. #include <string.h>
   
5. #include <unistd.h>
   
6. #include <sys/ioctl.h>
   
7. #include <signal.h>
   
8. #include "header.h"
   
9. 
   
10. static int fd;
    
11. 
    
12. void stop_sig(int sig)
    
13. {
    
14.     unsigned int sig_flag = 0;
    
15. 
    
16.     ioctl(fd, IOCTL_STOP_SIG, sig_flag);
    
17.     printf("stop_sig=%d, pid=%d\n", sig, getpid());
    
18.     (void) signal(SIGINT, SIG_DFL);
    
19. 
    
20. #if 0
    
21.     kill(getpid(), SIGINT);
    
22. #endif
    
23. }
    
24. 
    
25. 
    
26. void signal_handler(int signum)
    
27. {
    
28.     printf("signal_handler %d, pid=%d\n", signum, getpid());
    
29. 
    
30.     if (signum == SIGUSR2) {
    
31.         printf("SIGUSR2\n");
    
32.     } else if (signum == SIGUSR1) {
    
33.         printf("SIGUSR1\n");
    
34.     }
    
35. }
    
36. 
    
37. int main()
    
38. {
    
39.     pid_t pid = getpid();
    
40. 
    
41.     printf("PID=%u\n", pid);
    
42. 
    
43.     signal(SIGUSR2, signal_handler);
    
44.     signal(SIGINT, stop_sig);
    
45. 
    
46.     fd = open(DEVICE_PATH, O_RDWR);
    
47.     if (fd == -1) {
    
48.         printf("open fail\n");
    
49.         exit(-1);
    
50.     }
    
51. 
    
52.     ioctl(fd, IOCTL_SEND_PID, pid);
    
53.     printf("Ioctl executed\n");
    
54. 
    
55.     while(1) {}
    
56. 
    
57.     close(fd);
    
58.     return 0;
    
59. }
    

复制代码

运行步骤
sudo insmod sample.ko
sudo ./appln


下面是打印出来的log


// user space log
PID=6897
Ioctl executed
signal_handler 12, pid=6897
SIGUSR2
signal_handler 12, pid=6897
SIGUSR2
^Cstop_sig=2, pid=6897  // ctrl + c 发往 kernel 让kernel停止发送 SIGUSR2


// kernel log
[  681.335568] vrmonitor_sig_handler current pid=6898 send to PID=6897
[  682.339540] vrmonitor_sig_handler current pid=6898 send to PID=6897
[  682.871588] IOCTL_STOP_SIG send_sig_flag=0  // kernel 收到准备停止
[  682.871646] Module Released
[  683.343531] vrmonitor_sig_handler current pid=6898 send to PID=6897



我再一般pc上运行正常 ,


可是再 vmware  ubuntu kernel 只发两次 SIGUSR2 , 就打印出 Module Released
下面 log ,  user space 的 appln  prcoess 就莫名其妙结束 , 我还没按 ctrl+c
只是启动 sudo ./appln 这样




[  681.335568] vrmonitor_sig_handler current pid=6898 send to PID=6897
[  682.339540] vrmonitor_sig_handler current pid=6898 send to PID=6897
[  682.871646] Module Released

Tinnal

收到另的信号退出了呀。GDB一个就知道了呀。或者unlimit -c unlimited，产生个core文件看看

shihyu

ok... 我明天试试看 gdb
thanks