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, 87 insertions, 0 deletions

diff --git a/drivers/mfd/lp873x.c b/drivers/mfd/lp873x.c
new file mode 100644
index 000000000..d2c90302b
--- /dev/null
+++ b/drivers/mfd/lp873x.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2016 Texas Instruments Incorporated - https://www.ti.com/
+ *
+ * Author: Keerthy <j-keerthy@ti.com>
+ */
+
+#include <linux/interrupt.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#include <linux/mfd/lp873x.h>
+
+static const struct regmap_config lp873x_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = LP873X_REG_MAX,
+};
+
+static const struct mfd_cell lp873x_cells[] = {
+	{ .name = "lp873x-regulator", },
+	{ .name = "lp873x-gpio", },
+};
+
+static int lp873x_probe(struct i2c_client *client)
+{
+	struct lp873x *lp873;
+	int ret;
+	unsigned int otpid;
+
+	lp873 = devm_kzalloc(&client->dev, sizeof(*lp873), GFP_KERNEL);
+	if (!lp873)
+		return -ENOMEM;
+
+	lp873->dev = &client->dev;
+
+	lp873->regmap = devm_regmap_init_i2c(client, &lp873x_regmap_config);
+	if (IS_ERR(lp873->regmap)) {
+		ret = PTR_ERR(lp873->regmap);
+		dev_err(lp873->dev,
+			"Failed to initialize register map: %d\n", ret);
+		return ret;
+	}
+
+	ret = regmap_read(lp873->regmap, LP873X_REG_OTP_REV, &otpid);
+	if (ret) {
+		dev_err(lp873->dev, "Failed to read OTP ID\n");
+		return ret;
+	}
+
+	lp873->rev = otpid & LP873X_OTP_REV_OTP_ID;
+
+	i2c_set_clientdata(client, lp873);
+
+	ret = mfd_add_devices(lp873->dev, PLATFORM_DEVID_AUTO, lp873x_cells,
+			      ARRAY_SIZE(lp873x_cells), NULL, 0, NULL);
+
+	return ret;
+}
+
+static const struct of_device_id of_lp873x_match_table[] = {
+	{ .compatible = "ti,lp8733", },
+	{ .compatible = "ti,lp8732", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, of_lp873x_match_table);
+
+static const struct i2c_device_id lp873x_id_table[] = {
+	{ "lp873x" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, lp873x_id_table);
+
+static struct i2c_driver lp873x_driver = {
+	.driver	= {
+		.name	= "lp873x",
+		.of_match_table = of_lp873x_match_table,
+	},
+	.probe		= lp873x_probe,
+	.id_table	= lp873x_id_table,
+};
+module_i2c_driver(lp873x_driver);
+
+MODULE_AUTHOR("J Keerthy <j-keerthy@ti.com>");
+MODULE_DESCRIPTION("LP873X chip family Multi-Function Device driver");
+MODULE_LICENSE("GPL v2");