system hangs in case of driver

hi,
i am working on device drivers in linux kernel-2.6.11. Distribution is Mandrake-10.2. Basically i have to port the driver from kernel-2.4 to kernel-2.6.11.
My system hangs,when ever an application calls select.
Basically the kernel code for select,
contains only 2 apis
void poll_wait (struct file *, wait_queue_head_t *, poll_table *);
signal_pending(current);
and atlast pollmask is returned.
What might be the problem????
Any help is welcome

regards
sriram