1 files changed, 48 insertions, 0 deletions
diff --git a/include/net/dsa_stubs.h b/include/net/dsa_stubs.h
new file mode 100644
index 0000000000..361811750a
--- /dev/null
+++ b/include/net/dsa_stubs.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * include/net/dsa_stubs.h - Stubs for the Distributed Switch Architecture framework
+ */
+
+#include <linux/mutex.h>
+#include <linux/netdevice.h>
+#include <linux/net_tstamp.h>
+#include <net/dsa.h>
+
+#if IS_ENABLED(CONFIG_NET_DSA)
+
+extern const struct dsa_stubs *dsa_stubs;
+
+struct dsa_stubs {
+	int (*master_hwtstamp_validate)(struct net_device *dev,
+					const struct kernel_hwtstamp_config *config,
+					struct netlink_ext_ack *extack);
+};
+
+static inline int dsa_master_hwtstamp_validate(struct net_device *dev,
+					       const struct kernel_hwtstamp_config *config,
+					       struct netlink_ext_ack *extack)
+{
+	if (!netdev_uses_dsa(dev))
+		return 0;
+
+	/* rtnl_lock() is a sufficient guarantee, because as long as
+	 * netdev_uses_dsa() returns true, the dsa_core module is still
+	 * registered, and so, dsa_unregister_stubs() couldn't have run.
+	 * For netdev_uses_dsa() to start returning false, it would imply that
+	 * dsa_master_teardown() has executed, which requires rtnl_lock().
+	 */
+	ASSERT_RTNL();
+
+	return dsa_stubs->master_hwtstamp_validate(dev, config, extack);
+}
+
+#else
+
+static inline int dsa_master_hwtstamp_validate(struct net_device *dev,
+					       const struct kernel_hwtstamp_config *config,
+					       struct netlink_ext_ack *extack)
+{
+	return 0;
+}
+
+#endif