hw: More QDev cleanups

[PATCH 11/21] hw/usb: Add QOM parentship relation with hub devices

Philippe Mathieu-Daudé posted 21 patches 8 months, 2 weeks ago

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Maintainers: Peter Maydell <peter.maydell@linaro.org>, Jan Kiszka <jan.kiszka@web.de>, Paolo Bonzini <pbonzini@redhat.com>, "Daniel P. Berrangé" <berrange@redhat.com>, Eduardo Habkost <eduardo@habkost.net>, Alistair Francis <alistair@alistair23.me>, Richard Henderson <richard.henderson@linaro.org>, "Michael S. Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Pavel Pisa <pisa@cmp.felk.cvut.cz>, Vikram Garhwal <fnu.vikram@xilinx.com>, Francisco Iglesias <francisco.iglesias@amd.com>, Jason Wang <jasowang@redhat.com>, Chris Wulff <crwulff@gmail.com>, Marek Vasut <marex@denx.de>, "Hervé Poussineau" <hpoussin@reactos.org>, "Cédric Le Goater" <clg@kaod.org>, Nicholas Piggin <npiggin@gmail.com>, "Frédéric Barrat" <fbarrat@linux.ibm.com>, Daniel Henrique Barboza <danielhb413@gmail.com>, David Gibson <david@gibson.dropbear.id.au>, Harsh Prateek Bora <harshpb@linux.ibm.com>, Matthew Rosato <mjrosato@linux.ibm.com>, Eric Farman <farman@linux.ibm.com>, Thomas Huth <thuth@redhat.com>, David Hildenbrand <david@redhat.com>, Ilya Leoshkevich <iii@linux.ibm.com>, Halil Pasic <pasic@linux.ibm.com>, Christian Borntraeger <borntraeger@linux.ibm.com>, Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, Artyom Tarasenko <atar4qemu@gmail.com>, Bastian Koppelmann <kbastian@mail.uni-paderborn.de>, Gerd Hoffmann <kraxel@redhat.com>, Samuel Thibault <samuel.thibault@ens-lyon.org>, Aurelien Jarno <aurelien@aurel32.net>, Jiaxun Yang <jiaxun.yang@flygoat.com>, Aleksandar Rikalo <aleksandar.rikalo@syrmia.com>, Max Filippov <jcmvbkbc@gmail.com>

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[PATCH 11/21] hw/usb: Add QOM parentship relation with hub devices

Posted by Philippe Mathieu-Daudé 8 months, 2 weeks ago

QDev objects created with qdev_*new() need to manually add
their parent relationship with object_property_add_child().

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/usb/bus.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/usb/bus.c b/hw/usb/bus.c
index a599e2552b..baad04f466 100644
--- a/hw/usb/bus.c
+++ b/hw/usb/bus.c
@@ -439,6 +439,7 @@ void usb_claim_port(USBDevice *dev, Error **errp)
             /* Create a new hub and chain it on */
             hub = USB_DEVICE(qdev_try_new("usb-hub"));
             if (hub) {
+                object_property_add_child(OBJECT(dev), "hub", OBJECT(hub));
                 usb_realize_and_unref(hub, bus, NULL);
             }
         }
-- 
2.41.0

Re: [PATCH 11/21] hw/usb: Add QOM parentship relation with hub devices

Posted by Zhao Liu 8 months, 1 week ago

Hi Philippe,

On Fri, Feb 16, 2024 at 12:03:02PM +0100, Philippe Mathieu-Daudé wrote:
> Date: Fri, 16 Feb 2024 12:03:02 +0100
> From: Philippe Mathieu-Daudé <philmd@linaro.org>
> Subject: [PATCH 11/21] hw/usb: Add QOM parentship relation with hub devices
> X-Mailer: git-send-email 2.41.0
> 
> QDev objects created with qdev_*new() need to manually add
> their parent relationship with object_property_add_child().
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>  hw/usb/bus.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/usb/bus.c b/hw/usb/bus.c
> index a599e2552b..baad04f466 100644
> --- a/hw/usb/bus.c
> +++ b/hw/usb/bus.c
> @@ -439,6 +439,7 @@ void usb_claim_port(USBDevice *dev, Error **errp)
>              /* Create a new hub and chain it on */
>              hub = USB_DEVICE(qdev_try_new("usb-hub"));

One additional question comes to mind, should we use the qdev_new()
here?

The difference between qdev_try_new() and qdev_new() is the latter
uses assert() to ensure the passed type exists.

So if we know that type parameter is correct, we should just use
qdev_new().

Only when the caller is not sure whether the type is valid,
qdev_try_new() should be preferred.

Am I understand correctly? ;-)

>              if (hub) {
> +                object_property_add_child(OBJECT(dev), "hub", OBJECT(hub));

From the comment above the code:

/* Create a new hub and chain it on */

this only creates a new usb-hub, should the new usb-hub become the child
object of the original usb-hub?

>                  usb_realize_and_unref(hub, bus, NULL);
>              }
>          }
> -- 
> 2.41.0
> 
>