[PATCH v1] Bluetooth: hci_sync: Fix disconnect complete event timeout issue

[Cheng Jiang]

Sometimes, the remote device doesn't acknowledge the LL_TERMINATE_IND
in time, requiring the controller to wait for the supervision timeout,
which may exceed 2 seconds. In the current implementation, the
HCI_EV_DISCONN_COMPLETE event is ignored if it arrives late, since
the hci_abort_conn_sync has cleaned up the connection after 2 seconds.
This causes the mgmt to get stuck, resulting in bluetoothd waiting
indefinitely for the mgmt response to the disconnect. To recover,
restarting bluetoothd is necessary.

bluetoothctl log like this:
[Designer Mouse]# disconnect D9:B5:6C:F2:51:91
Attempting to disconnect from D9:B5:6C:F2:51:91
[Designer Mouse]#
[Designer Mouse]# power off
[Designer Mouse]#
Failed to set power off: org.freedesktop.DBus.Error.NoReply.

Signed-off-by: Cheng Jiang <quic_chejiang@xxxxxxxxxxx>
---
 include/net/bluetooth/hci_core.h |  2 ++
 net/bluetooth/hci_conn.c         |  9 +++++++++
 net/bluetooth/hci_event.c        |  9 +++++++++
 net/bluetooth/hci_sync.c         | 18 ++++++++++++++++++
 4 files changed, 38 insertions(+)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 734cd50cd..2ab079dcf 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -753,6 +753,8 @@ struct hci_conn {
 
 	struct bt_codec codec;
 
+	struct completion disc_ev_comp;
+
 	void (*connect_cfm_cb)	(struct hci_conn *conn, u8 status);
 	void (*security_cfm_cb)	(struct hci_conn *conn, u8 status);
 	void (*disconn_cfm_cb)	(struct hci_conn *conn, u8 reason);
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index d097e308a..e0244e191 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -1028,6 +1028,15 @@ static struct hci_conn *__hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t
 
 	hci_conn_init_sysfs(conn);
 
+	/* This disc_ev_comp is inited when we send a disconnect request to
+	 * the remote device but fail to receive the disconnect complete
+	 * event within the expected time (2 seconds). This occurs because
+	 * the remote device doesn't ack the terminate indication, forcing
+	 * the controller to wait for the supervision timeout.
+	 */
+	init_completion(&conn->disc_ev_comp);
+	complete(&conn->disc_ev_comp);
+
 	return conn;
 }
 
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 2cc7a9306..60ecb2b18 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3366,6 +3366,15 @@ static void hci_disconn_complete_evt(struct hci_dev *hdev, void *data,
 	if (!conn)
 		goto unlock;
 
+	/* Wake up disc_ev_comp here is ok. Since we hold the hdev lock
+	 * hci_abort_conn_sync will wait hdev lock release to continue.
+	 */
+	if (!completion_done(&conn->disc_ev_comp)) {
+		complete(&conn->disc_ev_comp);
+		/* Add some delay for hci_abort_conn_sync to handle the complete */
+		usleep_range(100, 1000);
+	}
+
 	if (ev->status) {
 		mgmt_disconnect_failed(hdev, &conn->dst, conn->type,
 				       conn->dst_type, ev->status);
diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 0badec712..783d04b57 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -5590,6 +5590,24 @@ int hci_abort_conn_sync(struct hci_dev *hdev, struct hci_conn *conn, u8 reason)
 		break;
 	}
 
+	/* Check whether the connection is successfully disconnected.
+	 * Sometimes the remote device doesn't acknowledge the
+	 * LL_TERMINATE_IND in time, requiring the controller to wait
+	 * for the supervision timeout, which may exceed 2 seconds. In
+	 * this case, we need to wait for the HCI_EV_DISCONN_COMPLETE
+	 * event before cleaning up the connection.
+	 */
+	if (err == -ETIMEDOUT) {
+		u32 idle_delay = msecs_to_jiffies(10 * conn->le_supv_timeout);
+
+		reinit_completion(&conn->disc_ev_comp);
+		if (!wait_for_completion_timeout(&conn->disc_ev_comp, idle_delay)) {
+			bt_dev_warn(hdev, "Failed to get complete");
+			mgmt_disconnect_failed(hdev, &conn->dst, conn->type,
+					       conn->dst_type, conn->abort_reason);
+		}
+	}
+
 	hci_dev_lock(hdev);
 
 	/* Check if the connection has been cleaned up concurrently */

base-commit: e25c8d66f6786300b680866c0e0139981273feba
-- 
2.34.1