Bluetooth: msft: Extended monitor tracking by address filter

Since limited tracking device per condition, this feature is to support
tracking multiple devices concurrently.
When a pattern monitor detects the device, this feature issues an address
monitor for tracking that device. Let pattern monitor can keep monitor
new devices.
This feature adds an address filter when receiving a LE monitor device
event which monitor handle is for a pattern, and the controller started
monitoring the device. And this feature also has cancelled the monitor
advertisement from address filters when receiving a LE monitor device
event when the controller stopped monitoring the device specified by an
address and monitor handle.

Below is an example to know the feature adds the address filter.

//Add MSFT pattern monitor
< HCI Command: Vendor (0x3f|0x00f0) plen 14          #142 [hci0] 55.552420
        03 b8 a4 03 ff 01 01 06 09 05 5f 52 45 46        .........._REF
> HCI Event: Command Complete (0x0e) plen 6          #143 [hci0] 55.653960
      Vendor (0x3f|0x00f0) ncmd 2
        Status: Success (0x00)
        03 00

//Got event from the pattern monitor
> HCI Event: Vendor (0xff) plen 18                   #148 [hci0] 58.384953
        23 79 54 33 77 88 97 68 02 00 fb c1 29 eb 27 b8  #yT3w..h....).'.
        00 01                                            ..

//Add MSFT address monitor (Sample address: B8:27:EB:29:C1:FB)
< HCI Command: Vendor (0x3f|0x00f0) plen 13          #149 [hci0] 58.385067
        03 b8 a4 03 ff 04 00 fb c1 29 eb 27 b8           .........).'.

//Report to userspace about found device (ADV Monitor Device Found)
@ MGMT Event: Unknown (0x002f) plen 38           {0x0003} [hci0] 58.680042
        01 00 fb c1 29 eb 27 b8 01 ce 00 00 00 00 16 00  ....).'.........
        0a 09 4b 45 59 42 44 5f 52 45 46 02 01 06 03 19  ..KEYBD_REF.....
        c1 03 03 03 12 18                                ......

//Got event from address monitor
> HCI Event: Vendor (0xff) plen 18                   #152 [hci0] 58.672956
        23 79 54 33 77 88 97 68 02 00 fb c1 29 eb 27 b8  #yT3w..h....).'.
        01 01
Signed-off-by: Alex Lu <alex_lu@realsil.com.cn>
Signed-off-by: Hilda Wu <hildawu@realtek.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

drivers/bluetooth/btrtl.c

@@ -1269,6 +1269,10 @@ void btrtl_set_quirks(struct hci_dev *hdev, struct btrtl_device_info *btrtl_dev)
 		if (btrtl_dev->project_id == CHIP_ID_8852C)
 			btrealtek_set_flag(hdev, REALTEK_ALT6_CONTINUOUS_TX_CHIP);
 
+		if (btrtl_dev->project_id == CHIP_ID_8852A ||
+		    btrtl_dev->project_id == CHIP_ID_8852C)
+			set_bit(HCI_QUIRK_USE_MSFT_EXT_ADDRESS_FILTER, &hdev->quirks);
+
 		hci_set_aosp_capable(hdev);
 		break;
 	default:

include/net/bluetooth/hci.h

@@ -309,6 +309,16 @@ enum {
 	 * to support it.
 	 */
 	HCI_QUIRK_BROKEN_SET_RPA_TIMEOUT,
+
+	/* When this quirk is set, MSFT extension monitor tracking by
+	 * address filter is supported. Since tracking quantity of each
+	 * pattern is limited, this feature supports tracking multiple
+	 * devices concurrently if controller supports multiple
+	 * address filters.
+	 *
+	 * This quirk must be set before hci_register_dev is called.
+	 */
+	HCI_QUIRK_USE_MSFT_EXT_ADDRESS_FILTER,
 };
 
