[RFC 15/15] Bluetooth: Auto connection and power off/on

[Andre Guedes <andre.guedes@openbossa.org>]

If hdev is closed (e.g. Mgmt power off command, RFKILL or controller is
reset), the established connections are dropped and no Disconnection
Complete Event is sent to host. This way, the background scan is not
triggered when devices configured with BT_AUTO_CONN_ALWAYS option
disconnect. To fix this issue, before dropping the LE connections, we
trigger the background scan for each connected device that requires
BT_AUTO_CONN_ALWAYS auto connection.

Moreover, once the adapter is powered on, we should start the background
scan if we have triggers registered. This way, we keep the background
scan running after a power off and power on sequence.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
---
 net/bluetooth/hci_conn.c | 35 +++++++++++++++++++++++++++++++++++
 net/bluetooth/hci_core.c |  2 ++
 2 files changed, 37 insertions(+)

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 5caf13b..66823eb 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -954,6 +954,31 @@ timer:
 				   msecs_to_jiffies(hdev->idle_timeout));
 }
 
+static void le_conn_drop_fixup(struct hci_conn *conn)
+{
+	struct hci_dev *hdev = conn->hdev;
+	struct hci_conn_param *param;
+	int err;
+
+	param = hci_find_conn_param(hdev, &conn->dst, conn->dst_type);
+	if (!param)
+		return;
+
+	if (param->auto_connect != BT_AUTO_CONN_ALWAYS)
+		goto done;
+
+	err = hci_trigger_background_scan(hdev);
+	if (err) {
+		BT_ERR("Failed to trigger background scanning: %d", err);
+		goto done;
+	}
+
+	param->bg_scan_triggered = true;
+
+done:
+	hci_conn_param_put(param);
+}
+
 /* Drop all connection on the device */
 void hci_conn_hash_flush(struct hci_dev *hdev)
 {
@@ -963,6 +988,16 @@ void hci_conn_hash_flush(struct hci_dev *hdev)
 	BT_DBG("hdev %s", hdev->name);
 
 	list_for_each_entry_safe(c, n, &h->list, list) {
+		/* If this is a LE connection in connected state we should do
+		 * some fixup before dropping this connection. Since no
+		 * Disconnection Complete Event will be sent to the host, we
+		 * have to trigger the background scan in case this is a
+		 * BT_AUTO_CONN_ALWAYS device. This is handled by the le_conn_
+		 * drop_fixup() helper.
+		 */
+		if (c->type == LE_LINK && c->state == BT_CONNECTED)
+			le_conn_drop_fixup(c);
+
 		c->state = BT_CLOSED;
 
 		hci_proto_disconn_cfm(c, HCI_ERROR_LOCAL_HOST_TERM);
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index ace77e3..fe18801 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -1748,6 +1748,8 @@ static void hci_power_on(struct work_struct *work)
 
 	if (test_and_clear_bit(HCI_SETUP, &hdev->dev_flags))
 		mgmt_index_added(hdev);
+
+	hci_check_background_scan(hdev);
 }
 
 static void hci_power_off(struct work_struct *work)
-- 
1.8.4