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, 130 insertions, 0 deletions

diff --git a/drivers/input/misc/ab8500-ponkey.c b/drivers/input/misc/ab8500-ponkey.c
new file mode 100644
index 000000000..a9b901368
--- /dev/null
+++ b/drivers/input/misc/ab8500-ponkey.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) ST-Ericsson SA 2010
+ *
+ * Author: Sundar Iyer <sundar.iyer@stericsson.com> for ST-Ericsson
+ *
+ * AB8500 Power-On Key handler
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/abx500/ab8500.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+/**
+ * struct ab8500_ponkey - ab8500 ponkey information
+ * @idev: pointer to input device
+ * @ab8500: ab8500 parent
+ * @irq_dbf: irq number for falling transition
+ * @irq_dbr: irq number for rising transition
+ */
+struct ab8500_ponkey {
+	struct input_dev	*idev;
+	struct ab8500		*ab8500;
+	int			irq_dbf;
+	int			irq_dbr;
+};
+
+/* AB8500 gives us an interrupt when ONKEY is held */
+static irqreturn_t ab8500_ponkey_handler(int irq, void *data)
+{
+	struct ab8500_ponkey *ponkey = data;
+
+	if (irq == ponkey->irq_dbf)
+		input_report_key(ponkey->idev, KEY_POWER, true);
+	else if (irq == ponkey->irq_dbr)
+		input_report_key(ponkey->idev, KEY_POWER, false);
+
+	input_sync(ponkey->idev);
+
+	return IRQ_HANDLED;
+}
+
+static int ab8500_ponkey_probe(struct platform_device *pdev)
+{
+	struct ab8500 *ab8500 = dev_get_drvdata(pdev->dev.parent);
+	struct ab8500_ponkey *ponkey;
+	struct input_dev *input;
+	int irq_dbf, irq_dbr;
+	int error;
+
+	irq_dbf = platform_get_irq_byname(pdev, "ONKEY_DBF");
+	if (irq_dbf < 0)
+		return irq_dbf;
+
+	irq_dbr = platform_get_irq_byname(pdev, "ONKEY_DBR");
+	if (irq_dbr < 0)
+		return irq_dbr;
+
+	ponkey = devm_kzalloc(&pdev->dev, sizeof(struct ab8500_ponkey),
+			      GFP_KERNEL);
+	if (!ponkey)
+		return -ENOMEM;
+
+	input = devm_input_allocate_device(&pdev->dev);
+	if (!input)
+		return -ENOMEM;
+
+	ponkey->idev = input;
+	ponkey->ab8500 = ab8500;
+	ponkey->irq_dbf = irq_dbf;
+	ponkey->irq_dbr = irq_dbr;
+
+	input->name = "AB8500 POn(PowerOn) Key";
+	input->dev.parent = &pdev->dev;
+
+	input_set_capability(input, EV_KEY, KEY_POWER);
+
+	error = devm_request_any_context_irq(&pdev->dev, ponkey->irq_dbf,
+					     ab8500_ponkey_handler, 0,
+					     "ab8500-ponkey-dbf", ponkey);
+	if (error < 0) {
+		dev_err(ab8500->dev, "Failed to request dbf IRQ#%d: %d\n",
+			ponkey->irq_dbf, error);
+		return error;
+	}
+
+	error = devm_request_any_context_irq(&pdev->dev, ponkey->irq_dbr,
+					     ab8500_ponkey_handler, 0,
+					     "ab8500-ponkey-dbr", ponkey);
+	if (error < 0) {
+		dev_err(ab8500->dev, "Failed to request dbr IRQ#%d: %d\n",
+			ponkey->irq_dbr, error);
+		return error;
+	}
+
+	error = input_register_device(ponkey->idev);
+	if (error) {
+		dev_err(ab8500->dev, "Can't register input device: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id ab8500_ponkey_match[] = {
+	{ .compatible = "stericsson,ab8500-ponkey", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, ab8500_ponkey_match);
+#endif
+
+static struct platform_driver ab8500_ponkey_driver = {
+	.driver		= {
+		.name	= "ab8500-poweron-key",
+		.of_match_table = of_match_ptr(ab8500_ponkey_match),
+	},
+	.probe		= ab8500_ponkey_probe,
+};
+module_platform_driver(ab8500_ponkey_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Sundar Iyer <sundar.iyer@stericsson.com>");
+MODULE_DESCRIPTION("ST-Ericsson AB8500 Power-ON(Pon) Key driver");