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.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 E62EEC4167B for ; Mon, 4 Dec 2023 12:46:47 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.646898.1009542 (Exim 4.92) (envelope-from ) id 1rA8LF-00065p-J1; Mon, 04 Dec 2023 12:46:29 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 646898.1009542; Mon, 04 Dec 2023 12:46:29 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1rA8LF-00065i-GL; Mon, 04 Dec 2023 12:46:29 +0000 Received: by outflank-mailman (input) for mailman id 646898; Mon, 04 Dec 2023 12:46:28 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1rA8LE-00065c-6X for xen-devel@lists.xenproject.org; Mon, 04 Dec 2023 12:46:28 +0000 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 23068d18-92a3-11ee-98e5-6d05b1d4d9a1; Mon, 04 Dec 2023 13:46:26 +0100 (CET) Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-587-WlsnWTGLP9CgoOClcumpYA-1; Mon, 04 Dec 2023 07:46:19 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (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 CF54285A58B; Mon, 4 Dec 2023 12:46:18 +0000 (UTC) Received: from redhat.com (unknown [10.39.194.237]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B032BC15983; Mon, 4 Dec 2023 12:46:14 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 23068d18-92a3-11ee-98e5-6d05b1d4d9a1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1701693985; 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=OdqJcUWrpkerK9dE7JvdF+gkdvliUlUpsIv/joFLTrU=; b=US/ZXufMixJF3shG3LE1TzC5TGQK8Uph39bM4XZ3DDtG4lCUjDkE1ymJwP+UmmNp3QKi6j wvSgX8MJNFgiY4TPXMBpcjxkxSVKlfxDHRoahAMw7Mxe+YPkqoAt/IpYpNcgatzJvu3JTA w7/jQkhN6KQckDVvjMdOgYODiZXsgkc= X-MC-Unique: WlsnWTGLP9CgoOClcumpYA-1 Date: Mon, 4 Dec 2023 13:46:13 +0100 From: Kevin Wolf To: Stefan Hajnoczi Cc: qemu-devel@nongnu.org, Hanna Reitz , Paul Durrant , Paolo Bonzini , Alberto Garcia , Emanuele Giuseppe Esposito , John Snow , Eric Blake , Wen Congyang , qemu-block@nongnu.org, xen-devel@lists.xenproject.org, Coiby Xu , Eduardo Habkost , Xie Changlong , Ari Sundholm , Li Zhijian , Cleber Rosa , Juan Quintela , "Michael S. Tsirkin" , Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , Jason Wang , Vladimir Sementsov-Ogievskiy , Zhang Chen , Peter Xu , Anthony Perard , Stefano Stabellini , Leonardo Bras , Pavel Dovgalyuk , Fam Zheng , Fabiano Rosas Subject: Re: [PATCH 01/12] virtio-scsi: replace AioContext lock with tmf_bh_lock Message-ID: References: <20231129195553.942921-1-stefanha@redhat.com> <20231129195553.942921-2-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231129195553.942921-2-stefanha@redhat.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 Am 29.11.2023 um 20:55 hat Stefan Hajnoczi geschrieben: > Protect the Task Management Function BH state with a lock. The TMF BH > runs in the main loop thread. An IOThread might process a TMF at the > same time as the TMF BH is running. Therefore tmf_bh_list and tmf_bh > must be protected by a lock. > > Run TMF request completion in the IOThread using aio_wait_bh_oneshot(). > This avoids more locking to protect the virtqueue and SCSI layer state. > > Signed-off-by: Stefan Hajnoczi The second part reminds me that the implicit protection of the virtqueue and SCSI data structures by having all accesses in a single thread is hard to review and I think we wanted to put some assertions there to check that we're really running in the right thread. I don't think we have done that so far, so I suppose after this patch would be the place in the series to add them, before we remove the protection by the AioContext lock? Kevin