 /* HCI device flags */

net/bluetooth/msft.c

@@ -91,6 +91,33 @@ struct msft_ev_le_monitor_device {
 struct msft_monitor_advertisement_handle_data {
 	__u8  msft_handle;
 	__u16 mgmt_handle;
+	__s8 rssi_high;
+	__s8 rssi_low;
+	__u8 rssi_low_interval;
+	__u8 rssi_sampling_period;
+	__u8 cond_type;
+	struct list_head list;
+};
+
+enum monitor_addr_filter_state {
+	AF_STATE_IDLE,
+	AF_STATE_ADDING,
+	AF_STATE_ADDED,
+	AF_STATE_REMOVING,
+};
+
+#define MSFT_MONITOR_ADVERTISEMENT_TYPE_ADDR	0x04
+struct msft_monitor_addr_filter_data {
+	__u8     msft_handle;
+	__u8     pattern_handle; /* address filters pertain to */
+	__u16    mgmt_handle;
+	int      state;
+	__s8     rssi_high;
+	__s8     rssi_low;
+	__u8     rssi_low_interval;
+	__u8     rssi_sampling_period;
+	__u8     addr_type;
+	bdaddr_t bdaddr;
 	struct list_head list;
 };
 
@@ -99,9 +126,12 @@ struct msft_data {
 	__u8  evt_prefix_len;
 	__u8  *evt_prefix;
 	struct list_head handle_map;
+	struct list_head address_filters;
 	__u8 resuming;
 	__u8 suspending;
 	__u8 filter_enabled;
+	/* To synchronize add/remove address filter and monitor device event.*/
+	struct mutex filter_lock;
 };
 
 bool msft_monitor_supported(struct hci_dev *hdev)
@@ -180,6 +210,24 @@ static struct msft_monitor_advertisement_handle_data *msft_find_handle_data
 	return NULL;
 }
 
+/* This function requires the caller holds msft->filter_lock */
+static struct msft_monitor_addr_filter_data *msft_find_address_data
+			(struct hci_dev *hdev, u8 addr_type, bdaddr_t *addr,
+			 u8 pattern_handle)
+{
+	struct msft_monitor_addr_filter_data *entry;
+	struct msft_data *msft = hdev->msft_data;
+
+	list_for_each_entry(entry, &msft->address_filters, list) {
+		if (entry->pattern_handle == pattern_handle &&
+		    addr_type == entry->addr_type &&
+		    !bacmp(addr, &entry->bdaddr))
+			return entry;
+	}
+
+	return NULL;
+}
+
 /* This function requires the caller holds hdev->lock */
 static int msft_monitor_device_del(struct hci_dev *hdev, __u16 mgmt_handle,
 				   bdaddr_t *bdaddr, __u8 addr_type,
@@ -240,6 +288,7 @@ static int msft_le_monitor_advertisement_cb(struct hci_dev *hdev, u16 opcode,
 
 	handle_data->mgmt_handle = monitor->handle;
 	handle_data->msft_handle = rp->handle;
+	handle_data->cond_type   = MSFT_MONITOR_ADVERTISEMENT_TYPE_PATTERN;
 	INIT_LIST_HEAD(&handle_data->list);
 	list_add(&handle_data->list, &msft->handle_map);
 
@@ -254,6 +303,70 @@ static int msft_le_monitor_advertisement_cb(struct hci_dev *hdev, u16 opcode,
 	return status;
 }
 
