From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: Netem does not work with loopback Date: Fri, 14 Jul 2006 08:38:47 -0700 Message-ID: <20060714083847.6997a460@localhost.localdomain> References: <44B7AB76.2030700@yahoo.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org Return-path: Received: from smtp.osdl.org ([65.172.181.4]:58271 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1161123AbWGNPi5 (ORCPT ); Fri, 14 Jul 2006 11:38:57 -0400 To: Guillaume Chazarain In-Reply-To: <44B7AB76.2030700@yahoo.fr> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Fri, 14 Jul 2006 16:34:30 +0200 Guillaume Chazarain wrote: > Hello, > > Is it a known problem that the Netem qdisc is very unreliable on the > loopback (unlike on a true NIC)? > > This seems to come from its usage of skb->cb which conflicts with IPCB. > For instance, the field > IPCB(skb)->opt.optlen becomes non-null and memory corruption follows. > > I ``worked around'' this conflict with the following ugly hack: Isn't the skb owned by netem at that point... -- If one would give me six lines written by the hand of the most honest man, I would find something in them to have him hanged. -- Cardinal Richlieu