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/acpi/acpi_lpat.h b/include/acpi/acpi_lpat.h
new file mode 100644
index 000000000..72d6264ef
--- /dev/null
+++ b/include/acpi/acpi_lpat.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * acpi_lpat.h - LPAT table processing functions
+ *
+ * Copyright (C) 2015 Intel Corporation. All rights reserved.
+ */
+
+#ifndef ACPI_LPAT_H
+#define ACPI_LPAT_H
+
+struct acpi_lpat {
+	int temp;
+	int raw;
+};
+
+struct acpi_lpat_conversion_table {
+	struct acpi_lpat *lpat;
+	int lpat_count;
+};
+
+#ifdef CONFIG_ACPI
+
+int acpi_lpat_raw_to_temp(struct acpi_lpat_conversion_table *lpat_table,
+			  int raw);
+int acpi_lpat_temp_to_raw(struct acpi_lpat_conversion_table *lpat_table,
+			  int temp);
+struct acpi_lpat_conversion_table *acpi_lpat_get_conversion_table(acpi_handle
+								  handle);
+void acpi_lpat_free_conversion_table(struct acpi_lpat_conversion_table
+				     *lpat_table);
+
+#else
+static int acpi_lpat_raw_to_temp(struct acpi_lpat_conversion_table *lpat_table,
+				 int raw)
+{
+	return 0;
+}
+
+static int acpi_lpat_temp_to_raw(struct acpi_lpat_conversion_table *lpat_table,
+				 int temp)
+{
+	return 0;
+}
+
+static struct acpi_lpat_conversion_table *acpi_lpat_get_conversion_table(
+							acpi_handle handle)
+{
+	return NULL;
+}
+
+static void acpi_lpat_free_conversion_table(struct acpi_lpat_conversion_table
+					    *lpat_table)
+{
+}
+
+#endif
+#endif