Re: [Xen-devel] [PATCH 04/18] xen/arm: While a domain is suspended put its watchdogs on pause

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 12.11.18 at 16:17, <mirela.simonovic@xxxxxxxxxx> wrote:
> Hi Jan,
> 
> On Mon, Nov 12, 2018 at 12:47 PM Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>
>> >>> On 12.11.18 at 12:30, <mirela.simonovic@xxxxxxxxxx> wrote:
>> > --- a/xen/include/xen/timer.h
>> > +++ b/xen/include/xen/timer.h
>> > @@ -18,6 +18,9 @@ struct timer {
>> >      /* System time expiry value (nanoseconds since boot). */
>> >      s_time_t expires;
>> >
>> > +    /* Suspend timestamp value (nanoseconds since boot). */
>> > +    s_time_t suspended;
>>
>> I can't see how this becomes a universally useful field, so I
>> don't think it belongs here. For your purpose deriving a new
>> structure containing struct timer and this one field should
>> work.
> 
> Each 'expires' value needs to be coupled with 'suspended' value to be
> able to deal with watchdogs when suspending a domain. This is specific
> to a watchdog.
> If we add a derived structure to contain this field we still need to
> associate such a structure with each watchdog of a domain, which is
> also domain generic info and requires a lot more (in my opinion
> unnecessary) changes. Please let me know if I misinterpreted your
> proposal.

You add the field to all timer instances, yet you need it only for
very few. Why not have a struct watchdog_timer, and use it
for struct domain's watchdog_timer[]? I'm afraid I don't see the
difficulties you appear to see.

Jan



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