Bluetooth: Fix Advertisement Monitor Suspend/Resume

During system suspend, advertisement monitoring is disabled by setting
the HCI_VS_MSFT_LE_Set_Advertisement_Filter_Enable to False. This
disables the monitoring during suspend, however, if the controller is
monitoring a device, it sends HCI_VS_MSFT_LE_Monitor_Device_Event to
indicate that the monitoring has been stopped for that particular
device. This event may occur after suspend depending on the
low_threshold_timeout and peer device advertisement frequency, which
causes early wake up.

Right way to disable the monitoring for suspend is by removing all the
monitors before suspend and re-monitor after resume to ensure no events
are received during suspend. This patch fixes this suspend/resume issue.

Following tests are performed:
- Add monitors before suspend and make sure DeviceFound gets triggered
- Suspend the system and verify that all monitors are removed by kernel
  but not Released by bluetoothd
- Wake up and verify that all monitors are added again and DeviceFound
  gets triggered

Signed-off-by: Manish Mandlik <mmandlik@google.com>
Reviewed-by: Archie Pusaka <apusaka@google.com>
Reviewed-by: Miao-chen Chou <mcchou@google.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/hci_request.c

@@ -1105,21 +1105,24 @@ static void suspend_req_complete(struct hci_dev *hdev, u8 status, u16 opcode)
 	}
 }
 
-static void hci_req_add_set_adv_filter_enable(struct hci_request *req,
+static void hci_req_prepare_adv_monitor_suspend(struct hci_request *req,
-					      bool enable)
+						bool suspending)
 {
 	struct hci_dev *hdev = req->hdev;
 
 	switch (hci_get_adv_monitor_offload_ext(hdev)) {
 	case HCI_ADV_MONITOR_EXT_MSFT:
-		msft_req_add_set_filter_enable(req, enable);
+		if (suspending)
+			msft_suspend(hdev);
+		else
+			msft_resume(hdev);
 		break;
 	default:
 		return;
 	}
 
 	/* No need to block when enabling since it's on resume path */
-	if (hdev->suspended && !enable)
+	if (hdev->suspended && suspending)
 		set_bit(SUSPEND_SET_ADV_FILTER, hdev->suspend_tasks);
 }
 
@@ -1186,7 +1189,7 @@ void hci_req_prepare_suspend(struct hci_dev *hdev, enum suspended_state next)
 		}
 
 		/* Disable advertisement filters */
-		hci_req_add_set_adv_filter_enable(&req, false);
+		hci_req_prepare_adv_monitor_suspend(&req, true);
 
 		/* Prevent disconnects from causing scanning to be re-enabled */
 		hdev->scanning_paused = true;
@@ -1228,7 +1231,7 @@ void hci_req_prepare_suspend(struct hci_dev *hdev, enum suspended_state next)
 		/* Reset passive/background scanning to normal */
 		__hci_update_background_scan(&req);
 		/* Enable all of the advertisement filters */
-		hci_req_add_set_adv_filter_enable(&req, true);
+		hci_req_prepare_adv_monitor_suspend(&req, false);
 
 		/* Unpause directed advertising */
 		hdev->advertising_paused = false;

net/bluetooth/msft.c

@@ -94,11 +94,14 @@ struct msft_data {
 	__u16 pending_add_handle;
 	__u16 pending_remove_handle;
 	__u8 reregistering;
+	__u8 suspending;
 	__u8 filter_enabled;
 };
 
 static int __msft_add_monitor_pattern(struct hci_dev *hdev,
 				      struct adv_monitor *monitor);
+static int __msft_remove_monitor(struct hci_dev *hdev,
+				 struct adv_monitor *monitor, u16 handle);
 
 bool msft_monitor_supported(struct hci_dev *hdev)
 {
@@ -154,7 +157,7 @@ static bool read_supported_features(struct hci_dev *hdev,
 }
 
