Error in make on Ubuntu 18.04 in AWS

[andermarce]

~/akvcam/src$ make
make -C /lib/modules/5.4.0-1029-aws/build M=/home/ubuntu/akvcam/src modules
make[1]: Entering directory '/usr/src/linux-headers-5.4.0-1029-aws'
CC [M] /home/ubuntu/akvcam/src/module.o
CC [M] /home/ubuntu/akvcam/src/attributes.o
CC [M] /home/ubuntu/akvcam/src/buffer.o
CC [M] /home/ubuntu/akvcam/src/buffers.o
CC [M] /home/ubuntu/akvcam/src/controls.o
CC [M] /home/ubuntu/akvcam/src/device.o
CC [M] /home/ubuntu/akvcam/src/driver.o
CC [M] /home/ubuntu/akvcam/src/events.o
CC [M] /home/ubuntu/akvcam/src/file_read.o
CC [M] /home/ubuntu/akvcam/src/format.o
CC [M] /home/ubuntu/akvcam/src/frame.o
CC [M] /home/ubuntu/akvcam/src/global_deleter.o
CC [M] /home/ubuntu/akvcam/src/ioctl.o
CC [M] /home/ubuntu/akvcam/src/list.o
CC [M] /home/ubuntu/akvcam/src/log.o
CC [M] /home/ubuntu/akvcam/src/map.o
CC [M] /home/ubuntu/akvcam/src/mmap.o
CC [M] /home/ubuntu/akvcam/src/node.o
CC [M] /home/ubuntu/akvcam/src/object.o
CC [M] /home/ubuntu/akvcam/src/rbuffer.o
CC [M] /home/ubuntu/akvcam/src/settings.o
CC [M] /home/ubuntu/akvcam/src/utils.o
LD [M] /home/ubuntu/akvcam/src/akvcam.o
Building modules, stage 2.
MODPOST 1 modules
ERROR: "video_device_release_empty" [/home/ubuntu/akvcam/src/akvcam.ko] undefined!
ERROR: "video_device_release" [/home/ubuntu/akvcam/src/akvcam.ko] undefined!
ERROR: "v4l2_device_unregister" [/home/ubuntu/akvcam/src/akvcam.ko] undefined!
ERROR: "__video_register_device" [/home/ubuntu/akvcam/src/akvcam.ko] undefined!
ERROR: "v4l2_device_register" [/home/ubuntu/akvcam/src/akvcam.ko] undefined!
ERROR: "video_device_alloc" [/home/ubuntu/akvcam/src/akvcam.ko] undefined!
ERROR: "video_unregister_device" [/home/ubuntu/akvcam/src/akvcam.ko] undefined!
scripts/Makefile.modpost:93: recipe for target '__modpost' failed
make[2]: *** [__modpost] Error 1
Makefile:1670: recipe for target 'modules' failed
make[1]: *** [modules] Error 2
make[1]: Leaving directory '/usr/src/linux-headers-5.4.0-1029-aws'
Makefile:42: recipe for target 'all' failed
make: *** [all] Error 2

[hipersayanX]

Check #40.