Re: [PATCH 2/3] hw/loongarch/virt: Remove unnecessary NULL pointer checking

[Markus Armbruster]

Bibo Mao <maob...@loongson.cn> writes:

> There is NULL pointer checking function error_propagate() already,
> it is not necessary to add checking for function parameter. Here remove
> NULL pointer checking with function parameter.
>
> Signed-off-by: Bibo Mao <maob...@loongson.cn>
> ---
>  hw/loongarch/virt.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
> index a5840ff968..ab951fc642 100644
> --- a/hw/loongarch/virt.c
> +++ b/hw/loongarch/virt.c
> @@ -913,9 +913,7 @@ static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev,
>      cs->cpu_index = cpu_slot - ms->possible_cpus->cpus;
>      numa_cpu_pre_plug(cpu_slot, dev, &err);
>  out:
> -    if (err) {
> -        error_propagate(errp, err);
> -    }
> +    error_propagate(errp, err);
>  }
>  
>  static void virt_cpu_unplug_request(HotplugHandler *hotplug_dev,
> @@ -935,9 +933,7 @@ static void virt_cpu_unplug_request(HotplugHandler 
> *hotplug_dev,
>      }
>  
>      hotplug_handler_unplug_request(HOTPLUG_HANDLER(lvms->acpi_ged), dev, 
> &err);
> -    if (err) {
> -        error_propagate(errp, err);
> -    }
> +    error_propagate(errp, err);
>  }

This looks correct.  But I believe we can eliminate error propagation
here.  Untested patch appended.

>  
>  static void virt_cpu_unplug(HotplugHandler *hotplug_dev,
> @@ -1001,9 +997,7 @@ static void virt_cpu_plug(HotplugHandler *hotplug_dev,
>  
>      if (lvms->acpi_ged) {
>          hotplug_handler_plug(HOTPLUG_HANDLER(lvms->acpi_ged), dev, &err);
> -        if (err) {
> -            error_propagate(errp, err);
> -        }
> +        error_propagate(errp, err);
>      }
>  
>      return;

Here, I'd recommend

       if (lvms->acpi_ged) {
           hotplug_handler_plug(HOTPLUG_HANDLER(lvms->acpi_ged), dev, &err);
           if (err) {
               error_propagate(errp, err);
  +            return;
           }

because it makes future screwups harder.


diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
index a5840ff968..4674bd9163 100644
--- a/hw/loongarch/virt.c
+++ b/hw/loongarch/virt.c
@@ -859,30 +859,29 @@ static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev,
     LoongArchCPU *cpu = LOONGARCH_CPU(dev);
     CPUState *cs = CPU(dev);
     CPUArchId *cpu_slot;
-    Error *err = NULL;
     LoongArchCPUTopo topo;
     int arch_id;
 
     if (lvms->acpi_ged) {
         if ((cpu->thread_id < 0) || (cpu->thread_id >= ms->smp.threads)) {
-            error_setg(&err,
+            error_setg(errp,
                        "Invalid thread-id %u specified, must be in range 1:%u",
                        cpu->thread_id, ms->smp.threads - 1);
-            goto out;
+            return;
         }
 
         if ((cpu->core_id < 0) || (cpu->core_id >= ms->smp.cores)) {
-            error_setg(&err,
+            error_setg(errp,
                        "Invalid core-id %u specified, must be in range 1:%u",
                        cpu->core_id, ms->smp.cores - 1);
-            goto out;
+            return;
         }
 
         if ((cpu->socket_id < 0) || (cpu->socket_id >= ms->smp.sockets)) {
-            error_setg(&err,
+            error_setg(errp,
                        "Invalid socket-id %u specified, must be in range 1:%u",
                        cpu->socket_id, ms->smp.sockets - 1);
-            goto out;
+            return;
         }
 
         topo.socket_id = cpu->socket_id;
@@ -891,11 +890,11 @@ static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev,
         arch_id =  virt_get_arch_id_from_topo(ms, &topo);
         cpu_slot = virt_find_cpu_slot(ms, arch_id);
         if (CPU(cpu_slot->cpu)) {
-            error_setg(&err,
+            error_setg(errp,
                        "cpu(id%d=%d:%d:%d) with arch-id %" PRIu64 " exists",
                        cs->cpu_index, cpu->socket_id, cpu->core_id,
                        cpu->thread_id, cpu_slot->arch_id);
-            goto out;
+            return;
         }
     } else {
         /* For cold-add cpu, find empty cpu slot */
@@ -911,33 +910,24 @@ static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev,
     cpu->env.address_space_iocsr = &lvms->as_iocsr;
     cpu->phy_id = cpu_slot->arch_id;
     cs->cpu_index = cpu_slot - ms->possible_cpus->cpus;
-    numa_cpu_pre_plug(cpu_slot, dev, &err);
-out:
-    if (err) {
-        error_propagate(errp, err);
-    }
+    numa_cpu_pre_plug(cpu_slot, dev, errp);
 }
 
 static void virt_cpu_unplug_request(HotplugHandler *hotplug_dev,
                                     DeviceState *dev, Error **errp)
 {
     LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(hotplug_dev);
-    Error *err = NULL;
     LoongArchCPU *cpu = LOONGARCH_CPU(dev);
     CPUState *cs = CPU(dev);
 
     if (cs->cpu_index == 0) {
-        error_setg(&err, "hot-unplug of boot cpu(id%d=%d:%d:%d) not supported",
+        error_setg(errp, "hot-unplug of boot cpu(id%d=%d:%d:%d) not supported",
                    cs->cpu_index, cpu->socket_id,
                    cpu->core_id, cpu->thread_id);
-        error_propagate(errp, err);
         return;
     }
 
-    hotplug_handler_unplug_request(HOTPLUG_HANDLER(lvms->acpi_ged), dev, &err);
-    if (err) {
-        error_propagate(errp, err);
-    }
+    hotplug_handler_unplug_request(HOTPLUG_HANDLER(lvms->acpi_ged), dev, errp);
 }
 
 static void virt_cpu_unplug(HotplugHandler *hotplug_dev,