 /* This function requires the caller holds hdev->lock */
-static void reregister_monitor_on_restart(struct hci_dev *hdev, int handle)
+static void reregister_monitor(struct hci_dev *hdev, int handle)
 {
 	struct adv_monitor *monitor;
 	struct msft_data *msft = hdev->msft_data;
@@ -182,6 +185,69 @@ static void reregister_monitor_on_restart(struct hci_dev *hdev, int handle)
 	}
 }
 
+/* This function requires the caller holds hdev->lock */
+static void remove_monitor_on_suspend(struct hci_dev *hdev, int handle)
+{
+	struct adv_monitor *monitor;
+	struct msft_data *msft = hdev->msft_data;
+	int err;
+
+	while (1) {
+		monitor = idr_get_next(&hdev->adv_monitors_idr, &handle);
+		if (!monitor) {
+			/* All monitors have been removed */
+			msft->suspending = false;
+			hci_update_background_scan(hdev);
+			return;
+		}
+
+		msft->pending_remove_handle = (u16)handle;
+		err = __msft_remove_monitor(hdev, monitor, handle);
+
+		/* If success, return and wait for monitor removed callback */
+		if (!err)
+			return;
+
+		/* Otherwise free the monitor and keep removing */
+		hci_free_adv_monitor(hdev, monitor);
+		handle++;
+	}
+}
+
+/* This function requires the caller holds hdev->lock */
+void msft_suspend(struct hci_dev *hdev)
+{
+	struct msft_data *msft = hdev->msft_data;
+
+	if (!msft)
+		return;
+
+	if (msft_monitor_supported(hdev)) {
+		msft->suspending = true;
+		/* Quitely remove all monitors on suspend to avoid waking up
+		 * the system.
+		 */
+		remove_monitor_on_suspend(hdev, 0);
+	}
+}
+
+/* This function requires the caller holds hdev->lock */
+void msft_resume(struct hci_dev *hdev)
+{
+	struct msft_data *msft = hdev->msft_data;
+
+	if (!msft)
+		return;
+
+	if (msft_monitor_supported(hdev)) {
+		msft->reregistering = true;
+		/* Monitors are removed on suspend, so we need to add all
+		 * monitors on resume.
+		 */
+		reregister_monitor(hdev, 0);
+	}
+}
+
 void msft_do_open(struct hci_dev *hdev)
 {
 	struct msft_data *msft = hdev->msft_data;
@@ -214,7 +280,7 @@ void msft_do_open(struct hci_dev *hdev)
 		/* Monitors get removed on power off, so we need to explicitly
 		 * tell the controller to re-monitor.
 		 */
-		reregister_monitor_on_restart(hdev, 0);
+		reregister_monitor(hdev, 0);
 	}
 }
 
@@ -382,8 +448,7 @@ static void msft_le_monitor_advertisement_cb(struct hci_dev *hdev,
 
 	/* If in restart/reregister sequence, keep registering. */
 	if (msft->reregistering)
-		reregister_monitor_on_restart(hdev,
+		reregister_monitor(hdev, msft->pending_add_handle + 1);
-					      msft->pending_add_handle + 1);
 
 	hci_dev_unlock(hdev);
 
@@ -420,13 +485,25 @@ static void msft_le_cancel_monitor_advertisement_cb(struct hci_dev *hdev,
 	if (handle_data) {
 		monitor = idr_find(&hdev->adv_monitors_idr,
 				   handle_data->mgmt_handle);
-		if (monitor)
+
+		if (monitor && monitor->state == ADV_MONITOR_STATE_OFFLOADED)
+			monitor->state = ADV_MONITOR_STATE_REGISTERED;
+
+		/* Do not free the monitor if it is being removed due to
+		 * suspend. It will be re-monitored on resume.
+		 */
+		if (monitor && !msft->suspending)
 			hci_free_adv_monitor(hdev, monitor);
 
