Re: [PATCH] qom/object: Display more helpful message when an interface is missing

[Paolo Bonzini <pbonzini@redhat.com>]

On 18/01/20 17:23, Philippe Mathieu-Daudé wrote:
> When adding new devices implementing QOM interfaces, we might
> forgot to add the Kconfig dependency that pulls the required
> objects in when building.
> 
> Since QOM dependencies are resolved at runtime, we don't get any
> link-time failures, and QEMU aborts while starting:
> 
>   $ qemu ...
>   Segmentation fault (core dumped)
> 
>   (gdb) bt
>   #0  0x00007ff6e96b1e35 in raise () from /lib64/libc.so.6
>   #1  0x00007ff6e969c895 in abort () from /lib64/libc.so.6
>   #2  0x00005572bc5051cf in type_initialize (ti=0x5572be6f1200) at qom/object.c:323
>   #3  0x00005572bc505074 in type_initialize (ti=0x5572be6f1800) at qom/object.c:301
>   #4  0x00005572bc505074 in type_initialize (ti=0x5572be6e48e0) at qom/object.c:301
>   #5  0x00005572bc506939 in object_class_by_name (typename=0x5572bc56109a) at qom/object.c:959
>   #6  0x00005572bc503dd5 in cpu_class_by_name (typename=0x5572bc56109a, cpu_model=0x5572be6d9930) at hw/core/cpu.c:286
> 
> Since the caller has access to the qdev parent/interface names,
> we can simply display them to avoid starting a debugger:
> 
>   $ qemu ...
>   qemu: missing interface 'fancy-if' for object 'fancy-dev'
>   Aborted (core dumped)
> 
> This commit is similar to e02bdf1cecd2 ("Display more helpful message
> when an object type is missing").
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> Cc: Cornelia Huck <cohuck@redhat.com>
> Cc: Stefano Garzarella <sgarzare@redhat.com>
> Cc: Daniel P. Berrangé <berrange@redhat.com>
> ---
>  qom/object.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/qom/object.c b/qom/object.c
> index 0d971ca897..36123fb330 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -317,6 +317,11 @@ static void type_initialize(TypeImpl *ti)
>  
>          for (i = 0; i < ti->num_interfaces; i++) {
>              TypeImpl *t = type_get_by_name(ti->interfaces[i].typename);
> +            if (!t) {
> +                error_report("missing interface '%s' for object '%s'",
> +                             ti->interfaces[i].typename, parent->name);
> +                abort();
> +            }
>              for (e = ti->class->interfaces; e; e = e->next) {
>                  TypeImpl *target_type = OBJECT_CLASS(e->data)->type;
>  
> 

Queued, thanks.

Paolo