Re: [PATCH v1 6/9] chardev: add appropriate getting address

[Maxim Davydov]

On 3/30/22 14:32, Vladimir Sementsov-Ogievskiy wrote:
> 29.03.2022 00:15, Maxim Davydov wrote:
> > Attempt to get address after initialization shouldn't fail on assert in
> > the qapi automatically generated code. As a possible solution, it can
> > return null type.
>
> But at some point this address appears? May be we try to query it too 
> early, or we need some more initialization steps?
For example, query address after object_new_with_class(). Without the 
patch it triggers assert(). I tried to implement the same solution as in 
hw/ppc/spapr_drc.c:prop_get_fdt
> Isn't it better to report failure, when we try to query things that 
> are not yet initialized?
Yes, maybe it should set errp after visit_type_null. And it should be a 
common error for unrealized devices to fix the same problem with 
MemoryRegion, etc.
> > Signed-off-by: Maxim Davydov <maxim.davydov@openvz.org>
> > ---
> >   chardev/char-socket.c | 9 +++++++++
> >   1 file changed, 9 insertions(+)
> >
> > diff --git a/chardev/char-socket.c b/chardev/char-socket.c
> > index fab2d791d4..f851e3346b 100644
> > --- a/chardev/char-socket.c
> > +++ b/chardev/char-socket.c
> > @@ -33,6 +33,7 @@
> >   #include "qapi/clone-visitor.h"
> >   #include "qapi/qapi-visit-sockets.h"
> >   #include "qemu/yank.h"
> > +#include "qapi/qmp/qnull.h"
> >     #include "chardev/char-io.h"
> >   #include "chardev/char-socket.h"
> > @@ -1509,6 +1510,14 @@ char_socket_get_addr(Object *obj, Visitor *v, 
> > const char *name,
> >   {
> >       SocketChardev *s = SOCKET_CHARDEV(obj);
> >   +    QNull *null = NULL;
> > +
> > +    /* Return NULL type if getting addr was called after init */
> > +    if (!s->addr) {
> > +        visit_type_null(v, NULL, &null, errp);
> > +        return;
> > +    }
> > +
> >       visit_type_SocketAddress(v, name, &s->addr, errp);
> >   }
--
Best regards,
Maxim Davydov