From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753322Ab3JFB3X (ORCPT ); Sat, 5 Oct 2013 21:29:23 -0400 Received: from mail-ea0-f170.google.com ([209.85.215.170]:60832 "EHLO mail-ea0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752673Ab3JFB3V (ORCPT ); Sat, 5 Oct 2013 21:29:21 -0400 Date: Sun, 6 Oct 2013 03:29:08 +0200 From: Alexander Aring To: Alan Ott Cc: Alexander Smirnov , Dmitry Eremin-Solenikov , "David S. Miller" , linux-zigbee-devel@lists.sourceforge.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] 6lowpan: Sync default hardware address of lowpan links to their wpan Message-ID: <20131006012907.GA25606@omega> References: <1381009080-15945-1-git-send-email-alan@signal11.us> <20131006002451.GA22623@omega> <5250B680.2080301@signal11.us> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <5250B680.2080301@signal11.us> 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 Sat, Oct 05, 2013 at 09:01:52PM -0400, Alan Ott wrote: > On 10/05/2013 08:24 PM, Alexander Aring wrote: > >Hi Alan, > > > >On Sat, Oct 05, 2013 at 05:38:00PM -0400, Alan Ott wrote: > >>When a lowpan link to a wpan device is created, set the hardware address > >>of the lowpan link to that of the wpan device. > >> > >>Signed-off-by: Alan Ott > >>--- > >> net/ieee802154/6lowpan.c | 3 +++ > >> 1 file changed, 3 insertions(+) > >> > >>diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c > >>index c85e71e..fb89133 100644 > >>--- a/net/ieee802154/6lowpan.c > >>+++ b/net/ieee802154/6lowpan.c > >>@@ -1386,6 +1386,9 @@ static int lowpan_newlink(struct net *src_net, struct net_device *dev, > >> entry->ldev = dev; > >>+ BUG_ON(IEEE802154_ADDR_LEN != dev->addr_len); > >So if somebody make a: > >"ip link add link $NOT_8BYTE_HWADDR_DEV name $NAME type lowpan" > > > >the kernel creates a BUG_ON? Okay it seems that case is very unusual but > >better is to return a errno so "maybe(I don't know it)" the userspace > >software will generate a error and the whole kernel doesn't crash. > > That line checks the length of the address of the lowpan device, not > the real device the lowpan device is attached to (and on second > look, I don't like the Yoda code; didn't notice that before). > > Further, running: > ip link add link eth0 name lowpan0 type lowpan > > like you suggest, crashes the kernel hard, with or without my patch. > More stuff to fix.... > Okay isn't the dev->addr_len some static value? Maybe we should check than for: if (real_dev->type != ARPHRD_IEEE802154) return -EINVAL; after we set real_dev. It's all ARPHRD_IEEE802154 specific code. > > >>+ memcpy(dev->dev_addr, real_dev->dev_addr, IEEE802154_ADDR_LEN); > >Is there one case where we read the dev->dev_addr? I saw a case when we > >set this [1], but I don't know why we need this. Did you detect some > >problems because this isn't the "real" hw addr? > > > >Other case is I am feeling uneasy when we have two netdev devices with > >the same hw addr. > >[1]https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/net/ieee802154/6lowpan.c?id=refs/tags/v3.12-rc3#n1102 > > In my testing, lowpan devices need a hardware address which is the > same as the wpan, or else stuff like ping doesn't work at all. In > all the examples I've ever seen, the lowpan's hardware address has > been set manually. > Ah ok. > What does your test setup look like that you don't have a hardware > address for your lowpan device? Are you able to ping other Linux > hosts? > I have a little script for setting up a lowpan device. I set the hardware address with: ip link set $LOWPAN_DEV address $EUI64_ADDR after I add the lowpan link. I am able to ping linux and contiki(without fragmentation). - Alex