From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48313) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fPxPl-0007ip-Dg for qemu-devel@nongnu.org; Mon, 04 Jun 2018 17:53:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fPxPi-0004wG-CA for qemu-devel@nongnu.org; Mon, 04 Jun 2018 17:53:21 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:44816 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fPxPi-0004w7-7f for qemu-devel@nongnu.org; Mon, 04 Jun 2018 17:53:18 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 607CC406DE3D for ; Mon, 4 Jun 2018 21:53:17 +0000 (UTC) Date: Mon, 4 Jun 2018 23:53:15 +0200 From: Igor Mammedov Message-ID: <20180604235315.0447d13f@redhat.com> In-Reply-To: <20180604120345.12955-3-berrange@redhat.com> References: <20180604120345.12955-1-berrange@redhat.com> <20180604120345.12955-3-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v2 2/2] vl: fix use of --daemonize with --preconfig List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. =?UTF-8?B?QmVycmFuZ8Op?=" Cc: qemu-devel@nongnu.org, Michal Privoznik , Markus Armbruster , Max Reitz , Paolo Bonzini On Mon, 4 Jun 2018 13:03:45 +0100 Daniel P. Berrang=C3=A9 wrote: > When using --daemonize, the initial lead process will fork a child and > then wait to be notified that setup is complete via a pipe, before it > exits. When using --preconfig there is an extra call to main_loop() > before the notification is done from os_setup_post(). Thus the parent > process won't exit until the mgmt application connects to the monitor > and tells QEMU to leave the RUN_STATE_PRECONFIG. The mgmt application > won't connect to the monitor until daemonizing has completed though. >=20 > This is a chicken and egg problem, leading to deadlock at startup. >=20 > The only viable way to fix this is to call os_setup_post() before > the early main_loop() call when in RUN_STATE_PRECONFIG. This has the > downside that any errors from this point onwards won't be handled > well by the mgmt application, because it will think QEMU has started > successfully, so not be expecting an abrupt exit. The only way to > deal with that is to move as much user input validation as possible > to before the main_loop() call. This is left as an exercise for > future interested developers. >=20 > Signed-off-by: Daniel P. Berrang=C3=A9 [...] How about combining ideas from yours and Michal's patches? It should fix broken iotests/libvirt sync point and we can think about NONE runstate idea at without rushing it. If it looks acceptable, I'll post proper patches + test case for it after some testing (to ensure that iotests Max pointed out are working as expected) diff --git a/vl.c b/vl.c index c4fe255..a2062d6 100644 --- a/vl.c +++ b/vl.c @@ -1953,10 +1953,15 @@ static bool main_loop_should_exit(void) =20 static void main_loop(void) { + static bool os_setup_post_done =3D false; #ifdef CONFIG_PROFILER int64_t ti; #endif - do { + if (!os_setup_post_done) { + os_setup_post(); + os_setup_post_done =3D true; + } + while (!main_loop_should_exit()) { #ifdef CONFIG_PROFILER ti =3D profile_getclock(); #endif @@ -1964,7 +1969,7 @@ static void main_loop(void) #ifdef CONFIG_PROFILER dev_time +=3D profile_getclock() - ti; #endif - } while (!main_loop_should_exit()); + } } =20 static void version(void)