Bluetooth: Add ncmd=0 recovery handling

During command status or command complete event, the controller may set
ncmd=0 indicating that it is not accepting any more commands. In such a
case, host holds off sending any more commands to the controller. If the
controller doesn't recover from such condition, host will wait forever,
until the user decides that the Bluetooth is broken and may power cycles
the Bluetooth.

This patch triggers the hardware error to reset the controller and
driver when it gets into such state as there is no other wat out.

Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Signed-off-by: Manish Mandlik <mmandlik@google.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

2 files changed, 41 insertions, 10 deletions

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 25484bb0773d..572f2362ddb7 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -1730,6 +1730,7 @@ int hci_dev_do_close(struct hci_dev *hdev)
 	}
 
 	cancel_delayed_work(&hdev->power_off);
+	cancel_delayed_work(&hdev->ncmd_timer);
 
 	hci_request_cancel_all(hdev);
 	hci_req_sync_lock(hdev);
@@ -2777,6 +2778,24 @@ static void hci_cmd_timeout(struct work_struct *work)
 	queue_work(hdev->workqueue, &hdev->cmd_work);
 }
 
+/* HCI ncmd timer function */
+static void hci_ncmd_timeout(struct work_struct *work)
+{
+	struct hci_dev *hdev = container_of(work, struct hci_dev,
+					    ncmd_timer.work);
+
+	bt_dev_err(hdev, "Controller not accepting commands anymore: ncmd = 0");
+
+	/* During HCI_INIT phase no events can be injected if the ncmd timer
+	 * triggers since the procedure has its own timeout handling.
+	 */
+	if (test_bit(HCI_INIT, &hdev->flags))
+		return;
+
+	/* This is an irrecoverable state, inject hardware error event */
+	hci_reset_dev(hdev);
+}
+
 struct oob_data *hci_find_remote_oob_data(struct hci_dev *hdev,
 					  bdaddr_t *bdaddr, u8 bdaddr_type)
 {
@@ -3841,6 +3860,7 @@ struct hci_dev *hci_alloc_dev(void)
 	init_waitqueue_head(&hdev->suspend_wait_q);
 
 	INIT_DELAYED_WORK(&hdev->cmd_timer, hci_cmd_timeout);
+	INIT_DELAYED_WORK(&hdev->ncmd_timer, hci_ncmd_timeout);
 
 	hci_request_setup(hdev);
 
@@ -4078,6 +4098,8 @@ int hci_reset_dev(struct hci_dev *hdev)
 	hci_skb_pkt_type(skb) = HCI_EVENT_PKT;
 	skb_put_data(skb, hw_err, 3);
 
+	bt_dev_err(hdev, "Injecting HCI hardware error event");
+
 	/* Send Hardware Error to upper stack */
 	return hci_recv_frame(hdev, skb);
 }
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 59c5329354e1..18339ebc5959 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3268,6 +3268,23 @@ unlock:
 	hci_dev_unlock(hdev);
 }
 
+static inline void handle_cmd_cnt_and_timer(struct hci_dev *hdev,
+					    u16 opcode, u8 ncmd)
+{
+	if (opcode != HCI_OP_NOP)
+		cancel_delayed_work(&hdev->cmd_timer);
+
+	if (!test_bit(HCI_RESET, &hdev->flags)) {
+		if (ncmd) {
+			cancel_delayed_work(&hdev->ncmd_timer);
+			atomic_set(&hdev->cmd_cnt, 1);
+		} else {
+			schedule_delayed_work(&hdev->ncmd_timer,
+					      HCI_NCMD_TIMEOUT);
+		}
+	}
+}
+
 static void hci_cmd_complete_evt(struct hci_dev *hdev, struct sk_buff *skb,
 				 u16 *opcode, u8 *status,
 				 hci_req_complete_t *req_complete,
@@ -3630,11 +3647,7 @@ static void hci_cmd_complete_evt(struct hci_dev *hdev, struct sk_buff *skb,
 		break;
 	}
 
-	if (*opcode != HCI_OP_NOP)
-		cancel_delayed_work(&hdev->cmd_timer);
-
-	if (ev->ncmd && !test_bit(HCI_RESET, &hdev->flags))
-		atomic_set(&hdev->cmd_cnt, 1);
+	handle_cmd_cnt_and_timer(hdev, *opcode, ev->ncmd);
 
 	hci_req_cmd_complete(hdev, *opcode, *status, req_complete,
 			     req_complete_skb);
@@ -3735,11 +3748,7 @@ static void hci_cmd_status_evt(struct hci_dev *hdev, struct sk_buff *skb,
 		break;
 	}
 
-	if (*opcode != HCI_OP_NOP)
-		cancel_delayed_work(&hdev->cmd_timer);
-
-	if (ev->ncmd && !test_bit(HCI_RESET, &hdev->flags))
-		atomic_set(&hdev->cmd_cnt, 1);
+	handle_cmd_cnt_and_timer(hdev, *opcode, ev->ncmd);
 
 	/* Indicate request completion if the command failed. Also, if
 	 * we're not waiting for a special event and we get a success