Kernel module that shuts down the device

Hi all, I am working on a kernel module that should shut down the device when USB is unplugged. I make a call to kernel_power_off(), but I see that it gets stuck trying to call blocking_notifier_call_chain(&reboot_notifier_list, (state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL); in kernel_shutdown_prepare(). There is currently another driver that has the same function, and shuts down the device by calling kernel_power_off() successfully. I have tried adding prints in blocking_notifier_call_chain, but then the kernel log is flooded with calls and I can't really see what is happening. Does anyone have any insight into why my call to kernel_power_off() is hanging? Thanks, Drew