From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:41917) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hFz98-0005Qq-MT for qemu-devel@nongnu.org; Mon, 15 Apr 2019 06:47:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hFz97-0005dr-IX for qemu-devel@nongnu.org; Mon, 15 Apr 2019 06:47:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58252) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hFz97-0005di-8u for qemu-devel@nongnu.org; Mon, 15 Apr 2019 06:47:29 -0400 Date: Mon, 15 Apr 2019 11:47:25 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Message-ID: <20190415104725.GI5718@redhat.com> Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20190410092652.22616-1-yury-kotov@yandex-team.ru> <20190411120421.GP3641@redhat.com> <219131554985898@iva6-8a76e93b6298.qloud-c.yandex.net> <20190411123911.GR3641@redhat.com> <226271554987011@iva6-8a76e93b6298.qloud-c.yandex.net> <243191555321803@vla1-1374b6242101.qloud-c.yandex.net> <20190415101101.GF5718@redhat.com> <251681555323421@vla1-1374b6242101.qloud-c.yandex.net> <20190415102520.GG5718@redhat.com> <259551555324396@vla1-1374b6242101.qloud-c.yandex.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <259551555324396@vla1-1374b6242101.qloud-c.yandex.net> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH] migration: Fix handling fd protocol List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Yury Kotov Cc: "Dr. David Alan Gilbert" , "qemu-devel@nongnu.org" , "yc-core@yandex-team.ru" , Juan Quintela On Mon, Apr 15, 2019 at 01:33:21PM +0300, Yury Kotov wrote: > 15.04.2019, 13:25, "Daniel P. Berrang=C3=A9" : > > On Mon, Apr 15, 2019 at 01:17:06PM +0300, Yury Kotov wrote: > >> =C2=A015.04.2019, 13:11, "Daniel P. Berrang=C3=A9" : > >> =C2=A0> On Mon, Apr 15, 2019 at 12:50:08PM +0300, Yury Kotov wrote: > >> =C2=A0>> =C2=A0Hi, > >> =C2=A0>> > >> =C2=A0>> =C2=A0Just to clarify. I see two possible solutions: > >> =C2=A0>> > >> =C2=A0>> =C2=A01) Since the migration code doesn't receive fd, it is= n't responsible for > >> =C2=A0>> =C2=A0closing it. So, it may be better to use migrate_fd_pa= ram for both > >> =C2=A0>> =C2=A0incoming/outgoing and add dupping for migrate_fd_para= m. Thus, clients must > >> =C2=A0>> =C2=A0close the fd themselves. But existing clients will ha= ve a leak. > >> =C2=A0> > >> =C2=A0> We can't break existing clients in this way as they are corr= ectly > >> =C2=A0> using the monitor with its current semantics. > >> =C2=A0> > >> =C2=A0>> =C2=A02) If we don't duplicate fd, then at least we should = remove fd from > >> =C2=A0>> =C2=A0the corresponding list. Therefore, the solution is to= fix qemu_close to find > >> =C2=A0>> =C2=A0the list and remove fd from it. But qemu_close is cur= rently consistent with > >> =C2=A0>> =C2=A0qemu_open (which opens/dups fd), so adding additional= logic might not be > >> =C2=A0>> =C2=A0a very good idea. > >> =C2=A0> > >> =C2=A0> qemu_close is not appropriate place to deal with something s= peciifc > >> =C2=A0> to the montor. > >> =C2=A0> > >> =C2=A0>> =C2=A0I don't see any other solution, but I might miss some= thing. > >> =C2=A0>> =C2=A0What do you think? > >> =C2=A0> > >> =C2=A0> All callers of monitor_get_fd() will close() the FD they get= back. > >> =C2=A0> Thus monitor_get_fd() should remove it from the list when it= returns > >> =C2=A0> it, and we should add API docs to monitor_get_fd() to explai= n this. > >> =C2=A0> > >> =C2=A0Ok, it sounds reasonable. But monitor_get_fd is only about out= going migration. > >> =C2=A0But what about the incoming migration? It doesn't use monitor_= get_fd but just > >> =C2=A0converts input string to int and use it as fd. > > > > The incoming migration expects the FD to be passed into QEMU by the m= gmt > > app when it is exec'ing the QEMU binary. It doesn't interact with the > > monitor at all AFAIR. > > >=20 > Oh, sorry. This use case is not obvious. We used add-fd to pass fd for > migrate-incoming and such way has described problems. That's a bug in your usage of QEMU IMHO, as the incoming code is not designed to use add-fd. Regards, Daniel --=20 |: https://berrange.com -o- https://www.flickr.com/photos/dberran= ge :| |: https://libvirt.org -o- https://fstop138.berrange.c= om :| |: https://entangle-photo.org -o- https://www.instagram.com/dberran= ge :| From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=FROM_EXCESS_BASE64, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 223C4C10F0E for ; Mon, 15 Apr 2019 10:48:24 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EA5D020684 for ; Mon, 15 Apr 2019 10:48:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EA5D020684 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([127.0.0.1]:48126 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hFz9z-0005n7-9v for