This is needed for i686 which doesn't have futex_timed_wait_bitset. commit 35df5a77f3ad2a35761631928440d2994a9e4bc5 Author: Carlos O'Donell Date: Tue Jun 12 16:17:05 2018 -0400 Fix fallback path in __pthread_mutex_timedlock (). Fix the typo in the fallback path in __pthread_mutex_timedlock () whic hcalls lll_futex_timed_wait (). This is only useful for cases where the patch is being backported to older distributions where only lll_futex_timed_wait () is available. Index: glibc-2.17-c758a686/nptl/pthread_mutex_timedlock.c =================================================================== --- glibc-2.17-c758a686.orig/nptl/pthread_mutex_timedlock.c +++ glibc-2.17-c758a686/nptl/pthread_mutex_timedlock.c @@ -272,7 +272,7 @@ pthread_mutex_timedlock (pthread_mutex_t /* Block using the futex. */ #if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \ || !defined lll_futex_timed_wait_bitset) - lll_futex_timed wait (&mutex->__data.__lock, oldval, + lll_futex_timed_wait (&mutex->__data.__lock, oldval, &rt, PTHREAD_ROBUST_MUTEX_PSHARED (mutex)); #else int err = lll_futex_timed_wait_bitset (&mutex->__data.__lock,