irqdomain: Refactor __irq_domain_alloc_irqs()

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: b62b2cf5 ("irqdomain: Fix handling of type settings for existing mappings")
Cc: stable@vger.kernel.org      # 4.8
Tested-by: Hsin-Yi Wang <hsinyi@chromium.org>
Tested-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230213104302.17307-6-johan+linaro@kernel.org

kernel/irq/irqdomain.c

@@ -1441,40 +1441,12 @@ int irq_domain_alloc_irqs_hierarchy(struct irq_domain *domain,
 	return domain->ops->alloc(domain, irq_base, nr_irqs, arg);
 }
 
-/**
- * __irq_domain_alloc_irqs - Allocate IRQs from domain
- * @domain:	domain to allocate from
- * @irq_base:	allocate specified IRQ number if irq_base >= 0
- * @nr_irqs:	number of IRQs to allocate
- * @node:	NUMA node id for memory allocation
- * @arg:	domain specific argument
- * @realloc:	IRQ descriptors have already been allocated if true
- * @affinity:	Optional irq affinity mask for multiqueue devices
- *
- * Allocate IRQ numbers and initialized all data structures to support
- * hierarchy IRQ domains.
- * Parameter @realloc is mainly to support legacy IRQs.
- * Returns error code or allocated IRQ number
- *
- * The whole process to setup an IRQ has been split into two steps.
- * The first step, __irq_domain_alloc_irqs(), is to allocate IRQ
- * descriptor and required hardware resources. The second step,
- * irq_domain_activate_irq(), is to program the hardware with preallocated
- * resources. In this way, it's easier to rollback when failing to
- * allocate resources.
- */
-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)
+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 (domain == NULL) {
-		domain = irq_default_domain;
-		if (WARN(!domain, "domain is NULL; cannot allocate IRQ\n"))
-			return -EINVAL;
-	}
-
 	if (realloc && irq_base >= 0) {
 		virq = irq_base;
 	} else {
@@ -1493,24 +1465,18 @@ int __irq_domain_alloc_irqs(struct irq_domain *domain, int irq_base,
 		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);
+	if (ret < 0)
 		goto out_free_irq_data;
-	}
 
 	for (i = 0; i < nr_irqs; i++) {
 		ret = irq_domain_trim_hierarchy(virq + i);
-		if (ret) {
-			mutex_unlock(&irq_domain_mutex);
+		if (ret)
 			goto out_free_irq_data;
-		}
 	}
-	
+
 	for (i = 0; i < nr_irqs; i++)
 		irq_domain_insert_irq(virq + i);
-	mutex_unlock(&irq_domain_mutex);
 
 	return virq;
 
@@ -1520,6 +1486,48 @@ int __irq_domain_alloc_irqs(struct irq_domain *domain, int irq_base,
 	irq_free_descs(virq, nr_irqs);
 	return ret;
 }
+
+/**
+ * __irq_domain_alloc_irqs - Allocate IRQs from domain
+ * @domain:	domain to allocate from
+ * @irq_base:	allocate specified IRQ number if irq_base >= 0
+ * @nr_irqs:	number of IRQs to allocate
+ * @node:	NUMA node id for memory allocation
+ * @arg:	domain specific argument
+ * @realloc:	IRQ descriptors have already been allocated if true
+ * @affinity:	Optional irq affinity mask for multiqueue devices
+ *
+ * Allocate IRQ numbers and initialized all data structures to support
+ * hierarchy IRQ domains.
+ * Parameter @realloc is mainly to support legacy IRQs.
+ * Returns error code or allocated IRQ number
+ *
+ * The whole process to setup an IRQ has been split into two steps.
+ * The first step, __irq_domain_alloc_irqs(), is to allocate IRQ
+ * descriptor and required hardware resources. The second step,
+ * irq_domain_activate_irq(), is to program the hardware with preallocated
+ * resources. In this way, it's easier to rollback when failing to
+ * allocate resources.
+ */
+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 ret;
+
+	if (domain == NULL) {
+		domain = irq_default_domain;
+		if (WARN(!domain, "domain is NULL; cannot allocate IRQ\n"))
+			return -EINVAL;
+	}
+
+	mutex_lock(&irq_domain_mutex);
+	ret = irq_domain_alloc_irqs_locked(domain, irq_base, nr_irqs, node, arg,
+					   realloc, affinity);
+	mutex_unlock(&irq_domain_mutex);
+
+	return ret;
+}
 EXPORT_SYMBOL_GPL(__irq_domain_alloc_irqs);
 
 /* The irq_data was moved, fix the revmap to refer to the new location */