From mboxrd@z Thu Jan  1 00:00:00 1970
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: [PATCH v9 09/25] tools/libx{l,
 c}: introduce should_checkpoint callback
Date: Tue, 26 Jan 2016 15:50:32 -0500
Message-ID: <20160126205032.GD27940@char.us.oracle.com>
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	<1451443075-27428-10-git-send-email-wency@cn.fujitsu.com>
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To: Wen Congyang <wency@cn.fujitsu.com>
Cc: Lars Kurth <lars.kurth@citrix.com>, Changlong Xie <xiecl.fnst@cn.fujitsu.com>, Wei Liu <wei.liu2@citrix.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>
List-Id: xen-devel@lists.xenproject.org

On Wed, Dec 30, 2015 at 10:37:39AM +0800, Wen Congyang wrote:
> Under COLO, we are doing checkpoint on demand, if this
> callback returns 1, we will take another checkpoint.

So 1 means OK.

> 0 indicates unexpected error.

Why not return an error?
> 
> Signed-off-by: Yang Hongyang <hongyang.yang@easystack.cn>
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> ---
>  tools/libxc/include/xenguest.h     | 18 ++++++++++++++++++
>  tools/libxl/libxl_save_msgs_gen.pl |  7 ++++---
>  2 files changed, 22 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/libxc/include/xenguest.h b/tools/libxc/include/xenguest.h
> index bd133af..88d6e13 100644
> --- a/tools/libxc/include/xenguest.h
> +++ b/tools/libxc/include/xenguest.h
> @@ -62,6 +62,15 @@ struct save_callbacks {
>       * 1: take another checkpoint */
>      int (*checkpoint)(void* data);
>  
> +    /*
> +     * Called after the checkpoint callback.
> +     *
> +     * returns:
> +     * 0: terminate checkpointing gracefully

checkpointing terminated gracefully

Why not return -EXX instead ?

> +     * 1: take another checkpoint