From owner-freebsd-bugs@FreeBSD.ORG Tue Oct 11 10:00:21 2011 Return-Path: Delivered-To: freebsd-bugs@hub.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 64E8510656D4 for ; Tue, 11 Oct 2011 10:00:21 +0000 (UTC) (envelope-from gnats@FreeBSD.org) Received: from freefall.freebsd.org (freefall.freebsd.org [IPv6:2001:4f8:fff6::28]) by mx1.freebsd.org (Postfix) with ESMTP id B7DAE8FC2A for ; Tue, 11 Oct 2011 10:00:19 +0000 (UTC) Received: from freefall.freebsd.org (localhost [127.0.0.1]) by freefall.freebsd.org (8.14.4/8.14.4) with ESMTP id p9BA0JAd036838 for ; Tue, 11 Oct 2011 10:00:19 GMT (envelope-from gnats@freefall.freebsd.org) Received: (from gnats@localhost) by freefall.freebsd.org (8.14.4/8.14.4/Submit) id p9BA0J3H036836; Tue, 11 Oct 2011 10:00:19 GMT (envelope-from gnats) Resent-Date: Tue, 11 Oct 2011 10:00:19 GMT Resent-Message-Id: <201110111000.p9BA0J3H036836@freefall.freebsd.org> Resent-From: FreeBSD-gnats-submit@FreeBSD.org (GNATS Filer) Resent-To: freebsd-bugs@FreeBSD.org Resent-Reply-To: FreeBSD-gnats-submit@FreeBSD.org, Damien Fleuriot Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 4894E106567D for ; Tue, 11 Oct 2011 09:50:11 +0000 (UTC) (envelope-from nobody@FreeBSD.org) Received: from red.freebsd.org (red.freebsd.org [IPv6:2001:4f8:fff6::22]) by mx1.freebsd.org (Postfix) with ESMTP id 2A4D28FC0C for ; Tue, 11 Oct 2011 09:50:02 +0000 (UTC) Received: from red.freebsd.org (localhost [127.0.0.1]) by red.freebsd.org (8.14.4/8.14.4) with ESMTP id p9B9o1Te022684 for ; Tue, 11 Oct 2011 09:50:01 GMT (envelope-from nobody@red.freebsd.org) Received: (from nobody@localhost) by red.freebsd.org (8.14.4/8.14.4/Submit) id p9B9o1wP022683; Tue, 11 Oct 2011 09:50:01 GMT (envelope-from nobody) Message-Id: <201110110950.p9B9o1wP022683@red.freebsd.org> Date: Tue, 11 Oct 2011 09:50:01 GMT From: Damien Fleuriot To: freebsd-gnats-submit@FreeBSD.org X-Send-Pr-Version: www-3.1 Cc: Subject: kern/161483: net / [carp] [patch] when preemption is enabled carp interface assumes MASTERship immediately even with higher advbase/advskew X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 11 Oct 2011 10:00:21 -0000 >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: