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, 72 insertions, 0 deletions

diff --git a/drivers/clk/mediatek/reset.h b/drivers/clk/mediatek/reset.h
new file mode 100644
index 000000000..562ffd290
--- /dev/null
+++ b/drivers/clk/mediatek/reset.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2022 MediaTek Inc.
+ */
+
+#ifndef __DRV_CLK_MTK_RESET_H
+#define __DRV_CLK_MTK_RESET_H
+
+#include <linux/reset-controller.h>
+#include <linux/types.h>
+
+#define RST_NR_PER_BANK 32
+
+/* Infra global controller reset set register */
+#define INFRA_RST0_SET_OFFSET 0x120
+#define INFRA_RST1_SET_OFFSET 0x130
+#define INFRA_RST2_SET_OFFSET 0x140
+#define INFRA_RST3_SET_OFFSET 0x150
+#define INFRA_RST4_SET_OFFSET 0x730
+
+/**
+ * enum mtk_reset_version - Version of MediaTek clock reset controller.
+ * @MTK_RST_SIMPLE: Use the same registers for bit set and clear.
+ * @MTK_RST_SET_CLR: Use separate registers for bit set and clear.
+ * @MTK_RST_MAX: Total quantity of version for MediaTek clock reset controller.
+ */
+enum mtk_reset_version {
+	MTK_RST_SIMPLE = 0,
+	MTK_RST_SET_CLR,
+	MTK_RST_MAX,
+};
+
+/**
+ * struct mtk_clk_rst_desc - Description of MediaTek clock reset.
+ * @version: Reset version which is defined in enum mtk_reset_version.
+ * @rst_bank_ofs: Pointer to an array containing base offsets of the reset register.
+ * @rst_bank_nr: Quantity of reset bank.
+ * @rst_idx_map:Pointer to an array containing ids if input argument is index.
+ *		This array is not necessary if our input argument does not mean index.
+ * @rst_idx_map_nr: Quantity of reset index map.
+ */
+struct mtk_clk_rst_desc {
+	enum mtk_reset_version version;
+	u16 *rst_bank_ofs;
+	u32 rst_bank_nr;
+	u16 *rst_idx_map;
+	u32 rst_idx_map_nr;
+};
+
+/**
+ * struct mtk_clk_rst_data - Data of MediaTek clock reset controller.
+ * @regmap: Pointer to base address of reset register address.
+ * @rcdev: Reset controller device.
+ * @desc: Pointer to description of the reset controller.
+ */
+struct mtk_clk_rst_data {
+	struct regmap *regmap;
+	struct reset_controller_dev rcdev;
+	const struct mtk_clk_rst_desc *desc;
+};
+
+/**
+ * mtk_register_reset_controller - Register mediatek clock reset controller with device
+ * @np: Pointer to device.
+ * @desc: Constant pointer to description of clock reset.
+ *
+ * Return: 0 on success and errorno otherwise.
+ */
+int mtk_register_reset_controller_with_dev(struct device *dev,
+					   const struct mtk_clk_rst_desc *desc);
+
+#endif /* __DRV_CLK_MTK_RESET_H */