qom: Drop parameter @errp of object_property_add() & friends

The only way object_property_add() can fail is when a property with
the same name already exists.  Since our property names are all
hardcoded, failure is a programming error, and the appropriate way to
handle it is passing &error_abort.

Same for its variants, except for object_property_add_child(), which
additionally fails when the child already has a parent.  Parentage is
also under program control, so this is a programming error, too.

We have a bit over 500 callers.  Almost half of them pass
&error_abort, slightly fewer ignore errors, one test case handles
errors, and the remaining few callers pass them to their own callers.

The previous few commits demonstrated once again that ignoring
programming errors is a bad idea.

Of the few ones that pass on errors, several violate the Error API.
The Error ** argument must be NULL, &error_abort, &error_fatal, or a
pointer to a variable containing NULL.  Passing an argument of the
latter kind twice without clearing it in between is wrong: if the
first call sets an error, it no longer points to NULL for the second
call.  ich9_pm_add_properties(), sparc32_ledma_realize(),
sparc32_dma_realize(), xilinx_axidma_realize(), xilinx_enet_realize()
are wrong that way.

When the one appropriate choice of argument is &error_abort, letting
users pick the argument is a bad idea.

Drop parameter @errp and assert the preconditions instead.

There's one exception to "duplicate property name is a programming
error": the way object_property_add() implements the magic (and
undocumented) "automatic arrayification".  Don't drop @errp there.
Instead, rename object_property_add() to object_property_try_add(),
and add the obvious wrapper object_property_add().

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200505152926.18877-15-armbru@redhat.com>
[Two semantic rebase conflicts resolved]

6 files changed, 9 insertions, 15 deletions

diff --git a/hw/net/cadence_gem.c b/hw/net/cadence_gem.c
index 22a0b1b1f9..e8f9cc7f1e 100644
--- a/hw/net/cadence_gem.c
+++ b/hw/net/cadence_gem.c
@@ -1600,8 +1600,7 @@ static void gem_init(Object *obj)
     object_property_add_link(obj, "dma", TYPE_MEMORY_REGION,
                              (Object **)&s->dma_mr,
                              qdev_prop_allow_set_link_before_realize,
-                             OBJ_PROP_LINK_STRONG,
-                             &error_abort);
+                             OBJ_PROP_LINK_STRONG);
 }
 
 static const VMStateDescription vmstate_cadence_gem = {
diff --git a/hw/net/can/can_kvaser_pci.c b/hw/net/can/can_kvaser_pci.c
index 16861b8f9f..4b941370d0 100644
--- a/hw/net/can/can_kvaser_pci.c
+++ b/hw/net/can/can_kvaser_pci.c
@@ -282,7 +282,7 @@ static void kvaser_pci_instance_init(Object *obj)
     object_property_add_link(obj, "canbus", TYPE_CAN_BUS,
                              (Object **)&d->canbus,
                              qdev_prop_allow_set_link_before_realize,
-                             0, &error_abort);
+                             0);
 }
 
 static void kvaser_pci_class_init(ObjectClass *klass, void *data)
diff --git a/hw/net/can/can_mioe3680_pci.c b/hw/net/can/can_mioe3680_pci.c
index 965e252d9d..695e762a8d 100644
--- a/hw/net/can/can_mioe3680_pci.c
+++ b/hw/net/can/can_mioe3680_pci.c
@@ -219,11 +219,11 @@ static void mioe3680_pci_instance_init(Object *obj)
     object_property_add_link(obj, "canbus0", TYPE_CAN_BUS,
                              (Object **)&d->canbus[0],
                              qdev_prop_allow_set_link_before_realize,
-                             0, &error_abort);
+                             0);
     object_property_add_link(obj, "canbus1", TYPE_CAN_BUS,
                              (Object **)&d->canbus[1],
                              qdev_prop_allow_set_link_before_realize,
-                             0, &error_abort);
+                             0);
 }
 
 static void mioe3680_pci_class_init(ObjectClass *klass, void *data)
diff --git a/hw/net/can/can_pcm3680_pci.c b/hw/net/can/can_pcm3680_pci.c
index 51b6540072..4218e63eb2 100644
--- a/hw/net/can/can_pcm3680_pci.c
+++ b/hw/net/can/can_pcm3680_pci.c
@@ -220,11 +220,11 @@ static void pcm3680i_pci_instance_init(Object *obj)
     object_property_add_link(obj, "canbus0", TYPE_CAN_BUS,
                              (Object **)&d->canbus[0],
                              qdev_prop_allow_set_link_before_realize,
-                             0, &error_abort);
+                             0);
     object_property_add_link(obj, "canbus1", TYPE_CAN_BUS,
                              (Object **)&d->canbus[1],
                              qdev_prop_allow_set_link_before_realize,
-                             0, &error_abort);
+                             0);
 }
 
 static void pcm3680i_pci_class_init(ObjectClass *klass, void *data)
diff --git a/hw/net/ne2000-isa.c b/hw/net/ne2000-isa.c
index e744eff153..fdf8faa0d9 100644
--- a/hw/net/ne2000-isa.c
+++ b/hw/net/ne2000-isa.c
@@ -133,7 +133,7 @@ static void isa_ne2000_instance_init(Object *obj)
 {
     object_property_add(obj, "bootindex", "int32",
                         isa_ne2000_get_bootindex,
-                        isa_ne2000_set_bootindex, NULL, NULL, NULL);
+                        isa_ne2000_set_bootindex, NULL, NULL);
     object_property_set_int(obj, -1, "bootindex", NULL);
 }
 static const TypeInfo ne2000_isa_info = {
diff --git a/hw/net/xilinx_axienet.c b/hw/net/xilinx_axienet.c
index 498afe2f54..44fe04d889 100644
--- a/hw/net/xilinx_axienet.c
+++ b/hw/net/xilinx_axienet.c
@@ -985,16 +985,11 @@ static void xilinx_enet_realize(DeviceState *dev, Error **errp)
     object_property_add_link(OBJECT(ds), "enet", "xlnx.axi-ethernet",
                              (Object **) &ds->enet,
                              object_property_allow_set_link,
-                             OBJ_PROP_LINK_STRONG,
-                             &local_err);
+                             OBJ_PROP_LINK_STRONG);
     object_property_add_link(OBJECT(cs), "enet", "xlnx.axi-ethernet",
                              (Object **) &cs->enet,
                              object_property_allow_set_link,
-                             OBJ_PROP_LINK_STRONG,
-                             &local_err);
-    if (local_err) {
-        goto xilinx_enet_realize_fail;
-    }
+                             OBJ_PROP_LINK_STRONG);
     object_property_set_link(OBJECT(ds), OBJECT(s), "enet", &local_err);
     object_property_set_link(OBJECT(cs), OBJECT(s), "enet", &local_err);
     if (local_err) {