refactoring of scanner state machine

include/zephyr/bluetooth/bluetooth.h

@@ -2294,6 +2294,7 @@ BUILD_ASSERT(BT_GAP_SCAN_FAST_WINDOW == BT_GAP_SCAN_FAST_INTERVAL_MIN,
  *
  * @return Zero on success or error code otherwise, positive in case of
  *         protocol error or negative (POSIX) in case of stack internal error.
+ * @retval -EBUSY if the scanner is already being started in a different thread.
  */
 int bt_le_scan_start(const struct bt_le_scan_param *param, bt_le_scan_cb_t cb);
 

subsys/bluetooth/host/conn.c

@@ -35,6 +35,7 @@
 #include "hci_core.h"
 #include "id.h"
 #include "adv.h"
+#include "scan.h"
 #include "conn_internal.h"
 #include "l2cap_internal.h"
 #include "keys.h"
@@ -1270,10 +1271,18 @@ void bt_conn_set_state(struct bt_conn *conn, bt_conn_state_t state)
 			 * the application through bt_conn_disconnect or by
 			 * timeout set by bt_conn_le_create_param.timeout.
 			 */
-			if (conn->err) {
-				notify_connected(conn);
-			}
+			if (IS_ENABLED(CONFIG_BT_CENTRAL)) {
+				int err = bt_le_scan_user_remove(BT_LE_SCAN_USER_CONN);
+
+				if (err) {
+					LOG_WRN("Error while removing conn user from scanner (%d)",
+						err);
+				}
 
+				if (conn->err) {
+					notify_connected(conn);
+				}
+			}
 			bt_conn_unref(conn);
 			break;
 		case BT_CONN_ADV_DIR_CONNECTABLE:
@@ -1698,7 +1707,7 @@ int bt_conn_disconnect(struct bt_conn *conn, uint8_t reason)
 		conn->err = reason;
 		bt_conn_set_state(conn, BT_CONN_DISCONNECTED);
 		if (IS_ENABLED(CONFIG_BT_CENTRAL)) {
-			bt_le_scan_update(false);
+			return bt_le_scan_user_add(BT_LE_SCAN_USER_CONN);
 		}
 		return 0;
 	case BT_CONN_INITIATING:
@@ -3365,27 +3374,32 @@ static int conn_le_create_common_checks(const bt_addr_le_t *peer,
 {
 
 	if (!atomic_test_bit(bt_dev.flags, BT_DEV_READY)) {
+		LOG_DBG("Conn check failed: BT dev not ready.");
 		return -EAGAIN;
 	}
 
 	if (!bt_le_conn_params_valid(conn_param)) {
+		LOG_DBG("Conn check failed: invalid parameters.");
 		return -EINVAL;
 	}
 
-	if (!BT_LE_STATES_SCAN_INIT(bt_dev.le.states) &&
-	    atomic_test_bit(bt_dev.flags, BT_DEV_EXPLICIT_SCAN)) {
+	if (!BT_LE_STATES_SCAN_INIT(bt_dev.le.states) && bt_le_explicit_scanner_running()) {
+		LOG_DBG("Conn check failed: scanner was explicitly requested.");
 		return -EAGAIN;
 	}
 
 	if (atomic_test_bit(bt_dev.flags, BT_DEV_INITIATING)) {
+		LOG_DBG("Conn check failed: device is already initiating.");
 		return -EALREADY;
 	}
 
 	if (!bt_id_scan_random_addr_check()) {
+		LOG_DBG("Conn check failed: invalid random address.");
 		return -EINVAL;
 	}
 
 	if (bt_conn_exists_le(BT_ID_DEFAULT, peer)) {
+		LOG_DBG("Conn check failed: ACL connection already exists.");
 		return -EINVAL;
 	}
 
@@ -3438,8 +3452,9 @@ int bt_conn_le_create(const bt_addr_le_t *peer, const struct bt_conn_le_create_p
 		/* Use host-based identity resolving. */
 		bt_conn_set_state(conn, BT_CONN_SCAN_BEFORE_INITIATING);
 