+/* This function requires the caller holds hci_req_sync_lock */
+static void msft_remove_addr_filters_sync(struct hci_dev *hdev, u8 handle)
+{
+	struct msft_monitor_addr_filter_data *address_filter, *n;
+	struct msft_cp_le_cancel_monitor_advertisement cp;
+	struct msft_data *msft = hdev->msft_data;
+	struct list_head head;
+	struct sk_buff *skb;
+
+	INIT_LIST_HEAD(&head);
+
+	/* Cancel all corresponding address monitors */
+	mutex_lock(&msft->filter_lock);
+
+	list_for_each_entry_safe(address_filter, n, &msft->address_filters,
+				 list) {
+		if (address_filter->pattern_handle != handle)
+			continue;
+
+		list_del(&address_filter->list);
+
+		/* Keep the address filter and let
+		 * msft_add_address_filter_sync() remove and free the address
+		 * filter.
+		 */
+		if (address_filter->state == AF_STATE_ADDING) {
+			address_filter->state = AF_STATE_REMOVING;
+			continue;
+		}
+
+		/* Keep the address filter and let
+		 * msft_cancel_address_filter_sync() remove and free the address
+		 * filter
+		 */
+		if (address_filter->state == AF_STATE_REMOVING)
+			continue;
+
+		list_add_tail(&address_filter->list, &head);
+	}
+
+	mutex_unlock(&msft->filter_lock);
+
+	list_for_each_entry_safe(address_filter, n, &head, list) {
+		list_del(&address_filter->list);
+
+		cp.sub_opcode = MSFT_OP_LE_CANCEL_MONITOR_ADVERTISEMENT;
+		cp.handle = address_filter->msft_handle;
+
+		skb = __hci_cmd_sync(hdev, hdev->msft_opcode, sizeof(cp), &cp,
+				     HCI_CMD_TIMEOUT);
+		if (IS_ERR_OR_NULL(skb)) {
+			kfree(address_filter);
+			continue;
+		}
+
+		kfree_skb(skb);
+
+		bt_dev_dbg(hdev, "MSFT: Canceled device %pMR address filter",
+			   &address_filter->bdaddr);
+
+		kfree(address_filter);
+	}
+}
+
 static int msft_le_cancel_monitor_advertisement_cb(struct hci_dev *hdev,
 						   u16 opcode,
 						   struct adv_monitor *monitor,
@@ -263,6 +376,7 @@ static int msft_le_cancel_monitor_advertisement_cb(struct hci_dev *hdev,
 	struct msft_monitor_advertisement_handle_data *handle_data;
 	struct msft_data *msft = hdev->msft_data;
 	int status = 0;
+	u8 msft_handle;
 
 	rp = (struct msft_rp_le_cancel_monitor_advertisement *)skb->data;
 	if (skb->len < sizeof(*rp)) {
@@ -293,12 +407,18 @@ static int msft_le_cancel_monitor_advertisement_cb(struct hci_dev *hdev,
 						NULL, 0, false);
 		}
 
+		msft_handle = handle_data->msft_handle;
+
 		list_del(&handle_data->list);
 		kfree(handle_data);
-	}
 
 		hci_dev_unlock(hdev);
 
+		msft_remove_addr_filters_sync(hdev, msft_handle);
+	} else {
+		hci_dev_unlock(hdev);
+	}
+
 done:
 	return status;
 }
@@ -394,12 +514,14 @@ static int msft_add_monitor_sync(struct hci_dev *hdev,
 {
 	struct msft_cp_le_monitor_advertisement *cp;
 	struct msft_le_monitor_advertisement_pattern_data *pattern_data;
+	struct msft_monitor_advertisement_handle_data *handle_data;
 	struct msft_le_monitor_advertisement_pattern *pattern;
 	struct adv_pattern *entry;
 	size_t total_size = sizeof(*cp) + sizeof(*pattern_data);
 	ptrdiff_t offset = 0;
 	u8 pattern_count = 0;
 	struct sk_buff *skb;
+	int err;
 
 	if (!msft_monitor_pattern_valid(monitor))
 		return -EINVAL;
@@ -436,16 +558,31 @@ static int msft_add_monitor_sync(struct hci_dev *hdev,
 
 	skb = __hci_cmd_sync(hdev, hdev->msft_opcode, total_size, cp,
 			     HCI_CMD_TIMEOUT);
-	kfree(cp);
 
 	if (IS_ERR_OR_NULL(skb)) {
-		if (!skb)
-			return -EIO;
-		return PTR_ERR(skb);
+		err = PTR_ERR(skb);
+		goto out_free;
 	}
 
-	return msft_le_monitor_advertisement_cb(hdev, hdev->msft_opcode,
+	err = msft_le_monitor_advertisement_cb(hdev, hdev->msft_opcode,
 					       monitor, skb);
+	if (err)
+		goto out_free;
+
+	handle_data = msft_find_handle_data(hdev, monitor->handle, true);
+	if (!handle_data) {
+		err = -ENODATA;
+		goto out_free;
+	}
+
+	handle_data->rssi_high	= cp->rssi_high;
+	handle_data->rssi_low	= cp->rssi_low;
+	handle_data->rssi_low_interval	  = cp->rssi_low_interval;
+	handle_data->rssi_sampling_period = cp->rssi_sampling_period;
+
+out_free:
+	kfree(cp);
+	return err;
 }
 
 /* This function requires the caller holds hci_req_sync_lock */
@@ -538,6 +675,7 @@ void msft_do_close(struct hci_dev *hdev)
 {
 	struct msft_data *msft = hdev->msft_data;
 	struct msft_monitor_advertisement_handle_data *handle_data, *tmp;
+	struct msft_monitor_addr_filter_data *address_filter, *n;
 	struct adv_monitor *monitor;
 
 	if (!msft)
@@ -559,6 +697,14 @@ void msft_do_close(struct hci_dev *hdev)
 		kfree(handle_data);
 	}
 
+	mutex_lock(&msft->filter_lock);
+	list_for_each_entry_safe(address_filter, n, &msft->address_filters,
+				 list) {
+		list_del(&address_filter->list);
+		kfree(address_filter);
+	}
+	mutex_unlock(&msft->filter_lock);
+
 	hci_dev_lock(hdev);
 
 	/* Clear any devices that are being monitored and notify device lost */
@@ -568,6 +714,49 @@ void msft_do_close(struct hci_dev *hdev)
 	hci_dev_unlock(hdev);
 }
 
+static int msft_cancel_address_filter_sync(struct hci_dev *hdev, void *data)
+{
+	struct msft_monitor_addr_filter_data *address_filter = data;
+	struct msft_cp_le_cancel_monitor_advertisement cp;
+	struct msft_data *msft = hdev->msft_data;
+	struct sk_buff *skb;
+	int err = 0;
+
+	if (!msft) {
+		bt_dev_err(hdev, "MSFT: msft data is freed");
+		return -EINVAL;
+	}
+
+	/* The address filter has been removed by hci dev close */
+	if (!test_bit(HCI_UP, &hdev->flags))
+		return 0;
+
+	mutex_lock(&msft->filter_lock);
+	list_del(&address_filter->list);
+	mutex_unlock(&msft->filter_lock);
+
+	cp.sub_opcode = MSFT_OP_LE_CANCEL_MONITOR_ADVERTISEMENT;
+	cp.handle = address_filter->msft_handle;
+
+	skb = __hci_cmd_sync(hdev, hdev->msft_opcode, sizeof(cp), &cp,
+			     HCI_CMD_TIMEOUT);
+	if (IS_ERR_OR_NULL(skb)) {
+		bt_dev_err(hdev, "MSFT: Failed to cancel address (%pMR) filter",
+			   &address_filter->bdaddr);
+		err = EIO;
+		goto done;
+	}
+	kfree_skb(skb);
+
+	bt_dev_dbg(hdev, "MSFT: Canceled device %pMR address filter",
+		   &address_filter->bdaddr);
+
+done:
+	kfree(address_filter);
+
+	return err;
+}
+
 void msft_register(struct hci_dev *hdev)
 {
 	struct msft_data *msft = NULL;
@@ -581,7 +770,9 @@ void msft_register(struct hci_dev *hdev)
 	}
 
 	INIT_LIST_HEAD(&msft->handle_map);
+	INIT_LIST_HEAD(&msft->address_filters);
 	hdev->msft_data = msft;
+	mutex_init(&msft->filter_lock);
 }
 
 void msft_unregister(struct hci_dev *hdev)
@@ -596,6 +787,7 @@ void msft_unregister(struct hci_dev *hdev)
 	hdev->msft_data = NULL;
 
 	kfree(msft->evt_prefix);
+	mutex_destroy(&msft->filter_lock);
 	kfree(msft);
 }
 
@@ -645,11 +837,149 @@ static void *msft_skb_pull(struct hci_dev *hdev, struct sk_buff *skb,
 	return data;
 }
 
