From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ding Tianhong Subject: Re: [PATCH v2 net-next 3/3] bonding: fix __get_active_agg() RCU logic Date: Thu, 9 Jan 2014 20:04:25 +0800 Message-ID: <52CE9049.6020206@huawei.com> References: <1389266425-28365-1-git-send-email-vfalico@redhat.com> <1389266425-28365-4-git-send-email-vfalico@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Jay Vosburgh , Andy Gospodarek To: Veaceslav Falico , Return-path: Received: from szxga01-in.huawei.com ([119.145.14.64]:18224 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753725AbaAIMEi (ORCPT ); Thu, 9 Jan 2014 07:04:38 -0500 In-Reply-To: <1389266425-28365-4-git-send-email-vfalico@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: 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()? > - 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); > >