[PATCH 6.1 774/885] irqdomain: Fix association race

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From: Johan Hovold <johan+linaro@xxxxxxxxxx>

commit b06730a571a9ff1ba5bd6b20bf9e50e5a12f1ec6 upstream.

The sanity check for an already mapped virq is done outside of the
irq_domain_mutex-protected section which means that an (unlikely) racing
association may not be detected.

Fix this by factoring out the association implementation, which will
also be used in a follow-on change to fix a shared-interrupt mapping
race.

Fixes: ddaf144c61da ("irqdomain: Refactor irq_domain_associate_many()")
Cc: stable@xxxxxxxxxxxxxxx      # 3.11
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/20230213104302.17307-2-johan+linaro@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 kernel/irq/irqdomain.c |   19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -559,8 +559,8 @@ static void irq_domain_disassociate(stru
 	irq_domain_clear_mapping(domain, hwirq);
 }
 
-int irq_domain_associate(struct irq_domain *domain, unsigned int virq,
-			 irq_hw_number_t hwirq)
+static int irq_domain_associate_locked(struct irq_domain *domain, unsigned int virq,
+				       irq_hw_number_t hwirq)
 {
 	struct irq_data *irq_data = irq_get_irq_data(virq);
 	int ret;
@@ -573,7 +573,6 @@ int irq_domain_associate(struct irq_doma
 	if (WARN(irq_data->domain, "error: virq%i is already associated", virq))
 		return -EINVAL;
 
-	mutex_lock(&irq_domain_mutex);
 	irq_data->hwirq = hwirq;
 	irq_data->domain = domain;
 	if (domain->ops->map) {
@@ -590,7 +589,6 @@ int irq_domain_associate(struct irq_doma
 			}
 			irq_data->domain = NULL;
 			irq_data->hwirq = 0;
-			mutex_unlock(&irq_domain_mutex);
 			return ret;
 		}
 
@@ -601,12 +599,23 @@ int irq_domain_associate(struct irq_doma
 
 	domain->mapcount++;
 	irq_domain_set_mapping(domain, hwirq, irq_data);
-	mutex_unlock(&irq_domain_mutex);
 
 	irq_clear_status_flags(virq, IRQ_NOREQUEST);
 
 	return 0;
 }
+
+int irq_domain_associate(struct irq_domain *domain, unsigned int virq,
+			 irq_hw_number_t hwirq)
+{
+	int ret;
+
+	mutex_lock(&irq_domain_mutex);
+	ret = irq_domain_associate_locked(domain, virq, hwirq);
+	mutex_unlock(&irq_domain_mutex);
+
+	return ret;
+}
 EXPORT_SYMBOL_GPL(irq_domain_associate);
 
 void irq_domain_associate_many(struct irq_domain *domain, unsigned int irq_base,





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