Re: [PATCH 1/5] xen/domain: Remove function pointers from domain pause helpers

[Bertrand Marquis <Bertrand.Marquis@xxxxxxx>]

Hi Jan,

> On 15 Nov 2021, at 10:55, Jan Beulich <jbeulich@xxxxxxxx> wrote:
> 
> On 15.11.2021 11:23, Bertrand Marquis wrote:
>> Hi Jan,
>> 
>>> On 15 Nov 2021, at 10:20, Jan Beulich <jbeulich@xxxxxxxx> wrote:
>>> 
>>> On 15.11.2021 11:13, Bertrand Marquis wrote:
>>>>> On 11 Nov 2021, at 17:57, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>>>>> --- a/xen/common/domain.c
>>>>> +++ b/xen/common/domain.c
>>>>> @@ -1234,15 +1234,18 @@ int vcpu_unpause_by_systemcontroller(struct vcpu 
>>>>> *v)
>>>>>   return 0;
>>>>> }
>>>>> 
>>>>> -static void do_domain_pause(struct domain *d,
>>>>> -                            void (*sleep_fn)(struct vcpu *v))
>>>>> +static void _domain_pause(struct domain *d, bool sync /* or nosync */)
>>>> 
>>>> Here you use comments inside the function definition.
>>>> I think this is something that should be avoided and in this specific case 
>>>> a
>>>> boolean sync is clear enough not to need to explain that false is nosing.
>>> 
>>> While I agree the comment here isn't overly useful, I think ...
>>> 
>>>>> @@ -1250,12 +1253,12 @@ static void do_domain_pause(struct domain *d,
>>>>> void domain_pause(struct domain *d)
>>>>> {
>>>>>   ASSERT(d != current->domain);
>>>>> -    do_domain_pause(d, vcpu_sleep_sync);
>>>>> +    _domain_pause(d, true /* sync */);
>>>> Same here.
>>> 
>>> ... comments like this one are pretty useful to disambiguate the plain
>>> "true" or "false" (without the reader needing to go look at the function
>>> declaration or definition).
>> 
>> I agree with that but the comment here is useful, it could be added before
>> the call instead of inside it.
> 
> Except the form Andrew has used is the one we've been using elsewhere
> for some time.

I know I found some other examples and that why I say “should” and not must.
If other consider that this is the right way to go and should not be changed 
this
is ok with me but I wanted to make the comment as this could ease the work
with FuSa and Misra compliance in the future.

Bertrand

> 
> Jan