From nobody Sat May 4 01:44:13 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=pass; 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-Seal: i=1; a=rsa-sha256; t=1614791189; cv=none; d=zohomail.com; s=zohoarc; b=Zdz9TEyGZolIb6XoaXn4NC2VtbPRpHnzOFxjKptTeykV8dKbqLU38pITlSluapJU1/pQMfm116KlyJXAg+T1wutHf3Ir9uTavyHVvcU7a164IKfMjNpzxnmATLfTm6rCkJ685EheRa0joFiDZ8sNrHWzKr4FXoaGefRTw5k4wWg= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1614791189; h=Cc:Date:From:List-Subscribe:List-Post:List-Id:List-Help:List-Unsubscribe:Message-ID:Sender:Subject:To; bh=9yPzP18IxQGu4Rh4EpOr1irO50bzzkHI1YvhVzGWuy8=; b=iLx7huznwM9M9OhHjMS+iWV5gfK1Qp4RJK2HqG2Ud6Uya3iaJaRJY97Df2dbmz/Y2zvQVZUdjnnX4Ep9sSqGko36iUdElKxH1KU2Y+8skg9UEPpq5n51jlJBTjlcMvScw89kDJP7cb3c3G/sdOkx+ZPq4gpRBYThX9I3D08gJF0= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; 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 Return-Path: Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) by mx.zohomail.com with SMTPS id 1614791189523267.25148758583373; Wed, 3 Mar 2021 09:06:29 -0800 (PST) Received: from list by lists.xenproject.org with outflank-mailman.92922.175248 (Exim 4.92) (envelope-from ) id 1lHUwI-00054s-5P; Wed, 03 Mar 2021 17:05:34 +0000 Received: by outflank-mailman (output) from mailman id 92922.175248; Wed, 03 Mar 2021 17:05:34 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lHUwI-00054l-1P; Wed, 03 Mar 2021 17:05:34 +0000 Received: by outflank-mailman (input) for mailman id 92922; Wed, 03 Mar 2021 17:05:32 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lHUwG-00054f-M4 for xen-devel@lists.xenproject.org; Wed, 03 Mar 2021 17:05:32 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lHUwF-0004yA-4M; Wed, 03 Mar 2021 17:05:31 +0000 Received: from 54-240-197-235.amazon.com ([54.240.197.235] helo=ufe34d9ed68d054.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lHUwE-0005q4-Ip; Wed, 03 Mar 2021 17:05:30 +0000 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" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Message-Id:Date:Subject:Cc:To:From; bh=9yPzP18IxQGu4Rh4EpOr1irO50bzzkHI1YvhVzGWuy8=; b=TmaV2u0t8q9F/Mbs3Bj88nGH4o Z1RRUcYfDXy1PM2L4g096zfl4uEjtehqGrl/Yd279G+iwYw4IEkUiTx+Di/xiq09v0c8Cil4LsoPJ mmTZL/S/TVKUxB9E2kflpg2mJm8uc712hhgrDjN5bd8+7QRLKqxi0OnvuppxEHz1N0EQ=; From: Julien Grall To: xen-devel@lists.xenproject.org Cc: raphning@amazon.co.uk, iwj@xenproject.org, Julien Grall , Wei Liu , Juergen Gross , Bjoern Doebel Subject: [PATCH for-4.15] tools/xenstored: liveupdate: Properly check long transaction Date: Wed, 3 Mar 2021 17:05:26 +0000 Message-Id: <20210303170526.15903-1-julien@xen.org> X-Mailer: git-send-email 2.17.1 X-ZohoMail-DKIM: pass (identity @xen.org) Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Julien Grall As XenStored is single-threaded, conn->ta_start_time will always be smaller than now. As we substract the latter from the former, it means a transaction will never be considered long running. Invert the two operands of the substraction in both lu_reject_reason() and lu_check_allowed(). In addition to that, the former also needs to check that conn->ta_start_time is not 0 (i.e the transaction is not active). Take the opportunity to document the return condition of lu_check_allowed(). Fixes: e04e53a5be20 ("tools/xenstore: allow live update only with no transa= ction active") Reported-by: Bjoern Doebel Signed-off-by: Julien Grall Reviewed-by: Juergen Gross --- I am a bit puzzled on how -F is implemented. From my understanding we will force LiveUpdate when one of the following conditions is met: 1) All the active transactions are long running 2) If we didn't manage to LiveUpdate after N sec It is not quite clear why we need the both as 2) would indirectly cover 1). However 2) is probably unsafe as we may reset transactions for "well-behaving" guest. So I am thinking to send a patch to drop 2). Any opinions? This patch is candidate for 4.15. Without it, the long-running transactions are not properly accounted. --- tools/xenstore/xenstored_control.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/tools/xenstore/xenstored_control.c b/tools/xenstore/xenstored_= control.c index d7ad112138b2..8e470f2b2056 100644 --- a/tools/xenstore/xenstored_control.c +++ b/tools/xenstore/xenstored_control.c @@ -459,11 +459,18 @@ static bool lu_check_lu_allowed(void) list_for_each_entry(conn, &connections, list) { if (conn->ta_start_time) { ta_total++; - if (conn->ta_start_time - now >=3D lu_status->timeout) + if (now - conn->ta_start_time >=3D lu_status->timeout) ta_long++; } } =20 + /* + * Allow LiveUpdate if one of the following conditions is met: + * - There is no active transactions + * - All transactions are long running (e.g. they have been + * active for more than lu_status->timeout sec) and the admin as + * requested to force the operation. + */ return ta_total ? (lu_status->force && ta_long =3D=3D ta_total) : true; } =20 @@ -474,11 +481,12 @@ static const char *lu_reject_reason(const void *ctx) time_t now =3D time(NULL); =20 list_for_each_entry(conn, &connections, list) { - if (conn->ta_start_time - now >=3D lu_status->timeout) { + if (conn->ta_start_time && + (now - conn->ta_start_time >=3D lu_status->timeout)) { ret =3D talloc_asprintf(ctx, "%s\nDomain %u: %ld s", ret ? : "Domains with long running transactions:", conn->id, - conn->ta_start_time - now); + now - conn->ta_start_time); } } =20 --=20 2.17.1