Re: [PATCH] esp: fix migration version check in esp_is_version_5()

[Philippe Mathieu-Daudé]

On 6/14/21 9:44 AM, Mark Cave-Ayland wrote:
> On 14/06/2021 06:42, Philippe Mathieu-Daudé wrote:
> 
>> On 6/13/21 12:26 PM, Mark Cave-Ayland wrote:
>>> Commit 4e78f3bf35 "esp: defer command completion interrupt on
>>> incoming data
>>> transfers" added a version check for use with VMSTATE_*_TEST macros
>>> to allow
>>> migration from older QEMU versions. Unfortunately the version check
>>> fails to
>>> work in its current form since if the VMStateDescription version_id is
>>> incremented, the test returns false and so the fields are not
>>> included in the
>>> outgoing migration stream.
>>>
>>> Change the version check to use >= rather == to ensure that migration
>>> works
>>> correctly when the ESPState VMStateDescription has version_id > 5.
>>>
>>> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
>>> Fixes: 4e78f3bf35 ("esp: defer command completion interrupt on
>>> incoming data transfers")
>>> ---
>> Well, it is not buggy yet :)
> 
> :)
> 
>>>   hw/scsi/esp.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
>>> index bfdb94292b..39756ddd99 100644
>>> --- a/hw/scsi/esp.c
>>> +++ b/hw/scsi/esp.c
>>> @@ -1120,7 +1120,7 @@ static bool esp_is_version_5(void *opaque, int
>>> version_id)
>>
>> Can you rename esp_is_at_least_version_5()?
> 
> Sure, I can rename it if you like but it will of course make the diff
> noisier. esp_is_at_least_version_5() seems quite a mouthful though, what
> about esp_min_version_5() instead?

I was looking at esp_is_before_version_5(). Following that logic it
should be named esp_is_after_version_4()? Or esp_min_version_5() and
rename esp_is_before_version_5() -> esp_max_version_4(). All options
seem confuse...

Maybe _V macros suggested by Paolo make all clearer?

> 
>>>       ESPState *s = ESP(opaque);
>>>         version_id = MIN(version_id, s->mig_version_id);
>>> -    return version_id == 5;
>>> +    return version_id >= 5;
>>>   }
>>>     int esp_pre_save(void *opaque)
> 
> 
> ATB,
> 
> Mark.
>