> I was unable to figure out what the logic of the '(smp_processor_id() <
> p->cpu)' test is.. (Why should the CPU number of the process being awoken
> matter?) My best guess is that this is to enforce a locking invariant -
> but if so, isn't this test backwards? If p->cpu > current->cpu then
> p->cpu's runqueue is locked first followed by this_rq - locking greatest to
> least, where the rest of the code does least to greatest..
OK, I replied I was unsure of the validity, but looking this over, I now
suspect it is wrong.
The test should be (smp_processor_id() > p->cpu). Thus it would be safe
to lock this_rq since it is of a lower cpu id than p's rq.
Robert Love
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