[PATCH for-6.2 v6 1/7] hw/acpi/memory_hotplug.c: avoid sending MEM_UNPLUG_ERROR if dev->id is NULL

[Daniel Henrique Barboza <danielhb413@gmail.com>]

qapi_event_send_mem_unplug_error() deals with @device being NULL by
replacing it with an empty string ("") when emitting the event. Aside
from the fact that this is a side effect that can be patched someday,
there's also the lack of utility that the event brings to listeners,
e.g.  "a memory unplug error happened somewhere".

We're better of not emitting the event if dev->id is NULL. Next patches
will introduce a new device unplug error event that is better suited to
deal with dev->id NULL scenarios. MEM_UNPLUG_ERROR will continue to be
emitted to avoid breaking existing APIs, but it'll be deprecated and
removed in the future.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/acpi/memory_hotplug.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/hw/acpi/memory_hotplug.c b/hw/acpi/memory_hotplug.c
index af37889423..e37acb0367 100644
--- a/hw/acpi/memory_hotplug.c
+++ b/hw/acpi/memory_hotplug.c
@@ -177,9 +177,14 @@ static void acpi_memory_hotplug_write(void *opaque, hwaddr addr, uint64_t data,
             /* call pc-dimm unplug cb */
             hotplug_handler_unplug(hotplug_ctrl, dev, &local_err);
             if (local_err) {
+                const char *error_pretty = error_get_pretty(local_err);
+
                 trace_mhp_acpi_pc_dimm_delete_failed(mem_st->selector);
-                qapi_event_send_mem_unplug_error(dev->id,
-                                                 error_get_pretty(local_err));
+
+                if (dev->id) {
+                    qapi_event_send_mem_unplug_error(dev->id, error_pretty);
+                }
+
                 error_free(local_err);
                 break;
             }
-- 
2.31.1