x86/amd_node: Fix PCI device reference counting in amd_smn_init()grafted

The local "root" pointer is a temporary variable used during the device
search. Therefore, refcount related to the search iterators should be cleaned
up after the search is complete.

Use the __free() cleanup macro to ensure the refcount is decremented when the
temporary pointer goes out of scope.

Additionally, increment the refcount when caching a root pointer. This ensures
the in-use refcount is separate from the temporary search refcounting.

Finally, drop the redundant "root = NULL" before the second search loop. The
pci_get_class() iterator always decrements the refcount of its "from"
argument, so the first loop can only fall through with "root" already NULL.

Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching")
Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com

1 files changed, 119 insertions, 0 deletions

diff --git a/drivers/input/misc/rt5120-pwrkey.c b/drivers/input/misc/rt5120-pwrkey.c
new file mode 100644
index 000000000..2262f5057
--- /dev/null
+++ b/drivers/input/misc/rt5120-pwrkey.c
@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022 Richtek Technology Corp.
+ * Author: ChiYuan Huang <cy_huang@richtek.com>
+ */
+
+#include <linux/bits.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define RT5120_REG_INTSTAT	0x1E
+#define RT5120_PWRKEYSTAT_MASK	BIT(7)
+
+struct rt5120_priv {
+	struct regmap *regmap;
+	struct input_dev *input;
+};
+
+static irqreturn_t rt5120_pwrkey_handler(int irq, void *devid)
+{
+	struct rt5120_priv *priv = devid;
+	unsigned int stat;
+	int error;
+
+	error = regmap_read(priv->regmap, RT5120_REG_INTSTAT, &stat);
+	if (error)
+		return IRQ_NONE;
+
+	input_report_key(priv->input, KEY_POWER,
+			 !(stat & RT5120_PWRKEYSTAT_MASK));
+	input_sync(priv->input);
+
+	return IRQ_HANDLED;
+}
+
+static int rt5120_pwrkey_probe(struct platform_device *pdev)
+{
+	struct rt5120_priv *priv;
+	struct device *dev = &pdev->dev;
+	int press_irq, release_irq;
+	int error;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->regmap = dev_get_regmap(dev->parent, NULL);
+	if (!priv->regmap) {
+		dev_err(dev, "Failed to init regmap\n");
+		return -ENODEV;
+	}
+
+	press_irq = platform_get_irq_byname(pdev, "pwrkey-press");
+	if (press_irq < 0)
+		return press_irq;
+
+	release_irq = platform_get_irq_byname(pdev, "pwrkey-release");
+	if (release_irq < 0)
+		return release_irq;
+
+	/* Make input device be device resource managed */
+	priv->input = devm_input_allocate_device(dev);
+	if (!priv->input)
+		return -ENOMEM;
+
+	priv->input->name = "rt5120_pwrkey";
+	priv->input->phys = "rt5120_pwrkey/input0";
+	priv->input->id.bustype = BUS_I2C;
+	input_set_capability(priv->input, EV_KEY, KEY_POWER);
+
+	error = input_register_device(priv->input);
+	if (error) {
+		dev_err(dev, "Failed to register input device: %d\n", error);
+		return error;
+	}
+
+	error = devm_request_threaded_irq(dev, press_irq,
+					  NULL, rt5120_pwrkey_handler,
+					  0, "pwrkey-press", priv);
+	if (error) {
+		dev_err(dev,
+			"Failed to register pwrkey press irq: %d\n", error);
+		return error;
+	}
+
+	error = devm_request_threaded_irq(dev, release_irq,
+					  NULL, rt5120_pwrkey_handler,
+					  0, "pwrkey-release", priv);
+	if (error) {
+		dev_err(dev,
+			"Failed to register pwrkey release irq: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id r5120_pwrkey_match_table[] = {
+	{ .compatible = "richtek,rt5120-pwrkey" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, r5120_pwrkey_match_table);
+
+static struct platform_driver rt5120_pwrkey_driver = {
+	.driver = {
+		.name = "rt5120-pwrkey",
+		.of_match_table = r5120_pwrkey_match_table,
+	},
+	.probe = rt5120_pwrkey_probe,
+};
+module_platform_driver(rt5120_pwrkey_driver);
+
+MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
+MODULE_DESCRIPTION("Richtek RT5120 power key driver");
+MODULE_LICENSE("GPL");