linux-kernel - [PATCH v2] genirq: update irq stats from NMI handlers

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Date:   Fri, 5 Jul 2019 07:56:20 +0000
From:   Shijith Thotton <sthotton@...vell.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Julien Thierry <julien.thierry@....com>
CC:     Shijith Thotton <sthotton@...vell.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        "Jayachandran Chandrasekharan Nair" <jnair@...vell.com>,
        Ganapatrao Kulkarni <gkulkarni@...vell.com>,
        Jan Glauber <jglauber@...vell.com>,
        Robert Richter <rrichter@...vell.com>,
        George Cherian <gcherian@...vell.com>
Subject: [PATCH v2] genirq: update irq stats from NMI handlers

The NMI handlers handle_percpu_devid_fasteoi_nmi() and
handle_fasteoi_nmi() added by commit 2dcf1fbcad35 ("genirq: Provide NMI
handlers") do not update the interrupt counts. Due to that the NMI
interrupt count does not show up correctly in /proc/interrupts.

Update the functions to fix this. With this change, we can see stats of
the perf NMI interrupts on arm64.

As NMI handlers can't update tot_count in irq descriptor, kstat_irqs()
has been updated not to return tot_count for NMI.

Fixes: 2dcf1fbcad35 ("genirq: Provide NMI handlers")

Signed-off-by: Shijith Thotton <sthotton@...vell.com>
---
Changes since v1:
- Don't touch tot_count from NMI handler.
- Update kstat_irqs() to not return tot_count for NMI.

 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)
-- 
2.17.0