From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759317AbcLARw5 (ORCPT ); Thu, 1 Dec 2016 12:52:57 -0500 Received: from mx2.suse.de ([195.135.220.15]:58772 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752021AbcLARw4 (ORCPT ); Thu, 1 Dec 2016 12:52:56 -0500 Date: Thu, 1 Dec 2016 18:52:51 +0100 From: Michal Kubecek To: Ben Hutchings Cc: Jon Maloy , Ying Xue , "David S. Miller" , tipc-discussion@lists.sourceforge.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Qian Zhang Subject: Re: [PATCH net v2] tipc: check minimum bearer MTU Message-ID: <20161201175251.GA18850@unicorn.suse.cz> References: <20161201110205.10749A0F33@unicorn.suse.cz> <1480608678.16599.94.camel@decadent.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1480608678.16599.94.camel@decadent.org.uk> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 01, 2016 at 04:11:18PM +0000, Ben Hutchings wrote: > On Thu, 2016-12-01 at 12:02 +0100, Michal Kubecek wrote: > [...]  > > +/* check if device MTU is sufficient for tipc headers */ > > +static inline bool tipc_check_mtu(struct net_device *dev, unsigned int reserve) > > +{ > > + if (dev->mtu >= TIPC_MIN_BEARER_MTU + reserve) > > + return false; > > + netdev_warn(dev, "MTU too low for tipc bearer\n"); > > + return true; > > +} > [...] > > The comment says "check if ... sufficient" but the return value > indicates the opposite. Could you make these consistent? Good point. I suppose renaming the function to e.g. tipc_mtu_bad() (and rewording the commment accordingly) would also make the code more readable without looking at the definition. I'll wait for other comments and send v3 tomorrow. > Other than that, this looks OK to me. I haven't tested any version as > I don't know how to use TIPC. I checked that the patch doesn't allow enabling a bearer on top of device with insufficient MTU and it does for sufficient (100/128), both in eth and udp case. I also checked that lowering MTU under 100 in eth case disables attached bearer. I didn't run any deeper test like sending an actual traffic but the patch shouldn't affect that. Michal Kubecek