The problem with atomic_read and atomic_write is that some people will interpret that as "atomic with a sequentially consistent ordering" and some as "atomic with a relaxed ordering" and everything in between. It's a fine name for a function that takes an argument that specifies memory ordering [1]. It's not great for anything else.

Read_once and Write_once convey that there's more nuance than that, and tries to convey the nuance.

[1] E.g. in rust anything that takes https://doc.rust-lang.org/std/sync/atomic/enum.Ordering.html