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 17:54:47 +0800 Message-ID: <5698C1E7.2020407@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> <56988731.5000206@cn.fujitsu.com> <1452851323.32341.42.camel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1452851323.32341.42.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 01/15/2016 05:48 PM, Ian Campbell wrote: > On Fri, 2016-01-15 at 13:44 +0800, Wen Congyang wrote: >> 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; > > This is (obviously) not documentation. OK, I will update the comment. Thanks Wen Congyang > > > > . >