Is the fibre channel being used. I don't know if the fibre channel is like a usb bus, an ethernet port, but if you have a device that uses the module, you need to shut down the device. If it is like having a usb drive plugged in, you will need to unmount partitions using the bus.
For example, you can't unload the ndiswrapper module before shutting down the wireless device, such as wlan0. Not doing so, you could crash the kernel.