Re: [Qemu-devel] [PATCH 7/7] block: dump to monitor for bdrv_snapshot_dump() and bdrv_image_info_dump()

[Luiz Capitulino]

On Thu, 16 May 2013 10:22:09 +0800
Wenchao Xia <address@hidden> wrote:

> 于 2013-5-15 20:28, Luiz Capitulino 写道:
> > On Wed, 15 May 2013 10:10:37 +0800
> > Wenchao Xia <address@hidden> wrote:
> >
> >> 于 2013-5-6 21:22, Luiz Capitulino 写道:
> >>> On Mon, 06 May 2013 10:09:43 +0800
> >>> Wenchao Xia <address@hidden> wrote:
> >>>
> >>>> 于 2013-5-3 10:51, Wenchao Xia 写道:
> >>>>> 于 2013-5-2 20:02, Luiz Capitulino 写道:
> >>>>>> On Thu, 02 May 2013 10:05:08 +0800
> >>>>>> Wenchao Xia <address@hidden> wrote:
> >>>>>>
> >>>>>>> 于 2013-4-30 3:05, Luiz Capitulino 写道:
> >>>>>>>> On Fri, 26 Apr 2013 16:46:57 +0200
> >>>>>>>> Stefan Hajnoczi <address@hidden> wrote:
> >>>>>>>>
> >>>>>>>>> On Fri, Apr 26, 2013 at 05:31:15PM +0800, Wenchao Xia wrote:
> >>>>>>>>>> @@ -2586,10 +2585,12 @@ void do_info_snapshots(Monitor *mon, const
> >>>>>>>>>> QDict *qdict)
> >>>>>>>>>>          }
> >>>>>>>>>>
> >>>>>>>>>>          if (total > 0) {
> >>>>>>>>>> -        monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf,
> >>>>>>>>>> sizeof(buf), NULL));
> >>>>>>>>>> +        bdrv_snapshot_dump(NULL);
> >>>>>>>>>> +        monitor_printf(mon, "\n");
> >>>>>>>>>
> >>>>>>>>> Luiz: any issue with mixing monitor_printf(mon) and
> >>>>>>>>> monitor_vprintf(cur_mon) calls?  I guess there was a reason for
> >>>>>>>>> explicitly passing mon instead of relying on cur_mon.
> >>>>>>>>
> >>>>>>>> where are they being mixed?
> >>>>>>>>
> >>>>>>>       bdrv_snapshot_dump() used a global variable "cur_mon" inside,
> >>>>>>> instead
> >>>>>>> of let caller pass in a explicit montior* "mon", I guess that is the
> >>>>>>> question.
> >>>>>>
> >>>>>> I'd have to see the code to tell, but yes, what Stefan described is the
> >>>>>> best practice for the Monitor.
> >>>>>>
> >>>>>      I think this would not be a problem until qemu wants more than one
> >>>>> human monitor console, and then we may require a data structure to tell
> >>>>> where to output the string: stdout, *mon, or even stderr, and
> >>>>> error_printf() also need to be changed.
> >>>>>
> >>>>      Luiz, what is your idea? I'd like to respin v2 if no issues for it.
> >>>
> >>> As I said before, I'd have to see the code to tell. But answering your 
> >>> comment,
> >>> the code does support multiple monitors.
> >>>
> >> Hi Luiz,
> >>     Sorry to ask again, do you think method above is OK now, waiting for
> >> your confirm.
> >
> > Can you point me to the code in question?
> >
> Sure, it is
> 
> +
> +/*
> + * Print to current monitor if we have one, else to stdout. It is 
> similar with
> + * error_printf().
> + * TODO just like error_vprintf()
> + */
> +void message_printf(const char *fmt, ...)
> +{
> +    va_list ap;
> +
> +    va_start(ap, fmt);
> +    if (cur_mon) {
> +        monitor_vprintf(cur_mon, fmt, ap);
> +    } else {
> +        vfprintf(stdout, fmt, ap);
> +    }
> +    va_end(ap);
> +}
> 
>    This function used global variable cur_mon instead of input parameter,
> similar to error_printf().

Why do you need it? Why can't you you use error_printf() for example?