Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755046AbZFDQ5k (ORCPT ); Thu, 4 Jun 2009 12:57:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752204AbZFDQ5c (ORCPT ); Thu, 4 Jun 2009 12:57:32 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123]:53427 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751557AbZFDQ5c (ORCPT ); Thu, 4 Jun 2009 12:57:32 -0400 Date: Thu, 4 Jun 2009 12:57:33 -0400 (EDT) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: Philipp Reh cc: LKML Subject: Re: When does Linux drop UDP packets? In-Reply-To: Message-ID: References: <20090604145347.GA27692@miyuki> <20090604155741.GA8999@goodmis.org> <20090604161015.GA17303@miyuki> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1408 Lines: 51 On Thu, 4 Jun 2009, Steven Rostedt wrote: > > Oh, btw, you don't need to strip LKML from replys (or any Cc), unless it > is off topic. LKML is a public forum, and as long as things are on topic, > it is nice to show others the solutions that are found. > > > > > On Thu, 4 Jun 2009, Philipp Reh wrote: > > > > > I'm not really sure it is dropped but tcpdump sees the packet and > > > recvfrom doesn't see it, so I think that the kernel might drop it > > > somewhere when processing the IP stack logic. > > > > Looking at the udp stack, selinux plays a role, and looks like it will > > drop a packet if it is not in the routing table. > > > > Try: > > > > # setenforce 0 > > > > and see if you start seeing packets. > > BTW, I used ftrace to look into this: > > Enable: > > CONFIG_FTRACE > CONFIG_FUNCTION_TRACER > CONFIG_FUNCITON_GRAPH_TRACER > CONFIG_DYNAMIC_FTRACE > > Compile and boot: > > # mount -t debugfs nodev /sys/kernel/debug > # cd /sys/kernel/debug > # echo udp_rcv > set_graph_function > # echo function_graph > current_tracer > # cat trace > Could you do the above and send me (off list) the output of the trace? -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/