linux-kernel - [PATCH v3 05/19] irqdomain: Fix disassociation race

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Date:   Fri,  9 Dec 2022 15:01:36 +0100
From:   Johan Hovold <johan+linaro@...nel.org>
To:     Marc Zyngier <maz@...nel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
        platform-driver-x86@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-mips@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Johan Hovold <johan+linaro@...nel.org>
Subject: [PATCH v3 05/19] irqdomain: Fix disassociation race

The global irq_domain_mutex is held when mapping interrupts from
non-hierarchical domains but currently not when disposing them.

This specifically means that updates of the domain mapcount is racy
(currently only used for statistics in debugfs).

Make sure to hold the global irq_domain_mutex also when disposing
mappings from non-hierarchical domains.

Fixes: 9dc6be3d4193 ("genirq/irqdomain: Add map counter")
Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
---
 kernel/irq/irqdomain.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index b2087f55a1ac..23f5919e58b7 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -537,6 +537,9 @@ static void irq_domain_disassociate(struct irq_domain *domain, unsigned int irq)
 		return;
 
 	hwirq = irq_data->hwirq;
+
+	mutex_lock(&irq_domain_mutex);
+
 	irq_set_status_flags(irq, IRQ_NOREQUEST);
 
 	/* remove chip and handler */
@@ -556,6 +559,8 @@ static void irq_domain_disassociate(struct irq_domain *domain, unsigned int irq)
 
 	/* Clear reverse map for this hwirq */
 	irq_domain_clear_mapping(domain, hwirq);
+
+	mutex_unlock(&irq_domain_mutex);
 }
 
 static int __irq_domain_associate(struct irq_domain *domain, unsigned int virq,
-- 
2.37.4