From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarod Wilson Subject: Re: Minimum MTU Mess Date: Wed, 7 Sep 2016 19:44:51 -0400 Message-ID: <20160907234451.GZ33916@redhat.com> References: <20160902170742.GA17677@redhat.com> <20160906.165529.496766310703537877.davem@davemloft.net> <20160907195356.GX33916@redhat.com> <20160907133535.2cfac7bc@xeon-e3> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Miller , netdev@vger.kernel.org To: Stephen Hemminger Return-path: Received: from mail-yw0-f179.google.com ([209.85.161.179]:35522 "EHLO mail-yw0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751824AbcIGXoz (ORCPT ); Wed, 7 Sep 2016 19:44:55 -0400 Received: by mail-yw0-f179.google.com with SMTP id j1so18830975ywb.2 for ; Wed, 07 Sep 2016 16:44:54 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20160907133535.2cfac7bc@xeon-e3> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Sep 07, 2016 at 01:35:35PM -0700, Stephen Hemminger wrote: > On Wed, 7 Sep 2016 15:53:56 -0400 > Jarod Wilson wrote: > > > --- a/net/core/dev.c > > +++ b/net/core/dev.c > > @@ -6466,9 +6466,17 @@ int dev_set_mtu(struct net_device *dev, int new_mtu) > > if (new_mtu == dev->mtu) > > return 0; > > > > - /* MTU must be positive. */ > > - if (new_mtu < 0) > > + if (new_mtu < dev->min_mtu) { > > + netdev_err(dev, "Invalid MTU %d requested, hw min %d\n", > > + new_mtu, dev->min_mtu); > > return -EINVAL; > > + } > > + > > + if (new_mtu > dev->max_mtu) { > > + netdev_err(dev, "Invalid MTU %d requested, hw max %d\n", > > + new_mtu, dev->min_mtu); > > + return -EINVAL; > > + } > > > > Maybe don't log something that can be triggered from a user program. > Or at least rate limit it. Yeah, I was a little bit on the fence on whether to log anything, make it netdev_err, netdev_dbg, or what. Quite a few drivers have a netdev_err for failed MTU changes, while others also have netdev_info spew for successful MTU changes. Maybe a rate-limited netdev_err is the way to go here. -- Jarod Wilson jarod@redhat.com