From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ding Tianhong Subject: Re: [PATCH net-next 5/6] bonding: restructure and simplify bond_for_each_slave_next() Date: Wed, 4 Sep 2013 14:23:51 +0800 Message-ID: <5226D1F7.2000803@huawei.com> References: <52206E4E.6010507@huawei.com> <5225B852.1010601@redhat.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: Nikolay Aleksandrov Return-path: Received: from szxga02-in.huawei.com ([119.145.14.65]:25133 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753556Ab3IDGYi (ORCPT ); Wed, 4 Sep 2013 02:24:38 -0400 In-Reply-To: <5225B852.1010601@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On 2013/9/3 18:22, Nikolay Aleksandrov wrote: > On 08/30/2013 12:05 PM, Ding Tianhong wrote: >> remove the wordy int and add bond_for_each_slave_next_rcu() for future use. >> >> Signed-off-by: Ding Tianhong >> Cc: Nikolay Aleksandrov >> --- >> drivers/net/bonding/bond_alb.c | 3 +-- >> drivers/net/bonding/bond_main.c | 6 ++---- >> drivers/net/bonding/bonding.h | 19 +++++++++++++++---- >> 3 files changed, 18 insertions(+), 10 deletions(-) >> >> diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c >> index 3a5db7b..d266c56 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 4264a76..8c9902a 100644 >> --- a/drivers/net/bonding/bond_main.c >> +++ b/drivers/net/bonding/bond_main.c >> @@ -904,7 +904,6 @@ 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; >> >> @@ -923,7 +922,7 @@ 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 && >> @@ -2891,7 +2890,6 @@ do_failover: >> static void bond_ab_arp_probe(struct bonding *bond) >> { >> struct slave *slave, *next_slave; >> - int i; >> >> read_lock(&bond->curr_slave_lock); >> >> @@ -2923,7 +2921,7 @@ 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 9898493..a3ab47f 100644 >> --- a/drivers/net/bonding/bonding.h >> +++ b/drivers/net/bonding/bonding.h >> @@ -119,14 +119,25 @@ >> * 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 (int cnt = 0, pos = start; pos && cnt < (bond)->slave_cnt; \ >> + cnt++, pos = bond_next_slave(bond, pos)) >> + > Please read below the argument against using the nested cnt definition. > >> +/** >> + * 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 (int cnt = 0, pos = start; pos && cnt < (bond)->slave_cnt; \ >> + cnt++, pos = bond_next_slave_rcu(bond, pos)) >> > I don't think you can rely on slave_cnt in RCU, you may go overboard and pass > twice over the same slave if a slave gets removed, or the opposite. Also this > definition of cnt is troublesome because the name is quite common, I don't know > if it's accepted, but it if it is at least change the name to something like > __cnt or anything that is less likely to be defined. > The cnt argument goes for bond_for_each_slave_from as well. > yes, more details need to think about, I modify the function to this: #define bond_for_each_slave_from(bond, pos, start) \ for (pos = start; (pos == bond_next_slave(bond, start) ? \ &pos->list != &bond->slave_list : \ &pos->list != &start->list); \ pos = bond_next_slave(bond, pos)) I think it is fine here, or I miss something, please tell me, thanks. :) >> /** >> * bond_for_each_slave - iterate over all slaves >> > > -- > 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 > > . >