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 14343C54F30 for ; Tue, 27 May 2025 17:21:30 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uJxzB-0008QI-Ia; Tue, 27 May 2025 13:21:12 -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 1uJxyw-0008NW-TV for qemu-devel@nongnu.org; Tue, 27 May 2025 13:20:54 -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 1uJxyv-0000kx-HQ for qemu-devel@nongnu.org; Tue, 27 May 2025 13:20:54 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1748366452; 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=/nnZyN6GhGbkhhomdoptaiFR97XzYCUJHgmhoRi89AA=; b=Am6TN3oWiNpp1HmhpgX18u2RGBJTNvoaJTyaG1/evtMwdibKtKFlSXAQHIzIkmcp0cIQcF 4UYpCmyNivS733lxRnbhfJB7/kXluZ7srpYhepOo0WFTelzrCOumihgu5qpsA61iWifaKn l8lipAYXxeBzkf43/wTKUGtHtfbD6tI= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-424-5TznExwePcOWJJEU6Mtd1g-1; Tue, 27 May 2025 13:20:49 -0400 X-MC-Unique: 5TznExwePcOWJJEU6Mtd1g-1 X-Mimecast-MFC-AGG-ID: 5TznExwePcOWJJEU6Mtd1g_1748366447 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A7B211955DAB; Tue, 27 May 2025 17:20:46 +0000 (UTC) Received: from redhat.com (unknown [10.44.34.20]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0D09719560AA; Tue, 27 May 2025 17:20:39 +0000 (UTC) Date: Tue, 27 May 2025 19:20:37 +0200 From: Kevin Wolf To: Fiona Ebner Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org, den@virtuozzo.com, andrey.drobyshev@virtuozzo.com, hreitz@redhat.com, stefanha@redhat.com, eblake@redhat.com, jsnow@redhat.com, vsementsov@yandex-team.ru, xiechanglong.d@gmail.com, wencongyang2@huawei.com, berto@igalia.com, fam@euphon.net, ari@tuxera.com Subject: Re: [PATCH v3 13/24] block: move drain outside of bdrv_attach_child() Message-ID: References: <20250526132140.1641377-1-f.ebner@proxmox.com> <20250526132140.1641377-14-f.ebner@proxmox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250526132140.1641377-14-f.ebner@proxmox.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -49 X-Spam_score: -5.0 X-Spam_bar: ----- X-Spam_report: (-5.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.907, 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_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=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: 2.1.29 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 Am 26.05.2025 um 15:21 hat Fiona Ebner geschrieben: > This is part of resolving the deadlock mentioned in commit "block: > move draining out of bdrv_change_aio_context() and mark GRAPH_RDLOCK". > > The function bdrv_attach_child() runs under the graph lock, so it is > not allowed to drain. It is called by: > 1. replication_start() > 2. quorum_add_child() > 3. bdrv_open_child_common() > 4. Throughout test-bdrv-graph-mod.c and test-bdrv-drain.c unit tests. > > In all callers, a drained section is introduced. > > The function quorum_add_child() runs under the graph lock, so it is > not actually allowed to drain. This will be addressed by the following > commit. > > Signed-off-by: Fiona Ebner You won't be surprised that bdrv_attach_child() should have a comment stating the draining requirement, too. With this fixed: Reviewed-by: Kevin Wolf