-		err = bt_le_scan_update(true);
+		err = bt_le_scan_user_add(BT_LE_SCAN_USER_CONN);
 		if (err) {
+			bt_le_scan_user_remove(BT_LE_SCAN_USER_CONN);
 			bt_conn_set_state(conn, BT_CONN_DISCONNECTED);
 			bt_conn_unref(conn);
 
@@ -3459,7 +3474,12 @@ int bt_conn_le_create(const bt_addr_le_t *peer, const struct bt_conn_le_create_p
 		bt_conn_set_state(conn, BT_CONN_DISCONNECTED);
 		bt_conn_unref(conn);
 
-		bt_le_scan_update(false);
+		/* Best-effort attempt to inform the scanner that the initiator stopped. */
+		int scan_check_err = bt_le_scan_user_add(BT_LE_SCAN_USER_NONE);
+
+		if (scan_check_err) {
+			LOG_WRN("Error while updating the scanner (%d)", scan_check_err);
+		}
 		return err;
 	}
 
@@ -3561,17 +3581,18 @@ int bt_le_set_auto_conn(const bt_addr_le_t *addr,
 		}
 	}
 
+	int err = 0;
 	if (conn->state == BT_CONN_DISCONNECTED &&
 	    atomic_test_bit(bt_dev.flags, BT_DEV_READY)) {
 		if (param) {
 			bt_conn_set_state(conn, BT_CONN_SCAN_BEFORE_INITIATING);
+			err = bt_le_scan_user_add(BT_LE_SCAN_USER_CONN);
 		}
-		bt_le_scan_update(false);
 	}
 
 	bt_conn_unref(conn);
 
-	return 0;
+	return err;
 }
 #endif /* !defined(CONFIG_BT_FILTER_ACCEPT_LIST) */
 #endif /* CONFIG_BT_CENTRAL */

subsys/bluetooth/host/hci_core.c

@@ -1010,7 +1010,12 @@ static void hci_disconn_complete(struct net_buf *buf)
 #if defined(CONFIG_BT_CENTRAL) && !defined(CONFIG_BT_FILTER_ACCEPT_LIST)
 	if (atomic_test_bit(conn->flags, BT_CONN_AUTO_CONNECT)) {
 		bt_conn_set_state(conn, BT_CONN_SCAN_BEFORE_INITIATING);
-		bt_le_scan_update(false);
+		/* Just a best-effort check if the scanner should be started. */
+		int err = bt_le_scan_user_remove(BT_LE_SCAN_USER_NONE);
+
+		if (err) {
+			LOG_WRN("Error while updating the scanner (%d)", err);
+		}
 	}
 #endif /* defined(CONFIG_BT_CENTRAL) && !defined(CONFIG_BT_FILTER_ACCEPT_LIST) */
 
@@ -1561,9 +1566,14 @@ void bt_hci_le_enh_conn_complete(struct bt_hci_evt_le_enh_conn_complete *evt)
 
 	bt_conn_unref(conn);
 
-	if (IS_ENABLED(CONFIG_BT_CENTRAL) &&
-	    conn->role == BT_HCI_ROLE_CENTRAL) {
-		bt_le_scan_update(false);
+	if (IS_ENABLED(CONFIG_BT_CENTRAL) && conn->role == BT_HCI_ROLE_CENTRAL) {
+		int err;
+
+		/* Just a best-effort check if the scanner should be started. */
+		err = bt_le_scan_user_remove(BT_LE_SCAN_USER_NONE);
+		if (err) {
+			LOG_WRN("Error while updating the scanner (%d)", err);
+		}
 	}
 }
 
@@ -1661,7 +1671,11 @@ static void enh_conn_complete_error_handle(uint8_t status)
 
 	if (IS_ENABLED(CONFIG_BT_CENTRAL) && status == BT_HCI_ERR_UNKNOWN_CONN_ID) {
 		le_conn_complete_cancel(status);
-		bt_le_scan_update(false);
+		int err = bt_le_scan_user_remove(BT_LE_SCAN_USER_NONE);
+
+		if (err) {
+			LOG_WRN("Error while updating the scanner (%d)", err);
+		}
 		return;
 	}
 
