Re: [Qemu-devel] [PATCH RFCv2 7/9] hmp: Handle virtio-pmem when printing memory device infos

[Markus Armbruster <armbru@redhat.com>]

"Dr. David Alan Gilbert" <dgilbert@redhat.com> writes:

> * Markus Armbruster (armbru@redhat.com) wrote:
>> "Dr. David Alan Gilbert" <dgilbert@redhat.com> writes:
>> 
>> > * David Hildenbrand (david@redhat.com) wrote:
>> >> Print the memory device info just like for PCDIMM/NVDIMM.
>> >> 
>> >> Signed-off-by: David Hildenbrand <david@redhat.com>
>> >> ---
>> >>  hmp.c | 27 +++++++++++++++------------
>> >>  1 file changed, 15 insertions(+), 12 deletions(-)
>> >> 
>> >> diff --git a/hmp.c b/hmp.c
>> >> index 8da5fd8760..25c32e0810 100644
>> >> --- a/hmp.c
>> >> +++ b/hmp.c
>> >> @@ -2553,6 +2553,7 @@ void hmp_info_memory_devices(Monitor *mon, const QDict *qdict)
>> >>      Error *err = NULL;
>> >>      MemoryDeviceInfoList *info_list = qmp_query_memory_devices(&err);
>> >>      MemoryDeviceInfoList *info;
>> >> +    VirtioPMEMDeviceInfo *vpi;
>> >>      MemoryDeviceInfo *value;
>> >>      PCDIMMDeviceInfo *di;
>> >>  
>> >> @@ -2562,19 +2563,9 @@ void hmp_info_memory_devices(Monitor *mon, const QDict *qdict)
>> >>          if (value) {
>> >>              switch (value->type) {
>> >>              case MEMORY_DEVICE_INFO_KIND_DIMM:
>> >> -                di = value->u.dimm.data;
>> >> -                break;
>> >> -
>> >>              case MEMORY_DEVICE_INFO_KIND_NVDIMM:
>> >> -                di = value->u.nvdimm.data;
>> >> -                break;
>> >> -
>> >> -            default:
>> >> -                di = NULL;
>> >> -                break;
>> >> -            }
>> >> -
>> >> -            if (di) {
>> >> +                di = value->type == MEMORY_DEVICE_INFO_KIND_DIMM ?
>> >> +                     value->u.dimm.data : value->u.nvdimm.data;
>> >>                  monitor_printf(mon, "Memory device [%s]: \"%s\"\n",
>> >>                                 MemoryDeviceInfoKind_str(value->type),
>> >>                                 di->id ? di->id : "");
>> >> @@ -2587,6 +2578,18 @@ void hmp_info_memory_devices(Monitor *mon, const QDict *qdict)
>> >>                                 di->hotplugged ? "true" : "false");
>> >>                  monitor_printf(mon, "  hotpluggable: %s\n",
>> >>                                 di->hotpluggable ? "true" : "false");
>> >> +                break;
>> >> +            case MEMORY_DEVICE_INFO_KIND_VIRTIO_PMEM:
>> >> +                vpi = value->u.virtio_pmem.data;
>> >> +                monitor_printf(mon, "Memory device [%s]: \"%s\"\n",
>> >> +                               MemoryDeviceInfoKind_str(value->type),
>> >> +                               vpi->id ? vpi->id : "");
>> >> +                monitor_printf(mon, "  memaddr: 0x%" PRIx64 "\n", vpi->memaddr);
>> >> +                monitor_printf(mon, "  size: %" PRIu64 "\n", vpi->size);
>> >> +                monitor_printf(mon, "  memdev: %s\n", vpi->memdev);
>> >> +                break;
>> >> +            default:
>> >> +                g_assert_not_reached();
>> >
>> >
>> > Although I'd prefer if that assert was replaced by a print
>> > saying it was an unknown type.
>> 
>> I would not.  If we reach this, something must have scribbled over
>> value->type and who knows what else.  Continuing is unsafe.  Looks like
>> a textbook use of assertions to me.
>
> Or it could be that someone added a new type of memory device and forgot
> to update the hmp code.

Programming error -> assert.  Nothing catches attention in testing like
an assertion failure.