Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753031Ab0LALVY (ORCPT ); Wed, 1 Dec 2010 06:21:24 -0500 Received: from mail-fx0-f46.google.com ([209.85.161.46]:55168 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751905Ab0LALVW (ORCPT ); Wed, 1 Dec 2010 06:21:22 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=RZFUm+wJXMn7ku+HSGKgjAXf9LKqULSFJhLZ6RE0hj/yJ6IUfuWOoXdNMhK9iMn4Lg U7+JufwbjEJuQL+U1hwkVBYeE1XH3WmQZFBomKN8xsOabpP3F+KulGOu8EobCkMLM2ha fgOWXqVYULGIaSmvDh841s5hLn6mEr6CqQhdo= Subject: Re: [Patch] net: kill an RCU warning in inet_fill_link_af() From: Eric Dumazet To: Amerigo Wang Cc: linux-kernel@vger.kernel.org, "David S. Miller" , Alexey Kuznetsov , "Pekka Savola (ipv6)" , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , netdev@vger.kernel.org In-Reply-To: <1291202063-6239-1-git-send-email-amwang@redhat.com> References: <1291202063-6239-1-git-send-email-amwang@redhat.com> Content-Type: text/plain; charset="UTF-8" Date: Wed, 01 Dec 2010 12:21:16 +0100 Message-ID: <1291202476.2856.584.camel@edumazet-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3349 Lines: 120 Le mercredi 01 décembre 2010 à 19:14 +0800, Amerigo Wang a écrit : > From: WANG Cong > > The latest net-next-2.6 triggers an RCU warning during boot, > lockdep complains that in inet_fill_link_af() we call rcu_dereference_check() > without rcu_read_lock() protection. > > This patch fixes it by replacing __in_dev_get_rcu() with in_dev_get(). > > Signed-off-by: WANG Cong > Sorry patch is not the right fix. Please take a look at commit 95ae6b22 We are working hard to remove all the not needed get()/put(), not to add new ones ;) > --- > diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c > index d9f71ba..73baed8 100644 > --- a/net/ipv4/devinet.c > +++ b/net/ipv4/devinet.c > @@ -1258,31 +1258,36 @@ errout: > > static size_t inet_get_link_af_size(const struct net_device *dev) > { > - struct in_device *in_dev = __in_dev_get_rcu(dev); > + struct in_device *in_dev = in_dev_get(dev); > > if (!in_dev) > return 0; > > + in_dev_put(in_dev); > return nla_total_size(IPV4_DEVCONF_MAX * 4); /* IFLA_INET_CONF */ > } > In this function why should we even take a reference, just to check if pointer exists ? If RTNL is held (I believe so), just use __in_dev_get_rtnl() > static int inet_fill_link_af(struct sk_buff *skb, const struct net_device *dev) > { > - struct in_device *in_dev = __in_dev_get_rcu(dev); > + struct in_device *in_dev = in_dev_get(dev); > struct nlattr *nla; > - int i; > + int i, ret = 0; > > if (!in_dev) > return -ENODATA; > > nla = nla_reserve(skb, IFLA_INET_CONF, IPV4_DEVCONF_MAX * 4); > - if (nla == NULL) > - return -EMSGSIZE; > + if (nla == NULL) { > + ret = -EMSGSIZE; > + goto out; > + } > > for (i = 0; i < IPV4_DEVCONF_MAX; i++) > ((u32 *) nla_data(nla))[i] = in_dev->cnf.data[i]; > > - return 0; > +out: > + in_dev_put(in_dev); > + return ret; > } In this function we hold RTNL... Please use __in_dev_get_rtnl() > > static const struct nla_policy inet_af_policy[IFLA_INET_MAX+1] = { > @@ -1293,11 +1298,14 @@ static int inet_validate_link_af(const struct net_device *dev, > const struct nlattr *nla) > { > struct nlattr *a, *tb[IFLA_INET_MAX+1]; > + struct in_device *in_dev = in_dev_get(dev); > int err, rem; > > - if (dev && !__in_dev_get_rcu(dev)) > + if (dev && !in_dev) > return -EAFNOSUPPORT; > > + in_dev_put(in_dev); > + > err = nla_parse_nested(tb, IFLA_INET_MAX, nla, inet_af_policy); > if (err < 0) > return err; > @@ -1319,7 +1327,7 @@ static int inet_validate_link_af(const struct net_device *dev, > > static int inet_set_link_af(struct net_device *dev, const struct nlattr *nla) > { > - struct in_device *in_dev = __in_dev_get_rcu(dev); > + struct in_device *in_dev = in_dev_get(dev); > struct nlattr *a, *tb[IFLA_INET_MAX+1]; > int rem; > > @@ -1334,6 +1342,7 @@ static int inet_set_link_af(struct net_device *dev, const struct nlattr *nla) > ipv4_devconf_set(in_dev, nla_type(a), nla_get_u32(a)); > } > > + in_dev_put(in_dev); > return 0; > } Same here. RTNL is held. Please use __in_dev_get_rtnl() -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/