Thomas Gleixner @ 2020-12-06 09:38 MST:
On Fri, Dec 04 2020 at 18:43, Jerry Snitselaar wrote:
Now that kstat_irqs is exported, get rid of count_interrupts in i915_pmu.c --- a/drivers/gpu/drm/i915/i915_pmu.c +++ b/drivers/gpu/drm/i915/i915_pmu.c @@ -423,22 +423,6 @@ static enum hrtimer_restart i915_sample(struct hrtimer *hrtimer) return HRTIMER_RESTART; }
-static u64 count_interrupts(struct drm_i915_private *i915) -{
- /* open-coded kstat_irqs() */
- struct irq_desc *desc = irq_to_desc(i915->drm.pdev->irq);
- u64 sum = 0;
- int cpu;
- if (!desc || !desc->kstat_irqs)
return 0;- for_each_possible_cpu(cpu)
sum += *per_cpu_ptr(desc->kstat_irqs, cpu);- return sum;
-}
May I ask why this has been merged in the first place?
Nothing in a driver has ever to fiddle with the internals of an irq descriptor. We have functions for properly accessing them. Just because C allows to fiddle with everything is not a justification. If the required function is not exported then adding the export with a proper explanation is not asked too much.
Also this lacks protection or at least a comment why this can be called safely and is not subject to a concurrent removal of the irq descriptor. The same problem exists when calling kstat_irqs(). It's even documented at the top of the function.
Thanks,
tglx
I don't know the history behind this bit. I stumbled across it in cscope when looking for places using kstat_irqs.