Remove USB Drive From USB-Storage Tree

[lee choon gay]

Hi, 
I use the following command to connect my USB drive to qemu. No issue with that.

sudo qemu-system-i386 -m 512 -kernel bzImage -initrd rootfs.cpio.gz -usb 
-device usb-host,vendorid=0x781,productid=0x5583 -net nic -net 
user,smb=/home/ubuntu/Desktop/drivers/usb_stick -append console=ttyS0 -nographic

But, I would like to remove the USB drive from 
"/sys/bus/usb/drivers/usb-storage" so that I can insmod my USB module.
I try to use 'echo -n "1-1:1.0" > /sys/bus/usb/drivers/usb-storage/unbind' to 
remove the USB drive but most of the time, the command will stuck with error 
message "usb-storage: Error in queuecommand_lck: us->srb = 384ac926". 

Is it a bad idea to do so?
Is there any method to prevent the usb-storage module from loading inside qemu?

Thanks all.