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, 30 insertions, 0 deletions

diff --git a/tools/testing/radix-tree/xarray.c b/tools/testing/radix-tree/xarray.c
new file mode 100644
index 000000000..253208a85
--- /dev/null
+++ b/tools/testing/radix-tree/xarray.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * xarray.c: Userspace shim for XArray test-suite
+ * Copyright (c) 2018 Matthew Wilcox <willy@infradead.org>
+ */
+
+#include "xarray-shared.h"
+#include "test.h"
+
+#undef XA_DEBUG
+#include "../../../lib/test_xarray.c"
+
+void xarray_tests(void)
+{
+	xarray_checks();
+	xarray_exit();
+}
+
+int __weak main(void)
+{
+	rcu_register_thread();
+	radix_tree_init();
+	xarray_tests();
+	radix_tree_cpu_dead(1);
+	rcu_barrier();
+	if (nr_allocated)
+		printf("nr_allocated = %d\n", nr_allocated);
+	rcu_unregister_thread();
+	return 0;
+}