Re: [PATCH 13/21] memory-device: Fix latent memory pre-plug error handling bugs

[Markus Armbruster]

David Hildenbrand <address@hidden> writes:

> On 30.11.19 20:42, Markus Armbruster wrote:
>> memory_device_get_free_addr() crashes when
>> memory_device_check_addable() fails and its @errp argument is null.
>> Messed up in commit 1b6d6af21b "pc-dimm: factor out capacity and slot
>> checks into MemoryDevice".
>> 
>> The bug can't bite as no caller actually passes null.  Fix it anyway.
>> 
>> Cc: David Hildenbrand <address@hidden>
>> Signed-off-by: Markus Armbruster <address@hidden>
>> ---
>>  hw/mem/memory-device.c | 6 ++++--
>>  1 file changed, 4 insertions(+), 2 deletions(-)
>> 
>> diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
>> index aef148c1d7..4bc9cf0917 100644
>> --- a/hw/mem/memory-device.c
>> +++ b/hw/mem/memory-device.c
>> @@ -99,6 +99,7 @@ static uint64_t memory_device_get_free_addr(MachineState 
>> *ms,
>>                                              uint64_t align, uint64_t size,
>>                                              Error **errp)
>>  {
>> +    Error *err = NULL;
>>      GSList *list = NULL, *item;
>>      Range as, new = range_empty;
>>  
>> @@ -123,8 +124,9 @@ static uint64_t memory_device_get_free_addr(MachineState 
>> *ms,
>>          return 0;
>>      }
>>  
>> -    memory_device_check_addable(ms, size, errp);
>> -    if (*errp) {
>> +    memory_device_check_addable(ms, size, &err);
>> +    if (err) {
>> +        error_propagate(errp, err);
>>          return 0;
>>      }
>
> I remember that some time ago, the best practice was to use "local_err",
> what is the latest state of that?

Hundreds of local Error * variables are named @local_err, and hundreds
more are named @err.

For what it's worth, the big comment in error.h uses @err, except in one
place where it needs two of them.

> I still disagree that these are BUGs or even latent BUGs. If somebody
> things these are BUGs and not cleanups, then we should probably have
> proper "Fixes: " tags instead.

Let's continue that discussion in the sub-thread where you first raised
this objection.

> Reviewed-by: David Hildenbrand <address@hidden>

Thanks!