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, 52 insertions, 0 deletions

diff --git a/scripts/Makefile.debug b/scripts/Makefile.debug
new file mode 100644
index 000000000..107db997c
--- /dev/null
+++ b/scripts/Makefile.debug
@@ -0,0 +1,52 @@
+DEBUG_CFLAGS	:=
+DEBUG_RUSTFLAGS	:=
+
+debug-flags-y	:= -g
+
+ifdef CONFIG_DEBUG_INFO_SPLIT
+DEBUG_CFLAGS	+= -gsplit-dwarf
+endif
+
+debug-flags-$(CONFIG_DEBUG_INFO_DWARF4)	+= -gdwarf-4
+debug-flags-$(CONFIG_DEBUG_INFO_DWARF5)	+= -gdwarf-5
+ifeq ($(CONFIG_CC_IS_CLANG)$(CONFIG_AS_IS_GNU),yy)
+# Clang does not pass -g or -gdwarf-* option down to GAS.
+# Add -Wa, prefix to explicitly specify the flags.
+KBUILD_AFLAGS	+= $(addprefix -Wa$(comma), $(debug-flags-y))
+endif
+DEBUG_CFLAGS	+= $(debug-flags-y)
+KBUILD_AFLAGS	+= $(debug-flags-y)
+
+ifdef CONFIG_DEBUG_INFO_DWARF4
+DEBUG_RUSTFLAGS	+= -Zdwarf-version=4
+else ifdef CONFIG_DEBUG_INFO_DWARF5
+DEBUG_RUSTFLAGS	+= -Zdwarf-version=5
+endif
+
+ifdef CONFIG_DEBUG_INFO_REDUCED
+DEBUG_CFLAGS	+= -fno-var-tracking
+DEBUG_RUSTFLAGS	+= -Cdebuginfo=1
+ifdef CONFIG_CC_IS_GCC
+DEBUG_CFLAGS	+= -femit-struct-debug-baseonly
+endif
+else
+DEBUG_RUSTFLAGS	+= -Cdebuginfo=2
+endif
+
+ifdef CONFIG_DEBUG_INFO_COMPRESSED_ZLIB
+DEBUG_CFLAGS	+= -gz=zlib
+DEBUG_RUSTFLAGS	+= -Zdebuginfo-compression=zlib
+KBUILD_AFLAGS	+= -gz=zlib
+KBUILD_LDFLAGS	+= --compress-debug-sections=zlib
+else ifdef CONFIG_DEBUG_INFO_COMPRESSED_ZSTD
+DEBUG_CFLAGS	+= -gz=zstd
+DEBUG_RUSTFLAGS	+= -Zdebuginfo-compression=zstd
+KBUILD_AFLAGS	+= -gz=zstd
+KBUILD_LDFLAGS	+= --compress-debug-sections=zstd
+endif
+
+KBUILD_CFLAGS	+= $(DEBUG_CFLAGS)
+export DEBUG_CFLAGS
+
+KBUILD_RUSTFLAGS += $(DEBUG_RUSTFLAGS)
+export DEBUG_RUSTFLAGS