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, 88 insertions, 0 deletions

diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
new file mode 100644
index 000000000..45dc59bb3
--- /dev/null
+++ b/drivers/mailbox/Makefile
@@ -0,0 +1,88 @@
+# SPDX-License-Identifier: GPL-2.0
+# Generic MAILBOX API
+
+obj-$(CONFIG_MAILBOX)		+= mailbox.o
+
+obj-$(CONFIG_MAILBOX_TEST)	+= mailbox-test.o
+
+obj-$(CONFIG_ARM_MHU)	+= arm_mhu.o arm_mhu_db.o
+
+obj-$(CONFIG_ARM_MHU_V2)	+= arm_mhuv2.o
+
+obj-$(CONFIG_ARM_MHU_V3)	+= arm_mhuv3.o
+
+obj-$(CONFIG_AST2700_MBOX)	+= ast2700-mailbox.o
+
+obj-$(CONFIG_CV1800_MBOX)	+= cv1800-mailbox.o
+
+obj-$(CONFIG_EXYNOS_MBOX)	+= exynos-mailbox.o
+
+obj-$(CONFIG_IMX_MBOX)	+= imx-mailbox.o
+
+obj-$(CONFIG_ARMADA_37XX_RWTM_MBOX)	+= armada-37xx-rwtm-mailbox.o
+
+obj-$(CONFIG_PLATFORM_MHU)	+= platform_mhu.o
+
+obj-$(CONFIG_PL320_MBOX)	+= pl320-ipc.o
+
+obj-$(CONFIG_OMAP2PLUS_MBOX)	+= omap-mailbox.o
+
+obj-$(CONFIG_ROCKCHIP_MBOX)	+= rockchip-mailbox.o
+
+obj-$(CONFIG_PCC)		+= pcc.o
+
+obj-$(CONFIG_ALTERA_MBOX)	+= mailbox-altera.o
+
+obj-$(CONFIG_BCM2835_MBOX)	+= bcm2835-mailbox.o
+
+obj-$(CONFIG_STI_MBOX)		+= mailbox-sti.o
+
+obj-$(CONFIG_TI_MESSAGE_MANAGER) += ti-msgmgr.o
+
+obj-$(CONFIG_XGENE_SLIMPRO_MBOX) += mailbox-xgene-slimpro.o
+
+obj-$(CONFIG_HI3660_MBOX)	+= hi3660-mailbox.o
+
+obj-$(CONFIG_HI6220_MBOX)	+= hi6220-mailbox.o
+
+obj-$(CONFIG_BCM_PDC_MBOX)	+= bcm-pdc-mailbox.o
+
+obj-$(CONFIG_BCM_FLEXRM_MBOX)	+= bcm-flexrm-mailbox.o
+
+obj-$(CONFIG_POLARFIRE_SOC_MAILBOX)	+= mailbox-mpfs.o
+
+obj-$(CONFIG_MCHP_SBI_IPC_MBOX)		+= mailbox-mchp-ipc-sbi.o
+
+obj-$(CONFIG_QCOM_APCS_IPC)	+= qcom-apcs-ipc-mailbox.o
+
+obj-$(CONFIG_TEGRA_HSP_MBOX)	+= tegra-hsp.o
+
+obj-$(CONFIG_STM32_IPCC) 	+= stm32-ipcc.o
+
+obj-$(CONFIG_MTK_ADSP_MBOX)	+= mtk-adsp-mailbox.o
+
+obj-$(CONFIG_MTK_CMDQ_MBOX)	+= mtk-cmdq-mailbox.o
+
+obj-$(CONFIG_MTK_GPUEB_MBOX)	+= mtk-gpueb-mailbox.o
+
+obj-$(CONFIG_MTK_VCP_MBOX)	+= mtk-vcp-mailbox.o
+
+obj-$(CONFIG_ZYNQMP_IPI_MBOX)	+= zynqmp-ipi-mailbox.o
+
+obj-$(CONFIG_SUN6I_MSGBOX)	+= sun6i-msgbox.o
+
+obj-$(CONFIG_SPRD_MBOX)		+= sprd-mailbox.o
+
+obj-$(CONFIG_QCOM_CPUCP_MBOX)	+= qcom-cpucp-mbox.o
+
+obj-$(CONFIG_QCOM_IPCC)		+= qcom-ipcc.o
+
+obj-$(CONFIG_THEAD_TH1520_MBOX)	+= mailbox-th1520.o
+
+obj-$(CONFIG_CIX_MBOX)	+= cix-mailbox.o
+
+obj-$(CONFIG_BCM74110_MAILBOX)	+= bcm74110-mailbox.o
+
+obj-$(CONFIG_RISCV_SBI_MPXY_MBOX)	+= riscv-sbi-mpxy-mbox.o
+
+obj-$(CONFIG_AXIADO_MAILBOX)	+= axiado-mailbox.o