Re: [PATCH v2 2/3] hw/loongarch/virt: Remove unnecessary NULL pointer checking

[bibo mao]

On 2025/3/14 下午5:11, Markus Armbruster wrote:
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 | 25 +++++++++++--------------
  1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
index a5840ff968..d82676d316 100644
--- a/hw/loongarch/virt.c
+++ b/hw/loongarch/virt.c
@@ -868,21 +868,24 @@ static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev,
              error_setg(&err,
                         "Invalid thread-id %u specified, must be in range 
1:%u",
                         cpu->thread_id, ms->smp.threads - 1);
-            goto out;
+            error_propagate(errp, err);
+            return;

Make this


                error_setg(&err, ...);
                return;
My bad. I remember replacing error_propagate with error_setg(errp, ...) 
already. Will do

          }
  
          if ((cpu->core_id < 0) || (cpu->core_id >= ms->smp.cores)) {
              error_setg(&err,
                         "Invalid core-id %u specified, must be in range 1:%u",
                         cpu->core_id, ms->smp.cores - 1);
-            goto out;
+            error_propagate(errp, err);
+            return;

Likewise.

          }
  
          if ((cpu->socket_id < 0) || (cpu->socket_id >= ms->smp.sockets)) {
              error_setg(&err,
                         "Invalid socket-id %u specified, must be in range 
1:%u",
                         cpu->socket_id, ms->smp.sockets - 1);
-            goto out;
+            error_propagate(errp, err);
+            return;

Likewise.

          }
  
          topo.socket_id = cpu->socket_id;
@@ -895,7 +898,8 @@ static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev,
                         "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;
+            error_propagate(errp, err);
+            return;

Likewise.

          }
      } else {
          /* For cold-add cpu, find empty cpu slot */
@@ -912,10 +916,6 @@ static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev,
      cpu->phy_id = cpu_slot->arch_id;
      cs->cpu_index = cpu_slot - ms->possible_cpus->cpus;
      numa_cpu_pre_plug(cpu_slot, dev, &err);

You need to pass errp instead of &err now.

-out:
-    if (err) {
-        error_propagate(errp, err);
-    }
  }
  
  static void virt_cpu_unplug_request(HotplugHandler *hotplug_dev,
@@ -935,9 +935,7 @@ 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);
  }

Correct, but I'd recomment to go one step further:

  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,
@@ -1001,9 +999,8 @@ static void virt_cpu_plug(HotplugHandler *hotplug_dev,
        cpu_slot = virt_find_cpu_slot(MACHINE(lvms), cpu->phy_id);
        cpu_slot->cpu = CPU(dev);
        if (lvms->ipi) {
            hotplug_handler_plug(HOTPLUG_HANDLER(lvms->ipi), dev, &err);
            if (err) {
                error_propagate(errp, err);
                return;
            }
        }

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

Better make this work exactly like the other checks above, and drop the
final return, which serves no purpose:

            if (err) {
                error_propagate(errp, err);
                return;
            }
        }
Here is report from commandline, it say err NULL check is not necessary
spatch --sp-file scripts/coccinelle/error_propagate_null.cocci --dir 
hw/loongarch/

@@ -1001,9 +997,7 @@ static void virt_cpu_plug(HotplugHandler

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

Regards
Bibo Mao
    }