genirq: Update irq stats from NMI handlers

[ Upstream commit c09cb12 ]

The NMI handlers handle_percpu_devid_fasteoi_nmi() and handle_fasteoi_nmi()
do not update the interrupt counts. Due to that the NMI interrupt count
does not show up correctly in /proc/interrupts.

Add the statistics and treat the NMI handlers in the same way as per cpu
interrupts and prevent them from updating irq_desc::tot_count as this might
be corrupted due to concurrency.

[ tglx: Massaged changelog ]

Fixes: 2dcf1fb ("genirq: Provide NMI handlers")
Signed-off-by: Shijith Thotton <sthotton@marvell.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1562313336-11888-1-git-send-email-sthotton@marvell.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

kernel/irq/chip.c

@@ -754,6 +754,8 @@ void handle_fasteoi_nmi(struct irq_desc *desc)
  unsigned int irq = irq_desc_get_irq(desc);
  irqreturn_t res;
 
+ __kstat_incr_irqs_this_cpu(desc);
+
  trace_irq_handler_entry(irq, action);
  /*
  * NMIs cannot be shared, there is only one action.
@@ -968,6 +970,8 @@ void handle_percpu_devid_fasteoi_nmi(struct irq_desc *desc)
  unsigned int irq = irq_desc_get_irq(desc);
  irqreturn_t res;
 
+ __kstat_incr_irqs_this_cpu(desc);
+
  trace_irq_handler_entry(irq, action);
  res = action->handler(irq, raw_cpu_ptr(action->percpu_dev_id));
  trace_irq_handler_exit(irq, action, res);

kernel/irq/irqdesc.c

@@ -945,6 +945,11 @@ unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
  *per_cpu_ptr(desc->kstat_irqs, cpu) : 0;
 }
 
+static bool irq_is_nmi(struct irq_desc *desc)
+{
+ return desc->istate & IRQS_NMI;
+}
+
 /**
  * kstat_irqs - Get the statistics for an interrupt
  * @irq: The interrupt number
@@ -962,7 +967,8 @@ unsigned int kstat_irqs(unsigned int irq)
  if (!desc || !desc->kstat_irqs)
  return 0;
  if (!irq_settings_is_per_cpu_devid(desc) &&
- !irq_settings_is_per_cpu(desc))
+ !irq_settings_is_per_cpu(desc) &&
+ !irq_is_nmi(desc))
  return desc->tot_count;
 
  for_each_possible_cpu(cpu)