linux-kernel - [PATCH] of/irq: add missing of_node

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Message-Id: <20230117144929.423089-1-clement.leger@bootlin.com>
Date:   Tue, 17 Jan 2023 15:49:29 +0100
From:   Clément Léger <clement.leger@...tlin.com>
To:     Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>
Cc:     Clément Léger <clement.leger@...tlin.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] of/irq: add missing of_node_put() for interrupt parent node

After calling of_irq_parse_one(), the node provided in the of_phandle_args
has a refcount increment by one. Add missing of_node_put in of_irq_get()
to decrement the refcount once used.

Signed-off-by: Clément Léger <clement.leger@...tlin.com>
---

While debugging a refcount problem with OF_DYNAMIC enabled (which is
actually the only case were node refcount are really used), I noticed that
platform_get_irq() was actually incrementing the refcount of an interrupt
controller node. Digging into that function shows that it calls
of_irq_get() which calls of_irq_parse_one() and finally of_irq_parse_raw().
Since it seems sane that the node returned in the of_phandle_args has a
refcount incremented, I thought it is better to put the of_node_put() in
the user even though it was hard to find any user doing so.

 drivers/of/irq.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/of/irq.c b/drivers/of/irq.c
index e9bf5236ed89..174900072c18 100644
--- a/drivers/of/irq.c
+++ b/drivers/of/irq.c
@@ -438,10 +438,16 @@ int of_irq_get(struct device_node *dev, int index)
 		return rc;

 	domain = irq_find_host(oirq.np);
-	if (!domain)
-		return -EPROBE_DEFER;
+	if (!domain) {
+		rc = -EPROBE_DEFER;
+		goto out;
+	}

-	return irq_create_of_mapping(&oirq);
+	rc = irq_create_of_mapping(&oirq);
+out:
+	of_node_put(oirq.np);
+
+	return rc;
 }
 EXPORT_SYMBOL_GPL(of_irq_get);

-- 
2.39.0