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, 40 insertions, 0 deletions

diff --git a/lib/zlib_dfltcc/dfltcc.c b/lib/zlib_dfltcc/dfltcc.c
new file mode 100644
index 000000000..ac6ac9739
--- /dev/null
+++ b/lib/zlib_dfltcc/dfltcc.c
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: Zlib
+/* dfltcc.c - SystemZ DEFLATE CONVERSION CALL support. */
+
+#include <linux/export.h>
+#include <linux/module.h>
+#include "dfltcc_util.h"
+#include "dfltcc.h"
+
+char *oesc_msg(
+    char *buf,
+    int oesc
+)
+{
+    if (oesc == 0x00)
+        return NULL; /* Successful completion */
+    else {
+#ifdef STATIC
+        return NULL; /* Ignore for pre-boot decompressor */
+#else
+        sprintf(buf, "Operation-Ending-Supplemental Code is 0x%.2X", oesc);
+        return buf;
+#endif
+    }
+}
+
+void dfltcc_reset_state(struct dfltcc_state *dfltcc_state) {
+    /* Initialize available functions */
+    if (is_dfltcc_enabled()) {
+        dfltcc(DFLTCC_QAF, &dfltcc_state->param, NULL, NULL, NULL, NULL, NULL);
+        memmove(&dfltcc_state->af, &dfltcc_state->param, sizeof(dfltcc_state->af));
+    } else
+        memset(&dfltcc_state->af, 0, sizeof(dfltcc_state->af));
+
+    /* Initialize parameter block */
+    memset(&dfltcc_state->param, 0, sizeof(dfltcc_state->param));
+    dfltcc_state->param.nt = 1;
+    dfltcc_state->param.ribm = DFLTCC_RIBM;
+}
+
+MODULE_LICENSE("GPL");