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, 77 insertions, 0 deletions

diff --git a/fs/xfs/scrub/rtbitmap.h b/fs/xfs/scrub/rtbitmap.h
new file mode 100644
index 000000000..fe52b8772
--- /dev/null
+++ b/fs/xfs/scrub/rtbitmap.h
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2023 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#ifndef __XFS_SCRUB_RTBITMAP_H__
+#define __XFS_SCRUB_RTBITMAP_H__
+
+/*
+ * We use an xfile to construct new bitmap blocks for the portion of the
+ * rtbitmap file that we're replacing.  Whereas the ondisk bitmap must be
+ * accessed through the buffer cache, the xfile bitmap supports direct
+ * word-level accesses.  Therefore, we create a small abstraction for linear
+ * access.
+ */
+typedef unsigned long long xrep_wordoff_t;
+typedef unsigned int xrep_wordcnt_t;
+
+/* Mask to round an rtx down to the nearest bitmap word. */
+#define XREP_RTBMP_WORDMASK	((1ULL << XFS_NBWORDLOG) - 1)
+
+
+struct xchk_rtbitmap {
+	struct xfs_scrub	*sc;
+
+	uint64_t		rextents;
+	uint64_t		rbmblocks;
+	unsigned int		rextslog;
+	unsigned int		resblks;
+
+	/* The next free rt group block number that we expect to see. */
+	xfs_rgblock_t		next_free_rgbno;
+
+#ifdef CONFIG_XFS_ONLINE_REPAIR
+	/* stuff for staging a new bitmap */
+	struct xfs_rtalloc_args	args;
+	struct xrep_tempexch	tempexch;
+#endif
+
+	/* The next rtgroup block we expect to see during our rtrmapbt walk. */
+	xfs_rgblock_t		next_rgbno;
+
+	/* rtgroup lock flags */
+	unsigned int		rtglock_flags;
+
+	/* rtword position of xfile as we write buffers to disk. */
+	xrep_wordoff_t		prep_wordoff;
+
+	/* In-Memory rtbitmap for repair. */
+	union xfs_rtword_raw	words[];
+};
+
+#ifdef CONFIG_XFS_ONLINE_REPAIR
+int xrep_setup_rtbitmap(struct xfs_scrub *sc, struct xchk_rtbitmap *rtb);
+
+/*
+ * How big should the words[] buffer be?
+ *
+ * For repairs, we want a full fsblock worth of space so that we can memcpy a
+ * buffer full of 1s into the xfile bitmap.  The xfile bitmap doesn't have
+ * rtbitmap block headers, so we don't use blockwsize.  Scrub doesn't use the
+ * words buffer at all.
+ */
+static inline unsigned int
+xchk_rtbitmap_wordcnt(
+	struct xfs_scrub	*sc)
+{
+	if (xchk_could_repair(sc))
+		return sc->mp->m_sb.sb_blocksize >> XFS_WORDLOG;
+	return 0;
+}
+#else
+# define xrep_setup_rtbitmap(sc, rtb)	(0)
+# define xchk_rtbitmap_wordcnt(sc)	(0)
+#endif /* CONFIG_XFS_ONLINE_REPAIR */
+
+#endif /* __XFS_SCRUB_RTBITMAP_H__ */