Bluetooth: Add hci_request support for hci_update_background_scan

Many places using hci_update_background_scan() try to synchronize
whatever they're doing with the help of hci_request callbacks. However,
since the hci_update_background_scan() function hasn't so far accepted a
hci_request pointer any commands triggered by it have been left out by
the synchronization. This patch modifies the API in a similar way as was
done for hci_update_page_scan, i.e. there's a variant that takes a
hci_request and another one that takes a hci_dev.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

1 files changed, 96 insertions, 0 deletions

diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c
index eba83a2a6556..e49f682f1550 100644
--- a/net/bluetooth/hci_request.c
+++ b/net/bluetooth/hci_request.c
@@ -395,3 +395,99 @@ int hci_update_random_address(struct hci_request *req, bool require_privacy,
 
         return 0;
 }
+
+/* This function controls the background scanning based on hdev->pend_le_conns
+ * list. If there are pending LE connection we start the background scanning,
+ * otherwise we stop it.
+ *
+ * This function requires the caller holds hdev->lock.
+ */
+void __hci_update_background_scan(struct hci_request *req)
+{
+        struct hci_dev *hdev = req->hdev;
+        struct hci_conn *conn;
+
+        if (!test_bit(HCI_UP, &hdev->flags) ||
+            test_bit(HCI_INIT, &hdev->flags) ||
+            test_bit(HCI_SETUP, &hdev->dev_flags) ||
+            test_bit(HCI_CONFIG, &hdev->dev_flags) ||
+            test_bit(HCI_AUTO_OFF, &hdev->dev_flags) ||
+            test_bit(HCI_UNREGISTER, &hdev->dev_flags))
+                return;
+
+        /* No point in doing scanning if LE support hasn't been enabled */
+        if (!test_bit(HCI_LE_ENABLED, &hdev->dev_flags))
+                return;
+
+        /* If discovery is active don't interfere with it */
+        if (hdev->discovery.state != DISCOVERY_STOPPED)
+                return;
+
+        /* Reset RSSI and UUID filters when starting background scanning
+         * since these filters are meant for service discovery only.
+         *
+         * The Start Discovery and Start Service Discovery operations
+         * ensure to set proper values for RSSI threshold and UUID
+         * filter list. So it is safe to just reset them here.
+         */
+        hci_discovery_filter_clear(hdev);
+
+        if (list_empty(&hdev->pend_le_conns) &&
+            list_empty(&hdev->pend_le_reports)) {
+                /* If there is no pending LE connections or devices
+                 * to be scanned for, we should stop the background
+                 * scanning.
+                 */
+
+                /* If controller is not scanning we are done. */
+                if (!test_bit(HCI_LE_SCAN, &hdev->dev_flags))
+                        return;
+
+                hci_req_add_le_scan_disable(req);
+
+                BT_DBG("%s stopping background scanning", hdev->name);
+        } else {
+                /* If there is at least one pending LE connection, we should
+                 * keep the background scan running.
+                 */
+
+                /* If controller is connecting, we should not start scanning
+                 * since some controllers are not able to scan and connect at
+                 * the same time.
+                 */
+                conn = hci_conn_hash_lookup_state(hdev, LE_LINK, BT_CONNECT);
+                if (conn)
+                        return;
+
+                /* If controller is currently scanning, we stop it to ensure we
+                 * don't miss any advertising (due to duplicates filter).
+                 */
+                if (test_bit(HCI_LE_SCAN, &hdev->dev_flags))
+                        hci_req_add_le_scan_disable(req);
+
+                hci_req_add_le_passive_scan(req);
+
+                BT_DBG("%s starting background scanning", hdev->name);
+        }
+}
+
+static void update_background_scan_complete(struct hci_dev *hdev, u8 status)
+{
+        if (status)
+                BT_DBG("HCI request failed to update background scanning: "
+                       "status 0x%2.2x", status);
+}
+
+void hci_update_background_scan(struct hci_dev *hdev)
+{
+        int err;
+        struct hci_request req;
+
+        hci_req_init(&req, hdev);
+
+        __hci_update_background_scan(&req);
+
+        err = hci_req_run(&req, update_background_scan_complete);
+        if (err && err != -ENODATA)
+                BT_ERR("Failed to run HCI request: err %d", err);
+}