ConversionStatus [FreeBSD WIKI]

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Project/routing status

===== Stage1: conversion =====
There are the following goals:
  * Remove llentry read lock from fast path
  * Use read rmlock for looking up lle data in fast path
  * Remove rtentry lock from all data paths
  * Use read rmlock for looking up routing next-hop data
==== Outstanding reviews ====
  * [[https://reviews.freebsd.org/D5009|D5009]] (IPv4 fast forwarding conversion)
  * [[https://reviews.freebsd.org/D5010|D5010]] (IPv6 forwarding conversion)
  * [[https://reviews.freebsd.org/D4794|D4794]] (Deal with per-ifa output counters)
  * [[https://reviews.freebsd.org/D4962|D4962]] (new LLE lookup functions, no sockaddrs in lltable data path)
  * [[https://reviews.freebsd.org/D4751|D4751]] (move all lltable code to separate files)
==== LLTABLE llentries ====
These changes are mostly done. Most interesting commits:
  * Removal of llentry read lock from fast path: IPv4: <del>[[https://reviews.freebsd.org/D3688|D3688]]</del> [[https://svnweb.freebsd.org/base?view=revision&revision=291853|r291853]], IPv6: <del>[[https://reviews.freebsd.org/D3780|D3780]]</del> [[https://svnweb.freebsd.org/base?view=revision&revision=292155|r292155]]
  * Struct llentry reshaping (addresses instead of sockaddrs, all necessary data in first 64 bytes): [[https://svnweb.freebsd.org/base?view=revision&revision=286624|r286624]]
  * Simplify attachin link-level header in IPv6 & make nd6_resolve() behave like arpresolve(): <del>[[https://reviews.freebsd.org/D1469|D1469]]</del> [[https://svnweb.freebsd.org/base?view=revision&revision=287861|r287861]]
  * Make lltable code use unified per-af callbacks: [[https://svnweb.freebsd.org/base?view=revision&revision=286577|r286577]]
  * Split IPv4/IPv6 lltable init/hash/lookup permitting having different hash functions/hash size for each address family: [[https://svnweb.freebsd.org/base?view=revision&revision=286616|r286616]]
==== LLTABLE rmlock(9) ====
No major depends on performing conversion. Waiting on [[https://reviews.freebsd.org/D4751|D4751]] to <del>timeout</del> be approved and the new LLE lookup functions patch [[https://reviews.freebsd.org/D4962|D4962]].

The only "tricky" thing is that lltable needs to be protected by its own (per-lltable) set of locks, instead of (ab)using AFDATA interface lock.

==== Data path changes ====
The goal was to exclude //struct rtentry// and //struct llentry// from if_output() routines and provide an abstract way of passing arbitrary prepend data. Mostly done.

The last remaining step is to deal with per-ifa output traffic accounting (numbers from //netstat -i//).

Given that it won't be possible to do it fast (no stable ifa pointer can be returned) (at least for IPv4), there is a proposal to remove these counters: [[https://reviews.freebsd.org/D4794|D4794]]

Most interesting commits:
  * Link precomputation API (remove lle cache from packet output routines): <del>[[https://reviews.freebsd.org/D4102|D4102]]</del> [[https://svnweb.freebsd.org/base?view=revision&revision=292978|r292978]]
  * Struct route changes (remove rtentry dereference from packet output routines): [[https://svnweb.freebsd.org/base?view=revision&revision=275196|r275196]] [[https://svnweb.freebsd.org/base?view=revision&revision=293544|r293544]]

==== New routing KPI conversion status ====
All rtalloc*() callers (along with code dereferencing //struct rtentry//) has to be converted to the new KPI. This is the pre-requisite for stage 2 (multipath, other advanced routing features).
This is also the requirement for switching data path read lock to rmlock(9).

Most interesting commits:
  * Introduce fibX KPI: [[https://svnweb.freebsd.org/base?view=revision&revision=291993|291993]]
  * Transparently support current RADIX_MPATH implementation in fibX: [[https://svnweb.freebsd.org/base?view=revision&revision=293657|293657]]
  * Last user changing rte (rt_mtu) w/o proper locking eliminated: <del>[[https://reviews.freebsd.org/D1125|D1125]]</del> [[https://svnweb.freebsd.org/base?view=revision&revision=274611|274611]]

=== Non-output consumers ===
Here we have lightweight routing KPI consumers: simple uRPF (reverse path versification), mtu checks, gateway or source address checks, etc.. Most of them are already converted.

The only **huge** problem is SCTP which caches //struct rtentry// and (which is much worse) actively uses its fields.

