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, 39 insertions, 0 deletions

diff --git a/net/dsa/trace.c b/net/dsa/trace.c
new file mode 100644
index 000000000..1b107165d
--- /dev/null
+++ b/net/dsa/trace.c
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Copyright 2022-2023 NXP
+ */
+
+#define CREATE_TRACE_POINTS
+#include "trace.h"
+
+void dsa_db_print(const struct dsa_db *db, char buf[DSA_DB_BUFSIZ])
+{
+	switch (db->type) {
+	case DSA_DB_PORT:
+		sprintf(buf, "port %s", db->dp->name);
+		break;
+	case DSA_DB_LAG:
+		sprintf(buf, "lag %s id %d", db->lag.dev->name, db->lag.id);
+		break;
+	case DSA_DB_BRIDGE:
+		sprintf(buf, "bridge %s num %d", db->bridge.dev->name,
+			db->bridge.num);
+		break;
+	default:
+		sprintf(buf, "unknown");
+		break;
+	}
+}
+
+const char *dsa_port_kind(const struct dsa_port *dp)
+{
+	switch (dp->type) {
+	case DSA_PORT_TYPE_USER:
+		return "user";
+	case DSA_PORT_TYPE_CPU:
+		return "cpu";
+	case DSA_PORT_TYPE_DSA:
+		return "dsa";
+	default:
+		return "unused";
+	}
+}