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 8D70BC77B73 for ; Tue, 2 May 2023 15:22:01 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.528726.822235 (Exim 4.92) (envelope-from ) id 1ptrp0-00051T-QA; Tue, 02 May 2023 15:21:42 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 528726.822235; Tue, 02 May 2023 15:21:42 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ptrp0-00051M-NB; Tue, 02 May 2023 15:21:42 +0000 Received: by outflank-mailman (input) for mailman id 528726; Tue, 02 May 2023 15:21:41 +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 1ptroy-00051B-LR for xen-devel@lists.xenproject.org; Tue, 02 May 2023 15:21:40 +0000 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 078a6cf0-e8fd-11ed-b225-6b7b168915f2; Tue, 02 May 2023 17:21:38 +0200 (CEST) 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-556-js-j9vUPNr-JzXSEn51u-w-1; Tue, 02 May 2023 11:21:07 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id CC73E18E5312; Tue, 2 May 2023 15:19:53 +0000 (UTC) Received: from redhat.com (unknown [10.39.193.211]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C7EB52026D25; Tue, 2 May 2023 15:19:47 +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: 078a6cf0-e8fd-11ed-b225-6b7b168915f2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1683040896; 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=O1kjfWbyj3zykPV4mxkot03UoMaYj696sk4Wl0CL1mY=; b=ZV0qWZFJvlO+3fqr3yJoSQXriwtRM7ZEl7fCXgrvSyXGOxM3d5zz7QshoCBqzlVSlPhtUn LnXCLR0lLfTNCXchNpIH4/j7NMAlfhuCymLiy1UmRIo48lSmZIchjJID4628wtsS1SwtNU jQHtkZSWdk2UZghJmRuJzlkU6f6IH54= X-MC-Unique: js-j9vUPNr-JzXSEn51u-w-1 Date: Tue, 2 May 2023 17:19:46 +0200 From: Kevin Wolf To: Stefan Hajnoczi Cc: qemu-devel@nongnu.org, Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , Juan Quintela , Julia Suvorova , xen-devel@lists.xenproject.org, eesposit@redhat.com, Richard Henderson , Fam Zheng , "Michael S. Tsirkin" , Coiby Xu , David Woodhouse , Marcel Apfelbaum , Peter Lieven , Paul Durrant , "Richard W.M. Jones" , qemu-block@nongnu.org, Stefano Garzarella , Anthony Perard , Stefan Weil , Xie Yongji , Paolo Bonzini , Aarushi Mehta , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= , Eduardo Habkost , Stefano Stabellini , Hanna Reitz , Ronnie Sahlberg , Daniil Tatianin Subject: Re: [PATCH v4 03/20] virtio-scsi: avoid race between unplug and transport event Message-ID: References: <20230425172716.1033562-1-stefanha@redhat.com> <20230425172716.1033562-4-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230425172716.1033562-4-stefanha@redhat.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 Am 25.04.2023 um 19:26 hat Stefan Hajnoczi geschrieben: > Only report a transport reset event to the guest after the SCSIDevice > has been unrealized by qdev_simple_device_unplug_cb(). > > qdev_simple_device_unplug_cb() sets the SCSIDevice's qdev.realized field > to false so that scsi_device_find/get() no longer see it. > > scsi_target_emulate_report_luns() also needs to be updated to filter out > SCSIDevices that are unrealized. > > These changes ensure that the guest driver does not see the SCSIDevice > that's being unplugged if it responds very quickly to the transport > reset event. > > Reviewed-by: Paolo Bonzini > Reviewed-by: Michael S. Tsirkin > Reviewed-by: Daniil Tatianin > Signed-off-by: Stefan Hajnoczi > @@ -1082,6 +1073,15 @@ static void virtio_scsi_hotunplug(HotplugHandler *hotplug_dev, DeviceState *dev, > blk_set_aio_context(sd->conf.blk, qemu_get_aio_context(), NULL); > virtio_scsi_release(s); > } > + > + if (virtio_vdev_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) { > + virtio_scsi_acquire(s); > + virtio_scsi_push_event(s, sd, > + VIRTIO_SCSI_T_TRANSPORT_RESET, > + VIRTIO_SCSI_EVT_RESET_REMOVED); > + scsi_bus_set_ua(&s->bus, SENSE_CODE(REPORTED_LUNS_CHANGED)); > + virtio_scsi_release(s); > + } > } s, sd and s->bus are all unrealized at this point, whereas before this patch they were still realized. I couldn't find any practical problem with it, but it made me nervous enough that I thought I should comment on it at least. Should we maybe have documentation on these functions that says that they accept unrealized objects as their parameters? Kevin