^ Done ^ Desc ^ Rev ^ Code ^
| ✓ | Need to return mask (e.g. RIB) | r293914 | sys/netgraph/netflow/netflow.c:         rt = rtalloc1_fib%%((%%struct sockaddr *)&sin, 0, 0, r->fib);\\ sys/netgraph/netflow/netflow.c:         rt = rtalloc1_fib%%((%%struct sockaddr *)&sin, 0, 0, r->fib);\\ sys/netgraph/netflow/netflow.c:         rin6.ro_rt = rtalloc1_fib%%((%%struct sockaddr *)dst, 0, 0, r->fib);\\ sys/netgraph/netflow/netflow.c:         rin6.ro_rt = rtalloc1_fib%%((%%struct sockaddr *)src, 0, 0, r->fib);\\  |
| ✓ | PF: basic is OK | D4763, r293311 | sys/netpfil/pf/pf.c:            in_rtalloc_ign(&ro, 0, rtableid);\\ sys/netpfil/pf/pf.c:            in6_rtalloc_ign(&ro6, 0, rtableid);\\ sys/netpfil/pf/pf.c:            in6_rtalloc_ign(&ro, 0, rtableid);\\ sys/netpfil/pf/pf.c:            in_rtalloc_ign%%((%%struct route *)&ro, 0, rtableid);\\ sys/netpfil/pf/pf.c:            rt = rtalloc1_fib(sintosa(&dst), 0, 0, M_GETFIB(m0%%))%%;\\  |
| ✓ | IPFW: basic is OK | r293626 | sys/netpfil/ipfw/ip_fw_table_algo.c:    return (rtalloc1_fib(s, 0, 0, fib%%))%%;\\  |
| ✓ | TOE: uRPF checks | r293309 | sys/dev/cxgb/ulp/tom/cxgb_cpl_io.c: * rtalloc1, RT_UNLOCK on rt.\\ sys/dev/cxgb/ulp/tom/cxgb_listen.c: rt = rtalloc1%%((%%struct sockaddr *)&nam, 0, 0);\\ sys/dev/cxgb/ulp/iw_cxgb/iw_cxgb_cm.c: rtalloc(&iproute);\\ sys/dev/cxgbe/tom/t4_connect.c: * rtalloc1, RT_UNLOCK on rt.\\ sys/dev/cxgbe/tom/t4_listen.c: rt = rtalloc1(dst, 0, 0);\\ sys/dev/cxgbe/iw_cxgbe/cm.c: rtalloc(&iproute);\\  |
|  | TOE: tod_connect() | https://people.freebsd.org/~melifaro/toe_rt_to_nh.diff (sent to np@) | sys/netinet/tcp_offload.c: rt = rtalloc1(nam, 0, 0);\\  |
| ✓ | ND6: proxyarp... | r293159 | sys/netinet6/nd6_nbr.c:         rtalloc_mpath_fib%%((%%struct route *)&ro, ntohl(taddr6.s6_addr32[3]),\\ sys/netinet6/nd6_nbr.c:         in6_rtalloc(&ro, RT_DEFAULT_FIB);\\  |
| ✓ | ND6: need rib (return prefix) | r293159 | sys/netinet6/nd6.c:                     rt = in6_rtalloc1%%((%%struct sockaddr *)&pr->ndpr_prefix, |
| ✓ | MTU checks, basic is OK, nearly done | r293169 | sys/netinet6/ip6_output.c:                      in6_rtalloc(ro_pmtu, fibnum);\\  |
| ✓ | rtsock RIB, should be easy | r293159 | sys/net/rtsock.c:               rtalloc_ign_fib(&gw_ro, 0, fibnum);\\  |
| ✓ | TCP MTU, _ext is OK | r294712 | sys/netinet/tcp_subr.c:         in_rtalloc_ign(&sro, 0, inc->inc_fibnum);\\ sys/netinet/tcp_subr.c:         in6_rtalloc_ign(&sro6, 0, inc->inc_fibnum);\\  |
|  | pcb: ext is OK |  | sys/netinet/in_pcb.c:           in_rtalloc_ign(&sro, 0, inp->inp_inc.inc_fibnum); |
|  | SCTP: NHOPS | Discussing w/ rrs@/tuexen@ | sys/netinet/sctp_pcb.c: SCTP_RTALLOC%%((%%sctp_route_t *) & net->ro,\\ sys/netinet/sctp_output.c:              SCTP_RTALLOC(ro, vrf_id, inp->fibnum);\\ sys/netinet/sctp_output.c:                                      SCTP_RTALLOC(ro, vrf_id, inp->fibnum);\\ sys/netinet/sctp_output.c:                                      SCTP_RTALLOC(ro, vrf_id, inp->fibnum);\\  |
|  | IB: _ext should be OK |  | sys/ofed/drivers/infiniband/core/addr.c:        rte = rtalloc1(dst_in, 1, 0);\\  |
| ✓ | rib lookup | r293159 | sys/netinet/in.c:       /* XXX rtalloc1_fib should take a const param */\\ sys/netinet/in.c:       rt = rtalloc1_fib(__DECONST(struct sockaddr *, l3addr), 0, 0,__ |
| ✓ | NFS: IPv6 SAS | r294084 | sys/fs/nfsclient/nfs_clport.c:          rt = rtalloc1_fib%%((%%struct sockaddr *)&sad, 0, 0UL,\\ sys/fs/nfsclient/nfs_clport.c:          rt = rtalloc1_fib%%((%%struct sockaddr *)&sad6, 0, 0UL, |
| ✓ | IPF: ext is OK | D4764, r293628 | sys/contrib/ipfilter/netinet/ip_fil_freebsd.c:  in_rtalloc(ro, M_GETFIB(m0%%))%%;\\ sys/contrib/ipfilter/netinet/ip_fil_freebsd.c:  in_rtalloc(&iproute, 0);\\  |
| ✓ | gif: uRPF | r291993 | sys/netinet/in_gif.c:           rt = in_rtalloc1%%((%%struct sockaddr *)&sin, 0,\\ sys/netinet6/in6_gif.c:         rt = in6_rtalloc1%%((%%struct sockaddr *)&sin6, 0, 0UL, |
| ✓ | mcast: ifp lookup | r292015 | sys/netinet/in_mcast.c:         in_rtalloc_ign(&ro, 0, inp ? inp->inp_inc.inc_fibnum : 0); |
| ✓ | lltable: rib rtcheck | r292015 | sys/netinet/if_ether.c:                 rt = in_rtalloc1%%((%%struct sockaddr *)&sin, 0, 0UL, 0);\\ sys/netinet/if_ether.c:                 rt = in_rtalloc1%%((%%struct sockaddr *)&sin, 0, 0UL, 0);\\ sys/netinet6/in6.c:     rt = in6_rtalloc1(__DECONST(struct sockaddr *, l3addr), 0, 0,__ |
| ✓ | mcast: ifp lookup | r292015 | sys/netinet6/in6_mcast.c:       rtalloc_ign_fib%%((%%struct route *)&ro6, 0, |
| ✓ | in6_ hlim | r292015 | sys/netinet6/in6_src.c:         in6_rtalloc(&ro6, in6p->inp_inc.inc_fibnum); |
| ✓ | icmp6 redirect | r292015 | sys/netinet6/icmp6.c:   rt = in6_rtalloc1%%((%%struct sockaddr *)&sin6, 0, 0UL, RT_DEFAULT_FIB); |
| ✓ | ipfw: uRPF | r291993 | sys/netpfil/ipfw/ip_fw2.c:      in_rtalloc_ign(&ro, 0, fib);\\ sys/netpfil/ipfw/ip_fw2.c:      in6_rtalloc_ign(&ro, 0, fib); |
| ✓ | if_stf: uRPF | r292331 | sys/net/if_stf.c:               rt = rtalloc1_fib%%((%%struct sockaddr *)&sin, 0, |

