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, 84 insertions, 0 deletions

diff --git a/include/uapi/asm-generic/statfs.h b/include/uapi/asm-generic/statfs.h
new file mode 100644
index 000000000..bd35c7619
--- /dev/null
+++ b/include/uapi/asm-generic/statfs.h
@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_GENERIC_STATFS_H
+#define _UAPI_GENERIC_STATFS_H
+
+#include <linux/types.h>
+
+
+/*
+ * Most 64-bit platforms use 'long', while most 32-bit platforms use '__u32'.
+ * Yes, they differ in signedness as well as size.
+ * Special cases can override it for themselves -- except for S390x, which
+ * is just a little too special for us. And MIPS, which I'm not touching
+ * with a 10' pole.
+ */
+#ifndef __statfs_word
+#if __BITS_PER_LONG == 64
+#define __statfs_word __kernel_long_t
+#else
+#define __statfs_word __u32
+#endif
+#endif
+
+struct statfs {
+	__statfs_word f_type;
+	__statfs_word f_bsize;
+	__statfs_word f_blocks;
+	__statfs_word f_bfree;
+	__statfs_word f_bavail;
+	__statfs_word f_files;
+	__statfs_word f_ffree;
+	__kernel_fsid_t f_fsid;
+	__statfs_word f_namelen;
+	__statfs_word f_frsize;
+	__statfs_word f_flags;
+	__statfs_word f_spare[4];
+};
+
+/*
+ * ARM needs to avoid the 32-bit padding at the end, for consistency
+ * between EABI and OABI 
+ */
+#ifndef ARCH_PACK_STATFS64
+#define ARCH_PACK_STATFS64
+#endif
+
+struct statfs64 {
+	__statfs_word f_type;
+	__statfs_word f_bsize;
+	__u64 f_blocks;
+	__u64 f_bfree;
+	__u64 f_bavail;
+	__u64 f_files;
+	__u64 f_ffree;
+	__kernel_fsid_t f_fsid;
+	__statfs_word f_namelen;
+	__statfs_word f_frsize;
+	__statfs_word f_flags;
+	__statfs_word f_spare[4];
+} ARCH_PACK_STATFS64;
+
+/* 
+ * IA64 and x86_64 need to avoid the 32-bit padding at the end,
+ * to be compatible with the i386 ABI
+ */
+#ifndef ARCH_PACK_COMPAT_STATFS64
+#define ARCH_PACK_COMPAT_STATFS64
+#endif
+
+struct compat_statfs64 {
+	__u32 f_type;
+	__u32 f_bsize;
+	__u64 f_blocks;
+	__u64 f_bfree;
+	__u64 f_bavail;
+	__u64 f_files;
+	__u64 f_ffree;
+	__kernel_fsid_t f_fsid;
+	__u32 f_namelen;
+	__u32 f_frsize;
+	__u32 f_flags;
+	__u32 f_spare[4];
+} ARCH_PACK_COMPAT_STATFS64;
+
+#endif /* _UAPI_GENERIC_STATFS_H */