linux-kernel - [RFC PATCH 5/5] irq: Add smp_affinity/list attributes to sysfs

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Message-Id: <20230530214550.864894-6-rrendec@redhat.com>
Date:   Tue, 30 May 2023 17:45:50 -0400
From:   Radu Rendec <rrendec@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Marc Zyngier <maz@...nel.org>, Thomas Gleixner <tglx@...utronix.de>
Subject: [RFC PATCH 5/5] irq: Add smp_affinity/list attributes to sysfs

This patch adds the smp_affinity and smp_affinity_list attributes to the
sysfs interrupt interface. The implementation is identical to procfs,
and the attributes are visible only when CONFIG_SMP is enabled.

The intention is to allow SMP affinity to be controlled for chained
interrupt parents, which are typically not visible in procfs because
they are not requested through request_irq().

Signed-off-by: Radu Rendec <rrendec@...hat.com>
---
 kernel/irq/irqdesc.c | 55 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index a46a76c29b8d1..5b014df9fd730 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -210,6 +210,9 @@ static struct kobject *irq_kobj_base;
 #define IRQ_ATTR_RO(_name) \
 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
 
+#define IRQ_ATTR_RW(_name) \
+static struct kobj_attribute _name##_attr = __ATTR_RW(_name)
+
 static ssize_t per_cpu_count_show(struct kobject *kobj,
 				  struct kobj_attribute *attr, char *buf)
 {
@@ -332,6 +335,54 @@ static ssize_t actions_show(struct kobject *kobj,
 }
 IRQ_ATTR_RO(actions);
 
+#ifdef CONFIG_SMP
+static ssize_t smp_affinity_show(struct kobject *kobj,
+				 struct kobj_attribute *attr, char *buf)
+{
+	struct irq_desc *desc = container_of(kobj, struct irq_desc, kobj);
+	const struct cpumask *mask = desc->irq_common_data.affinity;
+
+#ifdef CONFIG_GENERIC_PENDING_IRQ
+	if (irqd_is_setaffinity_pending(&desc->irq_data))
+		mask = desc->pending_mask;
+#endif
+
+	return scnprintf(buf, PAGE_SIZE, "%*pb\n", cpumask_pr_args(mask));
+}
+static ssize_t smp_affinity_store(struct kobject *kobj,
+				  struct kobj_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct irq_desc *desc = container_of(kobj, struct irq_desc, kobj);
+
+	return write_irq_affinity(desc->irq_data.irq, buf, count, false, false);
+}
+IRQ_ATTR_RW(smp_affinity);
+
+static ssize_t smp_affinity_list_show(struct kobject *kobj,
+				      struct kobj_attribute *attr, char *buf)
+{
+	struct irq_desc *desc = container_of(kobj, struct irq_desc, kobj);
+	const struct cpumask *mask = desc->irq_common_data.affinity;
+
+#ifdef CONFIG_GENERIC_PENDING_IRQ
+	if (irqd_is_setaffinity_pending(&desc->irq_data))
+		mask = desc->pending_mask;
+#endif
+
+	return scnprintf(buf, PAGE_SIZE, "%*pbl\n", cpumask_pr_args(mask));
+}
+static ssize_t smp_affinity_list_store(struct kobject *kobj,
+				       struct kobj_attribute *attr,
+				       const char *buf, size_t count)
+{
+	struct irq_desc *desc = container_of(kobj, struct irq_desc, kobj);
+
+	return write_irq_affinity(desc->irq_data.irq, buf, count, true, false);
+}
+IRQ_ATTR_RW(smp_affinity_list);
+#endif
+
 static struct attribute *irq_attrs[] = {
 	&per_cpu_count_attr.attr,
 	&chip_name_attr.attr,
@@ -340,6 +391,10 @@ static struct attribute *irq_attrs[] = {
 	&wakeup_attr.attr,
 	&name_attr.attr,
 	&actions_attr.attr,
+#ifdef CONFIG_SMP
+	&smp_affinity_attr.attr,
+	&smp_affinity_list_attr.attr,
+#endif
 	NULL
 };
 ATTRIBUTE_GROUPS(irq);
-- 
2.40.1