irqdomain: Fix association race

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@vger.kernel.org      # 3.11
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/20230213104302.17307-2-johan+linaro@kernel.org

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 8fe1da9614ee8db33ff75a21010e6da45f9dfbc2..6661de18550e9f836a33d727a586da7b5e0420de 100644 (file)
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -559,8 +559,8 @@ static void irq_domain_disassociate(struct irq_domain *domain, unsigned int irq)
        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_domain *domain, unsigned int virq,
        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_domain *domain, unsigned int virq,
                        }
                        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_domain *domain, unsigned int virq,
 
        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,