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 71DB4C43460 for ; Wed, 12 May 2021 15:21:40 +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 ED76661419 for ; Wed, 12 May 2021 15:21:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ED76661419 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]:36574 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lgqg6-0006rn-VC for qemu-devel@archiver.kernel.org; Wed, 12 May 2021 11:21:38 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:46588) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lgqeJ-00056x-NZ for qemu-devel@nongnu.org; Wed, 12 May 2021 11:19:48 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:38771) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lgqeG-0001Qo-Dn for qemu-devel@nongnu.org; Wed, 12 May 2021 11:19:46 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620832783; 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=QojuVRlnklgAJ/bD51ZvZJ2U2WK07kDwQbJcvHLCNEA=; b=R47q8XyzupdTKeeXAS81X+s0v9qGwZF5Hd9+0bLLBE7yxF7LvUDTpqgbbbbMLDZybNjfCJ SyNSFlYRwSGAOvCmj2Mfq7l71ifIa0x3oNPLLe1ZzsvXBCVpbf2KTNAmv+vB9IbyWW4Npk r1dquoBfq0a2L+stDwqChFyJp4Xw+nQ= 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-380-krAjhWI9O2uXaX9c9mkgvQ-1; Wed, 12 May 2021 11:19:41 -0400 X-MC-Unique: krAjhWI9O2uXaX9c9mkgvQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4EDB18189D4; Wed, 12 May 2021 15:19:40 +0000 (UTC) Received: from localhost (ovpn-115-51.ams2.redhat.com [10.36.115.51]) by smtp.corp.redhat.com (Postfix) with ESMTP id E6AEA5C8AA; Wed, 12 May 2021 15:19:39 +0000 (UTC) Date: Wed, 12 May 2021 16:19:38 +0100 From: Stefan Hajnoczi To: Emanuele Giuseppe Esposito Subject: Re: [PATCH 6/6] aiopool: protect with a mutex Message-ID: References: <20210510085941.22769-1-eesposit@redhat.com> <20210510085941.22769-7-eesposit@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210510085941.22769-7-eesposit@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=stefanha@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="tNyTxOVvBu4nqu8i" Content-Disposition: inline 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: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.7, 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: Kevin Wolf , Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org, qemu-devel@nongnu.org, Max Reitz , Paolo Bonzini , John Snow Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --tNyTxOVvBu4nqu8i Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Mon, May 10, 2021 at 10:59:41AM +0200, Emanuele Giuseppe Esposito wrote: > Divide the fields in AioTaskPool in IN and Status, and > introduce a CoQueue instead of .wait to take care of suspending > and resuming the calling coroutine, and a lock to protect the > busy_tasks counter accesses and the AioTask .ret field. The thread-safety concerns with the aio_task.h API are unclear to me. The API is designed to have a "main" coroutine that adds task functions to the pool and waits for them to complete. Task functions execute in coroutines (up to the pool's max_busy_tasks limit). It seems like the API was designed to be called only from its main coroutine so why make everything thread-safe? Is there a caller that shares an AioTaskPool between threads? Or will the task functions switch threads somehow? What exactly is the new thread-safety model? Please document it. Unfortunately aio_task.h doesn't have doc comments already but it will be necessary if there are thread-safety concerns. --tNyTxOVvBu4nqu8i Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmCb8goACgkQnKSrs4Gr c8isgAf/WYpTvtflct2mgV8rcS65mmGhZiAPH40QWCxbWsM0GAyEhtIByZP9sue3 AMbNmsMcHbVMdKR3DHerYItUMw28AdIU2fqwv954vIIhEHBTL9kBVcZhfSHZDqJd jwjjAO7hh8N8yLHDOUsosU+ENhZsBeUB7jvytmd6Ka1SzrVRn4jsW5I+QXfiJD+0 BA5qO4f77Mhp6Miw9VIwZFhVS6cehKWxsWJA+pjvUmJCSglxM8PM7ejlBge3i2Of vl9eD7TjG+iCNAyoAG1V8CZ10jmtF0gQJTs4qGvwOvOwSQKOgHvgGISArfJ+ddIr Pu5ulbUM3vBTf4Ow4eeGY3P19HmJ0Q== =HAZ2 -----END PGP SIGNATURE----- --tNyTxOVvBu4nqu8i--