From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wen Congyang Subject: Re: [PATCH v3 2/5] remus: resume immediately if libxl__xc_domain_save_done() completes Date: Fri, 15 Jan 2016 13:44:17 +0800 Message-ID: <56988731.5000206@cn.fujitsu.com> References: <1452235131-1861-1-git-send-email-wency@cn.fujitsu.com> <1452235131-1861-3-git-send-email-wency@cn.fujitsu.com> <1452270435.26438.44.camel@citrix.com> <56945984.9080600@cn.fujitsu.com> <1452766873.2185.9.camel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1452766873.2185.9.camel@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Ian Campbell , xen devel , Andrew Cooper Cc: Shriram Rajagopalan , Wei Liu , Changlong Xie , Ian Jackson , Yang Hongyang List-Id: xen-devel@lists.xenproject.org On 01/14/2016 06:21 PM, Ian Campbell wrote: > On Tue, 2016-01-12 at 09:40 +0800, Wen Congyang wrote: >> On 01/09/2016 12:27 AM, Ian Campbell wrote: >>> On Fri, 2016-01-08 at 14:38 +0800, Wen Congyang wrote: >>>> For example: if the secondary host is down, and we fail to send the >>>> data >>>> to >>>> the secondary host. xc_domain_save() returns 0. >>> >>> Just to be check: On failure in this way xc_domain_save() returns 0 >>> (i.e. >>> success)? >> >> Yes, it returns 0. I am not sure the return value is right. >> >>> >>>> So in the function >>>> libxl__xc_domain_save_done(), rc is 0(the helper program exits >>>> normally), >>>> and retval is 0(it is xc_domain_save()'s return value). In such case, >>>> we >>>> just need to complete the stream. >>>> >>>> Signed-off-by: Wen Congyang >>>> --- >>>> tools/libxl/libxl_stream_write.c | 13 +++++++++++-- >>>> 1 file changed, 11 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/tools/libxl/libxl_stream_write.c >>>> b/tools/libxl/libxl_stream_write.c >>>> index 80d9208..82e7719 100644 >>>> --- a/tools/libxl/libxl_stream_write.c >>>> +++ b/tools/libxl/libxl_stream_write.c >>>> @@ -354,8 +354,17 @@ void libxl__xc_domain_save_done(libxl__egc *egc, >>>> void *dss_void, >>>> * alive, and check_all_finished() may have torn it down around >>>> us. >>>> * If the stream is not still alive, we must not continue any >>>> work. >>>> */ >>>> - if (libxl__stream_write_inuse(stream)) >>>> - write_emulator_xenstore_record(egc, stream); >>>> + if (libxl__stream_write_inuse(stream)) { >>>> + if (dss->remus) >>>> + /* >>>> + * For remus, if libxl__xc_domain_save_done() completes, >>>> + * there was an error sending data to the secondary. >>>> + * Resume the primary ASAP. >>>> + */ >>>> + stream_complete(egc, stream, 0); >>> >>> Is there an indication to the caller that things have failed in this >>> way? >>> Would that information be of use to the caller? >> >> For remus, when we come here, something is wrong regardless of the return >> value. > > But does the caller know this? Can it tell. > >> >>> >>> Or does the called infer this has happened because >>> otherwise libxl_domain_remus_start is not supposed to return? >> >> Yes, libxl_domain_remus_start() should not return unless somethins is >> wrong. > > This really ought to be documented somewhere. libxl_domain_remus_start(): /* Point of no return */ libxl__remus_setup(egc, dss); return AO_INPROGRESS; Thanks Wen Congyang > > > > > . >