From nobody Tue Apr 23 17:06:01 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; helo=lists.xenproject.org; Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org; arc=fail (Bad Signature) Return-Path: Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) by mx.zohomail.com with SMTPS id 1619194943942302.4946751033549; Fri, 23 Apr 2021 09:22:23 -0700 (PDT) Received: from list by lists.xenproject.org with outflank-mailman.116540.222427 (Exim 4.92) (envelope-from ) id 1lZyZA-0001Xq-Ea; Fri, 23 Apr 2021 16:22:04 +0000 Received: by outflank-mailman (output) from mailman id 116540.222427; Fri, 23 Apr 2021 16:22:04 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lZyZA-0001Xj-Bb; Fri, 23 Apr 2021 16:22:04 +0000 Received: by outflank-mailman (input) for mailman id 116540; Fri, 23 Apr 2021 16:22:03 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lZyZ8-0001Xa-MG for xen-devel@lists.xenproject.org; Fri, 23 Apr 2021 16:22:03 +0000 Received: from mo6-p00-ob.smtp.rzone.de (unknown [2a01:238:400:100::2]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id fb3849d8-351b-4216-9449-dd2d07feb849; Fri, 23 Apr 2021 16:22:01 +0000 (UTC) Received: from sender by smtp.strato.de (RZmta 47.24.4 DYNA|AUTH) with ESMTPSA id e071aex3NGLr0iW (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256 bits)) (Client did not present a certificate); Fri, 23 Apr 2021 18:21:53 +0200 (CEST) X-Outflank-Mailman: Message body and most headers restored to incoming version X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: fb3849d8-351b-4216-9449-dd2d07feb849 ARC-Seal: i=1; a=rsa-sha256; t=1619194913; cv=none; d=strato.com; s=strato-dkim-0002; b=L83C2vPSZ3kknw7mtyBo69IhnWUctWIw2SOSh8pmu6MRfl/xkV2NmSWY0tB4JZgKB+ cAJQUlS6Uk40tVkbYNblJgOHit+PvKWi18uCFthfu3sMMffbB1xycc5VyCKJk98xsEX0 yk/LaaVoXS/b/uyu0BA2ZGN3QKKBMOHVIssnUKH13KAvIGSAY5uIvZiJTni5CSoTlYSi GQ0O2p1+1wIJVy4Be0o32zi5g0OQ64XCLB/sMVBg7lbgjT2B2DJQV+Oojl971kZbPGS2 qZP2MvBuVwE9/N8H6uHmAyBwuzp9j410GZ58Bhs8HG4ppyMWYEQR/x3VYfWU7/jscvTP VBfQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; t=1619194913; s=strato-dkim-0002; d=strato.com; h=Message-Id:Date:Subject:Cc:To:From:Cc:Date:From:Subject:Sender; bh=NLtbmPUVZOxoFRYRLyOAV6LxYEBpPXUNGQbrk248OYc=; b=XUKWGSWZz9vLthUndicw1m9Lsj4HorAeotBZ/88h7b69fUR6RuzJ21yloDPRb/kM0t BADqDXWA8xrnZxhoKZVOX5CeXBHK4kOn5HNSENq82WsxREdYKsb1MiYm1gbG+LCxVVYs hnuFlqhVF1wvcgaY9NcKev5GUuz8qJbAE/pRZLvYMQ6NW0SvxsIV/jTUtVUEW+pplRDh idlLOHEWurVeYqHR4ZFDZrXKR1plxuYpSJb+sajFJsJLnI/kGOPRXYLKT8yhQl8Ob2/+ HMuom6b6xgdfrgOqubF+Sz9LrsFvmlDhhJij1MsMZ22Rda6ciP7caKnJYBed/qMdbp+H F97Q== ARC-Authentication-Results: i=1; strato.com; dkim=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1619194913; s=strato-dkim-0002; d=aepfle.de; h=Message-Id:Date:Subject:Cc:To:From:Cc:Date:From:Subject:Sender; bh=NLtbmPUVZOxoFRYRLyOAV6LxYEBpPXUNGQbrk248OYc=; b=gxKMCzCXQX2Z69kfm8HYkfGycBbym8njCLzAevKnylVVRN+bMokkXexlTnumceOL94 6MLaEombQLnUg/uMGnkgNRTOLFdIhEU97BBEEU6Pwh2yJIwa75GXdrMCbmylyrWM9Tkw 6sY4Pkue25ExOyD6Uaih54Tat6xdJVbp57mzjeh2sHZqGrED9TS6xI24xjAD9wOJdU6V 0q+AWXsT9KOSC1eJWDFj3GYkZLfC7GmCX7UUU6f4Ffwjqma7/B8DyjV8fgsnxwyKF6mi