From mboxrd@z Thu Jan 1 00:00:00 1970 From: Debabrata Banerjee Subject: Re: [PATCH 1/2] ipv6: do not hold route table lock when send ndisc probe Date: Fri, 17 Aug 2012 14:54:26 -0400 Message-ID: References: <1345187499-16929-1-git-send-email-amwang@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: netdev@vger.kernel.org, "Banerjee, Debabrata" , "David S. Miller" , Hideaki YOSHIFUJI , Patrick McHardy To: Cong Wang Return-path: Received: from mail-ob0-f174.google.com ([209.85.214.174]:61838 "EHLO mail-ob0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932540Ab2HQSy0 (ORCPT ); Fri, 17 Aug 2012 14:54:26 -0400 Received: by obbuo13 with SMTP id uo13so5647957obb.19 for ; Fri, 17 Aug 2012 11:54:26 -0700 (PDT) In-Reply-To: <1345187499-16929-1-git-send-email-amwang@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: Well it get rids of the deadlock for sure, but I am not sure it doesn't break something else, one would have to know all of this code much better to tell. You'll notice read_unlock_bh(&table->tb6_lock) for the first lock in ip6_pol_route() has more in the critical section after the rt6_select() call, especially that rather scary BACKTRACK() macro. -Debabrata On Fri, Aug 17, 2012 at 3:11 AM, Cong Wang wrote: > In rt6_probe(), we call ndisc_send_ns() with root->rwlock, > but this is not necessary, so we can drop it before calling > ndisc_send_ns(). > > This could probably fix the deadlock reported by Debabrata: > https://lkml.org/lkml/2012/8/16/432 > > Reported-by: "Banerjee, Debabrata" > Cc: "Banerjee, Debabrata" > Cc: "David S. Miller" > Cc: Hideaki YOSHIFUJI > Cc: Patrick McHardy > Signed-off-by: Cong Wang > --- > net/ipv6/route.c | 7 ++++++- > 1 files changed, 6 insertions(+), 1 deletions(-) > > diff --git a/net/ipv6/route.c b/net/ipv6/route.c > index 0ddf2d1..7a36df2 100644 > --- a/net/ipv6/route.c > +++ b/net/ipv6/route.c > @@ -460,13 +460,18 @@ static void rt6_probe(struct rt6_info *rt) > time_after(jiffies, neigh->updated + rt->rt6i_idev->cnf.rtr_probe_interval)) { > struct in6_addr mcaddr; > struct in6_addr *target; > + struct net_device *dev = rt->dst.dev; > + struct fib6_table *table = rt->rt6i_table; > > neigh->updated = jiffies; > read_unlock_bh(&neigh->lock); > + read_unlock_bh(&table->tb6_lock); > > target = (struct in6_addr *)&neigh->primary_key; > addrconf_addr_solict_mult(target, &mcaddr); > - ndisc_send_ns(rt->dst.dev, NULL, target, &mcaddr, NULL); > + ndisc_send_ns(dev, NULL, target, &mcaddr, NULL); > + > + read_lock_bh(&table->tb6_lock); > } else { > read_unlock_bh(&neigh->lock); > } > -- > 1.7.7.6 > > -- > 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