Bluetooth: Mesh: Add support prioritized message relay

include/zephyr/bluetooth/mesh/cfg.h

@@ -153,6 +153,30 @@ enum bt_mesh_feat_state bt_mesh_relay_get(void);
  */
 uint8_t bt_mesh_relay_retransmit_get(void);
 
+/** Bluetooth mesh network priority relay request callback
+ *
+ *  Support for the priority relay feature must be enabled through the
+ *  :kconfig:option:`CONFIG_BT_MESH_RELAY_PRIORITY` configuration option.
+ *
+ *  @param ctx The Bluetooth mesh message context.
+ *
+ *  @note A high priority message will preempt an oldest low priority message if the
+ *        relay buffer :kconfig:option:`CONFIG_BT_MESH_RELAY_BUF_COUNT` is insufficient.
+ *
+ *  @return The priority of the relay message. The higher the value, the higher
+ *          the priority, and the faster the relay.
+ */
+typedef uint8_t (*bt_mesh_relay_prio_req_cb_t)(struct bt_mesh_msg_ctx *ctx);
+
+/** @brief Register the priority relay callback function.
+ *
+ *  Support for the priority relay feature must be enabled through the
+ *  :kconfig:option:`CONFIG_BT_MESH_RELAY_PRIORITY` configuration option.
+ *
+ *  @param cb The priority request callback function.
+ */
+void bt_mesh_relay_priority_cb_reg(bt_mesh_relay_prio_req_cb_t cb);
+
 /** @brief Enable or disable the GATT Proxy feature.
  *
  *  Support for the GATT Proxy feature must be enabled through the

include/zephyr/kernel.h

@@ -2004,6 +2004,22 @@ __syscall void *k_queue_peek_head(struct k_queue *queue);
  */
 __syscall void *k_queue_peek_tail(struct k_queue *queue);
 
+/**
+ * @brief Provide the primitive to iterate on a queue
+ * Note: the loop is unsafe and thus curr should not be removed
+ *
+ * User _MUST_ add the loop statement curly braces enclosing its own code:
+ *
+ *     K_QUEUE_FOR_EACH(l, n) {
+ *         <user code>
+ *     }
+ *
+ * @param queue Address of the queue.
+ * @param curr A node pointer to peek each node of the queue.
+ */
+#define K_QUEUE_FOR_EACH(queue, curr) \
+	SYS_SFLIST_FOR_EACH_NODE(&((queue)->data_q), curr)
+
 /**
  * @brief Statically define and initialize a queue.
  *

subsys/bluetooth/host/testing.c

@@ -7,9 +7,11 @@
 #include <zephyr/kernel.h>
 #include <stddef.h>
 
+#include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/testing.h>
 
 #if defined(CONFIG_BT_MESH)
+#include "mesh/adv.h"
 #include "mesh/net.h"
 #include "mesh/lpn.h"
 #include "mesh/rpl.h"

subsys/bluetooth/mesh/Kconfig

@@ -696,6 +696,19 @@ config BT_MESH_RELAY_BUF_COUNT
 	  BT_MESH_RELAY_ADV_SETS allows the increase in the number of buffers
 	  while maintaining the latency.
 
+config BT_MESH_RELAY_PRIORITY
+	bool "Support for prioritized relay messages"
+	help
+	  Prioritized relay messages will be sent before other lower priority
+	  relay messages. This ensures that the higher priority messages are sent in time.
+	  When considering the message latency, also consider the values of
+	  BT_MESH_RELAY_RETRANSMIT_COUNT and BT_MESH_RELAY_RETRANSMIT_INTERVAL.
+	  A higher number of BT_MESH_RELAY_ADV_SETS allows the increase in the number
+	  of buffers while maintaining the latency.
+
+	  Note: To enable this option, the application layer needs to register a callback
+	  function to determine the priority of each relay message. If it is not registered,
+	  the default priority is lowest (zero).
 endif
 
 config BT_MESH_BEACON_ENABLED