Re: [Qemu-devel] [PATCH 1/7] serial: add serial_chr_nonnull() to use the null backend when none provided

[Thomas Huth <thuth@redhat.com>]

On 31.08.2017 05:53, Philippe Mathieu-Daudé wrote:
> Suggested-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
>  include/hw/char/serial.h |  1 +
>  hw/char/serial.c         | 13 +++++++++++++
>  2 files changed, 14 insertions(+)
> 
> diff --git a/include/hw/char/serial.h b/include/hw/char/serial.h
> index c4daf11a14..96bccb39e1 100644
> --- a/include/hw/char/serial.h
> +++ b/include/hw/char/serial.h
> @@ -93,6 +93,7 @@ SerialState *serial_mm_init(MemoryRegion *address_space,
>                              hwaddr base, int it_shift,
>                              qemu_irq irq, int baudbase,
>                              Chardev *chr, enum device_endian end);
> +Chardev *serial_chr_nonnull(Chardev *chr);

Why do you need the prototype? Please make the function static if
possible (otherwise please add some rationale in the patch description).

>  /* serial-isa.c */
>  #define TYPE_ISA_SERIAL "isa-serial"
> diff --git a/hw/char/serial.c b/hw/char/serial.c
> index 9aec6c60d8..7a100db107 100644
> --- a/hw/char/serial.c
> +++ b/hw/char/serial.c
> @@ -1025,6 +1025,19 @@ static const MemoryRegionOps serial_mm_ops[3] = {
>      },
>  };
>  
> +Chardev *serial_chr_nonnull(Chardev *chr)
> +{
> +    static int serial_id;
> +    char *label;
> +
> +    label = g_strdup_printf("discarding-serial%d", serial_id++);
> +    chr = qemu_chr_new(label, "null");

That looks wrong - you're ignoring the input parameter and always open
the "null" device? Shouldn't there be a "if (chr) return chr;" in front
of this?

> +    assert(chr);
> +    g_free(label);
> +
> +    return chr;
> +}

 Thomas

PS: I think you should also merge the two patches together, they are
small enough.