linux程序编译问题

[root@localhost usb2]# make
make -C /lib/modules/2.6.32-279.el6.i686/build M=/home/czx/arm-usb/usb2 modules
make[1]: Entering directory `/usr/src/kernels/2.6.32-279.el6.i686'
CC [M] /home/czx/arm-usb/usb2/usb-skeleton-xiao.o
/home/czx/arm-usb/usb2/usb-skeleton-xiao.c: In function ‘skel_write_bulk_callback’:
/home/czx/arm-usb/usb2/usb-skeleton-xiao.c:423: error: implicit declaration of function ‘usb_free_coherent’
/home/czx/arm-usb/usb2/usb-skeleton-xiao.c: In function ‘skel_write’:
/home/czx/arm-usb/usb2/usb-skeleton-xiao.c:478: error: implicit declaration of function ‘usb_alloc_coherent’
/home/czx/arm-usb/usb2/usb-skeleton-xiao.c:479: warning: assignment makes pointer from integer without a cast
make[2]: *** [/home/czx/arm-usb/usb2/usb-skeleton-xiao.o] Error 1
make[1]: *** [_module_/home/czx/arm-usb/usb2] Error 2
make[1]: Leaving directory `/usr/src/kernels/2.6.32-279.el6.i686'
make: *** [kernel_modules] Error 2


usb_free_coheren是usb.h中的函数，文件包含了usb.h文件，是什么问题呢？