From nobody Mon Feb 9 09:22:46 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1642525487350143.12306018645347; Tue, 18 Jan 2022 09:04:47 -0800 (PST) Received: from localhost ([::1]:49010 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1n9ruX-00052a-Nb for importer@patchew.org; Tue, 18 Jan 2022 12:04:45 -0500 Received: from eggs.gnu.org ([209.51.188.92]:39266) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n9rVL-00075S-S0 for qemu-devel@nongnu.org; Tue, 18 Jan 2022 11:38:43 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:32058) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n9rVK-00065B-2f for qemu-devel@nongnu.org; Tue, 18 Jan 2022 11:38:43 -0500 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-213-oRJkJsH1PKuYVcqVOBXReA-1; Tue, 18 Jan 2022 11:38:39 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EA3AC10C44BB; Tue, 18 Jan 2022 16:28:21 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2CEF034D3F; Tue, 18 Jan 2022 16:28:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1642523921; 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=1mN4YprAtPYLW25ybvOA6+PmPtLEmh4URozvfVnbu10=; b=ERGBlA7kVU3JU4hzMc1Jkjdw82qFHiEoFQ6CVqsA7gBfszG/aFj9yoOkE6uVSs8dUpD9dt mrN9feqD4FgsjpqpHPV21emwav0Fwsgc6YzvDkKnkNxrRWiJoyJGlplRQvVJnNQ4NrozdA X7z5DLaTlDD1tvd6qxtUUfPHykO6gFs= X-MC-Unique: oRJkJsH1PKuYVcqVOBXReA-1 From: Emanuele Giuseppe Esposito To: qemu-block@nongnu.org Subject: [PATCH 04/12] block.c: bdrv_replace_child_noperm: first call ->attach(), and then add child Date: Tue, 18 Jan 2022 11:27:30 -0500 Message-Id: <20220118162738.1366281-5-eesposit@redhat.com> In-Reply-To: <20220118162738.1366281-1-eesposit@redhat.com> References: <20220118162738.1366281-1-eesposit@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eesposit@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=eesposit@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.7, 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_H3=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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Fam Zheng , Vladimir Sementsov-Ogievskiy , Emanuele Giuseppe Esposito , qemu-devel@nongnu.org, Hanna Reitz , Stefan Hajnoczi , Paolo Bonzini , John Snow Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZM-MESSAGEID: 1642525490018100001 Content-Type: text/plain; charset="utf-8" Doing the opposite can make adding the child node to a non-drained node, as apply_subtree_drain is only done in ->attach() and thus make assert_bdrv_graph_writable fail. This can happen for example during a transaction rollback (test 245, test_io_with_graph_changes): 1. a node is removed from the graph, thus it is undrained 2. then something happens, and we need to roll back the transactions through tran_abort() 3. at this point, the current code would first attach the undrained node to the graph via QLIST_INSERT_HEAD, and then call ->attach() that will take care of restoring the drain with apply_subtree_drain(), leaving the node undrained between the two operations. Signed-off-by: Emanuele Giuseppe Esposito --- block.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/block.c b/block.c index 29de2b62b5..fb5bc3077a 100644 --- a/block.c +++ b/block.c @@ -2879,8 +2879,6 @@ static void bdrv_replace_child_noperm(BdrvChild **chi= ldp, } =20 if (new_bs) { - assert_bdrv_graph_writable(new_bs); - QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent); =20 /* * Detaching the old node may have led to the new node's @@ -2897,6 +2895,10 @@ static void bdrv_replace_child_noperm(BdrvChild **ch= ildp, if (child->klass->attach) { child->klass->attach(child); } + + assert_bdrv_graph_writable(new_bs); + QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent); + } =20 /* --=20 2.31.1