#define umul_of(a, b, of) __builtin_umul_overflow(a, b, of)
#define umull_of(a, b, of) __builtin_umull_overflow(a, b, of)
#define offsetof(f, m) __builtin_offsetof(f, m)
#define umul_of(a, b, of) __builtin_umul_overflow(a, b, of)
#define umull_of(a, b, of) __builtin_umull_overflow(a, b, of)
#define offsetof(f, m) __builtin_offsetof(f, m)