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 16:09:50 -0500
Message-ID: <20160126210950.GA28211@char.us.oracle.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 Tue, Jan 26, 2016 at 03:50:32PM -0500, Konrad Rzeszutek Wilk wrote:
> 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

Also perhaps the function instead of 'should_checkpoint' should just be
called 'checkpoint' or 'do_checkpoint' ?