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, 57 insertions, 0 deletions

diff --git a/tools/testing/vma/main.c b/tools/testing/vma/main.c
new file mode 100644
index 000000000..18338f5d2
--- /dev/null
+++ b/tools/testing/vma/main.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "shared.h"
+/*
+ * Directly import the VMA implementation here. Our vma_internal.h wrapper
+ * provides userland-equivalent functionality for everything vma.c uses.
+ */
+#include "../../../mm/vma_init.c"
+#include "../../../mm/vma_exec.c"
+#include "../../../mm/vma.c"
+
+/* Tests are included directly so they can test static functions in mm/vma.c. */
+#include "tests/merge.c"
+#include "tests/mmap.c"
+#include "tests/vma.c"
+
+int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
+
+/* Helper functions which utilise static kernel functions. */
+
+struct vm_area_struct *merge_existing(struct vma_merge_struct *vmg)
+{
+	struct vm_area_struct *vma;
+
+	vma = vma_merge_existing_range(vmg);
+	if (vma)
+		vma_assert_attached(vma);
+	return vma;
+}
+
+int attach_vma(struct mm_struct *mm, struct vm_area_struct *vma)
+{
+	int res;
+
+	res = vma_link(mm, vma);
+	if (!res)
+		vma_assert_attached(vma);
+	return res;
+}
+
+/* Main test running which invokes tests/ *.c runners. */
+int main(void)
+{
+	int num_tests = 0, num_fail = 0;
+
+	maple_tree_init();
+	vma_state_init();
+
+	run_merge_tests(&num_tests, &num_fail);
+	run_mmap_tests(&num_tests, &num_fail);
+	run_vma_tests(&num_tests, &num_fail);
+
+	printf("%d tests run, %d passed, %d failed.\n",
+	       num_tests, num_tests - num_fail, num_fail);
+
+	return num_fail == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
+}