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, 45 insertions, 0 deletions

diff --git a/drivers/md/dm-vdo/permassert.h b/drivers/md/dm-vdo/permassert.h
new file mode 100644
index 000000000..c34f2ba65
--- /dev/null
+++ b/drivers/md/dm-vdo/permassert.h
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#ifndef PERMASSERT_H
+#define PERMASSERT_H
+
+#include <linux/compiler.h>
+
+#include "errors.h"
+
+/* Utilities for asserting that certain conditions are met */
+
+#define STRINGIFY(X) #X
+
+/*
+ * A hack to apply the "warn if unused" attribute to an integral expression.
+ *
+ * Since GCC doesn't propagate the warn_unused_result attribute to conditional expressions
+ * incorporating calls to functions with that attribute, this function can be used to wrap such an
+ * expression. With optimization enabled, this function contributes no additional instructions, but
+ * the warn_unused_result attribute still applies to the code calling it.
+ */
+static inline int __must_check vdo_must_use(int value)
+{
+	return value;
+}
+
+/* Assert that an expression is true and return an error if it is not. */
+#define VDO_ASSERT(expr, ...) vdo_must_use(__VDO_ASSERT(expr, __VA_ARGS__))
+
+/* Log a message if the expression is not true. */
+#define VDO_ASSERT_LOG_ONLY(expr, ...) __VDO_ASSERT(expr, __VA_ARGS__)
+
+#define __VDO_ASSERT(expr, ...)				      \
+	(likely(expr) ? VDO_SUCCESS			      \
+		      : vdo_assertion_failed(STRINGIFY(expr), __FILE__, __LINE__, __VA_ARGS__))
+
+/* Log an assertion failure message. */
+int vdo_assertion_failed(const char *expression_string, const char *file_name,
+			 int line_number, const char *format, ...)
+	__printf(4, 5);
+
+#endif /* PERMASSERT_H */