long strncpy_from_user(char *dst, const char __user *src, long count);
long __strncpy_from_user(char *dst, const char __user *src, long count);
long strnlen_user(const char __user *str, long n);
long strncpy_from_user(char *dst, const char __user *src, long count);
long __strncpy_from_user(char *dst, const char __user *src, long count);
long strnlen_user(const char __user *str, long n);