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, 62 insertions, 0 deletions

diff --git a/fs/hpfs/dentry.c b/fs/hpfs/dentry.c
new file mode 100644
index 000000000..89a36fdc6
--- /dev/null
+++ b/fs/hpfs/dentry.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/hpfs/dentry.c
+ *
+ *  Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 1998-1999
+ *
+ *  dcache operations
+ */
+
+#include "hpfs_fn.h"
+
+/*
+ * Note: the dentry argument is the parent dentry.
+ */
+
+static int hpfs_hash_dentry(const struct dentry *dentry, struct qstr *qstr)
+{
+	unsigned long	 hash;
+	int		 i;
+	unsigned l = qstr->len;
+
+	if (l == 1) if (qstr->name[0]=='.') goto x;
+	if (l == 2) if (qstr->name[0]=='.' || qstr->name[1]=='.') goto x;
+	hpfs_adjust_length(qstr->name, &l);
+	/*if (hpfs_chk_name(qstr->name,&l))*/
+		/*return -ENAMETOOLONG;*/
+		/*return -ENOENT;*/
+	x:
+
+	hash = init_name_hash(dentry);
+	for (i = 0; i < l; i++)
+		hash = partial_name_hash(hpfs_upcase(hpfs_sb(dentry->d_sb)->sb_cp_table,qstr->name[i]), hash);
+	qstr->hash = end_name_hash(hash);
+
+	return 0;
+}
+
+static int hpfs_compare_dentry(const struct dentry *dentry,
+		unsigned int len, const char *str, const struct qstr *name)
+{
+	unsigned al = len;
+	unsigned bl = name->len;
+
+	hpfs_adjust_length(str, &al);
+	/*hpfs_adjust_length(b->name, &bl);*/
+
+	/*
+	 * 'str' is the nane of an already existing dentry, so the name
+	 * must be valid. 'name' must be validated first.
+	 */
+
+	if (hpfs_chk_name(name->name, &bl))
+		return 1;
+	if (hpfs_compare_names(dentry->d_sb, str, al, name->name, bl, 0))
+		return 1;
+	return 0;
+}
+
+const struct dentry_operations hpfs_dentry_operations = {
+	.d_hash		= hpfs_hash_dentry,
+	.d_compare	= hpfs_compare_dentry,
+};