github.com/afumu/libc@v0.0.6/musl/src/thread/__wait.c (about)

     1  #include "pthread_impl.h"
     2  
     3  void __wait(volatile int *addr, volatile int *waiters, int val, int priv)
     4  {
     5  	int spins=100;
     6  	if (priv) priv = FUTEX_PRIVATE;
     7  	while (spins-- && (!waiters || !*waiters)) {
     8  		if (*addr==val) a_spin();
     9  		else return;
    10  	}
    11  	if (waiters) a_inc(waiters);
    12  	while (*addr==val) {
    13  		__syscall(SYS_futex, addr, FUTEX_WAIT|priv, val, 0) != -ENOSYS
    14  		|| __syscall(SYS_futex, addr, FUTEX_WAIT, val, 0);
    15  	}
    16  	if (waiters) a_dec(waiters);
    17  }