Re: [RFC PATCH v3 4/6] sched: secure access to other CPU statistics

From: Vincent Guittot
Date: Tue Mar 26 2013 - 09:06:43 EST


On 26 March 2013 13:50, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> On Fri, 2013-03-22 at 13:25 +0100, Vincent Guittot wrote:
>> @@ -3364,13 +3364,16 @@ done:
>> static bool is_buddy_busy(int cpu)
>> {
>> struct rq *rq = cpu_rq(cpu);
>> + u32 sum = rq->avg.runnable_avg_sum;
>> + u32 period = rq->avg.runnable_avg_period;
>> +
>> + sum = min(sum, period);
>
> OK this makes sense; use a simple sanity constraint instead of going
> overboard on serialization -- however, why is this a separate patch?

There is no real reason other than explaining why I have added this
additional check

>
> That is, this could easily be part of the patch that introduces
> is_buddy_busy(); also you likely want part of this patch's changelog
> to become a comment that goes right above this min() :-)

Yes, i 'm going to do that

>
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