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 2685FC76196 for ; Tue, 28 Mar 2023 15:52:22 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1phBbS-0002Y0-TK; Tue, 28 Mar 2023 11:51:18 -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 1phBb9-0002V9-CW for qemu-devel@nongnu.org; Tue, 28 Mar 2023 11:51:04 -0400 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 1phBb7-0001A7-SS for qemu-devel@nongnu.org; Tue, 28 Mar 2023 11:50:59 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680018656; 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; bh=KIIgTfUmYMsN3oXMtChNBA5eClLg3Q7WA81b0n5l5Pw=; b=VGF45QNMP0rbZNHHzMfr3stBCUN8na2EKT/JOc+vyGuAH+auCp+kR4O6Q15F66OzFsCZB5 a5sBR24XXSxICtxFC5R+wSFay227VVgl8yJZraFtBeOmz0hVmolqmv/7HMG0wtfHgepzVc 1UCzHp62bh0Qj3sFSm3yT3e8JieiIRQ= 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-635-ptMjq_0MNDmTmHeDsMdvjw-1; Tue, 28 Mar 2023 11:50:52 -0400 X-MC-Unique: ptMjq_0MNDmTmHeDsMdvjw-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 213A53C0C887; Tue, 28 Mar 2023 15:50:52 +0000 (UTC) Received: from localhost (unknown [10.39.195.24]) by smtp.corp.redhat.com (Postfix) with ESMTP id 96D65FD6E; Tue, 28 Mar 2023 15:50:51 +0000 (UTC) Date: Tue, 28 Mar 2023 11:50:50 -0400 From: Stefan Hajnoczi To: David Woodhouse , Paul Durrant Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org Subject: aio_set_event_notifier(is_external=true) in Xen code? Message-ID: <20230328155050.GA1632689@fedora> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="f6gUQ4S3t7TEC8fk" Content-Disposition: inline X-Scanned-By: MIMEDefang 3.1 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: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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_NONE=-0.0001, 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: 2.1.29 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 --f6gUQ4S3t7TEC8fk Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hi, I'm removing the aio_disable_external() API from QEMU and noticed that Xen code calls aio_set_fd_handler(is_external=true) in hw/xen/xen-bus.c and hw/i386/kvm/xen_xenstore.c. It wasn't clear to me whether is_external=true is necessary here. is_external=true is mainly used to temporarily pause I/O submission in the QEMU block layer. Maybe is_external=true was chosen out of caution but actually has no effect in this code. Does the Xen code rely on is_external=true? Thanks, Stefan --f6gUQ4S3t7TEC8fk Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmQjDNoACgkQnKSrs4Gr c8gNXQf/fC953Xa1eKe14eIys5OzTGEsPivI5xy7/TYPOKSPtMr4XBse/JW2wme+ eh+lzPx8kZnzSkAT+uvvNPeCAQZ7f1a5z/P2WRRPaRqSAY5NSFKpJuq0c/1xtgo8 vgDZLaXY7+KTFupgX1Auo32Zw/nBBv3PxvMSM2B+wIdpBASDGN8qz+hv0nugGJQB RmixWUuotWdnwz7Jz95TPZkgIw0D4EtSkT6hVJqgca4nWocU+7gFcp1xqdPSkBA9 gZYhvIMmVV2cmgtGN/B6s9HEiz0J87Z27XLwWJP6t9Y81TOciHmItbMtiOYUs0gN pNu8/Pb51ruCv+XpeN4Z0XBfuCj/Dg== =HkeW -----END PGP SIGNATURE----- --f6gUQ4S3t7TEC8fk--