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, 82 insertions, 0 deletions

diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild
new file mode 100644
index 000000000..2be1df80f
--- /dev/null
+++ b/tools/testing/cxl/Kbuild
@@ -0,0 +1,82 @@
+# SPDX-License-Identifier: GPL-2.0
+ldflags-y += --wrap=acpi_table_parse_cedt
+ldflags-y += --wrap=is_acpi_device_node
+ldflags-y += --wrap=acpi_evaluate_integer
+ldflags-y += --wrap=acpi_pci_find_root
+ldflags-y += --wrap=nvdimm_bus_register
+ldflags-y += --wrap=cxl_await_media_ready
+ldflags-y += --wrap=devm_cxl_add_rch_dport
+ldflags-y += --wrap=cxl_endpoint_parse_cdat
+ldflags-y += --wrap=devm_cxl_endpoint_decoders_setup
+ldflags-y += --wrap=hmat_get_extended_linear_cache_size
+ldflags-y += --wrap=devm_cxl_add_dport_by_dev
+ldflags-y += --wrap=devm_cxl_switch_port_decoders_setup
+ldflags-y += --wrap=walk_hmem_resources
+ldflags-y += --wrap=region_intersects
+ldflags-y += --wrap=region_intersects_soft_reserve
+
+DRIVERS := ../../../drivers
+DAX_HMEM_SRC := $(DRIVERS)/dax/hmem
+CXL_SRC := $(DRIVERS)/cxl
+CXL_CORE_SRC := $(DRIVERS)/cxl/core
+ccflags-y := -I$(srctree)/drivers/cxl/
+ccflags-y += -D__mock=__weak
+ccflags-y += -DCXL_TEST_ENABLE=1
+ccflags-y += -DTRACE_INCLUDE_PATH=$(CXL_CORE_SRC) -I$(srctree)/drivers/cxl/core/
+
+obj-m += cxl_acpi.o
+
+cxl_acpi-y := $(CXL_SRC)/acpi.o
+cxl_acpi-y += mock_acpi.o
+cxl_acpi-y += config_check.o
+cxl_acpi-y += cxl_acpi_test.o
+
+obj-m += cxl_pmem.o
+
+cxl_pmem-y := $(CXL_SRC)/pmem.o
+cxl_pmem-y += $(CXL_SRC)/security.o
+cxl_pmem-y += config_check.o
+cxl_pmem-y += cxl_pmem_test.o
+
+obj-m += cxl_port.o
+
+cxl_port-y := $(CXL_SRC)/port.o
+cxl_port-y += config_check.o
+cxl_port-y += cxl_port_test.o
+
+
+obj-m += cxl_mem.o
+
+cxl_mem-y := $(CXL_SRC)/mem.o
+cxl_mem-y += config_check.o
+cxl_mem-y += cxl_mem_test.o
+
+obj-m += cxl_core.o
+
+cxl_core-y := $(CXL_CORE_SRC)/port.o
+cxl_core-y += $(CXL_CORE_SRC)/pmem.o
+cxl_core-y += $(CXL_CORE_SRC)/regs.o
+cxl_core-y += $(CXL_CORE_SRC)/memdev.o
+cxl_core-y += $(CXL_CORE_SRC)/mbox.o
+cxl_core-y += $(CXL_CORE_SRC)/pci.o
+cxl_core-y += $(CXL_CORE_SRC)/hdm.o
+cxl_core-y += $(CXL_CORE_SRC)/pmu.o
+cxl_core-y += $(CXL_CORE_SRC)/cdat.o
+cxl_core-$(CONFIG_TRACING) += $(CXL_CORE_SRC)/trace.o
+cxl_core-$(CONFIG_CXL_REGION) += $(CXL_CORE_SRC)/region.o $(CXL_CORE_SRC)/region_pmem.o $(CXL_CORE_SRC)/region_dax.o
+cxl_core-$(CONFIG_CXL_MCE) += $(CXL_CORE_SRC)/mce.o
+cxl_core-$(CONFIG_CXL_FEATURES) += $(CXL_CORE_SRC)/features.o
+cxl_core-$(CONFIG_CXL_EDAC_MEM_FEATURES) += $(CXL_CORE_SRC)/edac.o
+cxl_core-$(CONFIG_CXL_RAS) += $(CXL_CORE_SRC)/ras.o
+cxl_core-$(CONFIG_CXL_RAS) += $(CXL_CORE_SRC)/ras_rch.o
+cxl_core-$(CONFIG_CXL_ATL) += $(CXL_CORE_SRC)/atl.o
+cxl_core-y += config_check.o
+cxl_core-y += cxl_core_test.o
+cxl_core-y += cxl_core_exports.o
+
+obj-m += dax_hmem.o
+dax_hmem-y := $(DAX_HMEM_SRC)/hmem.o
+
+KBUILD_CFLAGS := $(filter-out -Wmissing-prototypes -Wmissing-declarations, $(KBUILD_CFLAGS))
+
+obj-m += test/