On 11/26/21 01:31, Maciej S. Szmigiero wrote:
- if ((long)old == atomic_long_read(&slots->last_used_slot)) - atomic_long_set(&slots->last_used_slot, (long)new); + /* + * The atomicity isn't strictly required here since we are + * operating on an inactive memslots set anyway. + */ + atomic_long_cmpxchg(&slots->last_used_slot, + (unsigned long)old, (unsigned long)new);
I think using read/set is more readable than a comment saying that atomicity is not required.
It's a fairly common pattern, and while I agree that it's a PITA to write atomic_long_read and atomic_long_set, the person that reads the code is also helped by read/set, because they know they have to think about ownership invariants rather than concurrency invariants.
Paolo
