From patchwork Mon Oct 25 10:17:18 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Emanuele Giuseppe Esposito X-Patchwork-Id: 12581345 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E4238C433F5 for ; Mon, 25 Oct 2021 10:28:41 +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 7296A60E8C for ; Mon, 25 Oct 2021 10:28:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 7296A60E8C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:53484 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mexDc-0008Dn-EN for qemu-devel@archiver.kernel.org; Mon, 25 Oct 2021 06:28:40 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48898) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mex3z-000596-R1 for qemu-devel@nongnu.org; Mon, 25 Oct 2021 06:18:44 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:58906) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mex3w-0006lj-T0 for qemu-devel@nongnu.org; Mon, 25 Oct 2021 06:18:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1635157120; 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=6KhaDuVI+vNhBGX+madfeZ2IUPEBdp3SY9YHrjt54JE=; b=eq6M6zobw9H0E3Kpj7ttAYlnns0G8EawSVUDWmusdx2sw+GUN/pfX7Kln5qUVhgoeseadK 6eVFlavhHDMUJ0gZkXo/9lx62yAdR3P1kEfdUgugE+NuC0kp+3AICfv0Eg+GkbwNlUyylk qeHdLthexo305q12fgByRZjazeKmNtI= 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-549-MeXFJ1blO7uoQp8zkwVH_w-1; Mon, 25 Oct 2021 06:18:39 -0400 X-MC-Unique: MeXFJ1blO7uoQp8zkwVH_w-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 06E6B10A8E00; Mon, 25 Oct 2021 10:18:38 +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 76E885D9D5; Mon, 25 Oct 2021 10:18:34 +0000 (UTC) From: Emanuele Giuseppe Esposito To: qemu-block@nongnu.org Subject: [PATCH v4 08/25] block: introduce assert_bdrv_graph_writable Date: Mon, 25 Oct 2021 06:17:18 -0400 Message-Id: <20211025101735.2060852-9-eesposit@redhat.com> In-Reply-To: <20211025101735.2060852-1-eesposit@redhat.com> References: <20211025101735.2060852-1-eesposit@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 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 Received-SPF: pass client-ip=216.205.24.124; envelope-from=eesposit@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: Kevin Wolf , Fam Zheng , Vladimir Sementsov-Ogievskiy , =?utf-8?q?Daniel_P?= =?utf-8?q?=2E_Berrang=C3=A9?= , Eduardo Habkost , Juan Quintela , qemu-devel@nongnu.org, John Snow , Emanuele Giuseppe Esposito , Richard Henderson , Markus Armbruster , "Dr. David Alan Gilbert" , Hanna Reitz , Stefan Hajnoczi , Paolo Bonzini , Eric Blake Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" We want to be sure that the functions that write the child and parent list of a bs are under BQL and drain. BQL prevents from concurrent writings from the GS API, while drains protect from I/O. TODO: drains are missing in some functions using this assert. Therefore a proper assertion will fail. Because adding drains requires additional discussions, they will be added in future series. Signed-off-by: Emanuele Giuseppe Esposito Reviewed-by: Paolo Bonzini Reviewed-by: Stefan Hajnoczi --- block.c | 5 +++++ block/io.c | 11 +++++++++++ include/block/block_int-global-state.h | 10 +++++++++- 3 files changed, 25 insertions(+), 1 deletion(-) diff --git a/block.c b/block.c index 41c5883c5c..94bff5c757 100644 --- a/block.c +++ b/block.c @@ -2734,12 +2734,14 @@ static void bdrv_replace_child_noperm(BdrvChild *child, if (child->klass->detach) { child->klass->detach(child); } + assert_bdrv_graph_writable(old_bs); QLIST_REMOVE(child, next_parent); } child->bs = new_bs; if (new_bs) { + assert_bdrv_graph_writable(new_bs); QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent); /* @@ -2940,6 +2942,7 @@ static int bdrv_attach_child_noperm(BlockDriverState *parent_bs, return ret; } + assert_bdrv_graph_writable(parent_bs); QLIST_INSERT_HEAD(&parent_bs->children, *child, next); /* * child is removed in bdrv_attach_child_common_abort(), so don't care to @@ -3140,6 +3143,7 @@ static void bdrv_unset_inherits_from(BlockDriverState *root, BdrvChild *child, void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child) { assert(qemu_in_main_thread()); + assert_bdrv_graph_writable(parent); if (child == NULL) { return; } @@ -4903,6 +4907,7 @@ static void bdrv_remove_filter_or_cow_child_abort(void *opaque) BdrvRemoveFilterOrCowChild *s = opaque; BlockDriverState *parent_bs = s->child->opaque; + assert_bdrv_graph_writable(parent_bs); QLIST_INSERT_HEAD(&parent_bs->children, s->child, next); if (s->is_backing) { parent_bs->backing = s->child; diff --git a/block/io.c b/block/io.c index f271ab3684..1c71e354d6 100644 --- a/block/io.c +++ b/block/io.c @@ -740,6 +740,17 @@ void bdrv_drain_all(void) bdrv_drain_all_end(); } +void assert_bdrv_graph_writable(BlockDriverState *bs) +{ + /* + * TODO: this function is incomplete. Because the users of this + * assert lack the necessary drains, check only for BQL. + * Once the necessary drains are added, + * assert also for qatomic_read(&bs->quiesce_counter) > 0 + */ + assert(qemu_in_main_thread()); +} + /** * Remove an active request from the tracked requests list * diff --git a/include/block/block_int-global-state.h b/include/block/block_int-global-state.h index d08e80222c..6bd7746409 100644 --- a/include/block/block_int-global-state.h +++ b/include/block/block_int-global-state.h @@ -316,4 +316,12 @@ void bdrv_remove_aio_context_notifier(BlockDriverState *bs, */ void bdrv_drain_all_end_quiesce(BlockDriverState *bs); -#endif /* BLOCK_INT_GLOBAL_STATE*/ +/** + * Make sure that the function is either running under + * drain and BQL. The latter protects from concurrent writings + * from the GS API, while the former prevents concurrent reads + * from I/O. + */ +void assert_bdrv_graph_writable(BlockDriverState *bs); + +#endif /* BLOCK_INT_GLOBAL_STATE */