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 835D1C48297 for ; Tue, 6 Feb 2024 16:55:31 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rXOj6-00033G-KQ; Tue, 06 Feb 2024 11:55:16 -0500 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 1rXOj4-00031H-5E for qemu-devel@nongnu.org; Tue, 06 Feb 2024 11:55:14 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rXOj2-00084t-G2 for qemu-devel@nongnu.org; Tue, 06 Feb 2024 11:55:13 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1707238511; 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=SvQzN05da4wwhxICLYzXe/1B8t+DmJTqNKrrKkFE74Y=; b=iBTaouc2fIK3HS3G3ZhQsSj79LT5gi7jIOYV34TH1KmNTqETD1u+XJ0VsZ+ih3Uv824yq4 AwIdKPi/NIkliLa9TPc4LTc5Ss0BAdhbXJvLDnvHsk1QW/eTV8483ivWVRbY+Bek9HVaQq ddPB1Xfo26hk/om9d4EWy713ODzMsI8= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-13-Tuh223oONtirBKI2bQTM6A-1; Tue, 06 Feb 2024 11:55:09 -0500 X-MC-Unique: Tuh223oONtirBKI2bQTM6A-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id AAC311C06914; Tue, 6 Feb 2024 16:55:08 +0000 (UTC) Received: from localhost (unknown [10.39.195.40]) by smtp.corp.redhat.com (Postfix) with ESMTP id 42CF11103A; Tue, 6 Feb 2024 16:55:07 +0000 (UTC) Date: Tue, 6 Feb 2024 11:55:06 -0500 From: Stefan Hajnoczi To: Hanna Czenczek Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org, qemu-stable@nongnu.org, Kevin Wolf , Paolo Bonzini , Fam Zheng Subject: Re: [PATCH 1/2] block-backend: Allow concurrent context changes Message-ID: <20240206165506.GC66397@fedora> References: <20240202144755.671354-1-hreitz@redhat.com> <20240202144755.671354-2-hreitz@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="jiE0927v/rD3BNII" Content-Disposition: inline In-Reply-To: <20240202144755.671354-2-hreitz@redhat.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.5 Received-SPF: pass client-ip=170.10.129.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -23 X-Spam_score: -2.4 X-Spam_bar: -- X-Spam_report: (-2.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.294, 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=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 --jiE0927v/rD3BNII Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Feb 02, 2024 at 03:47:54PM +0100, Hanna Czenczek wrote: > Since AioContext locks have been removed, a BlockBackend's AioContext > may really change at any time (only exception is that it is often > confined to a drained section, as noted in this patch). Therefore, > blk_get_aio_context() cannot rely on its root node's context always > matching that of the BlockBackend. >=20 > In practice, whether they match does not matter anymore anyway: Requests > can be sent to BDSs from any context, so anyone who requests the BB's > context should have no reason to require the root node to have the same > context. Therefore, we can and should remove the assertion to that > effect. >=20 > In addition, because the context can be set and queried from different > threads concurrently, it has to be accessed with atomic operations. >=20 > Buglink: https://issues.redhat.com/browse/RHEL-19381 > Suggested-by: Kevin Wolf > Signed-off-by: Hanna Czenczek > --- > block/block-backend.c | 22 +++++++++++----------- > 1 file changed, 11 insertions(+), 11 deletions(-) Reviewed-by: Stefan Hajnoczi --jiE0927v/rD3BNII Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmXCZGoACgkQnKSrs4Gr c8iyBAf9ES+FOTDPQmSG66PM44gspR8ETnNX1rtNfaaMUgntdY8YZcH/P6xrbRl8 p5qHNNhw50Y+HZ27JbwkYXsqLMY+Yl4Ip4V0bDob/UyvE3StQA3ghDbgr68hKnpi WSFOoCmr6DLdBTX5H4iv+aa9wnl2lYY1hlkZRas0U1eE6VUBdiD1ADwuFtO9XglB OJewLY64hAMP7U68v+H2Hq8GIu5e6O1hWizMehq+XCEZRJVcGfYMt82yLiy395RN QnOxIRzm34mLMaPyRVQ31y612rKBvvMyVLXVqrxu+lEoP1TbVtCLFQ1SrRbFjrah dk/HlMrbauPyT2hB4nj54FNZzbGw4w== =uf+K -----END PGP SIGNATURE----- --jiE0927v/rD3BNII--