X/ClzK758uYw5djTLNXsLxxiQbpjC/nzl4SGy68qOmHN0n5/0CV1x3z1BA1qNLXMSJjh bIRg== Authentication-Results: strato.com; dkim=none X-RZG-AUTH: ":P2EQZWCpfu+qG7CngxMFH1J+3q8wa/QXkBR9MXjAuz7MdiQehTvc3RdcLGMdqQ==" X-RZG-CLASS-ID: mo00 From: Olaf Hering To: xen-devel@lists.xenproject.org Cc: Olaf Hering , Ian Jackson , Wei Liu Subject: [PATCH v3] hotplug/Linux: fix starting of xenstored with restarting systemd Date: Fri, 23 Apr 2021 18:21:48 +0200 Message-Id: <20210423162148.15735-1-olaf@aepfle.de> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" A hard to trigger race with another unrelated systemd service and xenstored.service unveiled a bug in the way how xenstored is launched with systemd. launch-xenstore may start either a daemon or a domain. In case a domain is used, systemd-notify was called. If another service triggered a restart of systemd while xenstored.service was executed, systemd may temporary lose track of services with Type=3Dnotify. As a result, xenstored.service would be marked as failed and units that depend on it will not be started. This breaks the enire Xen toolstack. The chain of events is basically: xenstored.service sends the notification to systemd, this is a one-way event. Then systemd may be restarted by the other unit. During this time, xenstored.service is done and exits. Once systemd is done with its restart, it collects the pending notifications and childs. If it does not find the unit which sent the notification it will declare it as failed. A workaround for this scenario is to leave the child processes running for a short time after sending the "READY=3D1" notification. If systemd happens to restart it will still find the unit it launched. Adjust the callers of launch-xenstore to specifiy the init system: Do not fork xenstored with systemd, preserve pid. This wil also avoid the need for a sleep because the process which sent the "READY=3D1" (the previously forked child) is still alive. Remove the --pid-file in the systemd case because the pid of the child is known, and the file had probably little effect anyway due to lack of PidFile=3D and Type=3Dforking in the unit file. Be verbose about xenstored startup only with sysv to avoid interleaved output in systemd journal. Do the same also for domain case, even if is not strictly needed because init-xenstore-domain has no output. The fix for upstream systemd which is supposed to fix it: 575b300b795b6 ("pid1: rework how we dispatch SIGCHLD and other signals") Signed-off-by: Olaf Hering --- v03: - remove run_xenstored function, follow style of shell built-in test functi= on v02: - preserve Type=3Dnotify --- tools/hotplug/Linux/init.d/xencommons.in | 2 +- tools/hotplug/Linux/launch-xenstore.in | 39 +++++++++++++------ .../Linux/systemd/xenstored.service.in | 2 +- 3 files changed, 30 insertions(+), 13 deletions(-) diff --git a/tools/hotplug/Linux/init.d/xencommons.in b/tools/hotplug/Linux= /init.d/xencommons.in index 7fd6903b98..dcb0ce4b73 100644 --- a/tools/hotplug/Linux/init.d/xencommons.in +++ b/tools/hotplug/Linux/init.d/xencommons.in @@ -60,7 +60,7 @@ do_start () { mkdir -m700 -p ${XEN_LOCK_DIR} mkdir -p ${XEN_LOG_DIR} =20 - @XEN_SCRIPT_DIR@/launch-xenstore || exit 1 + @XEN_SCRIPT_DIR@/launch-xenstore 'sysv' || exit 1 =20 echo Setting domain 0 name, domid and JSON config... ${LIBEXEC_BIN}/xen-init-dom0 ${XEN_DOM0_UUID} diff --git a/tools/hotplug/Linux/launch-xenstore.in b/tools/hotplug/Linux/l= aunch-xenstore.in index 991dec8d25..3c30010e3c 100644 --- a/tools/hotplug/Linux/launch-xenstore.in +++ b/tools/hotplug/Linux/launch-xenstore.in @@ -15,6 +15,17 @@ # License along with this library; If not, see . # =20 +initd=3D$1 + +case "$initd" in + sysv) nonl=3D'-n' ;; + systemd) nonl=3D ;; + *) + echo "first argument must be 'sysv' or 'systemd'" + exit 1 + ;; +esac + XENSTORED=3D@XENSTORED@ =20 . @XEN_SCRIPT_DIR@/hotplugpath.sh @@ -44,14 +55,15 @@ timeout_xenstore () { return 0 } =20 -test_xenstore && exit 0 +if test "$initd" =3D 'sysv' ; then + mkdir -p @XEN_RUN_DIR@ + test_xenstore && exit 0 +fi =20 test -f @CONFIG_DIR@/@CONFIG_LEAF_DIR@/xencommons && . @CONFIG_DIR@/@CONFI= G_LEAF_DIR@/xencommons =20 [ "$XENSTORETYPE" =3D "" ] && XENSTORETYPE=3Ddaemon =20 -/bin/mkdir -p @XEN_RUN_DIR@ - [ "$XENSTORETYPE" =3D "daemon" ] && { [ -z "$XENSTORED_ROOTDIR" ] && XENSTORED_ROOTDIR=3D"@XEN_LIB_STORED@" [ -z "$XENSTORED_TRACE" ] || XENSTORED_ARGS=3D"$XENSTORED_ARGS -T @XEN_LO= G_DIR@/xenstored-trace.log" @@ -60,13 +72,15 @@ test -f @CONFIG_DIR@/@CONFIG_LEAF_DIR@/xencommons && . = @CONFIG_DIR@/@CONFIG_LEAF echo "No xenstored found" exit 1 } + [ "$initd" =3D 'sysv' ] && { + echo $nonl Starting $XENSTORED... + $XENSTORED --pid-file @XEN_RUN_DIR@/xenstored.pid $XENSTORED_ARGS + timeout_xenstore $XENSTORED || exit 1 + exit 0 + } =20 - echo -n Starting $XENSTORED... - $XENSTORED --pid-file @XEN_RUN_DIR@/xenstored.pid $XENSTORED_ARGS - - systemd-notify --booted 2>/dev/null || timeout_xenstore $XENSTORED || exi= t 1 - - exit 0 + exec $XENSTORED -N $XENSTORED_ARGS + exit 1 } =20 [ "$XENSTORETYPE" =3D "domain" ] && { @@ -76,9 +90,12 @@ test -f @CONFIG_DIR@/@CONFIG_LEAF_DIR@/xencommons && . @= CONFIG_DIR@/@CONFIG_LEAF XENSTORE_DOMAIN_ARGS=3D"$XENSTORE_DOMAIN_ARGS --memory $XENSTORE_DOMAIN_S= IZE" [ -z "$XENSTORE_MAX_DOMAIN_SIZE" ] || XENSTORE_DOMAIN_ARGS=3D"$XENSTORE_D= OMAIN_ARGS --maxmem $XENSTORE_MAX_DOMAIN_SIZE" =20 - echo -n Starting $XENSTORE_DOMAIN_KERNEL... + echo $nonl Starting $XENSTORE_DOMAIN_KERNEL... ${LIBEXEC_BIN}/init-xenstore-domain $XENSTORE_DOMAIN_ARGS || exit 1 - systemd-notify --ready 2>/dev/null + [ "$initd" =3D 'systemd' ] && { + systemd-notify --ready + sleep 9 + } =20 exit 0 } diff --git a/tools/hotplug/Linux/systemd/xenstored.service.in b/tools/hotpl= ug/Linux/systemd/xenstored.service.in index 80c1d408a5..c226eb3635 100644 --- a/tools/hotplug/Linux/systemd/xenstored.service.in +++ b/tools/hotplug/Linux/systemd/xenstored.service.in @@ -11,7 +11,7 @@ Type=3Dnotify NotifyAccess=3Dall RemainAfterExit=3Dtrue ExecStartPre=3D/bin/grep -q control_d /proc/xen/capabilities -ExecStart=3D@XEN_SCRIPT_DIR@/launch-xenstore +ExecStart=3D@XEN_SCRIPT_DIR@/launch-xenstore 'systemd' =20 [Install] WantedBy=3Dmulti-user.target