用户空间与内核驱动的交互过程—ioctl

 1 struct vlan_ioctl_args {
 2     int cmd; /* Should be one of the vlan_ioctl_cmds enum above. */
 3     char device1[24];
 4 
 5         union {
 6         char device2[24];
 7         int VID;
 8         unsigned int skb_priority;
 9         unsigned int name_type;
10         unsigned int bind_type;
11         unsigned int flag; /* Matches vlan_dev_info flags */
12         } u;
13 
14     short vlan_qos;   
15 };

1    /* We use sockets now, instead of the file descriptor */
2    if ((fd = socket(AF_INET, SOCK_STREAM, 0)) <0) {
3       fprintf(stderr, "FATAL:  Couldn't open a socket..go figure!\n");
4       exit(2);
5    }   

1    /* add */
2    if (strcasecmp(cmd, "add") == 0) {
3       if_request.cmd = ADD_VLAN_CMD;
4       if (ioctl(fd, SIOCSIFVLAN, &if_request) <0) {
5          fprintf(stderr,"ERROR: trying to add VLAN #%u to IF -:%s:-  error: %s\n",
6                     vid, if_name, strerror(errno));                 
7       }
8    }//if

1 vlan_ioctl_set(vlan_ioctl_handler);

1 struct vlan_ioctl_args args;
2 
3 if (copy_from_user(&args, arg, sizeof(struct vlan_ioctl_args)))
4         return -EFAULT;

 1 static DEFINE_MUTEX(vlan_ioctl_mutex);
 2 static int (*vlan_ioctl_hook) (void __user *arg);
 3 
 4 void vlan_ioctl_set(int (*hook) (void __user *))
 5 {
 6     mutex_lock(&vlan_ioctl_mutex);
 7     vlan_ioctl_hook = hook;
 8     mutex_unlock(&vlan_ioctl_mutex);
 9 }
10 
11 EXPORT_SYMBOL(vlan_ioctl_set);

 1 case SIOCGIFVLAN:
 2 case SIOCSIFVLAN:
 3             err = -ENOPKG;
 4             if (!vlan_ioctl_hook)
 5                 request_module("8021q");
 6 
 7             mutex_lock(&vlan_ioctl_mutex);
 8             if (vlan_ioctl_hook)
 9                 err = vlan_ioctl_hook(argp);
10             mutex_unlock(&vlan_ioctl_mutex);
11             break;