Specifically, one thread reads the counter with proper synchronization, then another thread writes an incremented value to the counter with proper synchronization, then the first thread writes its own incremented value to the counter with proper synchronization. At every step the use of an AtomicU32 guarantees proper synchronization to the underlying memory, which is what Rust is concerned with.

The fix for the logic bug in this case would be to indicate that you want the increment itself to be an atomic operation, using the fetch_add method: https://doc.rust-lang.org/std/sync/atomic/struct.AtomicU32.h...