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, 36 insertions, 0 deletions

diff --git a/drivers/base/Makefile b/drivers/base/Makefile
new file mode 100644
index 000000000..435710f64
--- /dev/null
+++ b/drivers/base/Makefile
@@ -0,0 +1,36 @@
+# SPDX-License-Identifier: GPL-2.0
+# Makefile for the Linux device tree
+
+obj-y			:= component.o core.o bus.o dd.o syscore.o \
+			   driver.o class.o platform.o \
+			   cpu.o firmware.o init.o map.o devres.o \
+			   attribute_container.o transport_class.o \
+			   topology.o container.o property.o cacheinfo.o \
+			   swnode.o faux.o
+obj-$(CONFIG_AUXILIARY_BUS) += auxiliary.o
+obj-$(CONFIG_DEVTMPFS)	+= devtmpfs.o
+obj-y			+= power/
+obj-$(CONFIG_ISA_BUS_API)	+= isa.o
+obj-y				+= firmware_loader/
+obj-$(CONFIG_NUMA)	+= node.o
+obj-$(CONFIG_MEMORY_HOTPLUG) += memory.o
+ifeq ($(CONFIG_SYSFS),y)
+obj-$(CONFIG_MODULES)	+= module.o
+obj-$(CONFIG_AUXILIARY_BUS) += auxiliary_sysfs.o
+endif
+obj-$(CONFIG_SYS_HYPERVISOR) += hypervisor.o
+obj-$(CONFIG_REGMAP)	+= regmap/
+obj-$(CONFIG_SOC_BUS) += soc.o
+obj-$(CONFIG_PINCTRL) += pinctrl.o
+obj-$(CONFIG_DEV_COREDUMP) += devcoredump.o
+obj-$(CONFIG_GENERIC_MSI_IRQ) += platform-msi.o
+obj-$(CONFIG_GENERIC_ARCH_TOPOLOGY) += arch_topology.o
+obj-$(CONFIG_ACPI) += physical_location.o
+
+obj-y			+= test/
+
+ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
+
+# define_trace.h needs to know how to find our header
+CFLAGS_trace.o		:= -I$(src)
+obj-$(CONFIG_TRACING)	+= trace.o