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 D24C2C77B61 for ; Mon, 1 May 2023 16:03:37 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ptVyi-0000Ux-Te; Mon, 01 May 2023 12:02:19 -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 1ptVyL-0000CI-JH for qemu-devel@nongnu.org; Mon, 01 May 2023 12:02:04 -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 1ptVyJ-000303-Cd for qemu-devel@nongnu.org; Mon, 01 May 2023 12:01:52 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1682956910; 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=H4a4TRiPJmlX4SfND/Ww4f3lfek+b5VcGunIuszGPwg=; b=c7BEaOdKxgMY0TdwiWKKM0hZu09MImjRhwC83BILUOy4uQOEoEXagNt6yjFIDC1sxk17U3 0dsemGgAW9ms5UzSy7dRayYfpGhq5WBrvz6/isW1Srmt1lIZWBNuxEMfs5vMAldJbnrIZo Bxdz5QvRLV+VYE8/QNW+CK8gURYNhjY= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-550-TghNmgmqPdqDa295_JHMIw-1; Mon, 01 May 2023 12:01:40 -0400 X-MC-Unique: TghNmgmqPdqDa295_JHMIw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id BF07A1C075BD; Mon, 1 May 2023 16:01:39 +0000 (UTC) Received: from localhost (unknown [10.39.192.118]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3CF7363F2D; Mon, 1 May 2023 16:01:39 +0000 (UTC) Date: Mon, 1 May 2023 12:01:37 -0400 From: Stefan Hajnoczi To: Kevin Wolf Cc: qemu-block@nongnu.org, pbonzini@redhat.com, eesposit@redhat.com, qemu-devel@nongnu.org Subject: Re: [PATCH 08/20] block: .bdrv_open is non-coroutine and unlocked Message-ID: <20230501160137.GJ14869@fedora> References: <20230425173158.574203-1-kwolf@redhat.com> <20230425173158.574203-9-kwolf@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="vggftsAc1OigxgRu" Content-Disposition: inline In-Reply-To: <20230425173158.574203-9-kwolf@redhat.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Received-SPF: pass client-ip=170.10.133.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.171, 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_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable 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 --vggftsAc1OigxgRu Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Apr 25, 2023 at 07:31:46PM +0200, Kevin Wolf wrote: > Drivers were a bit confused about whether .bdrv_open can run in a > coroutine and whether or not it holds a graph lock. >=20 > It cannot keep a graph lock from the caller across the whole function > because it both changes the graph (requires a writer lock) and does I/O > (requires a reader lock). Therefore, it should take these locks > internally as needed. >=20 > The functions used to be called in coroutine context during image > creation. This was buggy for other reasons, and as of commit 32192301, > all block drivers go through no_co_wrappers. So it is not called in > coroutine context any more. >=20 > Fix qcow2 and qed to work with the correct assumptions: The graph lock > needs to be taken internally instead of just assuming it's already > there, and the coroutine path is dead code that can be removed. >=20 > Signed-off-by: Kevin Wolf > --- > include/block/block_int-common.h | 8 ++++---- > block.c | 6 +++--- > block/qcow2.c | 15 ++++++--------- > block/qed.c | 18 ++++++++---------- > 4 files changed, 21 insertions(+), 26 deletions(-) Reviewed-by: Stefan Hajnoczi --vggftsAc1OigxgRu Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmRP4mEACgkQnKSrs4Gr c8g8Dgf9GSoIp/TeqoggUGmEB5xaS7ThttL2zd7x/sGNd9fpJaw0LLYLZcaf1dUA 3njLo+GSuYMpPgdgb4cOnViP8Z9CvCbn8wmjbZQJWIhxAXAwB7DHhT3brjoRGfQ8 WNBDHFvnxNzU6+P6/NyyOxnG1S6Ckxw/eE4IcteMbZPqWwDjvrr1SSXsSMYXMNtP LEr/oiNw2kXDZlo20V04En84LHLqkbZXg0yWbmD6ImD05yhevDJFFmnw9c7SP7OC r6c49xhuJZRyd8E1Q4/Ziil+rhaLy7o1lbNFPkFm6gdllGrYkv+75apTVVoCdx9J 8UtfJ4WjV40pKqzWbRDdA35y+a4QGg== =4b7K -----END PGP SIGNATURE----- --vggftsAc1OigxgRu--