O_EXLOCK vs flock()

Question

What is the difference between calling open() with the O_EXLOCK flag versus calling just calling open() and then calling flock()? The latter has a potential race condition, but other than that both ways gets an exclusive process lock on a file, right?

Answer 1

The only difference is atomicity: open() with O_EXLOCK is atomic, whereas open() followed by flock() are two distinct operations.