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, 62 insertions, 0 deletions

diff --git a/include/drm/intel/step.h b/include/drm/intel/step.h
new file mode 100644
index 000000000..4de752010
--- /dev/null
+++ b/include/drm/intel/step.h
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright © 2026 Intel Corporation */
+
+#ifndef __STEP_H__
+#define __STEP_H__
+
+#define STEP_ENUM_VAL(name)  STEP_##name,
+
+#define STEP_NAME_LIST(func)		\
+	func(A0)			\
+	func(A1)			\
+	func(A2)			\
+	func(A3)			\
+	func(B0)			\
+	func(B1)			\
+	func(B2)			\
+	func(B3)			\
+	func(C0)			\
+	func(C1)			\
+	func(C2)			\
+	func(C3)			\
+	func(D0)			\
+	func(D1)			\
+	func(D2)			\
+	func(D3)			\
+	func(E0)			\
+	func(E1)			\
+	func(E2)			\
+	func(E3)			\
+	func(F0)			\
+	func(F1)			\
+	func(F2)			\
+	func(F3)			\
+	func(G0)			\
+	func(G1)			\
+	func(G2)			\
+	func(G3)			\
+	func(H0)			\
+	func(H1)			\
+	func(H2)			\
+	func(H3)			\
+	func(I0)			\
+	func(I1)			\
+	func(I2)			\
+	func(I3)			\
+	func(J0)			\
+	func(J1)			\
+	func(J2)			\
+	func(J3)
+
+/*
+ * Symbolic steppings that do not match the hardware. These are valid both as gt
+ * and display steppings as symbolic names.
+ */
+enum intel_step {
+	STEP_NONE = 0,
+	STEP_NAME_LIST(STEP_ENUM_VAL)
+	STEP_FUTURE,
+	STEP_FOREVER,
+};
+
+#endif /* __STEP_H__ */