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From: Wen Congyang <wency@cn.fujitsu.com>
To: Wei Liu <wei.liu2@citrix.com>
Cc: Lars Kurth <lars.kurth@citrix.com>,
	Changlong Xie <xiecl.fnst@cn.fujitsu.com>,
	Ian Campbell <ian.campbell@citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Jiang Yunhong <yunhong.jiang@intel.com>,
	Ian Jackson <ian.jackson@eu.citrix.com>,
	xen devel <xen-devel@lists.xen.org>,
	Dong Eddie <eddie.dong@intel.com>,
	Gui Jianfeng <guijianfeng@cn.fujitsu.com>,
	Shriram Rajagopalan <rshriram@cs.ubc.ca>,
	Yang Hongyang <hongyang.yang@easystack.cn>
Subject: Re: [PATCH v10 10/31] tools/libxl: add back channel support to write stream
Date: Fri, 26 Feb 2016 10:11:27 +0800	[thread overview]
Message-ID: <56CFB44F.5040607@cn.fujitsu.com> (raw)
In-Reply-To: <20160225155456.GG4235@citrix.com>

On 02/25/2016 11:54 PM, Wei Liu wrote:
> On Mon, Feb 22, 2016 at 10:52:14AM +0800, Wen Congyang wrote:
>> Add back channel support to write stream. If the write stream is
>> a back channel stream, this means the write stream is used by
>> Secondary to send some records back.
>>
>> Signed-off-by: Yang Hongyang <hongyang.yang@easystack.cn>
>> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
>> ---
>>  tools/libxl/libxl_dom_save.c     |  1 +
>>  tools/libxl/libxl_internal.h     |  1 +
>>  tools/libxl/libxl_stream_write.c | 26 ++++++++++++++++++++------
>>  3 files changed, 22 insertions(+), 6 deletions(-)
>>
>> diff --git a/tools/libxl/libxl_dom_save.c b/tools/libxl/libxl_dom_save.c
>> index 72b61c7..18946c5 100644
>> --- a/tools/libxl/libxl_dom_save.c
>> +++ b/tools/libxl/libxl_dom_save.c
>> @@ -404,6 +404,7 @@ void libxl__domain_save(libxl__egc *egc, libxl__domain_save_state *dss)
>>      dss->sws.ao  = dss->ao;
>>      dss->sws.dss = dss;
>>      dss->sws.fd  = dss->fd;
>> +    dss->sws.back_channel = false;
>>      dss->sws.completion_callback = stream_done;
>>  
>>      libxl__stream_write_start(egc, &dss->sws);
>> diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
>> index 3d3e8e8..e02e554 100644
>> --- a/tools/libxl/libxl_internal.h
>> +++ b/tools/libxl/libxl_internal.h
>> @@ -3044,6 +3044,7 @@ struct libxl__stream_write_state {
>>      libxl__ao *ao;
>>      libxl__domain_save_state *dss;
>>      int fd;
>> +    bool back_channel;
>>      void (*completion_callback)(libxl__egc *egc,
>>                                  libxl__stream_write_state *sws,
>>                                  int rc);
>> diff --git a/tools/libxl/libxl_stream_write.c b/tools/libxl/libxl_stream_write.c
>> index f6ea55d..5379126 100644
>> --- a/tools/libxl/libxl_stream_write.c
>> +++ b/tools/libxl/libxl_stream_write.c
>> @@ -49,6 +49,13 @@
>>   *  - if (hvm)
>>   *      - Emulator context record
>>   *  - Checkpoint end record
>> + *
>> + * For back channel stream:
>> + * - libxl__stream_write_start()
>> + *    - Set up the stream to running state
>> + *
>> + * - Add a new API to write the record. When the record is written
>> + *   out, call stream->checkpoint_callback() to return.
> 
> What does this mean? Which new API?

The next patch introduces this API. The commits is very old.

I think I can merge these two patches into one patch.

> 
>>   */
>>  
>>  /* Success/error/cleanup handling. */
>> @@ -225,6 +232,15 @@ void libxl__stream_write_start(libxl__egc *egc,
>>  
>>      stream->running = true;
>>  
>> +    dc->ao        = ao;
>> +    dc->readfd    = -1;
>> +    dc->copywhat  = "save v2 stream";
>> +    dc->writefd   = stream->fd;
>> +    dc->maxsz     = -1;
>> +
>> +    if (stream->back_channel)
>> +        return;
>> +
> 
> There seems to be very subtle change of behaviour.
> 
> Before this patch, the dc->* are not set until the emulator check is
> done. With this path, it is possible in the normal case some of the
> fields are initialised in the error path.
> 
> I think this is OK given the callbacks in the upper layer and in
> the writer don't rely on those fields to clean up. Just one thing to
> note.
> 
> That said, I suggest you move all initialisation of dc->* in one place.

