From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54077) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZkVJf-0003VR-Rf for qemu-devel@nongnu.org; Fri, 09 Oct 2015 06:54:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZkVJa-0003QW-O1 for qemu-devel@nongnu.org; Fri, 09 Oct 2015 06:54:23 -0400 Received: from e06smtp12.uk.ibm.com ([195.75.94.108]:58708) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZkVJa-0003QL-Fm for qemu-devel@nongnu.org; Fri, 09 Oct 2015 06:54:18 -0400 Received: from localhost by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 9 Oct 2015 11:54:16 +0100 Received: from b06cxnps3074.portsmouth.uk.ibm.com (d06relay09.portsmouth.uk.ibm.com [9.149.109.194]) by d06dlp03.portsmouth.uk.ibm.com (Postfix) with ESMTP id 8C5731B0805F for ; Fri, 9 Oct 2015 11:54:17 +0100 (BST) Received: from d06av11.portsmouth.uk.ibm.com (d06av11.portsmouth.uk.ibm.com [9.149.37.252]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t99AsEtR34668604 for ; Fri, 9 Oct 2015 10:54:14 GMT Received: from d06av11.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av11.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t99AsEVJ023446 for ; Fri, 9 Oct 2015 04:54:14 -0600 Date: Fri, 9 Oct 2015 12:54:09 +0200 From: Greg Kurz Message-ID: <20151009125409.2bd2912a@bahia.local> In-Reply-To: <20151009103639-mutt-send-email-mst@redhat.com> References: <20151005090710.20420.26941.stgit@bahia.huguette.org> <20151005090722.20420.71571.stgit@bahia.huguette.org> <20151006080914.GB19089@stefanha-thinkpad> <87pp0r12qz.fsf@linux.vnet.ibm.com> <20151009092349.16dc882c@bahia.local> <20151009103639-mutt-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 2/3] virtio-9p: add unrealize handler List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: Stefan Hajnoczi , "Aneesh Kumar K.V" , qemu-devel@nongnu.org On Fri, 9 Oct 2015 10:36:56 +0300 "Michael S. Tsirkin" wrote: > On Fri, Oct 09, 2015 at 09:23:49AM +0200, Greg Kurz wrote: > > On Wed, 07 Oct 2015 14:20:28 +0530 > > "Aneesh Kumar K.V" wrote: > > > > > Stefan Hajnoczi writes: > > > > > > > On Mon, Oct 05, 2015 at 11:07:23AM +0200, Greg Kurz wrote: > > > >> If the user tries to hot unplug a virtio-9p device, it seems to succeed but > > > >> in fact: > > > >> - virtio-9p coroutines thread pool and async queue are leaked > > > >> - QEMU crashes in virtio_vmstate_change() if the user tries to live migrate > > > >> > > > >> This patch brings hot unplug support to virtio-9p-device. It fixes both > > > >> above issues. > > > >> > > > >> Signed-off-by: Greg Kurz > > > >> --- > > > >> hw/9pfs/virtio-9p-device.c | 12 ++++++++++++ > > > >> 1 file changed, 12 insertions(+) > > > > > > > > What happens to in-flight I/O requests? We cannot assume that the guest > > > > driver quiesces the device. > > > > > > We enable migration blocker when we have an active mount. So if we get > > > here, that should indicate no active 9p mounts. > > > > > > -aneesh > > > > Oops.. Stefan is talking about hot-unplug versus in-flight requests... not > > about migration. And there is no such thing as a hot-unplug blocker... > > If unplug request fails, that should be enough. > Like setting @hotpluggable to false for the virtio-9p-pci class ? I see no other way for the unplug request to fail... but I will happily accept all suggestions :) -- Greg