Getting unregister_netdevice: waiting for eth0 to become free. Usage count = 4 error

Hi All, When i am trying to delete an interface from the application, while traffic is flowing through it, kernel throws the message unregister_netdevice: waiting for eth0 to become free. Usage count = 4 which means network device usage counter is more that zero and there are 4 references of this device still active, therefore the networking subsystem of the kernel defers it, to become the usage counter 0. Can somebody let me know what are the operations/ events increases the reference count of any network device. I looked in to the kernel code and found that a call to "dev_hold" increases the refrence count and "dev_put" decreases this. thanks, Vishwas S