genirq: Add a IRQF_NO_DEBUG flag

The whole call to note_interrupt() can be avoided or return early when
interrupts would be marked accordingly. For IPI handlers which always
return HANDLED the whole procedure is pretty pointless to begin with.

Add a IRQF_NO_DEBUG flag and mark the interrupt accordingly if supplied
when the interrupt is requested.

When noirqdebug is set on the kernel commandline, then the interrupt is
marked unconditionally so that there is only one condition in the hotpath
to evaluate.

 [ clg: Add changelog ]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/7a8ad02f-63a8-c1aa-fdd1-39d973593d02@kaod.org

6 files changed, 24 insertions, 2 deletions

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 4777850a6dc7..a52109c3f3a4 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -64,6 +64,8 @@
  * IRQF_NO_AUTOEN - Don't enable IRQ or NMI automatically when users request it.
  *                Users will enable it explicitly by enable_irq() or enable_nmi()
  *                later.
+ * IRQF_NO_DEBUG - Exclude from runnaway detection for IPI and similar handlers,
+ *		   depends on IRQF_PERCPU.
  */
 #define IRQF_SHARED		0x00000080
 #define IRQF_PROBE_SHARED	0x00000100
@@ -78,6 +80,7 @@
 #define IRQF_EARLY_RESUME	0x00020000
 #define IRQF_COND_SUSPEND	0x00040000
 #define IRQF_NO_AUTOEN		0x00080000
+#define IRQF_NO_DEBUG		0x00100000
 
 #define IRQF_TIMER		(__IRQF_TIMER | IRQF_NO_SUSPEND | IRQF_NO_THREAD)
 
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 31b347c9f8dd..8e9a9ae471a6 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -72,6 +72,7 @@ enum irqchip_irq_state;
  *				  mechanism and from core side polling.
  * IRQ_DISABLE_UNLAZY		- Disable lazy irq disable
  * IRQ_HIDDEN			- Don't show up in /proc/interrupts
+ * IRQ_NO_DEBUG			- Exclude from note_interrupt() debugging
  */
 enum {
 	IRQ_TYPE_NONE		= 0x00000000,
@@ -99,6 +100,7 @@ enum {
 	IRQ_IS_POLLED		= (1 << 18),
 	IRQ_DISABLE_UNLAZY	= (1 << 19),
 	IRQ_HIDDEN		= (1 << 20),
+	IRQ_NO_DEBUG		= (1 << 21),
 };
 
 #define IRQF_MODIFY_MASK	\
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 8cc8e5713287..7f04c7d8296e 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -481,7 +481,7 @@ void handle_nested_irq(unsigned int irq)
 	for_each_action_of_desc(desc, action)
 		action_ret |= action->thread_fn(action->irq, action->dev_id);
 
-	if (!noirqdebug)
+	if (!irq_settings_no_debug(desc))
 		note_interrupt(desc, action_ret);
 
 	raw_spin_lock_irq(&desc->lock);
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 762a928e18f9..221d80c31e94 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -197,7 +197,7 @@ irqreturn_t handle_irq_event_percpu(struct irq_desc *desc)
 
 	add_interrupt_randomness(desc->irq_data.irq, flags);
 
-	if (!noirqdebug)
+	if (!irq_settings_no_debug(desc))
 		note_interrupt(desc, retval);
 	return retval;
 }
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 4c14356543d9..7bdd09e7d5f0 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1686,8 +1686,13 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 		if (new->flags & IRQF_PERCPU) {
 			irqd_set(&desc->irq_data, IRQD_PER_CPU);
 			irq_settings_set_per_cpu(desc);
+			if (new->flags & IRQF_NO_DEBUG)
+				irq_settings_set_no_debug(desc);
 		}
 
+		if (noirqdebug)
+			irq_settings_set_no_debug(desc);
+
 		if (new->flags & IRQF_ONESHOT)
 			desc->istate |= IRQS_ONESHOT;
 
diff --git a/kernel/irq/settings.h b/kernel/irq/settings.h
index 403378b9947b..7b7efb1a114b 100644
--- a/kernel/irq/settings.h
+++ b/kernel/irq/settings.h
@@ -18,6 +18,7 @@ enum {
 	_IRQ_IS_POLLED		= IRQ_IS_POLLED,
 	_IRQ_DISABLE_UNLAZY	= IRQ_DISABLE_UNLAZY,
 	_IRQ_HIDDEN		= IRQ_HIDDEN,
+	_IRQ_NO_DEBUG		= IRQ_NO_DEBUG,
 	_IRQF_MODIFY_MASK	= IRQF_MODIFY_MASK,
 };
 
@@ -33,6 +34,7 @@ enum {
 #define IRQ_IS_POLLED		GOT_YOU_MORON
 #define IRQ_DISABLE_UNLAZY	GOT_YOU_MORON
 #define IRQ_HIDDEN		GOT_YOU_MORON
+#define IRQ_NO_DEBUG		GOT_YOU_MORON
 #undef IRQF_MODIFY_MASK
 #define IRQF_MODIFY_MASK	GOT_YOU_MORON
 
@@ -174,3 +176,13 @@ static inline bool irq_settings_is_hidden(struct irq_desc *desc)
 {
 	return desc->status_use_accessors & _IRQ_HIDDEN;
 }
+
+static inline void irq_settings_set_no_debug(struct irq_desc *desc)
+{
+	desc->status_use_accessors |= _IRQ_NO_DEBUG;
+}
+
+static inline bool irq_settings_no_debug(struct irq_desc *desc)
+{
+	return desc->status_use_accessors & _IRQ_NO_DEBUG;
+}