From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexei Starovoitov Subject: Re: [PATCH net-next 0/3] net: introduce IFF_PROTO_DOWN flag. Date: Fri, 20 Mar 2015 09:13:56 -0700 Message-ID: References: <1426864318-25132-1-git-send-email-anuradhak@cumulusnetworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: "David S. Miller" , "netdev@vger.kernel.org" , Roopa Prabhu , Andy Gospodarek , wkok@cumulusnetworks.com To: anuradhak@cumulusnetworks.com Return-path: Received: from mail-qg0-f54.google.com ([209.85.192.54]:32940 "EHLO mail-qg0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750777AbbCTQOS convert rfc822-to-8bit (ORCPT ); Fri, 20 Mar 2015 12:14:18 -0400 Received: by qgfa8 with SMTP id a8so96976671qgf.0 for ; Fri, 20 Mar 2015 09:14:17 -0700 (PDT) In-Reply-To: <1426864318-25132-1-git-send-email-anuradhak@cumulusnetworks.com> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, Mar 20, 2015 at 8:11 AM, wrote= : > From: Anuradha Karuppiah > > Applications can detect errors in the network that would require > disabling the device independent of the admin state. In the presence = of > these errors traffic could be black holed or looped resulting in a > network meltdown. Clearing the IFF_UP flag for error disabling the > device can be problematic because - > > 1. The administrator cannot distinguish between a user space daemon=E2= =80=99s > error-disable and a regular device disable. > 2. Applications can monitor the error state and enable the device onc= e > the error is removed. If IFF_UP is used for this purpose the applicat= ion > may end up enabling a device that the administrator has intentionally > disabled for other reasons. This could result in network changes not > expected by the admin. > Both reasons look like workaround for user space issues. Just keep this fake-down state in userspace. What's the point pushing it to kernel? looking at 3rd patch: + * @IF_LINK_PROTO_DOWN_MLAG: proto_down by a multi-chassis LAG applica= tion. + * @IF_LINK_PROTO_DOWN_STP: proto_down by an STP application. so there will be new flag for every application that cannot deal with normal down?