Re: [PATCH] serial COM: windows serial COM PollingFunc don't sleep

[Marc-André Lureau]

Hi Werner

On Tue, Aug 8, 2023 at 12:46 AM Werner de Carne <werner@carne.de> wrote:
>
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1802
> Signed-off-by: Werner de Carne <werner@carne.de>

This changes the polling callback to return 0 when I/O can't be
processed.  in util/main-loop.c, it results in an early break of
os_host_main_loop_wait().

How does that help?

thanks

> ---
>  chardev/char-win.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/chardev/char-win.c b/chardev/char-win.c
> index d4fb44c4dc..92a7016105 100644
> --- a/chardev/char-win.c
> +++ b/chardev/char-win.c
> @@ -28,7 +28,7 @@
>  #include "qapi/error.h"
>  #include "chardev/char-win.h"
>
> -static void win_chr_read(Chardev *chr, DWORD len)
> +static int win_chr_read(Chardev *chr, DWORD len)
>  {
>      WinChardev *s = WIN_CHARDEV(chr);
>      int max_size = qemu_chr_be_can_write(chr);
> @@ -40,7 +40,7 @@ static void win_chr_read(Chardev *chr, DWORD len)
>          len = max_size;
>      }
>      if (len == 0) {
> -        return;
> +        return 0;
>      }
>
>      ZeroMemory(&s->orecv, sizeof(s->orecv));
> @@ -56,6 +56,8 @@ static void win_chr_read(Chardev *chr, DWORD len)
>      if (size > 0) {
>          qemu_chr_be_write(chr, buf, size);
>      }
> +
> +    return size > 0 ? 1 : 0;
>  }
>
>  static int win_chr_serial_poll(void *opaque)
> @@ -67,8 +69,9 @@ static int win_chr_serial_poll(void *opaque)
>
>      ClearCommError(s->file, &comerr, &status);
>      if (status.cbInQue > 0) {
> -        win_chr_read(chr, status.cbInQue);
> -        return 1;
> +        if (win_chr_read(chr, status.cbInQue)) {
> +                       return 1;
> +               }
>      }
>      return 0;
>  }
> @@ -147,8 +150,9 @@ int win_chr_pipe_poll(void *opaque)
>
>      PeekNamedPipe(s->file, NULL, 0, NULL, &size, NULL);
>      if (size > 0) {
> -        win_chr_read(chr, size);
> -        return 1;
> +       if (win_chr_read(chr, size)) {
> +                       return 1;
> +               }
>      }
>      return 0;
>  }
> --
> 2.28.0.windows.1
>
>


-- 
Marc-André Lureau