Le Fri, Oct 04, 2024 at 02:27:33PM -0400, Mathieu Desnoyers a écrit :
> +void hp_scan(struct hp_slot __percpu *percpu_slots, void *addr,
> + void (*retire_cb)(int cpu, struct hp_slot *slot, void *addr))
> +{
> + int cpu;
> +
> + /*
> + * Store A precedes hp_scan(): it unpublishes addr (sets it to
> + * NULL or to a different value), and thus hides it from hazard
> + * pointer readers.
> + */
> +
> + if (!addr)
> + return;
> + /* Memory ordering: Store A before Load B. */
> + smp_mb();
> + /* Scan all CPUs slots. */
> + for_each_possible_cpu(cpu) {
> + struct hp_slot *slot = per_cpu_ptr(percpu_slots, cpu);
> +
> + if (retire_cb && smp_load_acquire(&slot->addr) == addr) /* Load
> B */
> + retire_cb(cpu, slot, addr);
> + /* Busy-wait if node is found. */
> + while ((smp_load_acquire(&slot->addr)) == addr) /* Load B */
> + cpu_relax();
You agree that having a single possible per-cpu pointer per context and a busy
waiting update side pointer release can't be a general purpose hazard pointer
implementation, right? :-)
Thanks.
> + }
> +}
> --
> 2.39.2
>
