CPUCLOCK_CLOCK_MASK   44 include/linux/posix-timers.h #define CPUCLOCK_WHICH(clock)	((clock) & (clockid_t) CPUCLOCK_CLOCK_MASK)
CPUCLOCK_CLOCK_MASK   51 include/linux/posix-timers.h #define CLOCKFD_MASK		(CPUCLOCK_PERTHREAD_MASK|CPUCLOCK_CLOCK_MASK)