Error while building kernel image

I am building a kernel image with drivers.
I have copied my driver in drivers/char
I have modified the makefile and Kconfig file.
when i do make zImage i am getting the below error.

CHK     include/linux/compile.h
  LD      vmlinux.o
net/built-in.o(.text+0x10ffc): In function `dev_open':
: multiple definition of `dev_open'
drivers/built-in.o(.text+0x2aa14): first defined here
arm-linux-ld: Warning: size of symbol `dev_open' changed from 32 in
drivers/built-in.o to 284 in net/built-in.o
net/built-in.o(.text+0x11d9c): In function `dev_ioctl':
: multiple definition of `dev_ioctl'
drivers/built-in.o(.text+0x2aa54): first defined here
arm-linux-ld: Warning: size of symbol `dev_ioctl' changed from 536 in
drivers/built-in.o to 2084 in net/built-in.o
make: *** [vmlinux.o] Error 1


Please guide me..

Could you please post you driver code? Possibly you use dev_* functions
which are already used. Add before dev_open and dev_ioctl static keyword.