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, 79 insertions, 0 deletions

diff --git a/tools/testing/shared/shared.mk b/tools/testing/shared/shared.mk
new file mode 100644
index 000000000..5bcdf26c8
--- /dev/null
+++ b/tools/testing/shared/shared.mk
@@ -0,0 +1,79 @@
+# SPDX-License-Identifier: GPL-2.0
+include ../../scripts/Makefile.arch
+
+CFLAGS += -I../shared -I. -I../../include -I../../arch/$(SRCARCH)/include \
+	  -I../../../lib -g -Og -Wall \
+	  -D_LGPL_SOURCE -fsanitize=address -fsanitize=undefined
+CFLAGS += $(EXTRA_CFLAGS)
+LDFLAGS += -fsanitize=address -fsanitize=undefined
+LDLIBS += -lpthread -lurcu
+LIBS := slab.o find_bit.o bitmap.o hweight.o vsprintf.o
+SHARED_OFILES = xarray-shared.o radix-tree.o idr.o linux.o $(LIBS)
+
+SHARED_DEPS = Makefile ../shared/shared.mk ../shared/*.h generated/map-shift.h \
+	generated/bit-length.h generated/autoconf.h \
+	../../include/linux/*.h \
+	../../include/asm/*.h \
+	../../arch/$(SRCARCH)/include/asm/*.h \
+	../../../include/linux/xarray.h \
+	../../../include/linux/maple_tree.h \
+	../../../include/linux/radix-tree.h \
+	../../../lib/radix-tree.h \
+	../../../include/linux/idr.h \
+	../../../lib/maple_tree.c \
+	../../../lib/test_maple_tree.c
+
+ifndef SHIFT
+	SHIFT=3
+endif
+
+ifeq ($(BUILD), 32)
+	CFLAGS += -m32
+	LDFLAGS += -m32
+LONG_BIT := 32
+endif
+
+ifndef LONG_BIT
+LONG_BIT := $(shell getconf LONG_BIT)
+endif
+
+%.o: ../shared/%.c
+	$(CC) -c $(CFLAGS) $< -o $@
+
+vpath %.c ../../lib
+
+$(SHARED_OFILES): $(SHARED_DEPS)
+
+radix-tree.c: ../../../lib/radix-tree.c
+	sed -e 's/^static //' -e 's/__always_inline //' -e 's/inline //' < $< > $@
+
+idr.c: ../../../lib/idr.c
+	sed -e 's/^static //' -e 's/__always_inline //' -e 's/inline //' < $< > $@
+
+xarray-shared.o: ../shared/xarray-shared.c ../../../lib/xarray.c \
+	../../../lib/test_xarray.c
+
+maple-shared.o: ../shared/maple-shared.c ../../../lib/maple_tree.c \
+	../../../lib/test_maple_tree.c
+
+generated/autoconf.h:
+	@mkdir -p generated
+	cp ../shared/autoconf.h generated/autoconf.h
+
+generated/map-shift.h:
+	@mkdir -p generated
+	@if ! grep -qws $(SHIFT) generated/map-shift.h; then            \
+		echo "Generating $@";                                   \
+		echo "#define XA_CHUNK_SHIFT $(SHIFT)" >                \
+				generated/map-shift.h;                  \
+	fi
+
+generated/bit-length.h: FORCE
+	@mkdir -p generated
+	@if ! grep -qws CONFIG_$(LONG_BIT)BIT generated/bit-length.h; then   \
+		echo "Generating $@";                                        \
+		echo "#define CONFIG_$(LONG_BIT)BIT 1" > $@;                 \
+		echo "#define CONFIG_PHYS_ADDR_T_$(LONG_BIT)BIT 1" >> $@;    \
+	fi
+
+FORCE: ;