From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nick Pegg Subject: Re: [PATCH] xen-netfront: drop skb when skb->len > 65535 Date: Wed, 06 Mar 2013 12:20:25 -0500 Message-ID: <51377AD9.80304@linode.com> References: <1362155488-24316-1-git-send-email-wei.liu2@citrix.com> <5130E9D602000078000C27CC@nat28.tlf.novell.com> <1362157246.2109.165.camel@zion.uk.xensource.com> <1362192857.4198.9.camel@hastur.hellion.org.uk> <20130302133243.GA6846@zion.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130302133243.GA6846@zion.uk.xensource.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Wei Liu Cc: "ij@2013.bluespice.org" , Ian Campbell , konrad.wilk@oracle.com, "xen-devel@lists.xen.org" , "annie.li@oracle.com" , Jan Beulich List-Id: xen-devel@lists.xenproject.org On 3/2/13 8:32 AM, Wei Liu wrote: > > As Nick (npegg@linode.com) pointed out in his email, he saw size 65538. > I can reproduce this as well by setting vif's mtu to 100 then run iperf. > 100 was just a random number I came up with when I played with > fragmentation. > Wei: How exactly did you set the MTU on the vif and what were your arguments to iperf? I tried this on a test host and was unable to trigger the XSA-39 protection. As for a more graceful punishment, I noticed that xenvif_carrier_off() uses netif_carrier_off() to discard queued packets. Would doing a netif_carrier_off() and then a netif_carrier_on() be sufficient to drop the bad packets and keep netback from spinning? Would blinking the vif's carrier in this way allow the DomU to gracefully resume network traffic? -Nick