From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nikolay Aleksandrov Subject: Re: [PATCH net-next v4 5/6] bonding: restructure and add rcu for bond_for_each_slave_next() Date: Fri, 06 Sep 2013 13:59:19 +0200 Message-ID: <5229C397.3080703@redhat.com> References: <5229841E.4020008@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Jay Vosburgh , Andy Gospodarek , "David S. Miller" , Veaceslav Falico , Netdev To: Ding Tianhong Return-path: Received: from mx1.redhat.com ([209.132.183.28]:14903 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751164Ab3IFMC6 (ORCPT ); Fri, 6 Sep 2013 08:02:58 -0400 In-Reply-To: <5229841E.4020008@huawei.com> Sender: netdev-owner@vger.kernel.org List-ID: On 09/06/2013 09:28 AM, Ding Tianhong wrote: > Restructure the bond_for_each_slave(), remove the checking for bond->slave_cnt, > make the new loop be more simple and racy. > > Add bond_for_each_slave_next_rcu() for next patch use. > > Suggested-by: Nikolay Aleksandrov > Suggested-by: Veaceslav Falico > Signed-off-by: Ding Tianhong > Cc: Nikolay Aleksandrov > Cc: Veaceslav Falico > --- > drivers/net/bonding/bond_alb.c | 3 +-- > drivers/net/bonding/bond_main.c | 6 ++---- > drivers/net/bonding/bonding.h | 21 +++++++++++++++++---- > 3 files changed, 20 insertions(+), 10 deletions(-) > > diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c > index 91f179d..c75d383 100644 > --- a/drivers/net/bonding/bond_alb.c > +++ b/drivers/net/bonding/bond_alb.c > @@ -383,7 +383,6 @@ static struct slave *rlb_next_rx_slave(struct bonding *bond) > { > struct alb_bond_info *bond_info = &(BOND_ALB_INFO(bond)); > struct slave *rx_slave, *slave, *start_at; > - int i = 0; > > if (bond_info->next_rx_slave) > start_at = bond_info->next_rx_slave; > @@ -392,7 +391,7 @@ static struct slave *rlb_next_rx_slave(struct bonding *bond) > > rx_slave = NULL; > > - bond_for_each_slave_from(bond, slave, i, start_at) { > + bond_for_each_slave_from(bond, slave, start_at) { > if (SLAVE_IS_OK(slave)) { > if (!rx_slave) { > rx_slave = slave; > diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c > index 39e5b1c..4190389 100644 > --- a/drivers/net/bonding/bond_main.c > +++ b/drivers/net/bonding/bond_main.c > @@ -782,7 +782,6 @@ static struct slave *bond_find_best_slave(struct bonding *bond) > struct slave *new_active, *old_active; > struct slave *bestslave = NULL; > int mintime = bond->params.updelay; > - int i; > > new_active = bond->curr_active_slave; > > @@ -801,7 +800,7 @@ static struct slave *bond_find_best_slave(struct bonding *bond) > /* remember where to stop iterating over the slaves */ > old_active = new_active; > > - bond_for_each_slave_from(bond, new_active, i, old_active) { > + bond_for_each_slave_from(bond, new_active, old_active) { > if (new_active->link == BOND_LINK_UP) { > return new_active; > } else if (new_active->link == BOND_LINK_BACK && > @@ -2756,7 +2755,6 @@ do_failover: > static void bond_ab_arp_probe(struct bonding *bond) > { > struct slave *slave, *next_slave; > - int i; > > read_lock(&bond->curr_slave_lock); > > @@ -2788,7 +2786,7 @@ static void bond_ab_arp_probe(struct bonding *bond) > > /* search for next candidate */ > next_slave = bond_next_slave(bond, bond->current_arp_slave); > - bond_for_each_slave_from(bond, slave, i, next_slave) { > + bond_for_each_slave_from(bond, slave, next_slave) { > if (IS_UP(slave->dev)) { > slave->link = BOND_LINK_BACK; > bond_set_slave_active_flags(slave); > diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h > index 419161d..d80e146 100644 > --- a/drivers/net/bonding/bonding.h > +++ b/drivers/net/bonding/bonding.h > @@ -124,18 +124,31 @@ > (bond_is_first_slave(bond, pos) ? bond_last_slave_rcu(bond) : \ > bond_to_slave_rcu((pos)->list.prev)) > > +/* Check whether the slave is the only one in bond */ > + > /** > * bond_for_each_slave_from - iterate the slaves list from a starting point > * @bond: the bond holding this list. > * @pos: current slave. > - * @cnt: counter for max number of moves > * @start: starting point. > * > * Caller must hold bond->lock > */ > -#define bond_for_each_slave_from(bond, pos, cnt, start) \ > - for (cnt = 0, pos = start; pos && cnt < (bond)->slave_cnt; \ > - cnt++, pos = bond_next_slave(bond, pos)) > +#define bond_for_each_slave_from(bond, pos, start) \ > + for (pos = start; pos; (pos = bond_next_slave(bond, pos)) != start ? \ > + (pos) : (pos = NULL)) > + > +/** > + * bond_for_each_slave_from_rcu - iterate the slaves list from a starting point > + * @bond: the bond holding this list. > + * @pos: current slave. > + * @start: starting point. > + * > + * Caller must hold rcu_read_lock > + */ > +#define bond_for_each_slave_from_rcu(bond, pos, start) \ > + for (pos = start; pos; (pos = bond_next_slave_rcu(bond, pos)) != start ? \ > + (pos) : (pos = NULL)) > The same bug here as before... What happens if start disappears ? - Infinite loop, pos will never be equal to start again. > /** > * bond_for_each_slave - iterate over all slaves >