From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Williams Subject: Re: [PATCH net RESEND] bonding: don't change to 802.3ad mode while ARP monitoring is running Date: Mon, 18 Nov 2013 16:50:32 -0600 Message-ID: <1384815032.4774.55.camel@dcbw.foobar.com> References: <528710F7.7050207@huawei.com> <1384796682.4774.26.camel@dcbw.foobar.com> <20131118.154838.776189725378131169.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: dingtianhong@huawei.com, fubar@us.ibm.com, andy@greyhouse.net, nikolay@redhat.com, vfalico@redhat.com, netdev@vger.kernel.org To: David Miller Return-path: Received: from mx1.redhat.com ([209.132.183.28]:6233 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751722Ab3KRWub (ORCPT ); Mon, 18 Nov 2013 17:50:31 -0500 In-Reply-To: <20131118.154838.776189725378131169.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 2013-11-18 at 15:48 -0500, David Miller wrote: > From: Dan Williams > Date: Mon, 18 Nov 2013 11:44:42 -0600 > > > On Sat, 2013-11-16 at 14:30 +0800, Ding Tianhong wrote: > >> Because the ARP monitoring is not support for 802.3ad, but I still > >> could change the mode to 802.3ad from ab mode while ARP monitoring > >> is running, it is incorrect. > >> > >> So add a check for 802.3ad in bonding_store_mode to fix the problem, > >> and make a new macro BOND_NO_USES_ARP() to simplify the code. > > > > Instead of failing, couldn't the code stop ARP monitoring and allow the > > mode change? This is similar to setting miimon, which disables ARP > > monitoring, or setting ARP monitoring, which disables miimon. > > > > if (new_value && bond->params.arp_interval) { > > pr_info("%s: MII monitoring cannot be used with ARP monitoring. Disabling ARP monitoring...\n", > > bond->dev->name); > > bond->params.arp_interval = 0; > > if (bond->params.arp_validate) > > bond->params.arp_validate = BOND_ARP_VALIDATE_NONE; > > } > > > > Bond mode is the most important bond option, so it seems like it should > > override any of the other sub-options. I know the code doesn't do this > > now, but maybe instead of the patch you propose, it would be nicer to > > allow the mode change instead? > > I agree with Dan, if other mode changes behave this way (by dropping the > incompatible feature) we should make 802.3ad do so as well at the very > least for consistency. Currently ALB and TLB modes will fail if arp_interval > 0, so Ding's patch is technically correct. Instead, I'm proposing that 'mode' trumps all, and if the user changes the mode, conflicting values should be cleared or reset. Otherwise userspace has to duplicate a lot of kernel logic/validation. For example: 1) set mode to ROUNDROBIN 2) set arp_interval 3) set mode to ALB or TLB 4) FAIL - incompatible with arp_interval 5) ok, set arp_interval to zero 6) set mode to ALB or TLB 7) SUCCESS Wouldn't it be nice if the kernel handled clearing arp_interval for us, since it knows that arp_interval is incompatible with ALB/TLB... Could be done separately. I have no objection to Ding's patch other than "life could be even better". Dan