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=-5.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 BACEDC433DF for ; Mon, 29 Jun 2020 12:11:35 +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 8645423B23 for ; Mon, 29 Jun 2020 12:11:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ixKimUjt" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8645423B23 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]:36056 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jpsdK-0007Ia-Q3 for qemu-devel@archiver.kernel.org; Mon, 29 Jun 2020 08:11:34 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34124) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jpsbk-0006Q9-9H for qemu-devel@nongnu.org; Mon, 29 Jun 2020 08:09:56 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:36195 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jpsbh-0001WR-6m for qemu-devel@nongnu.org; Mon, 29 Jun 2020 08:09:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593432591; 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: in-reply-to:in-reply-to:references:references; bh=fQnOtbN1Nslzs6MCLRwR9Rwoe28FDZGyTzzZtbcw+/I=; b=ixKimUjtcV1233nPoW7MquKy/E4fCx9aS9pXkxqyNO82eIg7+cz/nY6586nijibfggVU5u l6fUIvYQu5cZR0PN+3I53u4N+FCW39DNYYFPZGg+qDkYwfHvd98EDDnVH6Opo2sC0ihFGW YTToGpvBk8M/Lk1D1slL9QRL+kJup4I= 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-299-Y6GNt4e0OUGLwf_vweoWKg-1; Mon, 29 Jun 2020 08:09:49 -0400 X-MC-Unique: Y6GNt4e0OUGLwf_vweoWKg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8AB87804002; Mon, 29 Jun 2020 12:09:48 +0000 (UTC) Received: from work-vm (ovpn-114-210.ams2.redhat.com [10.36.114.210]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8487C7CAC5; Mon, 29 Jun 2020 12:09:41 +0000 (UTC) Date: Mon, 29 Jun 2020 13:09:39 +0100 From: "Dr. David Alan Gilbert" To: Peter Maydell Subject: Re: [PULL 08/14] migration: add new migration state wait-unplug Message-ID: <20200629120939.GI2908@work-vm> References: <20191029225932.14585-1-mst@redhat.com> <20191029225932.14585-9-mst@redhat.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.14.3 (2020-06-14) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=207.211.31.81; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/29 01:03:51 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action 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: Juan Quintela , "Michael S. Tsirkin" , QEMU Developers , Markus Armbruster , Jens Freimann Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Peter Maydell (peter.maydell@linaro.org) wrote: > On Tue, 29 Oct 2019 at 23:00, Michael S. Tsirkin wrote: > > > > From: Jens Freimann > > > > This patch adds a new migration state called wait-unplug. It is entered > > after the SETUP state if failover devices are present. It will transition > > into ACTIVE once all devices were succesfully unplugged from the guest. > > > > So if a guest doesn't respond or takes long to honor the unplug request > > the user will see the migration state 'wait-unplug'. > > > > In the migration thread we query failover devices if they're are still > > pending the guest unplug. When all are unplugged the migration > > continues. If one device won't unplug migration will stay in wait_unplug > > state. > > > > Signed-off-by: Jens Freimann > > Reviewed-by: Dr. David Alan Gilbert > > Message-Id: <20191029114905.6856-9-jfreimann@redhat.com> > > Reviewed-by: Michael S. Tsirkin > > Signed-off-by: Michael S. Tsirkin > > --- > > Hi; Coverity has just (rather belatedly) noticed a possible > issue in this code (CID 1429995): > > > @@ -3264,6 +3270,19 @@ static void *migration_thread(void *opaque) > > > > qemu_savevm_state_setup(s->to_dst_file); > > > > + if (qemu_savevm_nr_failover_devices()) { > > + migrate_set_state(&s->state, MIGRATION_STATUS_SETUP, > > + MIGRATION_STATUS_WAIT_UNPLUG); > > + > > + while (s->state == MIGRATION_STATUS_WAIT_UNPLUG && > > + qemu_savevm_state_guest_unplug_pending()) { > > + qemu_sem_timedwait(&s->wait_unplug_sem, 250); > > Here we call qemu_sem_timedwait() but ignore the return value, > whereas all the other callsites for that function do something > with the return value. Is the code correct? (This is just a > heuristic Coverity has, and it's wrong a fair amount of the > time, so if it's wrong here too I can just mark it as a > false-positive in the Coverity UI.) Hmm it's OK; that semaphore isn't really used at the moment, so it's pretty much just a sleep. And the loop always calls the qemu_savevm_state_guest_unplug_pending() before it goes around again; so it doesn't care if the return value indicates timeout or not. Dave > thanks > -- PMM > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK