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

[Marc-André Lureau]

Hi

On Thu, Aug 31, 2017 at 7:20 AM Thomas Huth <address@hidden> wrote:

> On 31.08.2017 05:53, Philippe Mathieu-Daudé wrote:
> > Suggested-by: Peter Maydell <address@hidden>
> > Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> > ---
> >  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).
>

It's being used from other units in following patches


> >  /* 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?
>

I think its missing too.

The function name and usage isn't obvious. I would rather see the caller
use "chr ?: serial_chr_null()" rather than "serial_chr_nonnull(chr)".


-- 
Marc-André Lureau