From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Re: [PATCH net] vlan:make mtu of vlan equal to physical dev Date: Tue, 18 Oct 2011 19:51:42 -0700 Message-ID: <4E9E3B3E.2070902@candelatech.com> References: <4E9E30B8.5030904@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: herbert@gondor.hengli.com.au, "open list:NETWORKING [GENERAL]" To: WeipingPan Return-path: Received: from mail.candelatech.com ([208.74.158.172]:32932 "EHLO ns3.lanforge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752805Ab1JSCvu (ORCPT ); Tue, 18 Oct 2011 22:51:50 -0400 In-Reply-To: <4E9E30B8.5030904@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: On 10/18/2011 07:06 PM, WeipingPan wrote: > Hi, Herbert, > > What do you think of this patch ? > > thanks > Weiping Pan > On 10/08/2011 06:12 PM, Weiping Pan wrote: >> Default mtu of vlan device is the same with mtu of physical device, >> for example 1500, but when change physics mtu to 1600, >> VLAN device's mtu is still 1500. >> Certainly, you can change vlan device's mtu to 1600 manually, >> but I think when you change physics device's mtu, VLAN's mtu should be changed >> automatically instead of by manually. I don't like the idea. It's perfectly valid to have the physical dev with 9000 MTU and have vlans with 1500 MTU. >> Steps to Reproduce: >> 1.vconfig add eth4 3 >> 2.ifconfig eth4 mtu 1600 >> 3.check mtu on eth4.3 >> >> And what's worse is that if you decrease mtu of pyhsical device, >> and when you want to increase it, the mtu of vlan device won't be changed. That *might* be worth fixing, but even so, some NICs might handle that just fine, so my opinion is that this should not change either. Thanks, Ben >> >> Steps to Reproduce: >> 1.vconfig add eth4 3 >> 2.ifconfig eth4 mtu 100 >> 3.ifconfig eth4 mtu 1500 >> 4.the mtu of eth4.3 is still 100 >> >> This bug is reported by Liang Zheng(lzheng@redhat.com). >> >> Signed-off-by: Weiping Pan >> --- >> net/8021q/vlan.c | 3 --- >> 1 files changed, 0 insertions(+), 3 deletions(-) >> >> diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c >> index 8970ba1..f6072b4 100644 >> --- a/net/8021q/vlan.c >> +++ b/net/8021q/vlan.c >> @@ -417,9 +417,6 @@ static int vlan_device_event(struct notifier_block *unused, unsigned long event, >> if (!vlandev) >> continue; >> >> - if (vlandev->mtu<= dev->mtu) >> - continue; >> - >> dev_set_mtu(vlandev, dev->mtu); >> } >> break; > > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Ben Greear Candela Technologies Inc http://www.candelatech.com