OK, I will do it.

> 
>>      if (dss->type == LIBXL_DOMAIN_TYPE_HVM) {
>>          stream->device_model_version =
>>              libxl__device_model_version_running(gc, dss->domid);
>> @@ -249,12 +265,7 @@ void libxl__stream_write_start(libxl__egc *egc,
>>          stream->emu_sub_hdr.index = 0;
>>      }
>>  
>> -    dc->ao        = ao;
>> -    dc->readfd    = -1;
>>      dc->writewhat = "stream header";
>> -    dc->copywhat  = "save v2 stream";
>> -    dc->writefd   = stream->fd;
>> -    dc->maxsz     = -1;
>>      dc->callback  = stream_header_done;
>>  
>>      rc = libxl__datacopier_start(dc);
>> @@ -279,6 +290,7 @@ void libxl__stream_write_start_checkpoint(libxl__egc *egc,
>>  {
>>      assert(stream->running);
>>      assert(!stream->in_checkpoint);
>> +    assert(!stream->back_channel);
>>      stream->in_checkpoint = true;
>>  
>>      write_emulator_xenstore_record(egc, stream);
>> @@ -590,7 +602,9 @@ static void stream_done(libxl__egc *egc,
>>          libxl__carefd_close(stream->emu_carefd);
>>      free(stream->emu_body);
>>  
>> -    check_all_finished(egc, stream, rc);
>> +    if (!stream->back_channel)
>> +        /* back channel stream doesn't have save helper */
>> +        check_all_finished(egc, stream, rc);
> 
> Though it doesn't have helper, do you not need to check if the back
> channel stream itself is OK? The comment itself doesn't seem to justify
> this change.

What do you want to check? assert(!stream->shs) or assert(!libxl__stream_write_inuse(stream))?

Thanks
Wen Congyang

> 
> Wei.
> 
>>  }
>>  
>>  static void checkpoint_done(libxl__egc *egc,
>> -- 
>> 2.5.0
>>
>>
>>
>>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@lists.xen.org
>> http://lists.xen.org/xen-devel
> 
> 
> .
> 




