From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [Patch] net: kill an RCU warning in inet_fill_link_af() Date: Wed, 01 Dec 2010 17:03:06 +0100 Message-ID: <1291219386.2856.924.camel@edumazet-laptop> References: <1291202063-6239-1-git-send-email-amwang@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-kernel@vger.kernel.org, "David S. Miller" , Alexey Kuznetsov , "Pekka Savola (ipv6)" , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , netdev@vger.kernel.org, Thomas Graf To: Amerigo Wang Return-path: In-Reply-To: <1291202063-6239-1-git-send-email-amwang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Le mercredi 01 d=C3=A9cembre 2010 =C3=A0 19:14 +0800, Amerigo Wang a =C3= =A9crit : > From: WANG Cong >=20 > 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. >=20 > This patch fixes it by replacing __in_dev_get_rcu() with in_dev_get()= =2E Here is a better version, thanks a lot for your report and initial patch. [PATCH net-next-2.6] net: kill an RCU warning in inet_fill_link_af() commits 9f0f7272 (ipv4: AF_INET link address family) and cf7afbfeb8c (rtnl: make link af-specific updates atomic) used incorrect __in_dev_get_rcu() in RTNL protected contexts, triggering PROVE_RCU warnings. Switch to __in_dev_get_rtnl(), wich is more appropriate, since we hold RTNL. Based on a report and initial patch from Amerigo Wang. Reported-by: Amerigo Wang Signed-off-by: Eric Dumazet Cc: Thomas Graf --- net/ipv4/devinet.c | 8 ++++---- 1 files changed, 4 insertions(+), 4 deletions(-) diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c index d9f71ba..3b06770 100644 --- a/net/ipv4/devinet.c +++ b/net/ipv4/devinet.c @@ -1258,7 +1258,7 @@ errout: =20 static size_t inet_get_link_af_size(const struct net_device *dev) { - struct in_device *in_dev =3D __in_dev_get_rcu(dev); + struct in_device *in_dev =3D __in_dev_get_rtnl(dev); =20 if (!in_dev) return 0; @@ -1268,7 +1268,7 @@ static size_t inet_get_link_af_size(const struct = net_device *dev) =20 static int inet_fill_link_af(struct sk_buff *skb, const struct net_dev= ice *dev) { - struct in_device *in_dev =3D __in_dev_get_rcu(dev); + struct in_device *in_dev =3D __in_dev_get_rtnl(dev); struct nlattr *nla; int i; =20 @@ -1295,7 +1295,7 @@ static int inet_validate_link_af(const struct net= _device *dev, struct nlattr *a, *tb[IFLA_INET_MAX+1]; int err, rem; =20 - if (dev && !__in_dev_get_rcu(dev)) + if (dev && !__in_dev_get_rtnl(dev)) return -EAFNOSUPPORT; =20 err =3D nla_parse_nested(tb, IFLA_INET_MAX, nla, inet_af_policy); @@ -1319,7 +1319,7 @@ static int inet_validate_link_af(const struct net= _device *dev, =20 static int inet_set_link_af(struct net_device *dev, const struct nlatt= r *nla) { - struct in_device *in_dev =3D __in_dev_get_rcu(dev); + struct in_device *in_dev =3D __in_dev_get_rtnl(dev); struct nlattr *a, *tb[IFLA_INET_MAX+1]; int rem; =20