CARP interfaces and mastership issue

[johan Hendriks]

Op 29-09-11 16:49, Damien Fleuriot schreef:
>>
>>
>> Quick follow-up again.
>>
>> This is the code for sys/netinet/ip_carp.c on FreeBSD 8.2, OpenBSD
>> 3.8, OpenBSD 3.9 in function carp_setrun(struct carp_softc *sc,
>> sa_family_t af)
>>
>>
>>
>> FREEBSD 8.2-PRERELEASE with init + preempt =>  auto MASTER bug
>> Function starts at line 1371.
>> ---
>>          switch (sc->sc_state) {
>>          case INIT:
>>                  if (carp_opts[CARPCTL_PREEMPT]&&  !carp_suppress_preempt) {
>>                          carp_send_ad_locked(sc);
>>                          carp_send_arp(sc);
>> #ifdef INET6
>>                          carp_send_na(sc);
>> #endif /* INET6 */
>>                          CARP_LOG("%s: INIT ->  MASTER (preempting)\n",
>>                              SC2IFP(sc)->if_xname);
>>                          carp_set_state(sc, MASTER);
>>                          carp_setroute(sc, RTM_ADD);
>>                  } else {
>>                          CARP_LOG("%s: INIT ->  BACKUP\n", SC2IFP(sc)->if_xname);
>>                          carp_set_state(sc, BACKUP);
>>                          carp_setroute(sc, RTM_DELETE);
>>                          carp_setrun(sc, 0);
>>                  }
>>                  break;
>> ---
>>
>> OPENBSD 3.8 with init + preempt =>  auto MASTER bug
>> Function starts at line 1293.
>> ---
>>          case INIT:
>>                  if (carp_opts[CARPCTL_PREEMPT]&&  !carp_suppress_preempt) {
>>                          carp_set_state(sc, MASTER);
>>                          carp_setroute(sc, RTM_ADD);
>>                          carp_send_ad(sc);
>>                          carp_send_arp(sc);
>> #ifdef INET6
>>                          carp_send_na(sc);
>> #endif /* INET6 */
>>                  } else {
>>                          carp_set_state(sc, BACKUP);
>>                          carp_setroute(sc, RTM_DELETE);
>>                          carp_setrun(sc, 0);
>>                  }
>>                  break;
>> ---
>>
>>
>>
>> OPENBSD 3.9 with bug fixed
>> Function starts at line 1348.
>> ---
>>          switch (sc->sc_state) {
>>          case INIT:
>>                  carp_set_state(sc, BACKUP);
>>                  carp_setroute(sc, RTM_DELETE);
>>                  carp_setrun(sc, 0);
>>                  break;
>> ---
>>
>>
>> It looks like the root cause is there.
>>
>> I'll rebuild and test, keep you updated.
>
>
>
> Find below my test results with the OpenBSD39 implementation which
> forces an INIT ->  BACKUP transition regardless of preempt.
>
>
>
>
>
>
> # sysctl net.inet.carp.preempt
> net.inet.carp.preempt: 1
>
> # sysctl net.inet.carp.suppress_preempt
> net.inet.carp.suppress_preempt: 0
>
> # ifconfig carp17
> carp17: flags=8<LOOPBACK>  metric 0 mtu 1500
> 	inet 46.182.[snip] netmask 0xffffffff
> 	inet 46.182.[snip] netmask 0xffffffff
> 	inet 46.182.[snip] netmask 0xffffffff
> 	inet 46.182.[snip] netmask 0xffffffff
> 	inet 46.182.[snip] netmask 0xffffffff
> 	carp: INIT vhid 117 advbase 1 advskew 200
>
> # ifconfig carp17 up; ./check_carp17_status.sh
> count: 0	carp: BACKUP vhid 117 advbase 1 advskew 200
> count: 1	carp: BACKUP vhid 117 advbase 1 advskew 200
> count: 2	carp: BACKUP vhid 117 advbase 1 advskew 200
> count: 3	carp: BACKUP vhid 117 advbase 1 advskew 200
> count: 4	carp: BACKUP vhid 117 advbase 1 advskew 200
> count: 5	carp: BACKUP vhid 117 advbase 1 advskew 200
> count: 6	carp: BACKUP vhid 117 advbase 1 advskew 200
> count: 7	carp: BACKUP vhid 117 advbase 1 advskew 200
> count: 8	carp: BACKUP vhid 117 advbase 1 advskew 200
> count: 9	carp: BACKUP vhid 117 advbase 1 advskew 200
> count: 10	carp: BACKUP vhid 117 advbase 1 advskew 200
>
> # dmesg
> carp17: INIT ->  BACKUP
> carp17: link state changed to DOWN
>
>
>
> Looks like it works.
>
> I'm afraid I cannot test actual preemption by shutting down a physical
> interface on the MASTER, because they're actually used in production and
> I've got users logged in to their VPN on pf1.
>
> I see no reason this should break anything however, it only forces the
> CARP interface to assume a BACKUP state right after INIT, as it normally
> should, regardless of preemption.
>
> I'm filling a PR + patch.
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Do you have the PR number for me and the patch, i have the same problem 
and like it to be fixed.

regards
Johan Hendriks