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  reply	other threads:[~2016-02-26  2:11 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-22  2:52 [PATCH v10 00/31] COarse-grain LOck-stepping Virtual Machines for Non-stop Service Wen Congyang
2016-02-22  2:52 ` [PATCH v10 01/31] tools/libxl: introduce libxl__domain_restore_device_model to load qemu state Wen Congyang
2016-02-25 15:53   ` Wei Liu
2016-02-26  1:55     ` Wen Congyang
2016-02-22  2:52 ` [PATCH v10 02/31] tools/libxl: introduce libxl__domain_common_switch_qemu_logdirty() Wen Congyang
2016-02-22  2:52 ` [PATCH v10 03/31] tools/libxl: Add back channel to allow migration target send data back Wen Congyang
2016-02-22  2:52 ` [PATCH v10 04/31] tools/libxl: Introduce new helper function dup_fd_helper() Wen Congyang
2016-02-25 15:53   ` Wei Liu
2016-02-22  2:52 ` [PATCH v10 05/31] tools/libx{l, c}: add back channel to libxc Wen Congyang
2016-02-25 15:54   ` Wei Liu
2016-02-22  2:52 ` [PATCH v10 06/31] docs: add colo readme Wen Congyang
2016-02-25 15:54   ` Wei Liu
2016-02-22  2:52 ` [PATCH v10 07/31] docs/libxl: Introduce CHECKPOINT_CONTEXT to support migration v2 colo streams Wen Congyang
2016-02-25 15:54   ` Wei Liu
2016-02-26  1:59     ` Wen Congyang
2016-02-22  2:52 ` [PATCH v10 08/31] libxc/migration: Specification update for DIRTY_PFN_LIST records Wen Congyang
2016-02-22  2:52 ` [PATCH v10 09/31] libxc/migration: export read_record for common use Wen Congyang
2016-02-22  2:52 ` [PATCH v10 10/31] tools/libxl: add back channel support to write stream Wen Congyang
2016-02-25 15:54   ` Wei Liu
2016-02-26  2:11     ` Wen Congyang [this message]
2016-03-02 15:02       ` Wei Liu
2016-03-03  1:25         ` Wen Congyang
2016-02-22  2:52 ` [PATCH v10 11/31] tools/libxl: write checkpoint_state records into the stream Wen Congyang
2016-02-22  2:52 ` [PATCH v10 12/31] tools/libxl: add back channel support to read stream Wen Congyang
2016-02-25 15:54   ` Wei Liu
2016-02-26  2:16     ` Wen Congyang
2016-03-02 15:03       ` Wei Liu
2016-02-22  2:52 ` [PATCH v10 13/31] tools/libxl: handle checkpoint_state records in a libxl migration v2 " Wen Congyang
2016-02-22  2:52 ` [PATCH v10 14/31] tools/libx{l, c}: introduce wait_checkpoint callback Wen Congyang
2016-02-22  2:52 ` [PATCH v10 15/31] tools/libx{l, c}: add postcopy/suspend callback to restore side Wen Congyang
2016-02-22  2:52 ` [PATCH v10 16/31] secondary vm suspend/resume/checkpoint code Wen Congyang
2016-02-25 15:56   ` Wei Liu
2016-02-26  2:30     ` Wen Congyang
2016-03-01 10:06     ` Wen Congyang
2016-02-22  2:52 ` [PATCH v10 17/31] primary " Wen Congyang
2016-02-25 15:57   ` Wei Liu
2016-02-26  2:32     ` Wen Congyang
2016-02-22  2:52 ` [PATCH v10 18/31] libxc/restore: support COLO restore Wen Congyang
2016-02-25 15:57   ` Wei Liu
2016-02-26  2:33     ` Wen Congyang
2016-02-22  2:52 ` [PATCH v10 19/31] libxc/restore: send dirty pfn list to primary when checkpoint under colo Wen Congyang
2016-02-22  2:52 ` [PATCH v10 20/31] send store gfn and console gfn to xl before resuming secondary vm Wen Congyang
2016-02-22  2:52 ` [PATCH v10 21/31] libxc/save: support COLO save Wen Congyang
2016-02-25 15:58   ` Wei Liu
2016-02-26  2:35     ` Wen Congyang
2016-02-22  2:52 ` [PATCH v10 22/31] implement the cmdline for COLO Wen Congyang
2016-03-02 15:03   ` Wei Liu
2016-03-03  1:30     ` Wen Congyang
2016-02-22  2:52 ` [PATCH v10 23/31] COLO: introduce new API to prepare/start/do/get_error/stop replication Wen Congyang
2016-03-02 15:03   ` Wei Liu
2016-02-22  2:52 ` [PATCH v10 24/31] Support colo mode for qemu disk Wen Congyang
2016-03-02 15:04   ` Wei Liu
2016-03-03  1:40     ` Wen Congyang
2016-02-22  2:52 ` [PATCH v10 25/31] COLO: use qemu block replication Wen Congyang
2016-03-02 15:03   ` Wei Liu
2016-02-22  2:52 ` [PATCH v10 26/31] COLO proxy: implement setup/teardown of COLO proxy module Wen Congyang
2016-03-02 15:04   ` Wei Liu
2016-03-11 22:25   ` Konrad Rzeszutek Wilk
2016-03-14  9:13     ` Wen Congyang
2016-03-22  3:40       ` Changlong Xie
2016-02-22  2:52 ` [PATCH v10 27/31] COLO proxy: preresume, postresume and checkpoint Wen Congyang
2016-03-02 15:04   ` Wei Liu
2016-02-22  2:52 ` [PATCH v10 28/31] COLO nic: implement COLO nic subkind Wen Congyang
2016-03-02 15:04   ` Wei Liu
2016-02-22  2:52 ` [PATCH v10 29/31] setup and control colo proxy on primary side Wen Congyang
2016-02-22  2:52 ` [PATCH v10 30/31] setup and control colo proxy on secondary side Wen Congyang
2016-02-22  2:52 ` [PATCH v10 31/31] cmdline switches and config vars to control colo-proxy Wen Congyang
2016-03-02 15:05   ` Wei Liu
2016-03-03  1:41     ` Wen Congyang
2016-02-25 16:05 ` [PATCH v10 00/31] COarse-grain LOck-stepping Virtual Machines for Non-stop Service Wei Liu

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