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, 46 insertions, 0 deletions

diff --git a/arch/hexagon/lib/modsi3.S b/arch/hexagon/lib/modsi3.S
new file mode 100644
index 000000000..9ea1c86ef
--- /dev/null
+++ b/arch/hexagon/lib/modsi3.S
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2021, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/linkage.h>
+
+SYM_FUNC_START(__hexagon_modsi3)
+        {
+                p2 = cmp.ge(r0,#0)
+                r2 = abs(r0)
+                r1 = abs(r1)
+        }
+        {
+                r3 = cl0(r2)
+                r4 = cl0(r1)
+                p0 = cmp.gtu(r1,r2)
+        }
+        {
+                r3 = sub(r4,r3)
+                if (p0) jumpr r31
+        }
+        {
+                p1 = cmp.eq(r3,#0)
+                loop0(1f,r3)
+                r0 = r2
+                r2 = lsl(r1,r3)
+        }
+        .falign
+1:
+        {
+                p0 = cmp.gtu(r2,r0)
+                if (!p0.new) r0 = sub(r0,r2)
+                r2 = lsr(r2,#1)
+                if (p1) r1 = #0
+        }:endloop0
+        {
+                p0 = cmp.gtu(r2,r0)
+                if (!p0.new) r0 = sub(r0,r1)
+                if (p2) jumpr r31
+        }
+        {
+                r0 = neg(r0)
+                jumpr r31
+        }
+SYM_FUNC_END(__hexagon_modsi3)