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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 742E7C43603 for ; Wed, 18 Dec 2019 16:54:04 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3D4612176D for ; Wed, 18 Dec 2019 16:54:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="IHCFhsI/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3D4612176D 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 ([::1]:57298 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ihcaJ-0004RD-3p for qemu-devel@archiver.kernel.org; Wed, 18 Dec 2019 11:54:03 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:39961) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ihcZD-0003QW-6d for qemu-devel@nongnu.org; Wed, 18 Dec 2019 11:52:56 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ihcZA-00021U-3C for qemu-devel@nongnu.org; Wed, 18 Dec 2019 11:52:53 -0500 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:25787 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ihcZ8-0001yV-Ig for qemu-devel@nongnu.org; Wed, 18 Dec 2019 11:52:51 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1576687968; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+9vpbT6YvgH1acpwTohzA5ljDFqLy76z/AM4YF9pzGM=; b=IHCFhsI/+s8Bz+Wk2BXAkMmTwA0PztBFlNCPiBuQHya0qagyEqiVNh7I7bYSwNAMvQyBNT K/C8CHg/niVNscqToQZDCqlL1e2MHySICNIHpe6VP579/91MYi9jilNkvWY6CetzRkt8lD j/URFKcCjVOaEhtVeTrKrrQeODTwxIo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-384--TgdsB7WO3Ohnp86_oBGTQ-1; Wed, 18 Dec 2019 11:52:47 -0500 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id 49D3A18C35C4 for ; Wed, 18 Dec 2019 16:52:46 +0000 (UTC) Received: from work-vm (unknown [10.36.118.19]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4A71260BC7; Wed, 18 Dec 2019 16:52:45 +0000 (UTC) Date: Wed, 18 Dec 2019 16:52:42 +0000 From: "Dr. David Alan Gilbert" To: Laurent Vivier , quintela@redhat.com Subject: Re: [PATCH] runstate: ignore finishmigrate -> prelaunch transition Message-ID: <20191218165242.GL3707@work-vm> References: <20191129115132.285988-1-lvivier@redhat.com> <20191206195230.GJ2878@work-vm> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.13.0 (2019-11-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: -TgdsB7WO3Ohnp86_oBGTQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.61 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paolo Bonzini , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Laurent Vivier (lvivier@redhat.com) wrote: > Ping? Juan says he's doing a migration pull soon - this seems like a good one for it. Dave > Thanks, > Laurent >=20 > On 12/12/2019 20:40, Laurent Vivier wrote: > > On 06/12/2019 20:52, Dr. David Alan Gilbert wrote: > >> * Laurent Vivier (lvivier@redhat.com) wrote: > >>> Commit 1bd71dce4bf2 tries to prevent a finishmigrate -> prelaunch > >>> transition by exiting at the beginning of the main_loop_should_exit() > >>> function if the state is already finishmigrate. > >>> > >>> As the finishmigrate state is set in the migration thread it can > >>> happen concurrently to the function. The migration thread and the > >>> function are normally protected by the iothread mutex and thus the > >>> state should no evolve between the start of the function and its end. > >>> > >>> Unfortunately during the function life the lock is released by > >>> pause_all_vcpus() just before the point we need to be sure we are > >>> not in finishmigrate state and if the migration thread is waiting > >>> for the lock it will take the opportunity to change the state > >>> to finishmigrate. > >> > >> Ewww. > >> I hate those short wakeups for pause_all_vcpus; I'm sure there are loa= ds > >> more corners that break. > >> > >> Still, I _think_ this is an improvement, so: > >> > >> Reviewed-by: Dr. David Alan Gilbert > >> > >=20 > > Who volunteers to take this in his queue? > >=20 > > Thanks, > > Laurent > >=20 > >=20 >=20 -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK