New: filter attached to prio qdisc breaks priomap handling of packets it does _not_ match

http://bugzilla.kernel.org/show_bug.cgi?id=8914

Summary: filter attached to prio qdisc breaks priomap handling of
packets it does _not_ match
Product: Networking
Version: 2.5
KernelVersion: 2.6.22.4
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: IPV4
AssignedTo: [email protected]
ReportedBy: [email protected]

Most recent kernel where this bug did not occur: none known to me
Distribution: Debian (sid / unstable / distro development bleeding edge) Hardware Environment: reproduced on i386 and x64-64 machines Software Environment: Debian, iproute 20070313-1
Problem Description:

When I attach a filter to a prio qdisc, the packets that it does _not_ match are not correctly handled (enqueued) according to the priomap anymore, that is the same way than when there is no filter attached to the qdisc. They seem to always fall in the map for best effort traffic.

Problem first noticed on Debian precompiled kernels (2.6.18-4-amd64, based on 2.6.18.7 and 2.6.22-1-686, based on 2.6.22.1), reproduced with self-compiled (with .config copied from Debian precompiled one) straight-from-kernel.org 2.6.22.4 .

Steps to reproduce:

Run attached script (as root), trying to ensure no other traffic happens over the interface: it installs qdiscs on interface ${TIF} (defaults to eth0), pings host ${PHOST} (defaults to master.debian.org - numerical IP hardcoded) with various IP TOS bits set, installs a filter that matches TCP (_not_ ICMP) and does the pings again. You have to ensure that pings to ${PHOST} leaver over ${TIF}. You may have to "modprobe em_cmp" before running the script.

Notice how the first pings (before filters get installed) get in the right queue according to their TOS bits, but after the filter gets installed, they all end up in the "best effort" queue.

The output I get (non-relevant bits snipped out) is:

Running test on interface eth0
by pinging host 70.103.162.29

Pinging with normal service 1 times
Pinging with minimise delay 2 times
Pinging with minimise cost 4 times
qdisc pfifo 22: parent 20:2 limit 1000p
Sent 196 bytes 2 pkt (dropped 0, overlimits 0 requeues 0)
qdisc pfifo 23: parent 20:3 limit 1000p
Sent 98 bytes 1 pkt (dropped 0, overlimits 0 requeues 0)
qdisc pfifo 24: parent 20:4 limit 1000p
Sent 392 bytes 4 pkt (dropped 0, overlimits 0 requeues 0)

Adding a filter that does _not_ match ICMP

Pinging with normal service 8 times
qdisc pfifo 22: parent 20:2 limit 1000p
Sent 196 bytes 2 pkt (dropped 0, overlimits 0 requeues 0)
qdisc pfifo 23: parent 20:3 limit 1000p
Sent 924 bytes 10 pkt (dropped 0, overlimits 0 requeues 0)
qdisc pfifo 24: parent 20:4 limit 1000p
Sent 392 bytes 4 pkt (dropped 0, overlimits 0 requeues 0)

Pinging with minimise delay 16 times
qdisc pfifo 22: parent 20:2 limit 1000p
Sent 196 bytes 2 pkt (dropped 0, overlimits 0 requeues 0)
qdisc pfifo 23: parent 20:3 limit 1000p
Sent 2492 bytes 26 pkt (dropped 0, overlimits 0 requeues 0)
qdisc pfifo 24: parent 20:4 limit 1000p
Sent 392 bytes 4 pkt (dropped 0, overlimits 0 requeues 0)

Pinging with minimise cost 32 times
qdisc pfifo 22: parent 20:2 limit 1000p
Sent 196 bytes 2 pkt (dropped 0, overlimits 0 requeues 0)
qdisc pfifo 23: parent 20:3 limit 1000p
Sent 5628 bytes 58 pkt (dropped 0, overlimits 0 requeues 0)
qdisc pfifo 24: parent 20:4 limit 1000p
Sent 392 bytes 4 pkt (dropped 0, overlimits 0 requeues 0)

The output I would expect is:

(... snip ...)

Adding a filter that does _not_ match ICMP

Pinging with normal service 8 times
qdisc pfifo 22: parent 20:2 limit 1000p
Sent XXX bytes 2 pkt (dropped 0, overlimits 0 requeues 0)
qdisc pfifo 23: parent 20:3 limit 1000p
Sent XXX bytes 10 pkt (dropped 0, overlimits 0 requeues 0)
qdisc pfifo 24: parent 20:4 limit 1000p
Sent XXX bytes 4 pkt (dropped 0, overlimits 0 requeues 0)

Pinging with minimise delay 16 times
qdisc pfifo 22: parent 20:2 limit 1000p
Sent XXX bytes 18 pkt (dropped 0, overlimits 0 requeues 0)
qdisc pfifo 23: parent 20:3 limit 1000p
Sent XXX bytes 10 pkt (dropped 0, overlimits 0 requeues 0)
qdisc pfifo 24: parent 20:4 limit 1000p
Sent XXX bytes 4 pkt (dropped 0, overlimits 0 requeues 0)

Pinging with minimise cost 32 times
qdisc pfifo 22: parent 20:2 limit 1000p
Sent XXX bytes 18 pkt (dropped 0, overlimits 0 requeues 0)
qdisc pfifo 23: parent 20:3 limit 1000p
Sent XXX bytes 10 pkt (dropped 0, overlimits 0 requeues 0)
qdisc pfifo 24: parent 20:4 limit 1000p
Sent XXX bytes 36 pkt (dropped 0, overlimits 0 requeues 0)