Re: [Qemu-devel] [PATCH 3/8] qemu-char: Add fe_open tracking

[Anthony Liguori <anthony@codemonkey.ws>]

Hans de Goede <hdegoede@redhat.com> writes:

> Add tracking of the fe_open state to struct CharDriverState.
>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  include/char/char.h | 1 +
>  qemu-char.c         | 2 ++
>  2 files changed, 3 insertions(+)
>
> diff --git a/include/char/char.h b/include/char/char.h
> index dd8f39a..3174575 100644
> --- a/include/char/char.h
> +++ b/include/char/char.h
> @@ -75,6 +75,7 @@ struct CharDriverState {
>      char *label;
>      char *filename;
>      int be_open;
> +    int fe_open;
>      int avail_connections;
>      QemuOpts *opts;
>      QTAILQ_ENTRY(CharDriverState) next;
> diff --git a/qemu-char.c b/qemu-char.c
> index 55795d7..554d72f 100644
> --- a/qemu-char.c
> +++ b/qemu-char.c
> @@ -3385,6 +3385,7 @@ void qemu_chr_fe_set_echo(struct CharDriverState *chr, bool echo)
>  
>  void qemu_chr_fe_open(struct CharDriverState *chr)
>  {
> +    chr->fe_open = 1;
>      if (chr->chr_guest_open) {
>          chr->chr_guest_open(chr);
>      }
> @@ -3392,6 +3393,7 @@ void qemu_chr_fe_open(struct CharDriverState *chr)
>  
>  void qemu_chr_fe_close(struct CharDriverState *chr)
>  {
> +    chr->fe_open = 0;

Even though this gets rewritten later on, you should avoid calling the
callback when open is called when fe_open=1.  Something like

if (!chr->fe_open) {
    return;
}

Then later when this becomes set_fe_open() the backend doesn't need to
deal with double open/close.

Regards,

Anthony Liguori

>      if (chr->chr_guest_close) {
>          chr->chr_guest_close(chr);
>      }
> -- 
> 1.8.1.4