error log: /var/lib/dkms/lttng-modules/2.4.0/build/make.log

DKMS make.log for lttng-modules-2.4.0 for kernel 4.1.0-rc4+ (x86_64)
Fri Jun 19 09:04:41 SGT 2015
make: Entering directory `/sda3/linux_latest'
  CC [M]  /var/lib/dkms/lttng-modules/2.4.0/build/lttng-ring-buffer-client-discard.o
In file included from /var/lib/dkms/lttng-modules/2.4.0/build/wrapper/ringbuffer/../../lib/ringbuffer/../../wrapper/ringbuffer/frontend_api.h:1:0,
                 from /var/lib/dkms/lttng-modules/2.4.0/build/wrapper/ringbuffer/../../lib/ringbuffer/api.h:35,
                 from /var/lib/dkms/lttng-modules/2.4.0/build/wrapper/ringbuffer/api.h:1,
                 from /var/lib/dkms/lttng-modules/2.4.0/build/lttng-ring-buffer-client.h:175,
                 from /var/lib/dkms/lttng-modules/2.4.0/build/lttng-ring-buffer-client-discard.c:29:
/var/lib/dkms/lttng-modules/2.4.0/build/wrapper/ringbuffer/../../lib/ringbuffer/../../wrapper/ringbuffer/../../lib/ringbuffer/frontend_api.h: In function ‘lib_ring_buffer_put_cpu’:
/var/lib/dkms/lttng-modules/2.4.0/build/wrapper/ringbuffer/../../lib/ringbuffer/../../wrapper/ringbuffer/../../lib/ringbuffer/frontend_api.h:76:2: error: implicit declaration of function ‘__get_cpu_var’ [-Werror=implicit-function-declaration]
  __get_cpu_var(lib_ring_buffer_nesting)--;
  ^
/var/lib/dkms/lttng-modules/2.4.0/build/wrapper/ringbuffer/../../lib/ringbuffer/../../wrapper/ringbuffer/../../lib/ringbuffer/frontend_api.h:76:40: error: lvalue required as decrement operand
  __get_cpu_var(lib_ring_buffer_nesting)--;
                                        ^
cc1: some warnings being treated as errors
make[1]: *** [/var/lib/dkms/lttng-modules/2.4.0/build/lttng-ring-buffer-client-discard.o] Error 1
make: *** [_module_/var/lib/dkms/lttng-modules/2.4.0/build] Error 2
make: Leaving directory `/sda3/linux_latest'