[PATCH 5.4 2/3] irqdomain: Refactor __irq_domain_alloc_irqs()

[Mark-PK Tsai <mark-pk.tsai@xxxxxxxxxxxx>]

From: Johan Hovold <johan+linaro@xxxxxxxxxx>

[ Upstream commit d55f7f4c58c07beb5050a834bf57ae2ede599c7e ]

Refactor __irq_domain_alloc_irqs() so that it can be called internally
while holding the irq_domain_mutex.

This will be used to fix a shared-interrupt mapping race, hence the
Fixes tag.

Fixes: b62b2cf5759b ("irqdomain: Fix handling of type settings for existing mappings")
Cc: stable@xxxxxxxxxxxxxxx      # 4.8
Tested-by: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx>
Tested-by: Mark-PK Tsai <mark-pk.tsai@xxxxxxxxxxxx>
Signed-off-by: Johan Hovold <johan+linaro@xxxxxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230213104302.17307-6-johan+linaro@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
Signed-off-by: Mark-PK Tsai <mark-pk.tsai@xxxxxxxxxxxx>
---
 kernel/irq/irqdomain.c | 74 ++++++++++++++++++++++++------------------
 1 file changed, 42 insertions(+), 32 deletions(-)

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 8d85eeb0f078..1eb34eaeaa94 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -1350,6 +1350,45 @@ int irq_domain_alloc_irqs_hierarchy(struct irq_domain *domain,
 	return domain->ops->alloc(domain, irq_base, nr_irqs, arg);
 }
 
+static int irq_domain_alloc_irqs_locked(struct irq_domain *domain, int irq_base,
+					unsigned int nr_irqs, int node, void *arg,
+					bool realloc, const struct irq_affinity_desc *affinity)
+{
+	int i, ret, virq;
+
+	if (realloc && irq_base >= 0) {
+		virq = irq_base;
+	} else {
+		virq = irq_domain_alloc_descs(irq_base, nr_irqs, 0, node,
+					      affinity);
+		if (virq < 0) {
+			pr_debug("cannot allocate IRQ(base %d, count %d)\n",
+				 irq_base, nr_irqs);
+			return virq;
+		}
+	}
+
+	if (irq_domain_alloc_irq_data(domain, virq, nr_irqs)) {
+		pr_debug("cannot allocate memory for IRQ%d\n", virq);
+		ret = -ENOMEM;
+		goto out_free_desc;
+	}
+
+	ret = irq_domain_alloc_irqs_hierarchy(domain, virq, nr_irqs, arg);
+	if (ret < 0)
+		goto out_free_irq_data;
+	for (i = 0; i < nr_irqs; i++)
+		irq_domain_insert_irq(virq + i);
+
+	return virq;
+
+out_free_irq_data:
+	irq_domain_free_irq_data(virq, nr_irqs);
+out_free_desc:
+	irq_free_descs(virq, nr_irqs);
+	return ret;
+}
+
 /**
  * __irq_domain_alloc_irqs - Allocate IRQs from domain
  * @domain:	domain to allocate from
@@ -1376,7 +1415,7 @@ int __irq_domain_alloc_irqs(struct irq_domain *domain, int irq_base,
 			    unsigned int nr_irqs, int node, void *arg,
 			    bool realloc, const struct irq_affinity_desc *affinity)
 {
-	int i, ret, virq;
+	int ret;
 
 	if (domain == NULL) {
 		domain = irq_default_domain;
@@ -1384,40 +1423,11 @@ int __irq_domain_alloc_irqs(struct irq_domain *domain, int irq_base,
 			return -EINVAL;
 	}
 
-	if (realloc && irq_base >= 0) {
-		virq = irq_base;
-	} else {
-		virq = irq_domain_alloc_descs(irq_base, nr_irqs, 0, node,
-					      affinity);
-		if (virq < 0) {
-			pr_debug("cannot allocate IRQ(base %d, count %d)\n",
-				 irq_base, nr_irqs);
-			return virq;
-		}
-	}
-
-	if (irq_domain_alloc_irq_data(domain, virq, nr_irqs)) {
-		pr_debug("cannot allocate memory for IRQ%d\n", virq);
-		ret = -ENOMEM;
-		goto out_free_desc;
-	}
-
 	mutex_lock(&irq_domain_mutex);
-	ret = irq_domain_alloc_irqs_hierarchy(domain, virq, nr_irqs, arg);
-	if (ret < 0) {
-		mutex_unlock(&irq_domain_mutex);
-		goto out_free_irq_data;
-	}
-	for (i = 0; i < nr_irqs; i++)
-		irq_domain_insert_irq(virq + i);
+	ret = irq_domain_alloc_irqs_locked(domain, irq_base, nr_irqs, node, arg,
+					   realloc, affinity);
 	mutex_unlock(&irq_domain_mutex);
 
-	return virq;
-
-out_free_irq_data:
-	irq_domain_free_irq_data(virq, nr_irqs);
-out_free_desc:
-	irq_free_descs(virq, nr_irqs);
 	return ret;
 }
 
-- 
2.18.0