Bluetooth: Mesh: advertiser: add disable function

Adds a disable function for the extended advertising which stops and
deletes the advertising instances, allowing them to be properly
reinitialized when calling `bt_mesh_adv_enable()` after bluetooth has
been disabled and re-enabled.

For the legacy advertising, the function terminates the advertising
thread. If legacy advertising is used, `bt_mesh_adv_init()` must be
called before `bt_mesh_adv_enable()` to properly resume advertising
after suspension.

Signed-off-by: Håvard Reierstad <haavard.reierstad@nordicsemi.no>

include/zephyr/bluetooth/mesh/main.h

@@ -607,6 +607,10 @@ void bt_mesh_reset(void);
  *  If at all possible, the Friendship feature should be used instead, to
  *  make the node into a Low Power Node.
  *
+ * @note Should not be called from work queue due to undefined behavior.
+ * This is due to k_work_flush_delayable() being used in disabling of the
+ * extended advertising.
+ *
  *  @return 0 on success, or (negative) error code on failure.
  */
 int bt_mesh_suspend(void);

subsys/bluetooth/mesh/adv.h

@@ -80,6 +80,9 @@ int bt_mesh_scan_disable(void);
 
 int bt_mesh_adv_enable(void);
 
+/* Should not be called from work queue due to undefined behavior */
+int bt_mesh_adv_disable(void);
+
 void bt_mesh_adv_buf_local_ready(void);
 
 void bt_mesh_adv_buf_relay_ready(void);

subsys/bluetooth/mesh/adv_ext.c

@@ -506,6 +506,36 @@ int bt_mesh_adv_enable(void)
 	return 0;
 }
 
+int bt_mesh_adv_disable(void)
+{
+	int err;
+	struct k_work_sync sync;
+
+	for (int i = 0; i < ARRAY_SIZE(advs); i++) {
+		k_work_flush_delayable(&advs[i].work, &sync);
+
+		err = bt_le_ext_adv_stop(advs[i].instance);
+		if (err) {
+			LOG_ERR("Failed to stop adv %d", err);
+			return err;
+		}
+
+		/* `adv_sent` is called to finish transmission of an adv buffer that was pushed to
+		 * the host before the advertiser was stopped, but did not finish.
+		 */
+		adv_sent(advs[i].instance, NULL);
+
+		err = bt_le_ext_adv_delete(advs[i].instance);
+		if (err) {
+			LOG_ERR("Failed to delete adv %d", err);
+			return err;
+		}
+		advs[i].instance = NULL;
+	}
+
+	return 0;
+}
+
 int bt_mesh_adv_gatt_start(const struct bt_le_adv_param *param,
 			   int32_t duration,
 			   const struct bt_data *ad, size_t ad_len,

subsys/bluetooth/mesh/adv_legacy.c

@@ -39,6 +39,7 @@ LOG_MODULE_REGISTER(bt_mesh_adv_legacy);
 static struct k_thread adv_thread_data;
 static K_KERNEL_STACK_DEFINE(adv_thread_stack, CONFIG_BT_MESH_ADV_STACK_SIZE);
 static int32_t adv_timeout;
+static bool enabled;
 
 static int bt_data_send(uint8_t num_events, uint16_t adv_int,
 			const struct bt_data *ad, size_t ad_len,
@@ -144,10 +145,9 @@ static inline void buf_send(struct net_buf *buf)
 static void adv_thread(void *p1, void *p2, void *p3)
 {
 	LOG_DBG("started");
+	struct net_buf *buf;
 
-	while (1) {
-		struct net_buf *buf;
-
+	while (enabled) {
 		if (IS_ENABLED(CONFIG_BT_MESH_GATT_SERVER)) {
 			buf = bt_mesh_adv_buf_get(K_NO_WAIT);
 			if (IS_ENABLED(CONFIG_BT_MESH_PROXY_SOLICITATION) && !buf) {
@@ -188,6 +188,12 @@ static void adv_thread(void *p1, void *p2, void *p3)
 		/* Give other threads a chance to run */
 		k_yield();
 	}
+
+	/* Empty the advertising pool when advertising is disabled */
+	while ((buf = bt_mesh_adv_buf_get(K_NO_WAIT))) {
+		bt_mesh_adv_send_start(0, -ENODEV, BT_MESH_ADV(buf));
+		net_buf_unref(buf);
+	}
 }
 
 void bt_mesh_adv_buf_local_ready(void)
@@ -221,10 +227,19 @@ void bt_mesh_adv_init(void)
 
 int bt_mesh_adv_enable(void)
 {
+	enabled = true;
 	k_thread_start(&adv_thread_data);
 	return 0;
 }
 
+int bt_mesh_adv_disable(void)
+{
+	enabled = false;
+	k_thread_join(&adv_thread_data, K_FOREVER);
+	LOG_DBG("Advertising disabled");
+	return 0;
+}
+
 int bt_mesh_adv_gatt_start(const struct bt_le_adv_param *param, int32_t duration,
 			   const struct bt_data *ad, size_t ad_len,
 			   const struct bt_data *sd, size_t sd_len)