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, 49 insertions, 0 deletions

diff --git a/arch/m68k/coldfire/cache.c b/arch/m68k/coldfire/cache.c
new file mode 100644
index 000000000..98ee89b87
--- /dev/null
+++ b/arch/m68k/coldfire/cache.c
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0
+/***************************************************************************/
+
+/*
+ *	cache.c -- general ColdFire Cache maintenance code
+ *
+ *	Copyright (C) 2010, Greg Ungerer (gerg@snapgear.com)
+ */
+
+/***************************************************************************/
+
+#include <linux/kernel.h>
+#include <asm/coldfire.h>
+#include <asm/mcfsim.h>
+
+/***************************************************************************/
+#ifdef CACHE_PUSH
+/***************************************************************************/
+
+/*
+ *	Use cpushl to push all dirty cache lines back to memory.
+ *	Older versions of GAS don't seem to know how to generate the
+ *	ColdFire cpushl instruction... Oh well, bit stuff it for now.
+ */
+
+void mcf_cache_push(void)
+{
+	__asm__ __volatile__ (
+		"clrl	%%d0\n\t"
+		"1:\n\t"
+		"movel	%%d0,%%a0\n\t"
+		"2:\n\t"
+		".word	0xf468\n\t"
+		"addl	%0,%%a0\n\t"
+		"cmpl	%1,%%a0\n\t"
+		"blt	2b\n\t"
+		"addql	#1,%%d0\n\t"
+		"cmpil	%2,%%d0\n\t"
+		"bne	1b\n\t"
+		: /* No output */
+		: "i" (CACHE_LINE_SIZE),
+		  "i" (DCACHE_SIZE / CACHE_WAYS),
+		  "i" (CACHE_WAYS)
+		: "d0", "a0" );
+}
+
+/***************************************************************************/
+#endif /* CACHE_PUSH */
+/***************************************************************************/