>Number: 161483 >Category: kern >Synopsis: net / [carp] [patch] when preemption is enabled carp interface >assumes MASTERship immediately even with higher advbase/advskew >Confidential: no >Severity: serious >Priority: medium >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Tue Oct 11 10:00:19 UTC 2011 >Closed-Date: >Last-Modified: >Originator: Damien Fleuriot >Release: applies to freebsd 8.x , 9.x >Organization: Hi-Media >Environment: irrelevant, problem still exists in SRC files for FreeBSD 9.0-BETA3 >Description: Refer: my post on -stable http://docs.freebsd.org/cgi/getmsg.cgi?fetch=368260+0+current/freebsd-stable
Refer the same problem on 8.x http://www.freebsd.org/cgi/query-pr.cgi?pr=161123 Under normal operating circumstances, a CARP interface goes through the following states: - INIT : when it's down - BACKUP : immediately upon being brought up, the interface assumes a BACKUP role and starts its timer to know if it should claim mastership. - MASTER : if the delay has expired (advbase * 3) without the interface seeing another master, it assumes mastership. BUG: When preemption is enabled (net.inet.carp.preempt=1) , the CARP interface immediately assumes MASTERship regardless of its advbase and advskew values. This causes CARP switchovers when a firewall from a CARP cluster is rebooted, for example. In our case, this actually led to lost client connections, lost database sessions, developers' daemons crashes because of lost java/db connections... This is a known problem with OpenBSD 3.8 and lower's implementation of CARP. This has been fixed as of OpenBSD 3.9. >How-To-Repeat: Set up 2 boxes with a shared CARP IP. Enable CARP preemption. Bring down your CARP interface on the BACKUP box. Bring it up again. Notice how your interface assumed MASTERship for a short time. Check with dmesg which confirms that your box actually preempted. >Fix: Remove all the code portion from sys/netinet/ip_carp.c that handles the INIT->MASTER transition immediately if preemption is enabled. Patch attached. Patch attached with submission follows: --- sys/netinet/ip_carp.c 2011-09-24 18:10:38.000000000 +0200 +++ sys/netinet/ip_carp.c 2011-10-11 10:11:27.000000000 +0200 @@ -1424,24 +1424,10 @@ switch (sc->sc_state) { case INIT: - if (carp_opts[CARPCTL_PREEMPT] && !carp_suppress_preempt) { - carp_send_ad_locked(sc); -#ifdef INET - carp_send_arp(sc); -#endif -#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); - } + 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; case BACKUP: callout_stop(&sc->sc_ad_tmo); >Release-Note: >Audit-Trail: >Unformatted: _______________________________________________ freebsd-bugs@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-bugs To unsubscribe, send any mail to "freebsd-bugs-unsubscr...@freebsd.org"
