From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754544Ab0KWOdc (ORCPT ); Tue, 23 Nov 2010 09:33:32 -0500 Received: from mail-ww0-f44.google.com ([74.125.82.44]:56064 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753303Ab0KWOdb (ORCPT ); Tue, 23 Nov 2010 09:33:31 -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=E7K3qA0TQvt1wvZkpDeJnLKrS9DZ/2WTQC8W3H9p2xho8ZbnyNezw5AN94bvmkwg8L vwk5gA9Bw0kuIB0h90c0hx/NleW1GVLgccvCGYSNRoYNhFr+piotFpe18mlbyJhF7Tp5 QsEXxI/ZTGjHW1Ox2+YQ0L+jKKh6I387CcXCU= Subject: Re: addrconf: refcnt with IPV6_PRIVACY enabled From: Eric Dumazet To: Sergey Senozhatsky Cc: "David S. Miller" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Pekka Savola (ipv6)" , Hideaki YOSHIFUJI In-Reply-To: <20101123134003.GB4142@swordfish.minsk.epam.com> References: <20101123134003.GB4142@swordfish.minsk.epam.com> Content-Type: text/plain; charset="UTF-8" Date: Tue, 23 Nov 2010 15:33:23 +0100 Message-ID: <1290522803.3046.11.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 Le mardi 23 novembre 2010 à 15:40 +0200, Sergey Senozhatsky a écrit : > Hello, > > I've sent a patch http://lkml.org/lkml/2010/11/21/124 > "[PATCH] ipv6: fix inet6_dev refcnt with IPV6_PRIVACY enabled" related > to wrong in6_dev refcnt value when IPV6_PRIVACY enabled. > > I've took a second look, and question arised - > Is it actually necessary to in6_dev_hold/in6_dev_put in ipv6_regen_rndid? > In ipv6_regen_rndid we call in6_dev_hold only when mod_timer == 0, > and always in6_dev_put. > > > I've removed check for < 0 and goto from __ipv6_regen_rndid call, since it > always return 0. > > > Please, kindly review V2. > > --- > > net/ipv6/addrconf.c | 10 +++------- > 1 files changed, 3 insertions(+), 7 deletions(-) > > diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c > index 2fc35b3..8187d14 100644 > --- a/net/ipv6/addrconf.c > +++ b/net/ipv6/addrconf.c > @@ -425,7 +425,6 @@ static struct inet6_dev * ipv6_add_dev(struct net_device *dev) > dev->name); > ndev->cnf.use_tempaddr = -1; > } else { > - in6_dev_hold(ndev); > ipv6_regen_rndid((unsigned long) ndev); > } > #endif > @@ -1653,8 +1652,7 @@ static void ipv6_regen_rndid(unsigned long data) > if (idev->dead) > goto out; > > - if (__ipv6_regen_rndid(idev) < 0) > - goto out; > + __ipv6_regen_rndid(idev); > > expires = jiffies + > idev->cnf.temp_prefered_lft * HZ - > @@ -1667,13 +1665,11 @@ static void ipv6_regen_rndid(unsigned long data) > goto out; > } > > - if (!mod_timer(&idev->regen_timer, expires)) > - in6_dev_hold(idev); > - > + mod_timer(&idev->regen_timer, expires); > + > out: > write_unlock_bh(&idev->lock); > rcu_read_unlock_bh(); > - in6_dev_put(idev); > } > > static int __ipv6_try_regen_rndid(struct inet6_dev *idev, struct in6_addr *tmpaddr) { > Sergey, I dont think your patches (V1 or V2) are correct. You leak a refcount if (idev->dead) is true ipv6_regen_rndid() is the timer handler function, it must call in6_dev_put() at the end, unless we rearm the timer. So this code is correct. if (!mod_timer(&idev->regen_timer, expires)) in6_dev_hold(idev); ... in6_dev_put(idev); And we must call in6_dev_hold() before calling the handler, either directly from ipv6_add_dev() [Where your first patch tried to remove the dev_hold() call], or when arming the timer. Are you sure the problem you try to solve is not already solved in commit 88b2a9a3d98a19496d64aadda7158c0ad51cbe7d in net-2.6 tree ? http://git.kernel.org/?p=linux/kernel/git/davem/net-2.6.git;a=commitdiff;h=88b2a9a3d98a19496d64aadda7158c0ad51cbe7d