Oleg Drokin <gr...@linuxhacker.ru> writes:
> Thanks!
> Seems there was a midair collsion with my own patch that was not as
> comprehensive
> wrt functions touched: https://lkml.org/lkml/2015/3/2/10
Yep, I posted this for completeness (and for your reference), but
figured you'd handle it.
> But on the other hand I also tried to clean up
> some of the NR_CPUS usage while I was at it and this raises
> this question, from me, in the code like:
>
> for_each_cpu_mask(i, blah) {
> blah
> if (something)
> break;
> }
> if (i == NR_CPUS)
> blah;
>
> when we are replacing for_each_cpu_mask with for_each_cpu,
> what do we check the counter against now to see that the entire loop was
> executed
> and we did not exit prematurely? nr_cpu_ids?
You want >= nr_cpu_ids here.
> Also I assume we still want to get rid of direct cpumask assignments like
>> mask = *cpumask_of_node(cpu_to_node(index));
Yes, but this code is wrong anyway:
mask = *cpumask_of_node(cpu_to_node(index));
for (i = max; i < num_online_cpus(); i++)
cpumask_clear_cpu(i, &mask);
*Never* iterate to num_online_cpus(). eg. if cpus 0 and 3 are online,
num_online_cpus() == 2. I'm not sure what this code is doing, but it's
not doing it well :)
There are several issues here. You need to handle cpus going offline
(during this routine, as well as after). You need to use a
cpumask_var_t, like so:
cpumask_var_t mask;
...
case PDB_POLICY_NEIGHBOR:
if (!alloc_cpumask_var(&mask, GFP_???)) {
rc = -ENOMEM;
break;
}
...
Or get rid of the mask altogether, eg:
pc->pc_npartners = -1;
for_each_cpu(i, cpu_online_mask) {
if (i < max)
pc->pc_npartners++;
}
...
pidx = 0;
for_each_cpu(i, cpu_online_mask) {
if (i >= max)
break;
ppc = &ptlrpcds->pd_threads[i];
pc->pc_partners[pidx++] = ppc;
ppc->pc_partners[ppc->pc_npartners++] = pc;
}
[ This is off the top of my head, no idea if it's right...]
Thanks,
Rusty.
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