> I don’t think it needs to be, there are no reads and writes to this variable about which the compiler could reorder other reads and writes, we only take the address of it, never reading/writing it directly.

@keithduncan All of the `OSAtomic` functions use `volatile` qualified storage. By not marking this variable as `volatile`, we're implicitly converting it for use with those functions — but that's a useless change, since it doesn't actually affect the semantics at the call point.

Besides, the semantics of `volatile` aren't very specific, and intentionally involve a lot of implementation-defined behavior. The compiler is free to do a lot of optimization without the qualifier, in ways that might affect the concurrency guarantees here.