[Qemu-devel] Re: [PATCH 22/23] monitor: fix muxing

[Jan Kiszka <jan.kiszka@web.de>]

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Gerd Hoffmann wrote:
> make the mux driver send mux_in and mux_out events when switching
> focus while hooking up more handlers.
> 
> stop using CharDriverState->focus in monitor.c, track state using
> the mux events instead.  This also removes the implicit assumtion
> that a muxed monitor allways has mux channel 0.

Nice patch in the right direction, but it comes with a regression: When
you enable the monitor on mux'ed stdio via CTRL-A C, you don't get a
prompt until pressing some key.

> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  monitor.c   |   33 ++++++++++++++++++++++-----------
>  qemu-char.c |    3 +++
>  2 files changed, 25 insertions(+), 11 deletions(-)
> 
> diff --git a/monitor.c b/monitor.c
> index f5f4d0e..edf48f3 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -85,6 +85,8 @@ struct mon_fd_t {
>  
>  struct Monitor {
>      CharDriverState *chr;
> +    int mux_out;
> +    int reset_seen;
>      int flags;
>      int suspend_cnt;
>      uint8_t outbuf[1024];
> @@ -129,7 +131,7 @@ static int monitor_read_password(Monitor *mon, ReadLineFunc *readline_func,
>  
>  void monitor_flush(Monitor *mon)
>  {
> -    if (mon && mon->outbuf_index != 0 && mon->chr->focus == 0) {
> +    if (mon && mon->outbuf_index != 0 && !mon->mux_out) {
>          qemu_chr_write(mon->chr, mon->outbuf, mon->outbuf_index);
>          mon->outbuf_index = 0;
>      }
> @@ -3111,23 +3113,34 @@ static void monitor_event(void *opaque, int event)
>  
>      switch (event) {
>      case CHR_EVENT_MUX_IN:
> -        readline_restart(mon->rs);
> -        monitor_resume(mon);
> -        monitor_flush(mon);
> +        if (mon->reset_seen) {
> +            readline_restart(mon->rs);
> +            monitor_resume(mon);
> +            monitor_flush(mon);
> +        } else {
> +            mon->suspend_cnt = 0;
> +        }
> +        mon->mux_out = 0;
>          break;
>  
>      case CHR_EVENT_MUX_OUT:
> -        if (mon->suspend_cnt == 0)
> -            monitor_printf(mon, "\n");
> -        monitor_flush(mon);
> -        monitor_suspend(mon);
> +        if (mon->reset_seen) {
> +            if (mon->suspend_cnt == 0)
> +                monitor_printf(mon, "\n");
> +            monitor_flush(mon);
> +            monitor_suspend(mon);
> +        } else {
> +            mon->suspend_cnt++;
> +        }
> +        mon->mux_out = 1;
>          break;
>  
>      case CHR_EVENT_RESET:
>          monitor_printf(mon, "QEMU %s monitor - type 'help' for more "
>                         "information\n", QEMU_VERSION);
> -        if (mon->chr->focus == 0)
> +        if (!mon->mux_out)
>              readline_show_prompt(mon->rs);

Please add braces at this chance.

> +        mon->reset_seen = 1;
>          break;
>      }
>  }
> @@ -3155,8 +3168,6 @@ void monitor_init(CharDriverState *chr, int flags)
>  
>      mon->chr = chr;
>      mon->flags = flags;
> -    if (mon->chr->focus != 0)
> -        mon->suspend_cnt = 1; /* mux'ed monitors start suspended */
>      if (flags & MONITOR_USE_READLINE) {
>          mon->rs = readline_init(mon, monitor_find_completion);
>          monitor_read_command(mon, 0);
> diff --git a/qemu-char.c b/qemu-char.c
> index 2e71038..daa8587 100644
> --- a/qemu-char.c
> +++ b/qemu-char.c
> @@ -456,8 +456,11 @@ static void mux_chr_update_read_handler(CharDriverState *chr)
>          qemu_chr_add_handlers(d->drv, mux_chr_can_read, mux_chr_read,
>                                mux_chr_event, chr);
>      }
> +    if (-1 != chr->focus)
> +        mux_chr_send_event(d, chr->focus, CHR_EVENT_MUX_OUT);

{ }

>      chr->focus = d->mux_cnt;
>      d->mux_cnt++;
> +    mux_chr_send_event(d, chr->focus, CHR_EVENT_MUX_IN);
>  }
>  
>  static CharDriverState *qemu_chr_open_mux(CharDriverState *drv)

Jan


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