Date: Sat, 01 Oct 2011 11:04:07 +0200 From: johan Hendriks <joh.hendriks@gmail.com> To: Damien Fleuriot <ml@my.gd>, freebsd-stable@freebsd.org Subject: Re: CARP interfaces and mastership issue Message-ID: <4E86D787.9050207@gmail.com> In-Reply-To: <4E848592.5050300@my.gd> References: <4E71C059.5060404@hi-media.com> <4E84627B.2050609@my.gd> <CAE63ME71mXfHeV7hxvtkv8q-m0rVQ8-z7aNfF61Cb0poVJCpRQ@mail.gmail.com> <4E848592.5050300@my.gd>
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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
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