@@ -4200,7 +4214,7 @@ void bt_finalize_init(void)
 	atomic_set_bit(bt_dev.flags, BT_DEV_READY);
 
 	if (IS_ENABLED(CONFIG_BT_OBSERVER)) {
-		bt_le_scan_update(false);
+		bt_scan_reset();
 	}
 
 	bt_dev_show_info();

subsys/bluetooth/host/hci_core.h

@@ -38,16 +38,11 @@ enum {
 	BT_DEV_HAS_PUB_KEY,
 	BT_DEV_PUB_KEY_BUSY,
 
-	/** The application explicitly instructed the stack to scan for advertisers
-	 * using the API @ref bt_le_scan_start().
-	 */
-	BT_DEV_EXPLICIT_SCAN,
-
 	/** The application either explicitly or implicitly instructed the stack to scan
 	 * for advertisers.
 	 *
 	 * Examples of such cases
-	 *  - Explicit scanning, @ref BT_DEV_EXPLICIT_SCAN.
+	 *  - Explicit scanning, @ref BT_LE_SCAN_USER_EXPLICIT_SCAN.
 	 *  - The application instructed the stack to automatically connect if a given device
 	 *    is detected.
 	 *  - The application wants to connect to a peer device using private addresses, but
@@ -63,13 +58,9 @@ enum {
 	 */
 	BT_DEV_SCANNING,
 
-	/* Cached parameters used when initially enabling the scanner.
-	 * These are needed to ensure the same parameters are used when restarting
-	 * the scanner after refreshing an RPA.
+	/**
+	 * Scanner is configured with a timeout.
 	 */
-	BT_DEV_ACTIVE_SCAN,
-	BT_DEV_SCAN_FILTER_DUP,
-	BT_DEV_SCAN_FILTERED,
 	BT_DEV_SCAN_LIMITED,
 
 	BT_DEV_INITIATING,
@@ -489,30 +480,6 @@ uint8_t bt_get_phy(uint8_t hci_phy);
  */
 int bt_get_df_cte_type(uint8_t hci_cte_type);
 
-/** Start or restart scanner if needed
- *
- * Examples of cases where it may be required to start/restart a scanner:
- * - When the auto-connection establishement feature is used:
- *   - When the host sets a connection context for auto-connection establishment.
- *   - When a connection was established.
- *     The host may now be able to retry to automatically set up a connection.
- *   - When a connection was disconnected/lost.
- *     The host may now be able to retry to automatically set up a connection.
- *   - When the application stops explicit scanning.
- *     The host may now be able to retry to automatically set up a connection.
- *   - The application tries to connect to another device, but fails.
- *     The host may now be able to retry to automatically set up a connection.
- * - When the application wants to connect to a device, but we need
- *   to fallback to host privacy.
- * - When the application wants to establish a periodic sync to a device
- *   and the application has not already started scanning.
- *
- * @param fast_scan Use fast scan parameters or slow scan parameters
- *
- * @return 0 in case of success, or a negative error code on failure.
- */
-int bt_le_scan_update(bool fast_scan);
-
 int bt_le_create_conn(const struct bt_conn *conn);
 int bt_le_create_conn_cancel(void);
 int bt_le_create_conn_synced(const struct bt_conn *conn, const struct bt_le_ext_adv *adv,

subsys/bluetooth/host/id.c

@@ -689,11 +689,11 @@ static void rpa_timeout(struct k_work *work)
 	le_rpa_invalidate();
 
 	/* IF no roles using the RPA is running we can stop the RPA timer */
-	if (!(adv_enabled ||
-	      atomic_test_bit(bt_dev.flags, BT_DEV_INITIATING) ||
-	      (atomic_test_bit(bt_dev.flags, BT_DEV_SCANNING) &&
-	       atomic_test_bit(bt_dev.flags, BT_DEV_ACTIVE_SCAN)))) {
-		return;
+	if (IS_ENABLED(CONFIG_BT_CENTRAL)) {
+		if (!(adv_enabled || atomic_test_bit(bt_dev.flags, BT_DEV_INITIATING) ||
+		      bt_le_scan_active_scanner_running())) {
+			return;
+		}
 	}
 
 	le_update_private_addr();