qom: Drop object_property_set_description() parameter @errp

object_property_set_description() and
object_class_property_set_description() fail only when property @name
is not found.

There are 85 calls of object_property_set_description() and
object_class_property_set_description().  None of them can fail:

* 84 immediately follow the creation of the property.

* The one in spapr_rng_instance_init() refers to a property created in
  spapr_rng_class_init(), from spapr_rng_properties[].

Every one of them still gets to decide what to pass for @errp.

51 calls pass &error_abort, 32 calls pass NULL, one receives the error
and propagates it to &error_abort, and one propagates it to
&error_fatal.  I'm actually surprised none of them violates the Error
API.

What are we gaining by letting callers handle the "property not found"
error?  Use when the property is not known to exist is simpler: you
don't have to guard the call with a check.  We haven't found such a
use in 5+ years.  Until we do, let's make life a bit simpler and drop
the @errp parameter.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200505152926.18877-8-armbru@redhat.com>
[One semantic rebase conflict resolved]

4 files changed, 13 insertions, 24 deletions

diff --git a/hw/arm/aspeed.c b/hw/arm/aspeed.c
index 4d57d1e436..231527c6c8 100644
--- a/hw/arm/aspeed.c
+++ b/hw/arm/aspeed.c
@@ -546,7 +546,7 @@ static void aspeed_machine_class_props_init(ObjectClass *oc)
                                    aspeed_get_mmio_exec,
                                    aspeed_set_mmio_exec, &error_abort);
     object_class_property_set_description(oc, "execute-in-place",
-                           "boot directly from CE0 flash device", &error_abort);
+                           "boot directly from CE0 flash device");
 }
 
 static void aspeed_machine_class_init(ObjectClass *oc, void *data)
diff --git a/hw/arm/vexpress.c b/hw/arm/vexpress.c
index ed683eeea5..5372ab6c9b 100644
--- a/hw/arm/vexpress.c
+++ b/hw/arm/vexpress.c
@@ -752,8 +752,7 @@ static void vexpress_instance_init(Object *obj)
                              vexpress_set_secure, NULL);
     object_property_set_description(obj, "secure",
                                     "Set on/off to enable/disable the ARM "
-                                    "Security Extensions (TrustZone)",
-                                    NULL);
+                                    "Security Extensions (TrustZone)");
 }
 
 static void vexpress_a15_instance_init(Object *obj)
@@ -770,8 +769,7 @@ static void vexpress_a15_instance_init(Object *obj)
     object_property_set_description(obj, "virtualization",
                                     "Set on/off to enable/disable the ARM "
                                     "Virtualization Extensions "
-                                    "(defaults to same as 'secure')",
-                                    NULL);
+                                    "(defaults to same as 'secure')");
 }
 
 static void vexpress_a9_instance_init(Object *obj)
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 9e76fa7b01..de66def51e 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -2272,7 +2272,7 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
         virt_get_acpi, virt_set_acpi,
         NULL, NULL, &error_abort);
     object_class_property_set_description(oc, "acpi",
-        "Enable ACPI", &error_abort);
+        "Enable ACPI");
 }
 
 static void virt_instance_init(Object *obj)
@@ -2289,8 +2289,7 @@ static void virt_instance_init(Object *obj)
                              virt_set_secure, NULL);
     object_property_set_description(obj, "secure",
                                     "Set on/off to enable/disable the ARM "
-                                    "Security Extensions (TrustZone)",
-                                    NULL);
+                                    "Security Extensions (TrustZone)");
 
     /* EL2 is also disabled by default, for similar reasons */
     vms->virt = false;
@@ -2299,8 +2298,7 @@ static void virt_instance_init(Object *obj)
     object_property_set_description(obj, "virtualization",
                                     "Set on/off to enable/disable emulating a "
                                     "guest CPU which implements the ARM "
-                                    "Virtualization Extensions",
-                                    NULL);
+                                    "Virtualization Extensions");
 
     /* High memory is enabled by default */
     vms->highmem = true;
@@ -2308,15 +2306,13 @@ static void virt_instance_init(Object *obj)
                              virt_set_highmem, NULL);
     object_property_set_description(obj, "highmem",
                                     "Set on/off to enable/disable using "
-                                    "physical address space above 32 bits",
-                                    NULL);
+                                    "physical address space above 32 bits");
     vms->gic_version = VIRT_GIC_VERSION_NOSEL;
     object_property_add_str(obj, "gic-version", virt_get_gic_version,
                         virt_set_gic_version, NULL);
     object_property_set_description(obj, "gic-version",
                                     "Set GIC version. "
-                                    "Valid values are 2, 3, host and max",
-                                    NULL);
+                                    "Valid values are 2, 3, host and max");
 
     vms->highmem_ecam = !vmc->no_highmem_ecam;
 
@@ -2329,8 +2325,7 @@ static void virt_instance_init(Object *obj)
                                  virt_set_its, NULL);
         object_property_set_description(obj, "its",
                                         "Set on/off to enable/disable "
-                                        "ITS instantiation",
-                                        NULL);
+                                        "ITS instantiation");
     }
 
     /* Default disallows iommu instantiation */
@@ -2338,8 +2333,7 @@ static void virt_instance_init(Object *obj)
     object_property_add_str(obj, "iommu", virt_get_iommu, virt_set_iommu, NULL);
     object_property_set_description(obj, "iommu",
                                     "Set the IOMMU type. "
-                                    "Valid values are none and smmuv3",
-                                    NULL);
+                                    "Valid values are none and smmuv3");
 
     /* Default disallows RAS instantiation */
     vms->ras = false;
@@ -2347,8 +2341,7 @@ static void virt_instance_init(Object *obj)
                              virt_set_ras, NULL);
     object_property_set_description(obj, "ras",
                                     "Set on/off to enable/disable reporting host memory errors "
-                                    "to a KVM guest using ACPI and guest external abort exceptions",
-                                    NULL);
+                                    "to a KVM guest using ACPI and guest external abort exceptions");
 
     vms->irqmap = a15irqmap;
 
diff --git a/hw/arm/xlnx-zcu102.c b/hw/arm/xlnx-zcu102.c
index a798e228b7..808fdae804 100644
--- a/hw/arm/xlnx-zcu102.c
+++ b/hw/arm/xlnx-zcu102.c
@@ -212,8 +212,7 @@ static void xlnx_zcu102_machine_instance_init(Object *obj)
                              zcu102_set_secure, NULL);
     object_property_set_description(obj, "secure",
                                     "Set on/off to enable/disable the ARM "
-                                    "Security Extensions (TrustZone)",
-                                    NULL);
+                                    "Security Extensions (TrustZone)");
 
     /* Default to virt (EL2) being disabled */
     s->virt = false;
@@ -222,8 +221,7 @@ static void xlnx_zcu102_machine_instance_init(Object *obj)
     object_property_set_description(obj, "virtualization",
                                     "Set on/off to enable/disable emulating a "
                                     "guest CPU which implements the ARM "
-                                    "Virtualization Extensions",
-                                    NULL);
+                                    "Virtualization Extensions");
 }
 
 static void xlnx_zcu102_machine_class_init(ObjectClass *oc, void *data)