From mboxrd@z Thu Jan 1 00:00:00 1970 From: Veaceslav Falico Subject: Re: [PATCH v2 net-next 3/3] bonding: fix __get_active_agg() RCU logic Date: Thu, 9 Jan 2014 13:13:28 +0100 Message-ID: <20140109121328.GL5786@redhat.com> References: <1389266425-28365-1-git-send-email-vfalico@redhat.com> <1389266425-28365-4-git-send-email-vfalico@redhat.com> <52CE9049.6020206@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Cc: netdev@vger.kernel.org, Jay Vosburgh , Andy Gospodarek To: Ding Tianhong Return-path: Received: from mx1.redhat.com ([209.132.183.28]:19231 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751201AbaAIMQ3 (ORCPT ); Thu, 9 Jan 2014 07:16:29 -0500 Content-Disposition: inline In-Reply-To: <52CE9049.6020206@huawei.com> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Jan 09, 2014 at 08:04:25PM +0800, Ding Tianhong wrote: >On 2014/1/9 19:20, Veaceslav Falico wrote: >> Currently, the implementation is meaningless - once again, we take the >> slave structure and use it after we've exited RCU critical section. >> >> Fix this by removing the rcu_read_lock() from __get_active_agg(), and >> ensuring that all its callers are holding either RCU or RTNL lock. >> >> Fixes: be79bd048 ("bonding: add RCU for bond_3ad_state_machine_handler()") >> CC: dingtianhong@huawei.com >> CC: Jay Vosburgh >> CC: Andy Gospodarek >> Signed-off-by: Veaceslav Falico >> --- >> >> Notes: >> v1 -> v2: >> Don't use RCU primitives as we can hold RTNL. >> >> drivers/net/bonding/bond_3ad.c | 12 +++++------- >> 1 file changed, 5 insertions(+), 7 deletions(-) >> >> diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c >> index d2782c8..845545b 100644 >> --- a/drivers/net/bonding/bond_3ad.c >> +++ b/drivers/net/bonding/bond_3ad.c >> @@ -674,6 +674,8 @@ static u32 __get_agg_bandwidth(struct aggregator *aggregator) >> /** >> * __get_active_agg - get the current active aggregator >> * @aggregator: the aggregator we're looking at >> + * >> + * Caller must hold either RCU or RTNL lock. >> */ >> static struct aggregator *__get_active_agg(struct aggregator *aggregator) >> { >> @@ -681,13 +683,9 @@ static struct aggregator *__get_active_agg(struct aggregator *aggregator) >> struct list_head *iter; >> struct slave *slave; >> >> - rcu_read_lock(); >> - bond_for_each_slave_rcu(bond, slave, iter) >> - if (SLAVE_AD_INFO(slave).aggregator.is_active) { >> - rcu_read_unlock(); >> + bond_for_each_slave(bond, slave, iter) >> + if (SLAVE_AD_INFO(slave).aggregator.is_active) >> return &(SLAVE_AD_INFO(slave).aggregator); >> - } > >Is the bond_for_each_slave safe in rcu_read_lock()? Yeah, good catch, responded in the second patch. Thanks for the review! > > >> - rcu_read_unlock(); >> >> return NULL; >> } >> @@ -1495,11 +1493,11 @@ static void ad_agg_selection_logic(struct aggregator *agg) >> struct slave *slave; >> struct port *port; >> >> + rcu_read_lock(); >> origin = agg; >> active = __get_active_agg(agg); >> best = (active && agg_device_up(active)) ? active : NULL; >> >> - rcu_read_lock(); >> bond_for_each_slave_rcu(bond, slave, iter) { >> agg = &(SLAVE_AD_INFO(slave).aggregator); >> >> > >