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]

7 files changed, 10 insertions, 14 deletions

diff --git a/hw/display/bochs-display.c b/hw/display/bochs-display.c
index e763a0a72d..a8e8ab8325 100644
--- a/hw/display/bochs-display.c
+++ b/hw/display/bochs-display.c
@@ -333,8 +333,7 @@ static void bochs_display_init(Object *obj)
     /* Expose framebuffer byteorder via QOM */
     object_property_add_bool(obj, "big-endian-framebuffer",
                              bochs_display_get_big_endian_fb,
-                             bochs_display_set_big_endian_fb,
-                             NULL);
+                             bochs_display_set_big_endian_fb);
 
     dev->cap_present |= QEMU_PCI_CAP_EXPRESS;
 }
diff --git a/hw/display/sm501.c b/hw/display/sm501.c
index de0ab9d977..296cd56c4a 100644
--- a/hw/display/sm501.c
+++ b/hw/display/sm501.c
@@ -2011,7 +2011,7 @@ static void sm501_sysbus_init(Object *o)
     qdev_prop_set_uint8(DEVICE(smm), "endianness", DEVICE_LITTLE_ENDIAN);
 
     object_property_add_alias(o, "chardev",
-                              OBJECT(smm), "chardev", &error_abort);
+                              OBJECT(smm), "chardev");
 }
 
 static const TypeInfo sm501_sysbus_info = {
diff --git a/hw/display/vga-pci.c b/hw/display/vga-pci.c
index 6b9db86e36..a640fd866d 100644
--- a/hw/display/vga-pci.c
+++ b/hw/display/vga-pci.c
@@ -270,7 +270,7 @@ static void pci_std_vga_init(Object *obj)
 {
     /* Expose framebuffer byteorder via QOM */
     object_property_add_bool(obj, "big-endian-framebuffer",
-                             vga_get_big_endian_fb, vga_set_big_endian_fb, NULL);
+                             vga_get_big_endian_fb, vga_set_big_endian_fb);
 }
 
 static void pci_secondary_vga_realize(PCIDevice *dev, Error **errp)
@@ -321,7 +321,7 @@ static void pci_secondary_vga_init(Object *obj)
 {
     /* Expose framebuffer byteorder via QOM */
     object_property_add_bool(obj, "big-endian-framebuffer",
-                             vga_get_big_endian_fb, vga_set_big_endian_fb, NULL);
+                             vga_get_big_endian_fb, vga_set_big_endian_fb);
 }
 
 static void pci_secondary_vga_reset(DeviceState *dev)
diff --git a/hw/display/vhost-user-gpu-pci.c b/hw/display/vhost-user-gpu-pci.c
index 7d9b1f5a8c..23ce655e0f 100644
--- a/hw/display/vhost-user-gpu-pci.c
+++ b/hw/display/vhost-user-gpu-pci.c
@@ -32,8 +32,7 @@ static void vhost_user_gpu_pci_initfn(Object *obj)
     VIRTIO_GPU_PCI_BASE(obj)->vgpu = VIRTIO_GPU_BASE(&dev->vdev);
 
     object_property_add_alias(obj, "chardev",
-                              OBJECT(&dev->vdev), "chardev",
-                              &error_abort);
+                              OBJECT(&dev->vdev), "chardev");
 }
 
 static const VirtioPCIDeviceTypeInfo vhost_user_gpu_pci_info = {
diff --git a/hw/display/vhost-user-gpu.c b/hw/display/vhost-user-gpu.c
index f0c7c6fb9a..4cdaee1bde 100644
--- a/hw/display/vhost-user-gpu.c
+++ b/hw/display/vhost-user-gpu.c
@@ -512,7 +512,7 @@ vhost_user_gpu_instance_init(Object *obj)
 
     g->vhost = VHOST_USER_BACKEND(object_new(TYPE_VHOST_USER_BACKEND));
     object_property_add_alias(obj, "chardev",
-                              OBJECT(g->vhost), "chardev", &error_abort);
+                              OBJECT(g->vhost), "chardev");
 }
 
 static void
diff --git a/hw/display/vhost-user-vga.c b/hw/display/vhost-user-vga.c
index a7195276d9..1690f6b610 100644
--- a/hw/display/vhost-user-vga.c
+++ b/hw/display/vhost-user-vga.c
@@ -33,8 +33,7 @@ static void vhost_user_vga_inst_initfn(Object *obj)
     VIRTIO_VGA_BASE(dev)->vgpu = VIRTIO_GPU_BASE(&dev->vdev);
 
     object_property_add_alias(obj, "chardev",
-                              OBJECT(&dev->vdev), "chardev",
-                              &error_abort);
+                              OBJECT(&dev->vdev), "chardev");
 }
 
 static const VirtioPCIDeviceTypeInfo vhost_user_vga_info = {
diff --git a/hw/display/xlnx_dp.c b/hw/display/xlnx_dp.c
index 7058443797..3e5fb44e06 100644
--- a/hw/display/xlnx_dp.c
+++ b/hw/display/xlnx_dp.c
@@ -1237,8 +1237,7 @@ static void xlnx_dp_init(Object *obj)
     object_property_add_link(obj, "dpdma", TYPE_XLNX_DPDMA,
                              (Object **) &s->dpdma,
                              xlnx_dp_set_dpdma,
-                             OBJ_PROP_LINK_STRONG,
-                             &error_abort);
+                             OBJ_PROP_LINK_STRONG);
 
     /*
      * Initialize AUX Bus.
@@ -1249,11 +1248,11 @@ static void xlnx_dp_init(Object *obj)
      * Initialize DPCD and EDID..
      */
     s->dpcd = DPCD(aux_create_slave(s->aux_bus, "dpcd"));
-    object_property_add_child(OBJECT(s), "dpcd", OBJECT(s->dpcd), NULL);
+    object_property_add_child(OBJECT(s), "dpcd", OBJECT(s->dpcd));
 
     s->edid = I2CDDC(qdev_create(BUS(aux_get_i2c_bus(s->aux_bus)), "i2c-ddc"));
     i2c_set_slave_address(I2C_SLAVE(s->edid), 0x50);
-    object_property_add_child(OBJECT(s), "edid", OBJECT(s->edid), NULL);
+    object_property_add_child(OBJECT(s), "edid", OBJECT(s->edid));
 
     fifo8_create(&s->rx_fifo, 16);
     fifo8_create(&s->tx_fifo, 16);