linux-kernel - [irqchip: irq/irqchip-next] irqdomain: Fix association race

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Date:   Mon, 13 Feb 2023 19:40:48 -0000
From:   "irqchip-bot for Johan Hovold" <tip-bot2@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     stable@...r.kernel.org, #@...-bot2.tec.linutronix.de,
        3.11@...-bot2.tec.linutronix.de,
        "Hsin-Yi Wang" <hsinyi@...omium.org>,
        "Mark-PK Tsai" <mark-pk.tsai@...iatek.com>,
        Johan Hovold <johan+linaro@...nel.org>,
        Marc Zyngier <maz@...nel.org>, tglx@...utronix.de
Subject: [irqchip: irq/irqchip-next] irqdomain: Fix association race

The following commit has been merged into the irq/irqchip-next branch of irqchip:

Commit-ID:     b06730a571a9ff1ba5bd6b20bf9e50e5a12f1ec6
Gitweb:        https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms/b06730a571a9ff1ba5bd6b20bf9e50e5a12f1ec6
Author:        Johan Hovold <johan+linaro@...nel.org>
AuthorDate:    Mon, 13 Feb 2023 11:42:43 +01:00
Committer:     Marc Zyngier <maz@...nel.org>
CommitterDate: Mon, 13 Feb 2023 19:31:24 

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@...r.kernel.org      # 3.11
Tested-by: Hsin-Yi Wang <hsinyi@...omium.org>
Tested-by: Mark-PK Tsai <mark-pk.tsai@...iatek.com>
Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
Signed-off-by: Marc Zyngier <maz@...nel.org>
Link: https://lore.kernel.org/r/20230213104302.17307-2-johan+linaro@kernel.org
---
 kernel/irq/irqdomain.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 8fe1da9..6661de1 100644
--- 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,