Messages in this thread |  | | | Date | Thu, 4 Jun 2009 12:57:33 -0400 (EDT) | | From | Steven Rostedt <> | | Subject | Re: When does Linux drop UDP packets? |
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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
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