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 X-Spam-Level: X-Spam-Status: No, score=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 00E5FC07E95 for ; Mon, 19 Jul 2021 14:56:06 +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 5FB05610F7 for ; Mon, 19 Jul 2021 14:56:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5FB05610F7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:36078 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m5Uge-0004FK-8v for qemu-devel@archiver.kernel.org; Mon, 19 Jul 2021 10:56:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38318) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m5UfK-0003El-OS for qemu-devel@nongnu.org; Mon, 19 Jul 2021 10:54:42 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:59874) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m5UfH-0001mo-Cb for qemu-devel@nongnu.org; Mon, 19 Jul 2021 10:54:41 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1626706477; 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=fv5RzRkoLuwImHtWd3x1YOGMoF+e1/54bXDBTKayp2o=; b=br+AsIlqWhOiyKZGyxk1WedUv3T6AYvhVM0oFpw/Pf6ioqZGd7BDkVjTFLPOLnr9D1sxlQ t6/4pOzDHfJnKgC7YxGAVFLsoo5RD/ItCz33hpzJZvTcfK41XS+yWKDjlYPFUV/x9Td9vH 8y+XDzJtaesgcMf/+prJKxMt8ayw2CY= 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-372-DLubOymlMJ2mwSlMnnBwGQ-1; Mon, 19 Jul 2021 10:54:33 -0400 X-MC-Unique: DLubOymlMJ2mwSlMnnBwGQ-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 A6642802E65; Mon, 19 Jul 2021 14:54:32 +0000 (UTC) Received: from redhat.com (ovpn-114-199.ams2.redhat.com [10.36.114.199]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DC2CA5D9DC; Mon, 19 Jul 2021 14:54:23 +0000 (UTC) Date: Mon, 19 Jul 2021 16:54:21 +0200 From: Kevin Wolf To: Stefan Hajnoczi Subject: Re: [RFC PATCH 0/6] job: replace AioContext lock with job_mutex Message-ID: References: <20210707165813.55361-1-eesposit@redhat.com> <6dadca95-632a-61fa-4a91-c2df25e19b52@redhat.com> <629fb077-9d0a-7c33-0b2e-d055c0493005@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="0WlN5xbkGr65N5Jf" Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.469, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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: Emanuele Giuseppe Esposito , Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org, Wen Congyang , Xie Changlong , qemu-devel@nongnu.org, Markus Armbruster , Paolo Bonzini , Max Reitz , John Snow Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --0WlN5xbkGr65N5Jf Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Am 19.07.2021 um 11:29 hat Stefan Hajnoczi geschrieben: > On Fri, Jul 16, 2021 at 05:23:50PM +0200, Kevin Wolf wrote: > > Am 13.07.2021 um 15:10 hat Stefan Hajnoczi geschrieben: > > > AIO_WAIT_WHILE() requires that AioContext is acquired according to it= s > > > documentation, but I'm not sure that's true anymore. Thread-safe/atom= ic > > > primitives are used by AIO_WAIT_WHILE(), so as long as the condition > > > being waited for is thread-safe too it should work without the > > > AioContext lock. > >=20 > > Polling something in a different AioContext from the main thread still > > temporarily drops the lock, which crashes if it isn't locked. I'm not > > sure if the documentation claims that the lock is needed in more cases, > > I guess you could interpret it either way. >=20 > I'm claiming that the lock doesn't need to be dropped in that case > anymore - as long as the condition we're polling is thread-safe. :) >=20 > Have I missed something that still need locking? I'm not sure if AIO_WAIT_WHILE() actually ever needed the locking. I think it's more a convenience thing since the callers would already hold the lock, so dropping it temporarily in AIO_WAIT_WHILE() means that the callers don't have to duplicate the temporary unlock everywhere. > We could temporarily introduce an AIO_WAIT_WHILE_UNLOCKED() macro so > that callers can be converted individually. Yes, this makes sense to me. Kevin --0WlN5xbkGr65N5Jf Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE3D3rFZqa+V09dFb+fwmycsiPL9YFAmD1kh0ACgkQfwmycsiP L9bKTBAAjiF3iMJHwMP+YKgWsimW2A0dOoCBAWqtu/42YuMB4fU3o8jRETCui+jf EqI4G4Z65DkyPx2pAkNz56/j99limTog1pbCaQSPCbS4ILyynGv3eMk10y8DYLKS RUE48MB4nSsOGdVOagy1Yy5oqJHJC2rXOQNqA9zZcJW0JuYcmZGSyht+p0kw9ktC 3AH6vA/k/kPF2UrnnsiQJzfGnwI5p6gwGmSpVgLVnSALcVmh0g+g0LSDT5MlHls2 Eq/eXoeQSYa4xHMqNZM+9V9ubcDW+nMyjRLi01hROBc6Gr42fpB8tGp52O/nPAe0 WYeSzhrKdB3q9g67gq2beJ2Lk1KKbMYPTnDU9k3ckXwPK3br9ZpQQn6CHhUf4L0o 6Cd9Oi8yERoFgtS7eJkGnpkY298Hqc+3RXydBUO0o2x+GRVP55oTmfPugE7FBeJ7 SFYfUyIRWbTxTx2Ux/igKkvG+SSXfUC83aF0Qj856l3KFD9mvdwS/lxUaE6mHqvN HVmOn0ZGZwzBS/JFn3NM6NY4d+AnvwoqUUAgBbNNRs03csCzTXXnRHlX1T5gRwgk mtqJc4jY9ENVM5m2ZeORv33yLc9e1aXtS4HcMMi7bd98ou64LpgzCuCzxLzgOCeo 0A95aVYEdpKbEIVgyTHaQjsRygharN0kDIzl5zpjqIRGSobrwYU= =Emyr -----END PGP SIGNATURE----- --0WlN5xbkGr65N5Jf--