Re: [PATCH] ioreq_broadcast(): accept partial broadcast success

[Jan Beulich <jbeulich@xxxxxxxx>]

On 28.11.2022 12:06, Roger Pau Monné wrote:
> On Mon, Nov 28, 2022 at 09:21:47AM +0100, Jan Beulich wrote:
>> On 26.11.2022 23:19, Julien Grall wrote:
>>> On 25/11/2022 14:15, Per Bilse wrote:
>>>> This patch modifies ioreq_broadcast() to allow partial success.
>>>
>>> The commit message is quite vague, so it is hard to know what you are 
>>> trying to solve exactly. AFAIU, there are two reasons for 
>>> ioreq_broadcast to fails:
>>>   1) The IOREQ server didn't register the bufioreq
>>>   2) The IOREQ buffer page is full
>>>
>>> While I would agree that the error message is not necessary for 1) (the 
>>> IOREQ server doesn't care about the event), I would disagree for 2) 
>>> because it would indicate something went horribly wrong in the IOREQ 
>>> server and there is a chance your domain may misbehave afterwards.
>>
>> In addition I think ignoring failure (and, as said by Julien, only because
>> of no bufioreq being registered) is (kind of implicitly) valid only for
>> buffered requests. Hence I'm unconvinced of the need of a new boolean
>> function parameter. Instead I think we need a new IOREQ_STATUS_... value
>> representing the "not registered" case. And that could then be used by
>> ioreq_broadcast() to skip incrementing of "failed".
> 
> So introduce an IOREQ_STATUS_UNREGISTERED return code and don't
> increase failed if buffered == true and UNREGISTERED is returned,
> would that be acceptable?

Yes afaic, but Paul is the maintainer of this code. And of course the
new error indicator shouldn't surprise any existing callers.

Jan