io_dontwantread man page
io_dontwantread — signal that you do not want to read from a descriptor
void io_dontwantread(int64 fd);
io_dontwantread tells the next io_wait() that you don't want to read from this descriptor for now. Call io_wantread() again if you change your mind.
You have to have called io_fd on the descriptor first (io_pipe and io_socketpair do this for you). Waiting on descriptors only works for sockets, fifos and pipes. It may also work on devices and TTYs, but that is platform dependent -- you should not rely on that.
io_wait(3), io_canread(3), io_wantread(3), io_fd(3)