Messages in this thread | | | Date | Mon, 19 Feb 2007 14:59:55 +0300 | From | Oleg Nesterov <> | Subject | Re: [PATCH 1/3] net/bridge/br_if.c: don't use _WORK_NAR |
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On 02/19, David Howells wrote: > > Oleg Nesterov <oleg@tv-sign.ru> wrote: > > > Afaics, noautorel work_struct buys nothing for "struct net_bridge_port". > > You may be right. > > > If del_nbp()->cancel_delayed_work(&p->carrier_check) fails, port_carrier_check > > may be called later anyway. > > Called by what? Something outside of br_if.c?
No. if cancel_delayed_work() fails, the work may sit pending in cwq->worklist, or it may be running right now, waiting for rtnl_mutex.
> > So the reading of *work in port_carrier_check() is equally unsafe with or > > without this patch. > > Hmmm... cancel_delayed_work() in del_nbp() probably ought to be followed by a > flush_scheduled_work().
Yes, but this deadlocks: we hold rtnl_mutex, and work->func() takes it too.
I think the fix should be so that port_carrier_check() does get/put on "struct net_bridge_port" (container), but not on "struct net_device", and
del_nbp(struct net_bridge_port *p)
if (cancel_delayed_work(&p->carrier_check)) - dev_put(p->dev); + kobject_put(&p->kobj);
Oleg.
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