=== Output/Forwarding ===
Here is the code which is actually doing packets output. IPv4 fastforwarding/IPv6 forwarding could be converted (more or less) easily, for other code there are 2 showstoppers:
  * rtentry caching in SCTP/flowtable. The plan is to implement simple nexthops (initally planned for stage 2) and cache nexthop references instead of caching //struct rtentry//.
  * Per-ifa output packet accounting. There is no good/easy way to make this accounting work. [[https://reviews.freebsd.org/D4794|D4794]] is the review with the discussion.

^ Done ^ Desc ^ Rev ^ Code ^
|  | fib6_lookup_nhop | [[https://reviews.freebsd.org/D5010|D5010]] | sys/netinet6/ip6_forward.c:     rin6.ro_rt = in6_rtalloc1%%((%%struct sockaddr *)dst, 0, 0, M_GETFIB(m%%))%%;\\  |
|  | selectroute(). NHOPS + lookup_prepend() |  | sys/netinet6/in6_src.c:                 in6_rtalloc(ron, fibnum); /* multi path case? */\\ sys/netinet6/in6_src.c:                         rtalloc_mpath_fib%%((%%struct route *)ro,\\ sys/netinet6/in6_src.c:                         ro->ro_rt = in6_rtalloc1%%((%%struct sockaddr *) |
|  | NHOPS + lookup_prepend() |  | sys/net/flowtable.c:    rtalloc_mpath_fib(ro, hash, fibnum);\\ sys/net/flowtable.c:    rtalloc_ign_fib(ro, 0, fibnum);\\  |
|  | fib4_lookup_prepend() | [[https://reviews.freebsd.org/D5009|D5009]] | sys/netinet/ip_fastfwd.c:       in_rtalloc_ign(ro, 0, M_GETFIB(m%%))%%;\\  |
|  | ip_forward() -- no so easy: need to pass cached route to ip_output(). NHOPS + lookup_prepend() |  | sys/netinet/ip_input.c: rtalloc_mpath_fib(&ro,\\ sys/netinet/ip_input.c: in_rtalloc_ign(&ro, 0, M_GETFIB(m%%))%%;\\  |
|  | NHOPS + lookup_prepend() |  | sys/netinet/ip_output.c:                        rtalloc_mpath_fib(ro,\\ sys/netinet/ip_output.c:                        in_rtalloc_ign(ro, 0, fibnum);\\  |

==== Routing rmlock(9) ====
Depends on on rtalloc* functions conversion