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, 44 insertions, 0 deletions

diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
new file mode 100644
index 000000000..a01f97fef
--- /dev/null
+++ b/drivers/bus/Makefile
@@ -0,0 +1,44 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the bus drivers.
+#
+
+# Interconnect bus drivers for ARM platforms
+obj-$(CONFIG_ARM_CCI)		+= arm-cci.o
+obj-$(CONFIG_ARM_INTEGRATOR_LM)	+= arm-integrator-lm.o
+obj-$(CONFIG_HISILICON_LPC)	+= hisi_lpc.o
+obj-$(CONFIG_BRCMSTB_GISB_ARB)	+= brcmstb_gisb.o
+obj-$(CONFIG_MOXTET)		+= moxtet.o
+
+# DPAA2 fsl-mc bus
+obj-$(CONFIG_FSL_MC_BUS)	+= fsl-mc/
+
+obj-$(CONFIG_IMX_AIPSTZ)	+= imx-aipstz.o
+obj-$(CONFIG_IMX_WEIM)		+= imx-weim.o
+obj-$(CONFIG_INTEL_IXP4XX_EB)	+= intel-ixp4xx-eb.o
+obj-$(CONFIG_MIPS_CDMM)		+= mips_cdmm.o
+obj-$(CONFIG_MVEBU_MBUS) 	+= mvebu-mbus.o
+
+# Interconnect bus driver for OMAP SoCs.
+obj-$(CONFIG_OMAP_INTERCONNECT)	+= omap_l3_smx.o omap_l3_noc.o
+
+obj-$(CONFIG_OMAP_OCP2SCP)	+= omap-ocp2scp.o
+obj-$(CONFIG_QCOM_EBI2)		+= qcom-ebi2.o
+obj-$(CONFIG_QCOM_SSC_BLOCK_BUS)	+= qcom-ssc-block-bus.o
+obj-$(CONFIG_STM32_DBG_BUS)	+= stm32_dbg_bus.o
+obj-$(CONFIG_STM32_FIREWALL)	+= stm32_firewall.o stm32_rifsc.o stm32_etzpc.o
+obj-$(CONFIG_SUN50I_DE2_BUS)	+= sun50i-de2.o
+obj-$(CONFIG_SUNXI_RSB)		+= sunxi-rsb.o
+obj-$(CONFIG_OF)		+= simple-pm-bus.o
+obj-$(CONFIG_TEGRA_ACONNECT)	+= tegra-aconnect.o
+obj-$(CONFIG_TEGRA_GMI)		+= tegra-gmi.o
+obj-$(CONFIG_TI_PWMSS)		+= ti-pwmss.o
+obj-$(CONFIG_TI_SYSC)		+= ti-sysc.o
+obj-$(CONFIG_TS_NBUS)		+= ts-nbus.o
+obj-$(CONFIG_UNIPHIER_SYSTEM_BUS)	+= uniphier-system-bus.o
+obj-$(CONFIG_VEXPRESS_CONFIG)	+= vexpress-config.o
+
+obj-$(CONFIG_DA8XX_MSTPRI)	+= da8xx-mstpri.o
+
+# MHI
+obj-y				+= mhi/