is_power_of_2
#define is_power_of_2(x) ((x) != 0 && (((x) & ((x) - 1)) == 0))
bool is_power_of_2(unsigned long n)
static int is_power_of_2(int x)
bool is_power_of_2(unsigned long n)
#define is_power_of_2(n) (n != 0 && ((n & (n - 1)) == 0))
static bool is_power_of_2(__u64 n)