+static int msft_add_address_filter_sync(struct hci_dev *hdev, void *data)
+{
+	struct msft_monitor_addr_filter_data *address_filter = data;
+	struct msft_rp_le_monitor_advertisement *rp;
+	struct msft_cp_le_monitor_advertisement *cp;
+	struct msft_data *msft = hdev->msft_data;
+	struct sk_buff *skb = NULL;
+	bool remove = false;
+	size_t size;
+
+	if (!msft) {
+		bt_dev_err(hdev, "MSFT: msft data is freed");
+		return -EINVAL;
+	}
+
+	/* The address filter has been removed by hci dev close */
+	if (!test_bit(HCI_UP, &hdev->flags))
+		return -ENODEV;
+
+	/* We are safe to use the address filter from now on.
+	 * msft_monitor_device_evt() wouldn't delete this filter because it's
+	 * not been added by now.
+	 * And all other functions that requiring hci_req_sync_lock wouldn't
+	 * touch this filter before this func completes because it's protected
+	 * by hci_req_sync_lock.
+	 */
+
+	if (address_filter->state == AF_STATE_REMOVING) {
+		mutex_lock(&msft->filter_lock);
+		list_del(&address_filter->list);
+		mutex_unlock(&msft->filter_lock);
+		kfree(address_filter);
+		return 0;
+	}
+
+	size = sizeof(*cp) +
+	       sizeof(address_filter->addr_type) +
+	       sizeof(address_filter->bdaddr);
+	cp = kzalloc(size, GFP_KERNEL);
+	if (!cp) {
+		bt_dev_err(hdev, "MSFT: Alloc cmd param err");
+		remove = true;
+		goto done;
+	}
+	cp->sub_opcode           = MSFT_OP_LE_MONITOR_ADVERTISEMENT;
+	cp->rssi_high		 = address_filter->rssi_high;
+	cp->rssi_low		 = address_filter->rssi_low;
+	cp->rssi_low_interval    = address_filter->rssi_low_interval;
+	cp->rssi_sampling_period = address_filter->rssi_sampling_period;
+	cp->cond_type            = MSFT_MONITOR_ADVERTISEMENT_TYPE_ADDR;
+	cp->data[0]              = address_filter->addr_type;
+	memcpy(&cp->data[1], &address_filter->bdaddr,
+	       sizeof(address_filter->bdaddr));
+
+	skb = __hci_cmd_sync(hdev, hdev->msft_opcode, size, cp,
+			     HCI_CMD_TIMEOUT);
+	if (IS_ERR_OR_NULL(skb)) {
+		bt_dev_err(hdev, "Failed to enable address %pMR filter",
+			   &address_filter->bdaddr);
+		skb = NULL;
+		remove = true;
+		goto done;
+	}
+
+	rp = skb_pull_data(skb, sizeof(*rp));
+	if (!rp || rp->sub_opcode != MSFT_OP_LE_MONITOR_ADVERTISEMENT ||
+	    rp->status)
+		remove = true;
+
+done:
+	mutex_lock(&msft->filter_lock);
+
+	if (remove) {
+		bt_dev_warn(hdev, "MSFT: Remove address (%pMR) filter",
+			    &address_filter->bdaddr);
+		list_del(&address_filter->list);
+		kfree(address_filter);
+	} else {
+		address_filter->state = AF_STATE_ADDED;
+		address_filter->msft_handle = rp->handle;
+		bt_dev_dbg(hdev, "MSFT: Address %pMR filter enabled",
+			   &address_filter->bdaddr);
+	}
+	mutex_unlock(&msft->filter_lock);
+
+	kfree_skb(skb);
+
+	return 0;
+}
+
+/* This function requires the caller holds msft->filter_lock */
+static struct msft_monitor_addr_filter_data *msft_add_address_filter
+		(struct hci_dev *hdev, u8 addr_type, bdaddr_t *bdaddr,
+		 struct msft_monitor_advertisement_handle_data *handle_data)
+{
+	struct msft_monitor_addr_filter_data *address_filter = NULL;
+	struct msft_data *msft = hdev->msft_data;
+	int err;
+
+	address_filter = kzalloc(sizeof(*address_filter), GFP_KERNEL);
+	if (!address_filter)
+		return NULL;
+
+	address_filter->state             = AF_STATE_ADDING;
+	address_filter->msft_handle       = 0xff;
+	address_filter->pattern_handle    = handle_data->msft_handle;
+	address_filter->mgmt_handle       = handle_data->mgmt_handle;
+	address_filter->rssi_high         = handle_data->rssi_high;
+	address_filter->rssi_low          = handle_data->rssi_low;
+	address_filter->rssi_low_interval = handle_data->rssi_low_interval;
+	address_filter->rssi_sampling_period = handle_data->rssi_sampling_period;
+	address_filter->addr_type            = addr_type;
+	bacpy(&address_filter->bdaddr, bdaddr);
+
+	/* With the above AF_STATE_ADDING, duplicated address filter can be
+	 * avoided when receiving monitor device event (found/lost) frequently
+	 * for the same device.
+	 */
+	list_add_tail(&address_filter->list, &msft->address_filters);
+
+	err = hci_cmd_sync_queue(hdev, msft_add_address_filter_sync,
+				 address_filter, NULL);
+	if (err < 0) {
+		bt_dev_err(hdev, "MSFT: Add address %pMR filter err", bdaddr);
+		list_del(&address_filter->list);
+		kfree(address_filter);
+		return NULL;
+	}
+
+	bt_dev_dbg(hdev, "MSFT: Add device %pMR address filter",
+		   &address_filter->bdaddr);
+
+	return address_filter;
+}
+
 /* This function requires the caller holds hdev->lock */
 static void msft_monitor_device_evt(struct hci_dev *hdev, struct sk_buff *skb)
 {
+	struct msft_monitor_addr_filter_data *n, *address_filter = NULL;
 	struct msft_ev_le_monitor_device *ev;
 	struct msft_monitor_advertisement_handle_data *handle_data;
+	struct msft_data *msft = hdev->msft_data;
+	u16 mgmt_handle = 0xffff;
 	u8 addr_type;
 
