Thread: Bad System Call

Code:

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/ipc.h>
#include <sys/shm.h>

int id;
int shared_mem_id;
int *s;

int sum (int n)
{
    printf("sum") ;
    int i;
    for (i = 1; i <= n; i++)
    {
        *s = *s + 1;
    }
    return *s;
}

int main (int argc, char *argv[])
{
    sleep (1);
    if (argc < 3)
    {
        printf ("usage: ./sum n1 n2\n");
        exit (1);
    }
    printf("memory allocating") ;
    shared_mem_id = shmget (IPC_PRIVATE, sizeof (int), 0644);
    printf("memory allocated") ;
    if (shared_mem_id < 0)
    {
                      perror ("error: unable to allocate");
                      exit (2);
    }
    s = (int *) shmat (shared_mem_id, NULL, 0644);
    if ((int) s == -1)
    {
              perror ("error: unable to attach");
              exit (2);
    }
    *s = 0;
    if ((id = fork ()))
    printf ("Process %5d: Count to %d is %d\n", id, atoi (argv[1]),
    sum (atoi (argv[1])));
    else
    printf ("Process %5d: Count to %d is %d\n", id, atoi (argv[2]),
    sum (atoi (argv[2])));
    
    return 0 ;
}

i successfully compiled the program in cygwin.
but when i try runinng it with 10 and 10 as parameters, i got a "Bad System Call" error.

any idea wat does it mean?
thanks in advance