linux-kernel - [RFC PATCH v2 3/4] irq: Introduce IRQ_HANDLED

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Message-ID: <20240216075948.131372-5-leobras@redhat.com>
Date: Fri, 16 Feb 2024 04:59:45 -0300
From: Leonardo Bras <leobras@...hat.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Tony Lindgren <tony@...mide.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	John Ogness <john.ogness@...utronix.de>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
	Leonardo Bras <leobras@...hat.com>,
	Florian Fainelli <florian.fainelli@...adcom.com>,
	Shanker Donthineni <sdonthineni@...dia.com>
Cc: linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org
Subject: [RFC PATCH v2 3/4] irq: Introduce IRQ_HANDLED_MANY

In threaded IRQs, some irq handlers are able to handle many requests at a
single run, but this is only accounted as a single IRQ_HANDLED when
increasing threads_handled.

In order to fix this, introduce IRQ_HANDLED_MANY, so the returned value of
those IRQ handlers are able to signal that many IRQs got handled at that
run.

Is scenarios where there is no need to keep track of IRQ handled, convert
it back to IRQ_HANDLED.

Signed-off-by: Leonardo Bras <leobras@...hat.com>
---
 include/linux/irqreturn.h | 23 ++++++++++++++++++++++-
 kernel/irq/chip.c         | 10 ++++++++--
 kernel/irq/handle.c       |  3 +++
 kernel/irq/manage.c       |  4 ++++
 4 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/include/linux/irqreturn.h b/include/linux/irqreturn.h
index d426c7ad92bfd..204030696676c 100644
--- a/include/linux/irqreturn.h
+++ b/include/linux/irqreturn.h
@@ -7,14 +7,35 @@
  * @IRQ_NONE:		interrupt was not from this device or was not handled
  * @IRQ_HANDLED:	interrupt was handled by this device
  * @IRQ_WAKE_THREAD:	handler requests to wake the handler thread
+ * @IRQ_HANDLED_MANY:	interrupt was handled by this device multiple times
+ *			should be the only bit set in the first 3 bits, and
+ *			carry a count > 1 in the next bits.
  */
 enum irqreturn {
 	IRQ_NONE		= (0 << 0),
 	IRQ_HANDLED		= (1 << 0),
 	IRQ_WAKE_THREAD		= (1 << 1),
+	IRQ_HANDLED_MANY	= (1 << 2),
+	IRQ_RETMASK		= IRQ_HANDLED |	IRQ_WAKE_THREAD | IRQ_HANDLED_MANY,
 };
 
-typedef enum irqreturn irqreturn_t;
+#define IRQ_HANDLED_MANY_SHIFT (3)
+
+typedef int irqreturn_t;
 #define IRQ_RETVAL(x)	((x) ? IRQ_HANDLED : IRQ_NONE)
+#define	IRQ_RETVAL_MANY(x)							\
+({										\
+	__typeof__(x) __x = (x);						\
+	irqreturn_t __ret;							\
+	if (__x == 0)								\
+		__ret = IRQ_NONE;						\
+	else if (__x == 1)							\
+		__ret = IRQ_HANDLED;						\
+	else									\
+		__ret = IRQ_HANDLED_MANY | (__x << IRQ_HANDLED_MANY_SHIFT);	\
+	__ret;									\
+})
+
+#define IRQ_HANDLED_MANY_GET(x)	((x) >> IRQ_HANDLED_MANY_SHIFT)
 
 #endif
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index dc94e0bf2c940..233cf22a5b771 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -482,8 +482,14 @@ void handle_nested_irq(unsigned int irq)
 	raw_spin_unlock_irq(&desc->lock);
 
 	action_ret = IRQ_NONE;
-	for_each_action_of_desc(desc, action)
-		action_ret |= action->thread_fn(action->irq, action->dev_id);
+	for_each_action_of_desc(desc, action) {
+		irqreturn_t ret = action->thread_fn(action->irq, action->dev_id);
+
+		if ((ret & IRQ_RETMASK) == IRQ_HANDLED_MANY)
+			ret = IRQ_HANDLED;
+
+		action_ret |= ret;
+	}
 
 	if (!irq_settings_no_debug(desc))
 		note_interrupt(desc, action_ret);
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 9489f93b3db34..bfc6e3e43045a 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -162,6 +162,9 @@ irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc)
 			      irq, action->handler))
 			local_irq_disable();
 
+		if ((res & IRQ_RETMASK) == IRQ_HANDLED_MANY)
+			res = IRQ_HANDLED;
+
 		switch (res) {
 		case IRQ_WAKE_THREAD:
 			/*
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 5bc609c7b728c..e684c7107ff90 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1192,6 +1192,8 @@ irq_forced_thread_fn(struct irq_desc *desc, struct irqaction *action)
 	ret = action->thread_fn(action->irq, action->dev_id);
 	if (ret == IRQ_HANDLED)
 		irq_add_handled(desc, 1);
+	else if ((ret & IRQ_RETMASK) == IRQ_HANDLED_MANY)
+		irq_add_handled(desc, IRQ_HANDLED_MANY_GET(ret));
 
 	irq_finalize_oneshot(desc, action);
 	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
@@ -1213,6 +1215,8 @@ static irqreturn_t irq_thread_fn(struct irq_desc *desc,
 	ret = action->thread_fn(action->irq, action->dev_id);
 	if (ret == IRQ_HANDLED)
 		irq_add_handled(desc, 1);
+	else if ((ret & IRQ_RETMASK) == IRQ_HANDLED_MANY)
+		irq_add_handled(desc, IRQ_HANDLED_MANY_GET(ret));
 
 	irq_finalize_oneshot(desc, action);
 	return ret;
-- 
2.43.2