kernel: current gids

From: vertigo (ax178_at_wp.pl)
Date: 10/31/04 

Date: Sun, 31 Oct 2004 15:09:00 +0100

Hello
I write module for kernel 2.6.
How can i read current user gid's ?

I found current->group_info, but how can i read group's id from that ?
I tried:
while(i<current->group_info->ngroups)
printk("Group id: %d\n",current->group_info->small_block[i++]);

but i hang my PC :(

How can i read user's group's numbers ?

Thanx
Michal