From mboxrd@z Thu Jan 1 00:00:00 1970 From: Veaceslav Falico Subject: Re: [PATCH v4 net-next 01/12] bonding: remove bond->lock from bond_arp_rcv Date: Tue, 18 Feb 2014 07:12:22 +0100 Message-ID: <20140218061222.GA18373@redhat.com> References: <1392648088-21336-1-git-send-email-vfalico@redhat.com> <1392648088-21336-2-git-send-email-vfalico@redhat.com> <5302DB61.4070505@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]:34571 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751222AbaBRGMe (ORCPT ); Tue, 18 Feb 2014 01:12:34 -0500 Content-Disposition: inline In-Reply-To: <5302DB61.4070505@huawei.com> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, Feb 18, 2014 at 12:02:41PM +0800, Ding Tianhong wrote: >On 2014/2/17 22:41, Veaceslav Falico wrote: >> We're always called with rcu_read_lock() held (bond_arp_rcv() is only >> called from bond_handle_frame(), which is rx_handler and always called >> under rcu from __netif_receive_skb_core() ). >> >> The slave active/passive and/or bonding params can change in-flight, however >> we don't really care about that - we only modify the last time packet was >> received, which is harmless. >> >> CC: Jay Vosburgh >> CC: Andy Gospodarek >> Signed-off-by: Veaceslav Falico >> --- >> drivers/net/bonding/bond_main.c | 3 --- >> 1 file changed, 3 deletions(-) >> >> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c >> index 3bce855..3c50bec 100644 >> --- a/drivers/net/bonding/bond_main.c >> +++ b/drivers/net/bonding/bond_main.c >> @@ -2260,8 +2260,6 @@ int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond, >> if (skb->protocol != __cpu_to_be16(ETH_P_ARP)) >> return RX_HANDLER_ANOTHER; >> >> - read_lock(&bond->lock); >> - >> if (!slave_do_arp_validate(bond, slave)) >> goto out_unlock; >> >> @@ -2318,7 +2316,6 @@ int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond, >> bond_validate_arp(bond, slave, tip, sip); >> >> out_unlock: >> - read_unlock(&bond->lock); >> if (arp != (struct arphdr *)skb->data) >> kfree(arp); >> return RX_HANDLER_ANOTHER; >> > >I think it is not enough, you should add rcu_dereference for bond->curr_active_slave, it may be changed during >the recv processing. bond->lock has absolutely nothing to du with bond->curr_active_slave . > >Regards >Ding > >