You need more than just atomic access I think. You need an atomic compare and swap. These are usually a hardware affordance. To properly use them most languages

You need more than just atomic access I think. You need an atomic compare and swap. These are usually a hardware affordance. To properly use them most languages provide an atomic int that expose the hardware version in an ergonomic interface. This is then typically wrapped in a Mutex library that exposes an even more ergonomic interface than the atomic primitive. You can sometimes rely just on the atomic primitive if that's all you need but most of the time you need more.