Re: [Qemu-devel] [PATCH] monitor: accept input on resume

[Marc-André Lureau]

Hi

On Tue, Jul 31, 2018 at 1:30 PM, Markus Armbruster <address@hidden> wrote:
> Marc-André Lureau <address@hidden> writes:
>
>> A chardev may stop trying to write if the associated can_read()
>> callback returned 0. This happens when the monitor is suspended.
>> The frontend is supposed to call qemu_chr_fe_accept_input() when it is
>> ready to accept data again.
>>
>> Signed-off-by: Marc-André Lureau <address@hidden>
>
> Impact?

I have observed the issue with a spice port, all pending commands
aren't flushed. Most chardev don't use the accept_input() callback,
and instead poll regularly, like char-socket.c:tcp_chr_read_poll()

>
> Is this to be considered for 3.0?

This is not a regression, afaik, and doesn't impact common monitor
chardev. So it could be delayed. But it's also a small fix for Spice
chardev that shouldn't create regression, so it should be fine for
3.0.

thanks

>
>> ---
>>  monitor.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/monitor.c b/monitor.c
>> index d580c5a79c..e1a14e02cf 100644
>> --- a/monitor.c
>> +++ b/monitor.c
>> @@ -4412,6 +4412,7 @@ void monitor_resume(Monitor *mon)
>>              assert(mon->rs);
>>              readline_show_prompt(mon->rs);
>>          }
>> +        qemu_chr_fe_accept_input(&mon->chr);
>>      }
>>      trace_monitor_suspend(mon, -1);
>>  }
>



-- 
Marc-André Lureau