From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: Re: [patch net-next 3/6] net_sched: cls_bpf: remove faulty use of list_for_each_entry_rcu Date: Wed, 3 Dec 2014 13:19:49 +0100 Message-ID: <20141203121949.GA24370@salvia> References: <1417539636-12710-1-git-send-email-jiri@resnulli.us> <1417539636-12710-4-git-send-email-jiri@resnulli.us> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, davem@davemloft.net, jhs@mojatatu.com To: Jiri Pirko Return-path: Received: from mail.us.es ([193.147.175.20]:37636 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752429AbaLCMRe (ORCPT ); Wed, 3 Dec 2014 07:17:34 -0500 Content-Disposition: inline In-Reply-To: <1417539636-12710-4-git-send-email-jiri@resnulli.us> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, Dec 02, 2014 at 06:00:33PM +0100, Jiri Pirko wrote: > rcu variant is not correct here. The code is called by updater (rtnl > lock is held), not by reader (no rcu_read_lock is held). > > Signed-off-by: Jiri Pirko > --- > net/sched/cls_bpf.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c > index cbfaf6f..d0de979 100644 > --- a/net/sched/cls_bpf.c > +++ b/net/sched/cls_bpf.c > @@ -141,7 +141,7 @@ static unsigned long cls_bpf_get(struct tcf_proto *tp, u32 handle) > if (head == NULL) > return 0UL; > > - list_for_each_entry_rcu(prog, &head->plist, link) { > + list_for_each_entry(prog, &head->plist, link) { > if (prog->handle == handle) { > ret = (unsigned long) prog; > break; > @@ -337,7 +337,7 @@ static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg) > struct cls_bpf_head *head = rtnl_dereference(tp->root); > struct cls_bpf_prog *prog; > > - list_for_each_entry_rcu(prog, &head->plist, link) { > + list_for_each_entry(prog, &head->plist, link) { We still need the _rcu here in the walk path. IIRC, this is called from the dump path and we hold no rtnl_lock there. > if (arg->count < arg->skip) > goto skip; > if (arg->fn(tp, (unsigned long) prog, arg) < 0) { > -- > 1.9.3 > > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html