From: Wei Liu <wei.liu2@citrix.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Olaf Hering <olaf@aepfle.de>,
Changlong Xie <xiecl.fnst@cn.fujitsu.com>,
Wei Liu <wei.liu2@citrix.com>,
Wen Congyang <wency@cn.fujitsu.com>,
Ian Jackson <Ian.Jackson@eu.citrix.com>,
Xen-devel <xen-devel@lists.xen.org>,
Yang Hongyang <hongyang.yang@easystack.cn>
Subject: Re: [PATCH for-4.7] tools/libxl: Fix legacy migration following COLO backchannel breakage
Date: Fri, 15 Apr 2016 10:00:55 +0100 [thread overview]
Message-ID: <20160415090055.GS18652@citrix.com> (raw)
In-Reply-To: <1460663655-8226-1-git-send-email-andrew.cooper3@citrix.com>
On Thu, Apr 14, 2016 at 08:54:15PM +0100, Andrew Cooper wrote:
> c/s f5d947bf1b "tools/libxl: add back channel support to read stream"
> made a bogus adjustment to libxl__stream_read_start(), including
> removing the comment hinting at what was going on, which breaks
> conversion of a legacy migration stream.
>
> Symptoms look like:
>
> root@anonymi:~ # xl migrate domU host
> migration target: Ready to receive domain.
> Saving to migration stream new xl format (info 0x1/0x0/2677)
> xc: error: error polling suspend notification channel: -1: Internal error
> Loading new save file <incoming migration stream> (new xl fmt info 0x1/0x0/2677)
> Savefile contains xl domain config in JSON format
> Parsing config from <saved>
> libxl: error: libxl_stream_read.c:327:stream_header_done: Invalid ident: expected 0x4c6962786c466d74, got 0x01f00f0000000000
> libxl: error: libxl_utils.c:430:libxl_read_exactly: file/stream truncated reading ipc msg header from domain 1 save/restore helper stdout pipe
>
> The adjustment is not required for backchannel support (as there is no
> interaction between back channels and legacy conversion), and caused
> stream->fd to be latched in the datacopier before legacy conversion
> substitutes it for the fd which is the output of the conversion script.
>
> This causes libxl to consume data from the legacy stream rather than the
> v2 stream, and for the conversion script to encounter an error as the
> legacy stream appears to skip ahead.
>
> Undo the adjustments to libxl__stream_read_start(), and introduce a
> better description of what is going on. Introduce some extra assertions
> to try and catch similar breakage in the future.
>
> Reported-by: Olaf Hering <olaf@aepfle.de>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>
Thank you for fixing this.
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next prev parent reply other threads:[~2016-04-15 9:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-14 19:54 [PATCH for-4.7] tools/libxl: Fix legacy migration following COLO backchannel breakage Andrew Cooper
2016-04-15 0:43 ` Wen Congyang
2016-04-15 9:00 ` Wei Liu [this message]
2016-04-15 11:02 ` Ian Jackson
2016-04-15 9:01 ` Olaf Hering
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