[patch V2 07/21] genirq/msi: Check for invalid MSI parent domain usage

[Thomas Gleixner <tglx@linutronix.de>]

In the upcoming per device MSI domain concept the MSI parent domains are
not allowed to be used as regular MSI domains where the MSI allocation/free
operations are applicable.

Add appropriate checks.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
V2: Made the error return understandable. (Kevin)
---
 kernel/irq/msi.c |   17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -937,13 +937,21 @@ int msi_domain_alloc_irqs_descs_locked(s
 
 	lockdep_assert_held(&dev->msi.data->mutex);
 
+	if (WARN_ON_ONCE(irq_domain_is_msi_parent(domain))) {
+		ret = -EINVAL;
+		goto free;
+	}
+
+	/* Frees allocated descriptors in case of failure. */
 	ret = msi_domain_add_simple_msi_descs(info, dev, nvec);
 	if (ret)
-		return ret;
+		goto free;
 
 	ret = ops->domain_alloc_irqs(domain, dev, nvec);
-	if (ret)
-		msi_domain_free_irqs_descs_locked(domain, dev);
+	if (!ret)
+		return 0;
+free:
+	msi_domain_free_irqs_descs_locked(domain, dev);
 	return ret;
 }
 
@@ -1013,6 +1021,9 @@ void msi_domain_free_irqs_descs_locked(s
 
 	lockdep_assert_held(&dev->msi.data->mutex);
 
+	if (WARN_ON_ONCE(irq_domain_is_msi_parent(domain)))
+		return;
+
 	ops->domain_free_irqs(domain, dev);
 	if (ops->msi_post_free)
 		ops->msi_post_free(domain, dev);