linux-kernel - [PATCH v4] irqchip/renesas-rzg2l: Fix missing put

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Message-Id: <20241011172003.1242841-1-fabrizio.castro.jz@renesas.com>
Date: Fri, 11 Oct 2024 18:20:03 +0100
From: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
To: Thomas Gleixner <tglx@...utronix.de>,
	Markus Elfring <elfring@...rs.sourceforge.net>,
	Markus Elfring <Markus.Elfring@....de>,
	Geert Uytterhoeven <geert+renesas@...der.be>
Cc: Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
	Marc Zyngier <maz@...nel.org>,
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
	linux-kernel@...r.kernel.org,
	Chris Paterson <Chris.Paterson2@...esas.com>,
	Biju Das <biju.das.jz@...renesas.com>,
	linux-renesas-soc@...r.kernel.org
Subject: [PATCH v4] irqchip/renesas-rzg2l: Fix missing put_device

rzg2l_irqc_common_init calls of_find_device_by_node, but the
corresponding put_device call is missing.
This also gets reported by make coccicheck.

Make use of the cleanup interfaces from cleanup.h to call into
__free_put_device (which in turn calls into put_device) when
leaving function rzg2l_irqc_common_init and variable "dev" goes
out of scope.

Mind that we don't want to "put" "dev" when rzg2l_irqc_common_init
completes successfully, therefore assign NULL to "dev" to prevent
__free_put_device from calling into put_device within the successful
path.

"make coccicheck" will still complain about missing put_device calls,
but those are false positives now.

Fixes: 3fed09559cd8 ("irqchip: Add RZ/G2L IA55 Interrupt Controller driver")
Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
---

v3->v4:
 * switched to using the cleanup interfaces as an alternative to using
   goto chains

 drivers/irqchip/irq-renesas-rzg2l.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-renesas-rzg2l.c b/drivers/irqchip/irq-renesas-rzg2l.c
index 693ff285ca2c..99e27e01b0b1 100644
--- a/drivers/irqchip/irq-renesas-rzg2l.c
+++ b/drivers/irqchip/irq-renesas-rzg2l.c
@@ -8,6 +8,7 @@
  */
 
 #include <linux/bitfield.h>
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/io.h>
@@ -530,12 +531,12 @@ static int rzg2l_irqc_parse_interrupts(struct rzg2l_irqc_priv *priv,
 static int rzg2l_irqc_common_init(struct device_node *node, struct device_node *parent,
 				  const struct irq_chip *irq_chip)
 {
+	struct platform_device *pdev = of_find_device_by_node(node);
+	struct device *dev __free(put_device) = pdev ? &pdev->dev : NULL;
 	struct irq_domain *irq_domain, *parent_domain;
-	struct platform_device *pdev;
 	struct reset_control *resetn;
 	int ret;
 
-	pdev = of_find_device_by_node(node);
 	if (!pdev)
 		return -ENODEV;
 
@@ -591,6 +592,17 @@ static int rzg2l_irqc_common_init(struct device_node *node, struct device_node *
 
 	register_syscore_ops(&rzg2l_irqc_syscore_ops);
 
+	/*
+	 * Prevent the cleanup function from invoking put_device by assigning
+	 * NULL to dev.
+	 *
+	 * make coccicheck will complain about missing put_device calls, but
+	 * those are false positives, as dev will be automatically "put" via
+	 * __free_put_device on the failing path.
+	 * On the successful path we don't actually want to "put" dev.
+	 */
+	dev = NULL;
+
 	return 0;
 
 pm_put:
-- 
2.34.1