[RFC PATCH] genirq: Avoid unnecessary low level irq function calls

From: Jeffy Chen
Date: Mon Jun 26 2017 - 02:13:28 EST


Check irq state in enable/disable/unmask/mask_irq to avoid unnecessary
low level irq function calls.

Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Jeffy Chen <jeffy.chen@xxxxxxxxxxxxxx>
---

kernel/irq/chip.c | 55 +++++++++++++++++++++++++++++++++++--------------------
1 file changed, 35 insertions(+), 20 deletions(-)

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 8a5b597..389cfdf 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -247,22 +247,33 @@ void irq_shutdown(struct irq_desc *desc)

void irq_enable(struct irq_desc *desc)
{
- irq_state_clr_disabled(desc);
- if (desc->irq_data.chip->irq_enable)
- desc->irq_data.chip->irq_enable(&desc->irq_data);
- else
- desc->irq_data.chip->irq_unmask(&desc->irq_data);
- irq_state_clr_masked(desc);
+ if (irqd_is_started(&desc->irq_data) &&
+ !irqd_irq_disabled(&desc->irq_data)) {
+ unmask_irq(desc);
+ } else {
+ irq_state_clr_disabled(desc);
+ if (desc->irq_data.chip->irq_enable) {
+ desc->irq_data.chip->irq_enable(&desc->irq_data);
+ irq_state_clr_masked(desc);
+ } else {
+ unmask_irq(desc);
+ }
+ }
}

static void __irq_disable(struct irq_desc *desc, bool mask)
{
- irq_state_set_disabled(desc);
- if (desc->irq_data.chip->irq_disable) {
- desc->irq_data.chip->irq_disable(&desc->irq_data);
- irq_state_set_masked(desc);
- } else if (mask) {
- mask_irq(desc);
+ if (irqd_irq_disabled(&desc->irq_data)) {
+ if (mask)
+ mask_irq(desc);
+ } else {
+ irq_state_set_disabled(desc);
+ if (desc->irq_data.chip->irq_disable) {
+ desc->irq_data.chip->irq_disable(&desc->irq_data);
+ irq_state_set_masked(desc);
+ } else if (mask) {
+ mask_irq(desc);
+ }
}
}

@@ -311,18 +322,21 @@ void irq_percpu_disable(struct irq_desc *desc, unsigned int cpu)

static inline void mask_ack_irq(struct irq_desc *desc)
{
- if (desc->irq_data.chip->irq_mask_ack)
+ if (desc->irq_data.chip->irq_mask_ack) {
desc->irq_data.chip->irq_mask_ack(&desc->irq_data);
- else {
- desc->irq_data.chip->irq_mask(&desc->irq_data);
+ irq_state_set_masked(desc);
+ } else {
+ mask_irq(desc);
if (desc->irq_data.chip->irq_ack)
desc->irq_data.chip->irq_ack(&desc->irq_data);
}
- irq_state_set_masked(desc);
}

void mask_irq(struct irq_desc *desc)
{
+ if (irqd_irq_masked(&desc->irq_data))
+ return;
+
if (desc->irq_data.chip->irq_mask) {
desc->irq_data.chip->irq_mask(&desc->irq_data);
irq_state_set_masked(desc);
@@ -331,6 +345,10 @@ void mask_irq(struct irq_desc *desc)

void unmask_irq(struct irq_desc *desc)
{
+ if (irqd_is_started(&desc->irq_data) &&
+ !irqd_irq_masked(&desc->irq_data))
+ return;
+
if (desc->irq_data.chip->irq_unmask) {
desc->irq_data.chip->irq_unmask(&desc->irq_data);
irq_state_clr_masked(desc);
@@ -344,10 +362,7 @@ void unmask_threaded_irq(struct irq_desc *desc)
if (chip->flags & IRQCHIP_EOI_THREADED)
chip->irq_eoi(&desc->irq_data);

- if (chip->irq_unmask) {
- chip->irq_unmask(&desc->irq_data);
- irq_state_clr_masked(desc);
- }
+ unmask_irq(desc);
}

/*
--
2.1.4