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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 26CA8CAC599 for ; Wed, 17 Sep 2025 14:08:05 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uysoc-000328-10; Wed, 17 Sep 2025 10:07:22 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uysob-00031i-0f for qemu-devel@nongnu.org; Wed, 17 Sep 2025 10:07:21 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uysoX-0007QS-U2 for qemu-devel@nongnu.org; Wed, 17 Sep 2025 10:07:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1758118036; 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=NrUeRa6/z4W9yEZEGZU7IYcGdBpM/80QyEhrv+IDJbs=; b=OMtYJriwQoaXnB30QAy4J7k+xt+uVzJ5LOtIZ0Epj76gZ57TG7/MHudH4iMEuux1ZG0Jze Z4qRwkRwh/PaCe69xrDm52MqietukTRz0ccGEAv/OZt//UmJFez04dtBHvZ3oUUaX30fXz a6fnWXVZNmXjGSSJKki6cAiWvXHSG4g= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-290-kqgyzXcaMTO1ab_XVSWNJw-1; Wed, 17 Sep 2025 10:07:11 -0400 X-MC-Unique: kqgyzXcaMTO1ab_XVSWNJw-1 X-Mimecast-MFC-AGG-ID: kqgyzXcaMTO1ab_XVSWNJw_1758118030 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9333818002CC; Wed, 17 Sep 2025 14:07:09 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.9]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id CFF98195608E; Wed, 17 Sep 2025 14:07:08 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 2287F21E6A27; Wed, 17 Sep 2025 16:07:06 +0200 (CEST) From: Markus Armbruster To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Hanna Reitz , Kevin Wolf , =?utf-8?Q?Marc-Andr?= =?utf-8?Q?=C3=A9?= Lureau , Christian Schoenebeck , Richard Henderson , Manos Pitsidianakis , Stefan Weil , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Gerd Hoffmann , Paolo Bonzini , "Dr. David Alan Gilbert" Subject: Re: [PATCH v3 02/20] monitor: initialize global data from a constructor In-Reply-To: <20250910180357.320297-3-berrange@redhat.com> ("Daniel P. =?utf-8?Q?Berrang=C3=A9=22's?= message of "Wed, 10 Sep 2025 19:03:39 +0100") References: <20250910180357.320297-1-berrange@redhat.com> <20250910180357.320297-3-berrange@redhat.com> Date: Wed, 17 Sep 2025 16:07:06 +0200 Message-ID: <871po541h1.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Daniel P. Berrang=C3=A9 writes: > Some monitor functions, most notably, monitor_cur() rely on global > data being initialized by 'monitor_init_globals()'. The latter is > called relatively late in startup. If code triggers error_report() > before monitor_init_globals() is called, QEMU will abort when > accessing the uninitialized monitor mutex. > > The critical monitor global data must be initialized from a > constructor function, to improve the guarantee that it is done > before any possible calls to monitor_cur(). Not only that, but > the constructor must be marked to run before the default > constructor in case any of them trigger error reporting. Is error reporting from constructors a good idea? I feel they're best used for simple initializations only. Do we actually do it? > Note in particular that the RCU constructor will spawn a background > thread so we might even have non-constructor QEMU code running > concurrently with other constructors. Ugh! Arguably Fixes: e69ee454b5f9 (monitor: Make current monitor a per-coroutine proper= ty) I never liked the @coroutine_mon hash table (which is what broke early monitor_cur()), but accepted it for want of better ideas. > Reviewed-by: Richard Henderson > Reviewed-by: Dr. David Alan Gilbert > Signed-off-by: Daniel P. Berrang=C3=A9