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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 7602BC49EA6 for ; Thu, 24 Jun 2021 17:34:15 +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 274E361075 for ; Thu, 24 Jun 2021 17:34:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 274E361075 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]:48166 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lwTF0-00008m-AB for qemu-devel@archiver.kernel.org; Thu, 24 Jun 2021 13:34:14 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43122) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lwTAb-0001dA-1u for qemu-devel@nongnu.org; Thu, 24 Jun 2021 13:29:41 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:29217) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lwTAR-0004sr-Jh for qemu-devel@nongnu.org; Thu, 24 Jun 2021 13:29:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624555770; 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=W1inlmn3ydqLorGxeeeeRtSw6X1Q41HFsjOSZiAowPY=; b=hDuBuj5U3BDEQ6Ot8df1AW14cjE/wMF0l8W94HQK3ME5D0wl0Owl7G1pVWx9CvgTAXbviY kd3QHDU1JrKBMObHtQT+NPNzgDTBDq2EopMGGZo/to9MuyEd9pWoEcfA8Adyq47drZR80/ 3/S4IF9W1vXRk2YLxWYE7B1mD6AAriI= Received: from mail-il1-f197.google.com (mail-il1-f197.google.com [209.85.166.197]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-313-quDXIzyhPdKaQxgK8PidLA-1; Thu, 24 Jun 2021 13:29:29 -0400 X-MC-Unique: quDXIzyhPdKaQxgK8PidLA-1 Received: by mail-il1-f197.google.com with SMTP id f4-20020a056e020c64b02901ee69c9b838so899597ilj.20 for ; Thu, 24 Jun 2021 10:29:29 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=W1inlmn3ydqLorGxeeeeRtSw6X1Q41HFsjOSZiAowPY=; b=HfVN59sHZvxCtsIoa+fTaiVfNy7ZqnAM+B4l9fRAZ95H5eN26V21IZXMnWKSa7DgeK WrUCTqUNIwYhsXhppUg7R1XSwYqB9IXRqE22V5cra1d+MeSYciEmVWRdPZ0ar/vlcUaB 3zqdDKD4HkZykmW5s3b33L5SM6SeHijlN/8mwHL+c/nW+UeDJ/NTJXnPbgGk4vAX74wI QNemem1DNXiPAEj8MkpuuaEjaVHVN1KS5xo7vf7/51dl+giYhm0FoCNO7OEU90s7RneN F8e7Ccra2B4esfFVmXmgvKVFBckTYYRtnlDb5qMRzznC0Xh4AGkuqufEl35NbRG9jfER ZvKA== X-Gm-Message-State: AOAM5307c7wd9/aTNvH/VAcnZtgc1eW1yFoHIb1ElyljUYpmKnWj5kau b66moG171wWCSPVsWWsT3YvyuVg5KcxxWJzC/UNDGv4J1OLvMSfFB3NOjv3IZzqQbLM4GMdk0yA pxe43OoRbc3jJls0= X-Received: by 2002:a5d:8996:: with SMTP id m22mr4924788iol.6.1624555768712; Thu, 24 Jun 2021 10:29:28 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwKVX5AeFCzs8LP8KdWrTaYmue9P9xl74j4jhXfPI7LHk6dcXKLBp7ethbt3y80ZOnR0+KMPg== X-Received: by 2002:a5d:8996:: with SMTP id m22mr4924770iol.6.1624555768512; Thu, 24 Jun 2021 10:29:28 -0700 (PDT) Received: from t490s (bras-base-toroon474qw-grc-65-184-144-111-238.dsl.bell.ca. [184.144.111.238]) by smtp.gmail.com with ESMTPSA id k3sm1836830ilv.83.2021.06.24.10.29.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Jun 2021 10:29:27 -0700 (PDT) Date: Thu, 24 Jun 2021 13:29:26 -0400 From: Peter Xu To: "Dr. David Alan Gilbert" Subject: Re: [PATCH v1 1/1] migration: Unregister yank if migration setup fails Message-ID: References: <20210622024236.600347-1-leobras@redhat.com> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.362, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no 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: Lukas Straub , Leonardo Bras , qemu-devel@nongnu.org, Juan Quintela Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Jun 24, 2021 at 06:14:39PM +0100, Dr. David Alan Gilbert wrote: > * Leonardo Bras (leobras@redhat.com) wrote: > > Currently, if a qemu instance is started with "-incoming defer" and > > an incorect parameter is passed to "migrate_incoming", it will print the > > expected error and reply with "duplicate yank instance" for any upcoming > > "migrate_incoming" command. > > > > This renders current qemu process unusable, and requires a new qemu > > process to be started before accepting a migration. > > > > This is caused by a yank_register_instance() that happens in > > qemu_start_incoming_migration() but is never reverted if any error > > happens. > > > > Solves this by unregistering the instance if anything goes wrong > > in the function, allowing a new "migrate_incoming" command to be > > accepted. > > > > Fixes: b5eea99ec2f ("migration: Add yank feature", 2021-01-13) > > Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1974366 > > Signed-off-by: Leonardo Bras > > > > --- > > migration/migration.c | 6 +++++- > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > diff --git a/migration/migration.c b/migration/migration.c > > index 4228635d18..ddcf9e1868 100644 > > --- a/migration/migration.c > > +++ b/migration/migration.c > > @@ -474,9 +474,13 @@ static void qemu_start_incoming_migration(const char *uri, Error **errp) > > } else if (strstart(uri, "fd:", &p)) { > > fd_start_incoming_migration(p, errp); > > } else { > > - yank_unregister_instance(MIGRATION_YANK_INSTANCE); > > error_setg(errp, "unknown migration protocol: %s", uri); > > } > > + > > + if (*errp) { > > + yank_unregister_instance(MIGRATION_YANK_INSTANCE); > > + } > > My understanding is that testing *errp isn't allowed, because > it's legal to pass NULL to ignore errors, or legal to pass > &error_abort to mean that any error you do hit will cause the > process to assert; so you need to have something separate you can test. Per my understanding error_abort should be fine, as the value of error_abort is still NULL (in error_setg() we only check against &error_abort as the pointer, and its value seems to be better always be NULL..). But indeed at least we need "errp && *errp", but that won't capture the case when errp==NULL. So I think we may need to define a local error, check here when unregister yank, and do error_propagate() before return.. -- Peter Xu