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, 59 insertions, 0 deletions

diff --git a/rust/helpers/pci.c b/rust/helpers/pci.c
new file mode 100644
index 000000000..a714cc2bf
--- /dev/null
+++ b/rust/helpers/pci.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/pci.h>
+
+__rust_helper u16 rust_helper_pci_dev_id(struct pci_dev *dev)
+{
+	return PCI_DEVID(dev->bus->number, dev->devfn);
+}
+
+__rust_helper resource_size_t
+rust_helper_pci_resource_start(struct pci_dev *pdev, int bar)
+{
+	return pci_resource_start(pdev, bar);
+}
+
+__rust_helper resource_size_t rust_helper_pci_resource_len(struct pci_dev *pdev,
+							   int bar)
+{
+	return pci_resource_len(pdev, bar);
+}
+
+__rust_helper bool rust_helper_dev_is_pci(const struct device *dev)
+{
+	return dev_is_pci(dev);
+}
+
+__rust_helper unsigned int rust_helper_pci_irq_type(struct pci_dev *pdev)
+{
+	return pci_irq_type(pdev);
+}
+
+#ifndef CONFIG_PCI_IOV
+__rust_helper unsigned int
+rust_helper_pci_sriov_get_totalvfs(struct pci_dev *pdev)
+{
+	return pci_sriov_get_totalvfs(pdev);
+}
+#endif
+
+#ifndef CONFIG_PCI_MSI
+__rust_helper int rust_helper_pci_alloc_irq_vectors(struct pci_dev *dev,
+						    unsigned int min_vecs,
+						    unsigned int max_vecs,
+						    unsigned int flags)
+{
+	return pci_alloc_irq_vectors(dev, min_vecs, max_vecs, flags);
+}
+
+__rust_helper void rust_helper_pci_free_irq_vectors(struct pci_dev *dev)
+{
+	pci_free_irq_vectors(dev);
+}
+
+__rust_helper int rust_helper_pci_irq_vector(struct pci_dev *pdev,
+					     unsigned int nvec)
+{
+	return pci_irq_vector(pdev, nvec);
+}
+#endif