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, 56 insertions, 0 deletions

diff --git a/arch/alpha/lib/ev67-strcat.S b/arch/alpha/lib/ev67-strcat.S
new file mode 100644
index 000000000..f8c7305b1
--- /dev/null
+++ b/arch/alpha/lib/ev67-strcat.S
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * arch/alpha/lib/ev67-strcat.S
+ * 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com>
+ *
+ * Append a null-terminated string from SRC to DST.
+ *
+ * Much of the information about 21264 scheduling/coding comes from:
+ *	Compiler Writer's Guide for the Alpha 21264
+ *	abbreviated as 'CWG' in other comments here
+ *	ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html
+ * Scheduling notation:
+ *	E	- either cluster
+ *	U	- upper subcluster; U0 - subcluster U0; U1 - subcluster U1
+ *	L	- lower subcluster; L0 - subcluster L0; L1 - subcluster L1
+ * Try not to change the actual algorithm if possible for consistency.
+ * Commentary: It seems bogus to walk the input string twice - once
+ * to determine the length, and then again while doing the copy.
+ * A significant (future) enhancement would be to only read the input
+ * string once.
+ */
+
+#include <linux/export.h>
+	.text
+
+	.align 4
+	.globl strcat
+	.ent strcat
+strcat:
+	.frame $30, 0, $26
+	.prologue 0
+
+	mov	$16, $0		# E : set up return value
+	/* Find the end of the string.  */
+	ldq_u   $1, 0($16)	# L : load first quadword (a0 may be misaligned)
+	lda     $2, -1		# E :
+	insqh   $2, $16, $2	# U :
+
+	andnot  $16, 7, $16	# E :
+	or      $2, $1, $1	# E :
+	cmpbge  $31, $1, $2	# E : bits set iff byte == 0
+	bne     $2, $found	# U :
+
+$loop:	ldq     $1, 8($16)	# L :
+	addq    $16, 8, $16	# E :
+	cmpbge  $31, $1, $2	# E :
+	beq     $2, $loop	# U :
+
+$found:	cttz	$2, $3		# U0 :
+	addq	$16, $3, $16	# E :
+	/* Now do the append.  */
+	mov	$26, $23	# E :
+	br	__stxcpy	# L0 :
+
+	.end strcat
+	EXPORT_SYMBOL(strcat)