RFC RCU'ify the net:sched classifier chains

There appears to be some interest in a few topics around the qdisc layer which could benefit from having the ability to run the filters and actions without holding the qdisc lock.

Recently Cong Wang proposed a patch series to drop the ingress qdisc and asked for comments. This series I think gets closer to that goal.

The ingress qdisc is a simple qdisc which doesn't maintain any actual list of skb's and is primarily a hook to attach filters. Further the only qdisc that can be attached to the ingress qdisc is sch_ingress. The qdisc lock is currently serializing two operations (1) tc_classify which is addressed here and (2) statistics accounting. The second point is not solved here but it could be a matter of making the bstats and qstats per cpu stats.

This is an RFC for now and needs some more work. Some items I know about are (a) an audit of the ematch code paths, (b) resolving the checpatch errors mostly due to moving code around that generates those errors, (c) run smatch, (d) audit u32 code for correctness, (e) do a lot more testing so far only very basic testing has been done. I tried to put some reasonable comments in the commit logs but yes they need more work.

Cong, if its not too much to ask can we use this as a base set of patches for this work? I think its reasonably close to correct as is.

Thanks! John.

---

John Fastabend (12):
net: qdisc: use rcu prefix and silence sparse warnings
net: rcu-ify tcf_proto
net: sched: cls_basic use RCU
net: sched: cls_cgroup use RCU
net: sched: cls_flow use RCU
net: sched: fw use RCU
net: sched: RCU cls_route
net: sched: RCU cls_tcindex
net: sched: make cls_u32 lockless
net: sched: rcu'ify cls_rsvp
net: make cls_bpf rcu safe
net: sched: make tc_action safe to walk under RCU

 include/linux/netdevice.h |   41 +-----
 include/linux/rtnetlink.h |   10 +
 include/net/act_api.h     |    1 
 include/net/pkt_cls.h     |   12 +-
 include/net/sch_generic.h |   34 ++++-
 net/core/dev.c            |   54 +++++++
 net/sched/act_api.c       |   18 +-
 net/sched/cls_api.c       |   44 +++---
 net/sched/cls_basic.c     |   82 ++++++-----
 net/sched/cls_bpf.c       |   79 ++++++-----
 net/sched/cls_cgroup.c    |   65 ++++++---
 net/sched/cls_flow.c      |  145 ++++++++++++--------
 net/sched/cls_fw.c        |  112 +++++++++++----
 net/sched/cls_route.c     |  218 +++++++++++++++++-------------
 net/sched/cls_rsvp.h      |  152 ++++++++++++---------
 net/sched/cls_tcindex.c   |  327 ++++++++++++++++++++++++++-------------------
 net/sched/cls_u32.c       |  258 +++++++++++++++++++++++-------------
 net/sched/sch_api.c       |    6 -
 net/sched/sch_atm.c       |   30 +++-
 net/sched/sch_cbq.c       |   21 ++-
 net/sched/sch_choke.c     |   18 ++
 net/sched/sch_drr.c       |   10 +
 net/sched/sch_dsmark.c    |    8 +
 net/sched/sch_fq_codel.c  |   11 +-
 net/sched/sch_generic.c   |    4 -
 net/sched/sch_hfsc.c      |   17 ++
 net/sched/sch_htb.c       |   23 ++-
 net/sched/sch_ingress.c   |    8 +
 net/sched/sch_mqprio.c    |    4 -
 net/sched/sch_multiq.c    |    8 +
 net/sched/sch_prio.c      |   11 +-
 net/sched/sch_qfq.c       |    9 +
 net/sched/sch_sfb.c       |   15 +-
 net/sched/sch_sfq.c       |   11 +-
 net/sched/sch_teql.c      |    9 +
 35 files changed, 1139 insertions(+), 736 deletions(-)

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