On 09/07/2018 04:17 PM, Jan Beulich wrote:
>>>> On 07.09.18 at 15:56, <andrew.coop...@citrix.com> wrote:
>> On 07/09/18 09:03, Jan Beulich wrote:
>>>>>> On 06.09.18 at 14:08, <andrew.coop...@citrix.com> wrote:
>>>> @@ -2059,11 +2058,10 @@ csched_dump_pcpu(const struct scheduler *ops, int
>>>> cpu)
>>>> spc = CSCHED_PCPU(cpu);
>>>> runq = &spc->runq;
>>>>
>>>> - cpumask_scnprintf(cpustr, sizeof(cpustr), per_cpu(cpu_sibling_mask,
>>>> cpu));
>>>> - printk("CPU[%02d] nr_run=%d, sort=%d, sibling=%s, ",
>>>> - cpu, spc->nr_runnable, spc->runq_sort_last, cpustr);
>>>> - cpumask_scnprintf(cpustr, sizeof(cpustr), per_cpu(cpu_core_mask,
>>>> cpu));
>>>> - printk("core=%s\n", cpustr);
>>>> + printk("CPU[%02d] nr_run=%d, sort=%d, sibling=%*pb, core=%*pb\n",
>>>> + cpu, spc->nr_runnable, spc->runq_sort_last,
>>>> + nr_cpu_ids, per_cpu(cpu_sibling_mask, cpu),
>>>> + nr_cpu_ids, per_cpu(cpu_core_mask, cpu));
>>> Strictly speaking here and elsewhere you should wrap the CPU mask
>>> accesses in cpumask_bits().
>>
>> Why? Its barely used, and is another example of a helper which only adds
>> to code volume.
>
> If anyone added (e.g. for debugging) a leading field to struct cpumask,
> your code would break, while all code anywhere else would still be fine.
Do all other current users use cpumask_bits() for dereferencing?
I took Andy's "Its[sic] barely used" comment to mean there were lots of
other places which also just passed a cpumask_t pointer directly into
something expecting a bitmap. If all other use cases either use
cpumask_bits() or ->bits, then we should do the same here. If there are
lots of places where we assume (void *)mask == (void *)mask->bits, then
we should probably document that the structure should match that (and
maybe add a BUILD_BUG_ON() if we can manage it).
-George
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