[PATCH AUTOSEL 5.2 238/249] genirq: Update irq stats from NMI handlers

[Sasha Levin]

From: Shijith Thotton <sthotton@xxxxxxxxxxx>

[ Upstream commit c09cb1293523dd786ae54a12fd88001542cba2f6 ]

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: 2dcf1fbcad35 ("genirq: Provide NMI handlers")
Signed-off-by: Shijith Thotton <sthotton@xxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/1562313336-11888-1-git-send-email-sthotton@xxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 kernel/irq/chip.c    | 4 ++++
 kernel/irq/irqdesc.c | 8 +++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 29d6c7d070b4..04c850fb70cb 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -748,6 +748,8 @@ 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.
@@ -962,6 +964,8 @@ 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);
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index c52b737ab8e3..9149dde5a7b0 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -946,6 +946,11 @@ 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
@@ -963,7 +968,8 @@ 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)
-- 
2.20.1