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=-0.6 required=3.0 tests=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 11558C432C0 for ; Fri, 29 Nov 2019 12:43:42 +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 D098E20869 for ; Fri, 29 Nov 2019 12:43:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="gKWHxVkm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D098E20869 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]:58448 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iafca-0006fF-RU for qemu-devel@archiver.kernel.org; Fri, 29 Nov 2019 07:43:40 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:35015) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iafaI-0005K7-7e for qemu-devel@nongnu.org; Fri, 29 Nov 2019 07:41:19 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iafaC-0001la-K1 for qemu-devel@nongnu.org; Fri, 29 Nov 2019 07:41:14 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:27124 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iafaC-0001fm-CU for qemu-devel@nongnu.org; Fri, 29 Nov 2019 07:41:12 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1575031268; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=LefiRVZq6vvmGxdToinGL95lCi6FpxY8ErQNEKkjQns=; b=gKWHxVkmzsS3o3p84ec6jnZJZb1U2foiE5kjAA4kT0jcjJtOYRX4uECBo2uqL4koVGiwt0 0Qm/xS0MakWpeF8j2E9JKsRnqLH5txK3hGH1WgkVWPYexR+hW6C7KfYBfWmkb4wWDTXE5G 3ppa5IDvCPnLj0QjJ42p2DreHXhdUNQ= 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-45-gXJDuNDpPy-Lo_n_NRNMkA-1; Fri, 29 Nov 2019 07:41:05 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 70EF7100E378; Fri, 29 Nov 2019 12:41:04 +0000 (UTC) Received: from localhost (unknown [10.43.2.114]) by smtp.corp.redhat.com (Postfix) with ESMTP id 44528600CA; Fri, 29 Nov 2019 12:40:56 +0000 (UTC) Date: Fri, 29 Nov 2019 13:40:55 +0100 From: Igor Mammedov To: Eduardo Habkost Subject: Re: qom device lifecycle interaction with hotplug/hotunplug ? Message-ID: <20191129134055.08f27e7a@redhat.com> In-Reply-To: <20191128163358.GC14595@habkost.net> References: <20191128163358.GC14595@habkost.net> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: gXJDuNDpPy-Lo_n_NRNMkA-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 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: Damien Hedde , Peter Maydell , QEMU Developers , Stefan Hajnoczi , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, 28 Nov 2019 13:33:58 -0300 Eduardo Habkost wrote: > On Thu, Nov 28, 2019 at 04:00:06PM +0000, Peter Maydell wrote: > > Hi; this is a question which came up in Damien's reset series > > which I don't know the answer to: > > > > What is the interaction of the QOM device lifecycle (instance_init/realize/ > > unrealize/instance_finalize) with hotplug and hot-unplug ? I couldn't > > find any documentation of this but maybe I was looking in the wrong > > place... > > > > Looking at device_set_realized() it seems like we treat "realize" > > as meaning "and also do the hot-plug if this is a device we're > > trying to hotplug". On the other hand hot-unplug is I think the > > other way around: when we get a hot-unplug event we assume that > > it should also imply an "unrealize" (but just unrealizing doesn't > > auto-hot-unplug) ? > > Your description seems accurate, and I agree it is confusing. > > It would be more consistent if realized=true didn't plug the > device automatically, and qdev_device_add() asked the hotplug > handler to plug the device instead. agreed, it's confusing. But that would not allow to o = object_new() set props o.realize() reuse the same plug handlers. we potentially can convert it to device_add input arguments and then call qdev_device_add() instead, which would then handle plug handlers, not sure it's doable though. Other than that I don't have any ideas how to make it less confusing. > > Once a device is hot-unplugged (and thus unrealized) is it valid > > for it to be re-hot-plugged, or is the assumption that it's then > > destroyed and a fresh device is created if the user wants to plug > > something in again later ? Put another way, is it valid for a qdev > > device to see state transitions realize -> unrealize -> realize ? > > My interpretation is that this is valid in theory, but likely to > crash a large portion of our devices if we tried it. >