From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59271) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YWOhR-00007r-9Y for qemu-devel@nongnu.org; Fri, 13 Mar 2015 08:28:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YWOhM-0001Fc-Si for qemu-devel@nongnu.org; Fri, 13 Mar 2015 08:28:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60634) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YWOhM-0001FQ-JW for qemu-devel@nongnu.org; Fri, 13 Mar 2015 08:28:16 -0400 Date: Fri, 13 Mar 2015 12:28:08 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20150313122807.GG2486@work-vm> References: <1425883543-8852-1-git-send-email-zhang.zhanghailiang@huawei.com> <1425883543-8852-5-git-send-email-zhang.zhanghailiang@huawei.com> <5502C0C1.60903@redhat.com> <5502D728.5030904@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5502D728.5030904@redhat.com> Subject: Re: [Qemu-devel] [PATCH v4 4/4] migration: Expose 'cancelling' status to user List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: zhanghailiang , quintela@redhat.com, libvir-list@redhat.com, armbru@redhat.com, qemu-devel@nongnu.org, amit.shah@redhat.com, Paolo Bonzini , peter.huangpeng@huawei.com, lcapitulino@redhat.com * Eric Blake (eblake@redhat.com) wrote: > On 03/13/2015 04:49 AM, Paolo Bonzini wrote: > > > > > > On 09/03/2015 07:45, zhanghailiang wrote: > >> 'cancelling' status was introduced by commit 51cf4c1a, mainly to avoid a > >> possible start of a new migration process while the previous one still exists. > >> But we didn't expose this status to user, instead we returned the 'active' state. > >> > >> Here, we expose it to the user (such as libvirt), 'cancelling' status only > >> occurs for a short window before the migration aborts, so for users, > >> if they cancel a migration process, it will observe 'cancelling' status > >> occasionally. > >> > >> Testing revealed that with older libvirt (anything 1.2.13 or less) will > >> print an odd error message if the state is seen, but that the migration > >> is still properly cancelled. Newer libvirt will be patched to recognize > >> the new state without the odd error message. > >> > >> Signed-off-by: zhanghailiang > >> Reviewed-by: Eric Blake > >> Cc: libvir-list@redhat.com > > > > Why is this necessary? > > It simplifies qemu's job of reporting migration status information (qemu > is no longer maintaining one set of states internally and a different > set of states externally), and I already have the libvirt counterpart > patch ready to go to gracefully accept the new state name. Yes, it does make life simpler in the long run. (It does worry me a bit what happens to new qemu on old libvirt) Dave > -- > Eric Blake eblake redhat com +1-919-301-3266 > Libvirt virtualization library http://libvirt.org > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK