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, 32 insertions, 0 deletions

diff --git a/scripts/mod/mk_elfconfig.c b/scripts/mod/mk_elfconfig.c
new file mode 100644
index 000000000..e8cee4e4b
--- /dev/null
+++ b/scripts/mod/mk_elfconfig.c
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <elf.h>
+
+int
+main(int argc, char **argv)
+{
+	unsigned char ei[EI_NIDENT];
+
+	if (fread(ei, 1, EI_NIDENT, stdin) != EI_NIDENT) {
+		fprintf(stderr, "Error: input truncated\n");
+		return 1;
+	}
+	if (memcmp(ei, ELFMAG, SELFMAG) != 0) {
+		fprintf(stderr, "Error: not ELF\n");
+		return 1;
+	}
+	switch (ei[EI_CLASS]) {
+	case ELFCLASS32:
+		printf("#define KERNEL_ELFCLASS ELFCLASS32\n");
+		break;
+	case ELFCLASS64:
+		printf("#define KERNEL_ELFCLASS ELFCLASS64\n");
+		break;
+	default:
+		exit(1);
+	}
+
+	return 0;
+}