/home/user/kernrk.c: In function ‘getdents64_post_handler’:
/home/user/kernrk.c:18:5: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
     struct linux_dirent64 __user *dirent = (struct linux_dirent64 __user *)regs->si;
     ^
/home/user/kernrk.c:26:5: error: implicit declaration of function ‘copy_from_user’ [-Werror=implicit-function-declaration]
     if (copy_from_user(kbuf, dirent, nread)) {
     ^
/home/user/kernrk.c:31:5: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
     long bpos = 0;
     ^
/home/user/kernrk.c:44:5: error: implicit declaration of function ‘copy_to_user’ [-Werror=implicit-function-declaration]
     if (copy_to_user(dirent, kbuf, new_nread)) {
     ^
/home/user/kernrk.c:19:9: warning: unused variable ‘count’ [-Wunused-variable]
     int count = regs->dx;
         ^
/home/user/kernrk.c: At top level:
/home/user/kernrk.c:56:5: warning: initialization from incompatible pointer type [enabled by default]
     .post_handler = getdents64_post_handler,
     ^
/home/user/kernrk.c:56:5: warning: (near initialization for ‘kp.post_handler’) [enabled by default]
cc1: some warnings being treated as errors
make[2]: *** [/home/user/kernrk.o] Error 1
make[1]: *** [_module_/home/user] Error 2
make[1]: Leaving directory `/usr/src/linux-headers-4.4.0-142-generic'
make: *** [all] Error 2