Re: [PATCH v9 10/17] refcount: introduce __refcount_{add|inc}_not_zero_limited

Hillf Danton
2025-01-11T06:32:12Z

On Fri, 10 Jan 2025 20:25:57 -0800 Suren Baghdasaryan <surenb@google.com>
> -bool __refcount_add_not_zero(int i, refcount_t *r, int *oldp)
> +bool __refcount_add_not_zero_limited(int i, refcount_t *r, int *oldp,
> + int limit)
> {
> int old = refcount_read(r);
>
> do {
> if (!old)
> break;
> +
> + if (statically_true(limit == INT_MAX))
> + continue;
> +
> + if (i > limit - old) {
> + if (oldp)
> + *oldp = old;
> + return false;
> + }
> } while (!atomic_try_cmpxchg_relaxed(&r->refs, &old, old + i));

The acquire version should be used, see atomic_long_try_cmpxchg_acquire()
in kernel/locking/rwsem.c.

Why not use the atomic_long_t without bothering to add this limited version?