Re: [Xen-devel] [PATCH v5 for Xen 4.7 1/4] xen: enable per-VCPU parameter settings for RTDS scheduler

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 01.03.16 at 18:58, <lichong659@xxxxxxxxx> wrote:
> On Tue, Feb 9, 2016 at 12:17 PM, Dario Faggioli
> <dario.faggioli@xxxxxxxxxx> wrote:
>> On Thu, 2016-02-04 at 16:50 -0600, Chong Li wrote:
>>> --- a/xen/common/sched_rt.c
>>> +++ b/xen/common/sched_rt.c
> 
>>
>>> +        for ( index = op->u.v.vcpu_index; index < op->u.v.nr_vcpus;
>>> index++ )
>>> +        {
>>> +            spin_lock_irqsave(&prv->lock, flags);
>>> +            if ( copy_from_guest_offset(&local_sched,
>>> +                          op->u.v.vcpus, index, 1) )
>>> +            {
>>> +                rc = -EFAULT;
>>> +                spin_unlock_irqrestore(&prv->lock, flags);
>>> +                break;
>>> +            }
>>> +            if ( local_sched.vcpuid >= d->max_vcpus ||
>>> +                          d->vcpu[local_sched.vcpuid] == NULL )
>>> +            {
>>> +                rc = -EINVAL;
>>> +                spin_unlock_irqrestore(&prv->lock, flags);
>>> +                break;
>>> +            }
>>> +            svc = rt_vcpu(d->vcpu[local_sched.vcpuid]);
>>> +            period = MICROSECS(local_sched.s.rtds.period);
>>> +            budget = MICROSECS(local_sched.s.rtds.budget);
>>> +            if ( period > RTDS_MAX_PERIOD || budget <
>>> RTDS_MIN_BUDGET ||
>>> +                          budget > period )
>>>
>> Isn't checking against RTDS_MIN_PERIOD missing?
> 
> Because RTDS_MIN_PERIOD==RTDS_MIN_BUDGET, by checking budget <
> RTDS_MIN_BUDGET and budget > period, the checking against
> RTDS_MIN_PERIOD is already covered.

If you make code dependent upon such value matches, the
dependency should be documented and enforced to be
noticed if broken by a BUILD_BUG_ON().

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel