select에서 timeout 조정이 되질 않습니다.

여기서 select에서 timeout을 하면 블럭이 되어야 하는데 안됩니다.
open 시 플레그에서 설정을 하여야하는 것 같기도 한는데..
O_NONBLOCK 대신 일단.. 타임아웃 동안은 블럭되게 좀 만들어주세요..

#include <stdio.h>
#include <unistd.h>
#include <termios.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/select.h>
#include <time.h>
#include <sys/time.h>

#define COM1 "/dev/ttyS0"
#define BAUDRATE 4800
#define FLOW 1
#define HWCONTROL 1 
 

int serialOpen()
{
	long baudrate;
	struct termios tio;
	int fd = open(COM1, O_RDWR | O_NOCTTY | O_NONBLOCK, 0644);
	if(fd < 0)
	{	
		fprintf(stderr, "Can't open device %s\n", COM1);	
		return -1;
	}
	else
	{
		bzero(&tio, sizeof(tio));
		tio.c_cflag &= ~CSIZE;
		tio.c_cflag |= CS8;					/* 8 data bit	    */
		tio.c_cflag &= ~CSTOPB;             /* 1 stop bit       */
		tio.c_cflag &= ~(PARENB | PARODD);  /* NO PARITY BIT    */
		tio.c_cflag &= ~CRTSCTS;            /* NOT FLOW CONTROL */
	}
	baudrate = B4800;
    if((cfsetispeed(&tio, baudrate) < 0 || cfsetospeed(&tio, baudrate) < 0))  /* baudrate set */ 
	{ 
     	fprintf(stderr, "Failed baudrate set.\n"); 
        close(fd); 
        return -1; 
    }
	else   /* SUCCESS */
	{ 
        if(tcsetattr(fd, TCSANOW, &tio) < 0)								 /* termios set */ 
		{     
        	printf("Can't set Termios struct.\n"); 
        	close(fd); 
        	return -1; 
        }
		else
	 	{ 
            if(tcflush(fd, TCIOFLUSH) < 0)
			{ 
           		close(fd); 
                return -1; 
            }    
        } 
   } 
	printf("fd '%d' open\n", fd);
	return fd;
}



int main(int argc, char* argv[])
{
	int terminated = 0;
	struct timeval tv;
	fd_set rfd, wfd;
	int max_fd, result;
	int fd = serialOpen();
	if(fd < 0)
	{
		printf("File open '%d'\n", fd);	
		close(fd);
		exit (1);
	}


	while(!terminated)
	{	
FD_ZERO(&rfd);
	FD_ZERO(&wfd);

		FD_SET(fd, &rfd);
		FD_SET(fd, &wfd);

		tv.tv_sec = 4;
		tv.tv_usec = 0;
		
		result = select(fd + 1, &rfd, &wfd, (fd_set*)0, &tv);
		if(result < 0)
		{
            if(errno != EINTR)
            {
                perror("select");
            }
            fprintf(stderr, "select error : %s(%d)\n", strerror(errno), errno);
			continue;
        } 
		else if(result == 0)
			fprintf(stderr, "select timeout\n");
		printf("result '%d'\n", result);