[PATCH net v3 0/7] net/sched: Fix packet loops in mirred and netem

[Stephen Hemminger <stephen@networkplumber.org>]

This a minor revision of Jamal's series that
fixes packet loops caused by mirred ingress redirects
and netem duplication in stacked qdisc trees.

The core idea is a 2-bit per-skb tc_depth counter that travels with
the packet.  The existing per-CPU mirred nest tracking loses state
when a packet is deferred through the backlog or moves between CPUs
via XPS/RPS.  A per-skb field covers both cases.

Patch 1 adds the tc_depth field in a padding hole in sk_buff.
Patches 2-3 revert the check_netem_in_tree() fix and its tests,
which broke legitimate multi-netem configurations.
Patch 4 uses tc_depth to stop netem duplicate recursion.
Patch 5 uses tc_depth to catch mirred ingress redirect loops.
Patches 6-7 add mirred and netem test cases.

Thanks to Jamal and Victor for fixing this.

There are additional netem bug fixes in the pipeline but those
are held back until this series lands.

Changes in v3:
- Renamed skb->ttl to skb->tc_depth to avoid confusion with IP TTL
- Expanded commit messages
- Split mirred and netem test cases into separate patches
- No code changes from v2

Changes in v2:
- Do not reuse skb->from_ingress (which was moved to skb->cb)

Jamal Hadi Salim (5):
  net: Introduce skb tc depth field to track packet loops
  net/sched: Revert "net/sched: Restrict conditions for adding
    duplicating netems to qdisc tree"
  Revert "selftests/tc-testing: Add tests for restrictions on netem
    duplication"
  net/sched: fix packet loop on netem when duplicate is on
  net/sched: Fix ethx:ingress -> ethy:egress -> ethx:ingress mirred loop

Victor Nogueira (2):
  selftests/tc-testing: Add mirred test cases exercising loops
  selftests/tc-testing: Add netem test case exercising loops

 include/linux/skbuff.h                        |   2 +
 net/sched/act_mirred.c                        |  47 +-
 net/sched/sch_netem.c                         |  47 +-
 .../tc-testing/tc-tests/actions/mirred.json   | 616 +++++++++++++++++-
 .../tc-testing/tc-tests/infra/qdiscs.json     |   5 +-
 .../tc-testing/tc-tests/qdiscs/netem.json     |  96 +--
 6 files changed, 676 insertions(+), 137 deletions(-)

-- 
2.53.0