qemu-devel@archiver.kernel.org; Mon, 15 Apr 2019 06:48:23 -0400 Received: from eggs.gnu.org ([209.51.188.92]:41917) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hFz98-0005Qq-MT for qemu-devel@nongnu.org; Mon, 15 Apr 2019 06:47:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hFz97-0005dr-IX for qemu-devel@nongnu.org; Mon, 15 Apr 2019 06:47:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58252) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hFz97-0005di-8u for qemu-devel@nongnu.org; Mon, 15 Apr 2019 06:47:29 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9349689C3A; Mon, 15 Apr 2019 10:47:28 +0000 (UTC) Received: from redhat.com (unknown [10.42.22.189]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6AB0B6013D; Mon, 15 Apr 2019 10:47:27 +0000 (UTC) Date: Mon, 15 Apr 2019 11:47:25 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Yury Kotov Message-ID: <20190415104725.GI5718@redhat.com> References: <20190410092652.22616-1-yury-kotov@yandex-team.ru> <20190411120421.GP3641@redhat.com> <219131554985898@iva6-8a76e93b6298.qloud-c.yandex.net> <20190411123911.GR3641@redhat.com> <226271554987011@iva6-8a76e93b6298.qloud-c.yandex.net> <243191555321803@vla1-1374b6242101.qloud-c.yandex.net> <20190415101101.GF5718@redhat.com> <251681555323421@vla1-1374b6242101.qloud-c.yandex.net> <20190415102520.GG5718@redhat.com> <259551555324396@vla1-1374b6242101.qloud-c.yandex.net> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline In-Reply-To: <259551555324396@vla1-1374b6242101.qloud-c.yandex.net> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Mon, 15 Apr 2019 10:47:28 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH] migration: Fix handling fd protocol X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Juan Quintela , "Dr. David Alan Gilbert" , "yc-core@yandex-team.ru" , "qemu-devel@nongnu.org" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Message-ID: <20190415104725.64kMwQmLLJArqHONpMbuj9PO9YpsJ3TE6OJ2vQksKTg@z> On Mon, Apr 15, 2019 at 01:33:21PM +0300, Yury Kotov wrote: > 15.04.2019, 13:25, "Daniel P. Berrang=C3=A9" : > > On Mon, Apr 15, 2019 at 01:17:06PM +0300, Yury Kotov wrote: > >> =C2=A015.04.2019, 13:11, "Daniel P. Berrang=C3=A9" : > >> =C2=A0> On Mon, Apr 15, 2019 at 12:50:08PM +0300, Yury Kotov wrote: > >> =C2=A0>> =C2=A0Hi, > >> =C2=A0>> > >> =C2=A0>> =C2=A0Just to clarify. I see two possible solutions: > >> =C2=A0>> > >> =C2=A0>> =C2=A01) Since the migration code doesn't receive fd, it is= n't responsible for > >> =C2=A0>> =C2=A0closing it. So, it may be better to use migrate_fd_pa= ram for both > >> =C2=A0>> =C2=A0incoming/outgoing and add dupping for migrate_fd_para= m. Thus, clients must > >> =C2=A0>> =C2=A0close the fd themselves. But existing clients will ha= ve a leak. > >> =C2=A0> > >> =C2=A0> We can't break existing clients in this way as they are corr= ectly > >> =C2=A0> using the monitor with its current semantics. > >> =C2=A0> > >> =C2=A0>> =C2=A02) If we don't duplicate fd, then at least we should = remove fd from > >> =C2=A0>> =C2=A0the corresponding list. Therefore, the solution is to= fix qemu_close to find > >> =C2=A0>> =C2=A0the list and remove fd from it. But qemu_close is cur= rently consistent with > >> =C2=A0>> =C2=A0qemu_open (which opens/dups fd), so adding additional= logic might not be > >> =C2=A0>> =C2=A0a very good idea. > >> =C2=A0> > >> =C2=A0> qemu_close is not appropriate place to deal with something s= peciifc > >> =C2=A0> to the montor. > >> =C2=A0> > >> =C2=A0>> =C2=A0I don't see any other solution, but I might miss some= thing. > >> =C2=A0>> =C2=A0What do you think? > >> =C2=A0> > >> =C2=A0> All callers of monitor_get_fd() will close() the FD they get= back. > >> =C2=A0> Thus monitor_get_fd() should remove it from the list when it= returns > >> =C2=A0> it, and we should add API docs to monitor_get_fd() to explai= n this. > >> =C2=A0> > >> =C2=A0Ok, it sounds reasonable. But monitor_get_fd is only about out= going migration. > >> =C2=A0But what about the incoming migration? It doesn't use monitor_= get_fd but just > >> =C2=A0converts input string to int and use it as fd. > > > > The incoming migration expects the FD to be passed into QEMU by the m= gmt > > app when it is exec'ing the QEMU binary. It doesn't interact with the > > monitor at all AFAIR. > > >=20 > Oh, sorry. This use case is not obvious. We used add-fd to pass fd for > migrate-incoming and such way has described problems. That's a bug in your usage of QEMU IMHO, as the incoming code is not designed to use add-fd. Regards, Daniel --=20 |: https://berrange.com -o- https://www.flickr.com/photos/dberran= ge :| |: https://libvirt.org -o- https://fstop138.berrange.c= om :| |: https://entangle-photo.org -o- https://www.instagram.com/dberran= ge :|