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/drivers/iommu/Makefile b/drivers/iommu/Makefile
new file mode 100644
index 000000000..2f05725ea
--- /dev/null
+++ b/drivers/iommu/Makefile
@@ -0,0 +1,40 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-y += arm/ iommufd/
+obj-$(CONFIG_AMD_IOMMU) += amd/
+obj-$(CONFIG_INTEL_IOMMU) += intel/
+obj-$(CONFIG_RISCV_IOMMU) += riscv/
+obj-$(CONFIG_GENERIC_PT) += generic_pt/fmt/
+obj-$(CONFIG_HYPERV) += hyperv/
+obj-$(CONFIG_IOMMU_API) += iommu.o
+obj-$(CONFIG_IOMMU_SUPPORT) += iommu-pages.o
+obj-$(CONFIG_IOMMU_API) += iommu-traces.o
+obj-$(CONFIG_IOMMU_API) += iommu-sysfs.o
+obj-$(CONFIG_IOMMU_DEBUGFS) += iommu-debugfs.o
+obj-$(CONFIG_IOMMU_DMA) += dma-iommu.o
+obj-$(CONFIG_IOMMU_IO_PGTABLE) += io-pgtable.o
+obj-$(CONFIG_IOMMU_IO_PGTABLE_ARMV7S) += io-pgtable-arm-v7s.o
+obj-$(CONFIG_IOMMU_IO_PGTABLE_LPAE) += io-pgtable-arm.o
+obj-$(CONFIG_IOMMU_IO_PGTABLE_LPAE_KUNIT_TEST) += io-pgtable-arm-selftests.o
+obj-$(CONFIG_IOMMU_IO_PGTABLE_DART) += io-pgtable-dart.o
+obj-$(CONFIG_IOMMU_IOVA) += iova.o
+obj-$(CONFIG_OF_IOMMU)	+= of_iommu.o
+obj-$(CONFIG_MSM_IOMMU) += msm_iommu.o
+obj-$(CONFIG_IPMMU_VMSA) += ipmmu-vmsa.o
+obj-$(CONFIG_IRQ_REMAP) += irq_remapping.o
+obj-$(CONFIG_MTK_IOMMU) += mtk_iommu.o
+obj-$(CONFIG_MTK_IOMMU_V1) += mtk_iommu_v1.o
+obj-$(CONFIG_OMAP_IOMMU) += omap-iommu.o
+obj-$(CONFIG_OMAP_IOMMU_DEBUG) += omap-iommu-debug.o
+obj-$(CONFIG_ROCKCHIP_IOMMU) += rockchip-iommu.o
+obj-$(CONFIG_SUN50I_IOMMU) += sun50i-iommu.o
+obj-$(CONFIG_TEGRA_IOMMU_SMMU) += tegra-smmu.o
+obj-$(CONFIG_EXYNOS_IOMMU) += exynos-iommu.o
+obj-$(CONFIG_FSL_PAMU) += fsl_pamu.o fsl_pamu_domain.o
+obj-$(CONFIG_S390_IOMMU) += s390-iommu.o
+obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o
+obj-$(CONFIG_IOMMU_SVA) += iommu-sva.o
+obj-$(CONFIG_IOMMU_IOPF) += io-pgfault.o
+obj-$(CONFIG_SPRD_IOMMU) += sprd-iommu.o
+obj-$(CONFIG_APPLE_DART) += apple-dart.o
+obj-$(CONFIG_VSI_IOMMU) += vsi-iommu.o
+obj-$(CONFIG_IOMMU_DEBUG_PAGEALLOC) += iommu-debug-pagealloc.o