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, 137 insertions, 0 deletions

diff --git a/fs/f2fs/hash.c b/fs/f2fs/hash.c
new file mode 100644
index 000000000..14082fe5e
--- /dev/null
+++ b/fs/f2fs/hash.c
@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * fs/f2fs/hash.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * Portions of this code from linux/fs/ext3/hash.c
+ *
+ * Copyright (C) 2002 by Theodore Ts'o
+ */
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/f2fs_fs.h>
+#include <linux/pagemap.h>
+#include <linux/unicode.h>
+
+#include "f2fs.h"
+
+/*
+ * Hashing code copied from ext3
+ */
+#define DELTA 0x9E3779B9
+
+static void TEA_transform(unsigned int buf[4], unsigned int const in[])
+{
+	__u32 sum = 0;
+	__u32 b0 = buf[0], b1 = buf[1];
+	__u32 a = in[0], b = in[1], c = in[2], d = in[3];
+	int n = 16;
+
+	do {
+		sum += DELTA;
+		b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
+		b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
+	} while (--n);
+
+	buf[0] += b0;
+	buf[1] += b1;
+}
+
+static void str2hashbuf(const unsigned char *msg, size_t len,
+				unsigned int *buf, int num)
+{
+	unsigned pad, val;
+	int i;
+
+	pad = (__u32)len | ((__u32)len << 8);
+	pad |= pad << 16;
+
+	val = pad;
+	if (len > num * 4)
+		len = num * 4;
+	for (i = 0; i < len; i++) {
+		if ((i % 4) == 0)
+			val = pad;
+		val = msg[i] + (val << 8);
+		if ((i % 4) == 3) {
+			*buf++ = val;
+			val = pad;
+			num--;
+		}
+	}
+	if (--num >= 0)
+		*buf++ = val;
+	while (--num >= 0)
+		*buf++ = pad;
+}
+
+static u32 TEA_hash_name(const u8 *p, size_t len)
+{
+	__u32 in[8], buf[4];
+
+	/* Initialize the default seed for the hash checksum functions */
+	buf[0] = 0x67452301;
+	buf[1] = 0xefcdab89;
+	buf[2] = 0x98badcfe;
+	buf[3] = 0x10325476;
+
+	while (1) {
+		str2hashbuf(p, len, in, 4);
+		TEA_transform(buf, in);
+		p += 16;
+		if (len <= 16)
+			break;
+		len -= 16;
+	}
+	return buf[0] & ~F2FS_HASH_COL_BIT;
+}
+
+/*
+ * Compute @fname->hash.  For all directories, @fname->disk_name must be set.
+ * For casefolded directories, @fname->usr_fname must be set, and also
+ * @fname->cf_name if the filename is valid Unicode and is not "." or "..".
+ */
+void f2fs_hash_filename(const struct inode *dir, struct f2fs_filename *fname)
+{
+	const u8 *name = fname->disk_name.name;
+	size_t len = fname->disk_name.len;
+
+	WARN_ON_ONCE(!name);
+
+	if (name_is_dot_dotdot(name, len)) {
+		fname->hash = 0;
+		return;
+	}
+
+#if IS_ENABLED(CONFIG_UNICODE)
+	if (IS_CASEFOLDED(dir)) {
+		/*
+		 * If the casefolded name is provided, hash it instead of the
+		 * on-disk name.  If the casefolded name is *not* provided, that
+		 * should only be because the name wasn't valid Unicode or was
+		 * "." or "..", so fall back to treating the name as an opaque
+		 * byte sequence.  Note that to handle encrypted directories,
+		 * the fallback must use usr_fname (plaintext) rather than
+		 * disk_name (ciphertext).
+		 */
+		WARN_ON_ONCE(!fname->usr_fname->name);
+		if (fname->cf_name.name) {
+			name = fname->cf_name.name;
+			len = fname->cf_name.len;
+		} else {
+			name = fname->usr_fname->name;
+			len = fname->usr_fname->len;
+		}
+		if (IS_ENCRYPTED(dir)) {
+			struct qstr tmp = QSTR_INIT(name, len);
+
+			fname->hash =
+				cpu_to_le32(fscrypt_fname_siphash(dir, &tmp));
+			return;
+		}
+	}
+#endif
+	fname->hash = cpu_to_le32(TEA_hash_name(name, len));
+}