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Date: Tue, 19 Mar 2013 15:45:05 +0100
From: Laszlo Ersek <lersek@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] fix monitor
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To: Gerd Hoffmann <kraxel@redhat.com>
Cc: amit.shah@redhat.com, Luiz Capitulino <lcapitulino@redhat.com>, qemu-devel@nongnu.org, anthony@codemonkey.ws, Markus Armbruster <armbru@redhat.com>

On 03/19/13 15:04, Gerd Hoffmann wrote:
> chardev flow control broke monitor, fix it by adding watch support.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
> v2: fix tyops

Well played, Sir :)

> ---
>  monitor.c |   23 +++++++++++++++++++++--
>  1 file changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/monitor.c b/monitor.c
> index 112e920..74807f9 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -261,11 +261,30 @@ int monitor_read_password(Monitor *mon, ReadLineFunc *readline_func,
>      }
>  }
>  
> +static gboolean monitor_unblocked(GIOChannel *chan, GIOCondition cond,
> +                                  void *opaque)
> +{
> +    monitor_flush(opaque);
> +    return FALSE;
> +}
> +
>  void monitor_flush(Monitor *mon)
>  {
> +    int rc;
> +
>      if (mon && mon->outbuf_index != 0 && !mon->mux_out) {
> -        qemu_chr_fe_write(mon->chr, mon->outbuf, mon->outbuf_index);
> -        mon->outbuf_index = 0;
> +        rc = qemu_chr_fe_write(mon->chr, mon->outbuf, mon->outbuf_index);
> +        if (rc == mon->outbuf_index) {
> +            /* all flushed */
> +            mon->outbuf_index = 0;
> +            return;
> +        }
> +        if (rc > 0) {
> +            /* partial write */
> +            memmove(mon->outbuf, mon->outbuf + rc, mon->outbuf_index - rc);
> +            mon->outbuf_index -= rc;
> +        }
> +        qemu_chr_fe_add_watch(mon->chr, G_IO_OUT, monitor_unblocked, mon);
>      }
>  }
>  
> 

Looks good to me.

Should we maybe forego (re)installing the (new) watch when rc<0?
(Especially because on a persistent error the fd might immediately
report writability.)

Laszlo