On 2023-12-04 17:15, Halil Pasic wrote:
On Mon, 4 Dec 2023 16:16:31 +0100
Christian Borntraeger <borntraeger@xxxxxxxxxxxxx> wrote:
Am 04.12.23 um 15:53 schrieb Tony Krowiak:
>
>
> On 11/29/23 12:12, Christian Borntraeger wrote:
>> Am 29.11.23 um 15:35 schrieb Tony Krowiak:
>>> In the current implementation, response code 01 (AP queue number not valid)
>>> is handled as a default case along with other response codes returned from
>>> a queue reset operation that are not handled specifically. Barring a bug,
>>> response code 01 will occur only when a queue has been externally removed
>>> from the host's AP configuration; nn this case, the queue must
>>> be reset by the machine in order to avoid leaking crypto data if/when the
>>> queue is returned to the host's configuration. The response code 01 case
>>> will be handled specifically by logging a WARN message followed by cleaning
>>> up the IRQ resources.
>>>
>>
>> To me it looks like this can be triggered by the LPAR admin, correct? So it
>> is not desireable but possible.
>> In that case I prefer to not use WARN, maybe use dev_warn or dev_err instead.
>> WARN can be a disruptive event if panic_on_warn is set.
>
> Yes, it can be triggered by the LPAR admin. I can't use dev_warn here because we don't have a reference to any device, but I can use pr_warn if that suffices.
Ok, please use pr_warn then.
Shouldn't we rather make this an 'info'. I mean we probably do not want
people complaining about this condition. Yes it should be a best
practice
to coordinate such things with the guest, and ideally remove the
resource
from the guest first. But AFAIU our stack is supposed to be able to
handle something like this. IMHO issuing a warning is excessive
measure.
I know Reinhard and Tony probably disagree with the last sentence
though.
Halil, Tony, the thing about about info versus warning versus error is
our
own stuff. Keep in mind that these messages end up in the "debug
feature"
as FFDC data. So it comes to the point which FFDC data do you/Tony want
to
see there ? It should be enough to explain to a customer what happened
without the need to "recreate with higher debug level" if something
serious
happened. So my private decision table is:
1) is it something serious, something exceptional, something which may
not
come up again if tried to recreate ? Yes -> make it visible on the
first
occurrence as error msg.
2) is it something you want to read when a customer hits it and you tell
him
to extract and examine the debug feature data ? Yes -> make it a
warning
and make sure your debug feature by default records warnings.
3) still serious, but may flood the debug feature. Good enough and high
probability to reappear on a recreate ? Yes -> make it an info
message
and live with the risk that you may not be able to explain to a
customer
what happened without a recreate and higher debug level.
4) not 1-3, -> maybe a debug msg but still think about what happens when
a
customer enables "debug feature" with highest level. Does it squeeze
out
more important stuff ? Maybe make it dynamic debug with pr_debug()
(see
kernel docu admin-guide/dynamic-debug-howto.rst).
Regards,
Halil
