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 63F30C43334 for ; Tue, 5 Jul 2022 13:10:32 +0000 (UTC) Received: from localhost ([::1]:44186 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1o8iJz-0005yq-4S for qemu-devel@archiver.kernel.org; Tue, 05 Jul 2022 09:10:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39880) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o8iHz-0004Sb-Em for qemu-devel@nongnu.org; Tue, 05 Jul 2022 09:08:27 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:46282) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o8iHv-0007QA-JB for qemu-devel@nongnu.org; Tue, 05 Jul 2022 09:08:25 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1657026502; 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=VMWGsG4Ho4ldrtoMlMPvd36db3HkOJYDJmBIxCRlZEw=; b=eQ1m52LYauoNX8JKNb5y+ln1g699EV+31hs8O1pu4aUZ0iGuexHfYtjkfd0x0saXiav8w1 pGyEpX9jyPNzqlkKWZpCjO9uF6ekbX7Rm/f0BEIZT6Iw1vtgaIjWtmCoL54BKGYiTqjfwb sUUH3yRONVzlyhztJllVw3f/nUWEF68= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-180-OlVC8xLQNn6XqbqoK_CNzw-1; Tue, 05 Jul 2022 09:08:01 -0400 X-MC-Unique: OlVC8xLQNn6XqbqoK_CNzw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 0C9C1811E80; Tue, 5 Jul 2022 13:08:01 +0000 (UTC) Received: from localhost (unknown [10.39.194.109]) by smtp.corp.redhat.com (Postfix) with ESMTP id AE5AD1121315; Tue, 5 Jul 2022 13:08:00 +0000 (UTC) Date: Tue, 5 Jul 2022 14:07:59 +0100 From: Stefan Hajnoczi To: Emanuele Giuseppe Esposito Cc: qemu-block@nongnu.org, Kevin Wolf , Hanna Reitz , Paolo Bonzini , John Snow , Vladimir Sementsov-Ogievskiy , Wen Congyang , Xie Changlong , Markus Armbruster , Fam Zheng , qemu-devel@nongnu.org Subject: Re: [PATCH v8 17/20] job.c: enable job lock/unlock and remove Aiocontext locks Message-ID: References: <20220629141538.3400679-1-eesposit@redhat.com> <20220629141538.3400679-18-eesposit@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="zDaEhvfEkfB7l/b9" Content-Disposition: inline In-Reply-To: <20220629141538.3400679-18-eesposit@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 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: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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" --zDaEhvfEkfB7l/b9 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jun 29, 2022 at 10:15:35AM -0400, Emanuele Giuseppe Esposito wrote: > Change the job_{lock/unlock} and macros to use job_mutex. >=20 > Now that they are not nop anymore, remove the aiocontext > to avoid deadlocks. >=20 > Therefore: > - when possible, remove completely the aiocontext lock/unlock pair > - if it is used by some other function too, reduce the locking > section as much as possible, leaving the job API outside. >=20 > There is only one JobDriver callback, ->free() that assumes that > the aiocontext lock is held (because it calls bdrv_unref), so for > now keep that under aiocontext lock. This discussion shouldn't hold up the patch series, it's a separate issue: Why does bdrv_unref() need the AioContext lock? The reference count itself is protected by the BQL (bdrv_ref() is GS too). I/O requests should be using fine-grained locks now, so I'm not sure if we still need to hold the AioContext lock to drain them? Reviewed-by: Stefan Hajnoczi --zDaEhvfEkfB7l/b9 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmLEN68ACgkQnKSrs4Gr c8hsYQf9HrOIhB3oq+LrIhKr6xHDv567N6U+HS7uCPl1T+aCQPRL1OOD1nZdYtKa 5av71HRiDSe1Idxelr8pO4iMjsVKQcjYlKGINIOlXhgUIjUMexSHj17o1oaW5JQs SS2HAqe1ZeiwrBJe1GJ2RAUw263J9CvmCT3u5Z+BsF1KJUQ7C2gHvL83GNnTAbpf VuQwSHul4nrPOHUTuNSqwuO/Qupe/CISdRHzJgA/mlvkp4wYBhQaQ94PUY7FKiNK RXYfP1dE4v56hAcG76BPxoktqtttLPYzrYGl6WMhTr2Cft/YTA4XwvEDmlqcwL3E qFAewggT6pky1kMOpbidFiCmk1R5jw== =V4QD -----END PGP SIGNATURE----- --zDaEhvfEkfB7l/b9--