 		list_del(&handle_data->list);
 		kfree(handle_data);
 	}
 
+	/* If in suspend/remove sequence, keep removing. */
+	if (msft->suspending)
+		remove_monitor_on_suspend(hdev,
+					  msft->pending_remove_handle + 1);
+
 	/* If remove all monitors is required, we need to continue the process
 	 * here because the earlier it was paused when waiting for the
 	 * response from controller.
@@ -445,7 +522,8 @@ static void msft_le_cancel_monitor_advertisement_cb(struct hci_dev *hdev,
 	hci_dev_unlock(hdev);
 
 done:
-	hci_remove_adv_monitor_complete(hdev, status);
+	if (!msft->suspending)
+		hci_remove_adv_monitor_complete(hdev, status);
 }
 
 static void msft_le_set_advertisement_filter_enable_cb(struct hci_dev *hdev,
@@ -578,15 +656,15 @@ int msft_add_monitor_pattern(struct hci_dev *hdev, struct adv_monitor *monitor)
 	if (!msft)
 		return -EOPNOTSUPP;
 
-	if (msft->reregistering)
+	if (msft->reregistering || msft->suspending)
 		return -EBUSY;
 
 	return __msft_add_monitor_pattern(hdev, monitor);
 }
 
 /* This function requires the caller holds hdev->lock */
-int msft_remove_monitor(struct hci_dev *hdev, struct adv_monitor *monitor,
+static int __msft_remove_monitor(struct hci_dev *hdev,
-			u16 handle)
+				 struct adv_monitor *monitor, u16 handle)
 {
 	struct msft_cp_le_cancel_monitor_advertisement cp;
 	struct msft_monitor_advertisement_handle_data *handle_data;
@@ -594,12 +672,6 @@ int msft_remove_monitor(struct hci_dev *hdev, struct adv_monitor *monitor,
 	struct msft_data *msft = hdev->msft_data;
 	int err = 0;
 
-	if (!msft)
-		return -EOPNOTSUPP;
-
-	if (msft->reregistering)
-		return -EBUSY;
-
 	handle_data = msft_find_handle_data(hdev, monitor->handle, true);
 
 	/* If no matched handle, just remove without telling controller */
@@ -619,6 +691,21 @@ int msft_remove_monitor(struct hci_dev *hdev, struct adv_monitor *monitor,
 	return err;
 }
 
+/* This function requires the caller holds hdev->lock */
+int msft_remove_monitor(struct hci_dev *hdev, struct adv_monitor *monitor,
+			u16 handle)
+{
+	struct msft_data *msft = hdev->msft_data;
+
+	if (!msft)
+		return -EOPNOTSUPP;
+
+	if (msft->reregistering || msft->suspending)
+		return -EBUSY;
+
+	return __msft_remove_monitor(hdev, monitor, handle);
+}
+
 void msft_req_add_set_filter_enable(struct hci_request *req, bool enable)
 {
 	struct hci_dev *hdev = req->hdev;

net/bluetooth/msft.h

@@ -24,6 +24,8 @@ int msft_remove_monitor(struct hci_dev *hdev, struct adv_monitor *monitor,
 			u16 handle);
 void msft_req_add_set_filter_enable(struct hci_request *req, bool enable);
 int msft_set_filter_enable(struct hci_dev *hdev, bool enable);
+void msft_suspend(struct hci_dev *hdev);
+void msft_resume(struct hci_dev *hdev);
 bool msft_curve_validity(struct hci_dev *hdev);
 
 #else
@@ -59,6 +61,9 @@ static inline int msft_set_filter_enable(struct hci_dev *hdev, bool enable)
 	return -EOPNOTSUPP;
 }
 
+static inline void msft_suspend(struct hci_dev *hdev) {}
+static inline void msft_resume(struct hci_dev *hdev) {}
+
 static inline bool msft_curve_validity(struct hci_dev *hdev)
 {
 	return false;