Re: [Qemu-devel] [RFC][PATCH 01/16 v6] monitor: introduce qemu_suspend_monitor()/qemu_resume_monitor()

[Jan Kiszka]

On 2012-02-15 03:54, Wen Congyang wrote:
> At 02/15/2012 12:19 AM, Jan Kiszka Wrote:
>> On 2012-02-09 04:19, Wen Congyang wrote:
>>> Sync command needs these two APIs to suspend/resume monitor.
>>>
>>> Signed-off-by: Wen Congyang <address@hidden>
>>> ---
>>>  monitor.c |   27 +++++++++++++++++++++++++++
>>>  monitor.h |    2 ++
>>>  2 files changed, 29 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/monitor.c b/monitor.c
>>> index 11639b1..7e72739 100644
>>> --- a/monitor.c
>>> +++ b/monitor.c
>>> @@ -4442,6 +4442,26 @@ static void monitor_command_cb(Monitor *mon, const 
>>> char *cmdline, void *opaque)
>>>      monitor_resume(mon);
>>>  }
>>>  
>>> +int qemu_suspend_monitor(const char *fmt, ...)
>>> +{
>>> +    int ret;
>>> +
>>> +    if (cur_mon) {
>>> +        ret = monitor_suspend(cur_mon);
>>> +    } else {
>>> +        ret = -ENOTTY;
>>> +    }
>>> +
>>> +    if (ret < 0 && fmt) {
>>> +        va_list ap;
>>> +        va_start(ap, fmt);
>>> +        monitor_vprintf(cur_mon, fmt, ap);
>>> +        va_end(ap);
>>> +    }
>>> +
>>> +    return ret;
>>> +}
>>> +
>>>  int monitor_suspend(Monitor *mon)
>>>  {
>>>      if (!mon->rs)
>>> @@ -4450,6 +4470,13 @@ int monitor_suspend(Monitor *mon)
>>>      return 0;
>>>  }
>>>  
>>> +void qemu_resume_monitor(void)
>>> +{
>>> +    if (cur_mon) {
>>> +        monitor_resume(cur_mon);
>>> +    }
>>> +}
>>> +
>>>  void monitor_resume(Monitor *mon)
>>>  {
>>>      if (!mon->rs)
>>> diff --git a/monitor.h b/monitor.h
>>> index 58109af..60a1e17 100644
>>> --- a/monitor.h
>>> +++ b/monitor.h
>>> @@ -46,7 +46,9 @@ int monitor_cur_is_qmp(void);
>>>  void monitor_protocol_event(MonitorEvent event, QObject *data);
>>>  void monitor_init(CharDriverState *chr, int flags);
>>>  
>>> +int qemu_suspend_monitor(const char *fmt, ...) GCC_FMT_ATTR(1, 2);
>>>  int monitor_suspend(Monitor *mon);
>>> +void qemu_resume_monitor(void);
>>>  void monitor_resume(Monitor *mon);
>>>  
>>>  int monitor_read_bdrv_key_start(Monitor *mon, BlockDriverState *bs,
>>
>> I don't see any added value in this API, specifically as it is built on
>> top of cur_mon. Just use the existing services like the migration code
>> does. If you properly pass down the monitor reference from the command
>> to the suspend and store what monitor you suspended, all should be fine.
> 
> This API is like qemu_get_fd() which is not merged into upstream qemu.
> I need this API because I cannot use monitor in qapi command.

OK, then I need to comment on that approach. QMP looks flawed here.
Either you have a need for a Monitor object (or a generic HMP/QMP
context), then you also have a handle. Or your don't, then you do not
need monitor suspend/resume or get_fd as well.

Jan

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