On 2025-02-22 16:13:35 [+0800], Yunsheng Lin wrote:
> > @@ -99,11 +106,19 @@ bool page_pool_get_stats(const struct page_pool *pool,
> > const struct page_pool_recycle_stats *pcpu =
> > per_cpu_ptr(pool->recycle_stats, cpu);
> >
> > - stats->recycle_stats.cached += pcpu->cached;
> > - stats->recycle_stats.cache_full += pcpu->cache_full;
> > - stats->recycle_stats.ring += pcpu->ring;
> > - stats->recycle_stats.ring_full += pcpu->ring_full;
> > - stats->recycle_stats.released_refcnt += pcpu->released_refcnt;
> > + do {
> > + start = u64_stats_fetch_begin(&pcpu->syncp);
> > + u64_stats_add(&stats->recycle_stats.cached,
> > + u64_stats_read(&pcpu->cached));
> > + u64_stats_add(&stats->recycle_stats.cache_full,
> > + u64_stats_read(&pcpu->cache_full));
> > + u64_stats_add(&stats->recycle_stats.ring,
> > + u64_stats_read(&pcpu->ring));
> > + u64_stats_add(&stats->recycle_stats.ring_full,
> > + u64_stats_read(&pcpu->ring_full));
> > + u64_stats_add(&stats->recycle_stats.released_refcnt,
> > + u64_stats_read(&pcpu->released_refcnt));
>
> It seems the above u64_stats_add() may be called more than one time
> if the below u64_stats_fetch_retry() returns true, which might mean
> the stats is added more than it is needed.
>
> It seems more correct to me that pool->alloc_stats is read into a
> local varible in the while loop and then do the addition outside
> the while loop?
indeed, indeed, what was I thinking…
>
> > + } while (u64_stats_fetch_retry(&pcpu->syncp, start));
> > }
> >
> > return true;
Sebastian
