[lttng-dev] cds_lfht_count_nodes always returns -1 for before/after counts

[jlayton@poochiereds.net (Jeff Layton)]

Hi, I have some code using the cds_lfht infrastructure, and recently
added a function to check to see if the table was empty using
cds_lfht_count_nodes. That function just does this:

        rcu_read_lock();
        cds_lfht_count_nodes(ht, &before, &count, &after);
        rcu_read_unlock();

What I've found though is that when the table is empty and I know that
there are no concurrent inserts going on, the before and after counters
are always set to -1 after this call.

Is that expected behavior? For the record, I'm using this package from
the Fedora 21 repos:

    userspace-rcu-0.8.1-5.fc21.x86_64

Thanks in advance!
-- 
Jeff Layton <jlayton at poochiereds.net>