[PATCH v7 08/10] irqchip/imx-irqsteer: Dispose of child IRQ mappings in remove()

[Zhipeng.wang_1 at oss.nxp.com]

From: Zhipeng Wang <zhipeng.wang_1 at nxp.com>

Once the driver can be unloaded, the IRQ domain mappings handed out to
downstream consumers must be released on remove(), otherwise:

 - a parent interrupt racing with the teardown can run the chained
   handler while irqsteer_data is freed (no synchronize_irq());
 - downstream irq_descs keep dangling chip pointers into the unloaded
   module.

Dispose of every child hwirq mapping in remove(). irq_dispose_mapping()
calls irq_domain_disassociate(), which runs synchronize_irq() and frees
the descriptor, closing both races.

Signed-off-by: Zhipeng Wang <zhipeng.wang_1 at nxp.com>
---
 drivers/irqchip/irq-imx-irqsteer.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/irqchip/irq-imx-irqsteer.c b/drivers/irqchip/irq-imx-irqsteer.c
index a14a8b80d60e..d15b806b278c 100644
--- a/drivers/irqchip/irq-imx-irqsteer.c
+++ b/drivers/irqchip/irq-imx-irqsteer.c
@@ -272,6 +272,7 @@ static int imx_irqsteer_probe(struct platform_device *pdev)
 static void imx_irqsteer_remove(struct platform_device *pdev)
 {
 	struct irqsteer_data *irqsteer_data = platform_get_drvdata(pdev);
+	unsigned int hwirq;
 	int i, ret;
 
 	/*
@@ -294,6 +295,9 @@ static void imx_irqsteer_remove(struct platform_device *pdev)
 		irq_dispose_mapping(irqsteer_data->irq[i]);
 	}
 
+	for (hwirq = 0; hwirq < irqsteer_data->reg_num * 32; hwirq++)
+		irq_dispose_mapping(irq_find_mapping(irqsteer_data->domain, hwirq));
+
 	irq_domain_remove(irqsteer_data->domain);
 
 	if (ret >= 0)
-- 
2.34.1