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, 60 insertions, 0 deletions

diff --git a/include/asm-generic/pci_iomap.h b/include/asm-generic/pci_iomap.h
new file mode 100644
index 000000000..8fbb0a555
--- /dev/null
+++ b/include/asm-generic/pci_iomap.h
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/* Generic I/O port emulation.
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+#ifndef __ASM_GENERIC_PCI_IOMAP_H
+#define __ASM_GENERIC_PCI_IOMAP_H
+
+struct pci_dev;
+#ifdef CONFIG_PCI
+/* Create a virtual mapping cookie for a PCI BAR (memory or IO) */
+extern void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long max);
+extern void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long max);
+extern void __iomem *pci_iomap_range(struct pci_dev *dev, int bar,
+				     unsigned long offset,
+				     unsigned long maxlen);
+extern void __iomem *pci_iomap_wc_range(struct pci_dev *dev, int bar,
+					unsigned long offset,
+					unsigned long maxlen);
+extern void pci_iounmap(struct pci_dev *dev, void __iomem *);
+/* Create a virtual mapping cookie for a port on a given PCI device.
+ * Do not call this directly, it exists to make it easier for architectures
+ * to override */
+#ifdef CONFIG_NO_GENERIC_PCI_IOPORT_MAP
+extern void __iomem *__pci_ioport_map(struct pci_dev *dev, unsigned long port,
+				      unsigned int nr);
+#elif !defined(CONFIG_HAS_IOPORT_MAP)
+#define __pci_ioport_map(dev, port, nr) NULL
+#else
+#define __pci_ioport_map(dev, port, nr) ioport_map((port), (nr))
+#endif
+
+#elif defined(CONFIG_GENERIC_PCI_IOMAP)
+static inline void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long max)
+{
+	return NULL;
+}
+
+static inline void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long max)
+{
+	return NULL;
+}
+static inline void __iomem *pci_iomap_range(struct pci_dev *dev, int bar,
+					    unsigned long offset,
+					    unsigned long maxlen)
+{
+	return NULL;
+}
+static inline void __iomem *pci_iomap_wc_range(struct pci_dev *dev, int bar,
+					       unsigned long offset,
+					       unsigned long maxlen)
+{
+	return NULL;
+}
+static inline void pci_iounmap(struct pci_dev *dev, void __iomem *addr)
+{ }
+#endif
+
+#endif /* __ASM_GENERIC_PCI_IOMAP_H */