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, 40 insertions, 0 deletions

diff --git a/scripts/Makefile.thinlto b/scripts/Makefile.thinlto
new file mode 100644
index 000000000..bb83f13f3
--- /dev/null
+++ b/scripts/Makefile.thinlto
@@ -0,0 +1,40 @@
+PHONY := __default
+__default:
+
+include include/config/auto.conf
+include $(srctree)/scripts/Kbuild.include
+include $(srctree)/scripts/Makefile.lib
+
+native-objs := $(patsubst %.o,%.thinlto-native.o,$(call read-file, vmlinux.thinlto-index))
+
+__default: $(native-objs)
+
+# Generate .thinlto-native.o (obj) from .o (bitcode) and .thinlto.bc (summary) files
+# ---------------------------------------------------------------------------
+quiet_cmd_cc_o_bc = CC $(quiet_modtag)  $@
+      be_flags = $(shell sed -n '/saved_c_flags_/s/.*:= //p' \
+                $(dir $(<)).$(notdir $(<)).cmd)
+      cmd_cc_o_bc = \
+      $(CC) $(be_flags) -x ir -fno-lto -Wno-unused-command-line-argument \
+      -fthinlto-index=$(word 2, $^) -c -o $@ $<
+
+targets += $(native-objs)
+$(native-objs): %.thinlto-native.o: %.o %.o.thinlto.bc   FORCE
+	$(call if_changed,cc_o_bc)
+
+# Add FORCE to the prerequisites of a target to force it to be always rebuilt.
+# ---------------------------------------------------------------------------
+
+PHONY += FORCE
+FORCE:
+
+# Read all saved command lines and dependencies for the $(targets) we
+# may be building above, using $(if_changed{,_dep}). As an
+# optimization, we don't need to read them if the target does not
+# exist, we will rebuild anyway in that case.
+
+existing-targets := $(wildcard $(sort $(targets)))
+
+-include $(foreach f, $(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
+
+.PHONY: $(PHONY)