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, 211 insertions, 0 deletions

diff --git a/drivers/acpi/acpica/utstring.c b/drivers/acpi/acpica/utstring.c
new file mode 100644
index 000000000..aae71b8c5
--- /dev/null
+++ b/drivers/acpi/acpica/utstring.c
@@ -0,0 +1,211 @@
+// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+/*******************************************************************************
+ *
+ * Module Name: utstring - Common functions for strings and characters
+ *
+ ******************************************************************************/
+
+#include <acpi/acpi.h>
+#include "accommon.h"
+#include "acnamesp.h"
+
+#define _COMPONENT          ACPI_UTILITIES
+ACPI_MODULE_NAME("utstring")
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ut_print_string
+ *
+ * PARAMETERS:  string          - Null terminated ASCII string
+ *              max_length      - Maximum output length. Used to constrain the
+ *                                length of strings during debug output only.
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Dump an ASCII string with support for ACPI-defined escape
+ *              sequences.
+ *
+ ******************************************************************************/
+void acpi_ut_print_string(char *string, u16 max_length)
+{
+	u32 i;
+
+	if (!string) {
+		acpi_os_printf("<\"NULL STRING PTR\">");
+		return;
+	}
+
+	acpi_os_printf("\"");
+	for (i = 0; (i < max_length) && string[i]; i++) {
+
+		/* Escape sequences */
+
+		switch (string[i]) {
+		case 0x07:
+
+			acpi_os_printf("\\a");	/* BELL */
+			break;
+
+		case 0x08:
+
+			acpi_os_printf("\\b");	/* BACKSPACE */
+			break;
+
+		case 0x0C:
+
+			acpi_os_printf("\\f");	/* FORMFEED */
+			break;
+
+		case 0x0A:
+
+			acpi_os_printf("\\n");	/* LINEFEED */
+			break;
+
+		case 0x0D:
+
+			acpi_os_printf("\\r");	/* CARRIAGE RETURN */
+			break;
+
+		case 0x09:
+
+			acpi_os_printf("\\t");	/* HORIZONTAL TAB */
+			break;
+
+		case 0x0B:
+
+			acpi_os_printf("\\v");	/* VERTICAL TAB */
+			break;
+
+		case '\'':	/* Single Quote */
+		case '\"':	/* Double Quote */
+		case '\\':	/* Backslash */
+
+			acpi_os_printf("\\%c", (int)string[i]);
+			break;
+
+		default:
+
+			/* Check for printable character or hex escape */
+
+			if (isprint((int)string[i])) {
+				/* This is a normal character */
+
+				acpi_os_printf("%c", (int)string[i]);
+			} else {
+				/* All others will be Hex escapes */
+
+				acpi_os_printf("\\x%2.2X", (s32)string[i]);
+			}
+			break;
+		}
+	}
+
+	acpi_os_printf("\"");
+
+	if (i == max_length && string[i]) {
+		acpi_os_printf("...");
+	}
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ut_repair_name
+ *
+ * PARAMETERS:  name            - The ACPI name to be repaired
+ *
+ * RETURN:      Repaired version of the name
+ *
+ * DESCRIPTION: Repair an ACPI name: Change invalid characters to '*' and
+ *              return the new name. NOTE: the Name parameter must reside in
+ *              read/write memory, cannot be a const.
+ *
+ * An ACPI Name must consist of valid ACPI characters. We will repair the name
+ * if necessary because we don't want to abort because of this, but we want
+ * all namespace names to be printable. A warning message is appropriate.
+ *
+ * This issue came up because there are in fact machines that exhibit
+ * this problem, and we want to be able to enable ACPI support for them,
+ * even though there are a few bad names.
+ *
+ ******************************************************************************/
+
+void acpi_ut_repair_name(char *name)
+{
+	u32 i;
+	u8 found_bad_char = FALSE;
+	u32 original_name;
+
+	ACPI_FUNCTION_NAME(ut_repair_name);
+
+	/*
+	 * Special case for the root node. This can happen if we get an
+	 * error during the execution of module-level code.
+	 */
+	if (ACPI_COMPARE_NAMESEG(name, ACPI_ROOT_PATHNAME)) {
+		return;
+	}
+
+	ACPI_COPY_NAMESEG(&original_name, &name[0]);
+
+	/* Check each character in the name */
+
+	for (i = 0; i < ACPI_NAMESEG_SIZE; i++) {
+		if (acpi_ut_valid_name_char(name[i], i)) {
+			continue;
+		}
+
+		/*
+		 * Replace a bad character with something printable, yet technically
+		 * "odd". This prevents any collisions with existing "good"
+		 * names in the namespace.
+		 */
+		name[i] = '_';
+		found_bad_char = TRUE;
+	}
+
+	if (found_bad_char) {
+
+		/* Report warning only if in strict mode or debug mode */
+
+		if (!acpi_gbl_enable_interpreter_slack) {
+			ACPI_WARNING((AE_INFO,
+				      "Invalid character(s) in name (0x%.8X) %p, repaired: [%4.4s]",
+				      original_name, name, &name[0]));
+		} else {
+			ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+					  "Invalid character(s) in name (0x%.8X), repaired: [%4.4s]",
+					  original_name, name));
+		}
+	}
+}
+
+#if defined ACPI_ASL_COMPILER || defined ACPI_EXEC_APP
+/*******************************************************************************
+ *
+ * FUNCTION:    ut_convert_backslashes
+ *
+ * PARAMETERS:  pathname        - File pathname string to be converted
+ *
+ * RETURN:      Modifies the input Pathname
+ *
+ * DESCRIPTION: Convert all backslashes (0x5C) to forward slashes (0x2F) within
+ *              the entire input file pathname string.
+ *
+ ******************************************************************************/
+
+void ut_convert_backslashes(char *pathname)
+{
+
+	if (!pathname) {
+		return;
+	}
+
+	while (*pathname) {
+		if (*pathname == '\\') {
+			*pathname = '/';
+		}
+
+		pathname++;
+	}
+}
+#endif