Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:
> On Wed, 2016-08-24 at 13:55 +0200, Florian Westphal wrote:
> > Conntrack gc worker to evict stale entries.
>
>
> > static struct nf_conn *
> > __nf_conntrack_alloc(struct net *net,
> > const struct nf_conntrack_zone *zone,
> > @@ -1527,6 +1597,7 @@ static int untrack_refs(void)
> >
> > void nf_conntrack_cleanup_start(void)
> > {
> > + conntrack_gc_work.exiting = true;
> > RCU_INIT_POINTER(ip_ct_attach, NULL);
> > }
> >
> > @@ -1536,6 +1607,9 @@ void nf_conntrack_cleanup_end(void)
> > while (untrack_refs() > 0)
> > schedule();
> >
> > + cancel_delayed_work_sync(&conntrack_gc_work.dwork);
> > + /* can be re-scheduled once */
>
> Are you sure ?
>
> As conntrack_gc_work.exiting = true, I do not see how this can happen ?
nf_conntrack_cleanup_start() sets exiting = true
current cpu blocks in
cancel_delayed_work_sync(&conntrack_gc_work.dwork);
Iff the work queue was running on other cpu but was already past
gc_work->exiting check then when cancel_delayed_work_sync() (first one)
returns it will have re-armed itself via schedule_delayed_work().
So I think the 2nd cancel_delayed_work_sync is needed.
Let me know if you'd like to see a v3 with more verbose
comment about this.
Thanks!
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