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, 57 insertions, 0 deletions

diff --git a/include/soc/tegra/common.h b/include/soc/tegra/common.h
new file mode 100644
index 000000000..8ec1ac07f
--- /dev/null
+++ b/include/soc/tegra/common.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2014 NVIDIA Corporation
+ */
+
+#ifndef __SOC_TEGRA_COMMON_H__
+#define __SOC_TEGRA_COMMON_H__
+
+#include <linux/errno.h>
+#include <linux/types.h>
+
+struct device;
+
+/**
+ * Tegra SoC core device OPP table configuration
+ *
+ * @init_state: pre-initialize OPP state of a device
+ */
+struct tegra_core_opp_params {
+	bool init_state;
+};
+
+#ifdef CONFIG_ARCH_TEGRA
+bool soc_is_tegra(void);
+
+int devm_tegra_core_dev_init_opp_table(struct device *dev,
+				       struct tegra_core_opp_params *params);
+#else
+static inline bool soc_is_tegra(void)
+{
+	return false;
+}
+
+static inline int
+devm_tegra_core_dev_init_opp_table(struct device *dev,
+				   struct tegra_core_opp_params *params)
+{
+	return -ENODEV;
+}
+#endif
+
+static inline int
+devm_tegra_core_dev_init_opp_table_common(struct device *dev)
+{
+	struct tegra_core_opp_params opp_params = {};
+	int err;
+
+	opp_params.init_state = true;
+
+	err = devm_tegra_core_dev_init_opp_table(dev, &opp_params);
+	if (err != -ENODEV)
+		return err;
+
+	return 0;
+}
+
+#endif /* __SOC_TEGRA_COMMON_H__ */