看ioctl 调用过程

/20080311
　　
　　1ioctl (网络中 application)
　　2defined ioctl in include/asm-mips/unistd.h
　　 #define __NR_ioctl (__NR_Linux + 54)
　　3 implemented in sys_call_table,arch/mips/kernel/scall64-o32.S
　　sys_call_table:
　　...
　　PTR compat_sys_ioctl
　　...
　　4 implemented compat_sys_ioctl in linux/fs/compat.c
　　
　　5 called
　　compat_sys_ioctl
　　1.0-->filp = fget_light(fd, &fput_needed);
　　1.1-->filp->f_op->unlocked_ioctl (socket.c defined,it is sock_ioctl)
　　1.2-->vfs_ioctl
　　1.2.1-->do_ioctl (linux/fs/ioctl.c)
　　1.2.1.1-->filp->f_op->unlocked_ioctl (sock_ioctl)
　　1.2.1.1.1-->dev_ioctl

sys_socket (kernel process the "socket" function in user level)
　　1.1-->sock_create
　　1.2-->sock_map_fd
　　1.2.1-->get_unused_fd
　　1.2.2-->get_empty_filp
　　1.2.3-->sock->file = file
　　1.2.4-->file->f_op = SOCK_INODE(sock)->i_fop = &socket_file_ops; (where socket_file_ops.unlocked_ioctl =sock_ioctl)
　　1.2.5-->fd_install (fdt->fd[fd]=file,this can help us find the file by fd)