How to get userID when writing Linux kernel module

Question

Here is my function in my kernel module which I insert using insmod command after make at later stages. I am working on goldfish (2.6.29)

asmlinkage long our_sys_read(unsigned int fd, char  *buf, size_t count)
{
      printk("------->> our_sys_read getuid() ---------- %d\n", getuid());

      return original_call_read(fd,buf,count);
}

I want to trap system calls and find out which user made these system calls. But when I run 'make', it throws me following error.

/home/mohsin/LKM/trapcall.c:245: error: implicit declaration of function 'getuid'

Any suggestion would be appreciated.