 	ev = msft_skb_pull(hdev, skb, MSFT_EV_LE_MONITOR_DEVICE, sizeof(*ev));
@@ -662,9 +992,53 @@ static void msft_monitor_device_evt(struct hci_dev *hdev, struct sk_buff *skb)
 		   ev->monitor_state, &ev->bdaddr);
 
 	handle_data = msft_find_handle_data(hdev, ev->monitor_handle, false);
+
+	if (!test_bit(HCI_QUIRK_USE_MSFT_EXT_ADDRESS_FILTER, &hdev->quirks)) {
 		if (!handle_data)
 			return;
+		mgmt_handle = handle_data->mgmt_handle;
+		goto report_state;
+	}
 
+	if (handle_data) {
+		/* Don't report any device found/lost event from pattern
+		 * monitors. Pattern monitor always has its address filters for
+		 * tracking devices.
+		 */
+
+		address_filter = msft_find_address_data(hdev, ev->addr_type,
+							&ev->bdaddr,
+							handle_data->msft_handle);
+		if (address_filter)
+			return;
+
+		if (ev->monitor_state && handle_data->cond_type ==
+				MSFT_MONITOR_ADVERTISEMENT_TYPE_PATTERN)
+			msft_add_address_filter(hdev, ev->addr_type,
+						&ev->bdaddr, handle_data);
+
+		return;
+	}
+
+	/* This device event is not from pattern monitor.
+	 * Report it if there is a corresponding address_filter for it.
+	 */
+	list_for_each_entry(n, &msft->address_filters, list) {
+		if (n->state == AF_STATE_ADDED &&
+		    n->msft_handle == ev->monitor_handle) {
+			mgmt_handle = n->mgmt_handle;
+			address_filter = n;
+			break;
+		}
+	}
+
+	if (!address_filter) {
+		bt_dev_warn(hdev, "MSFT: Unexpected device event %pMR, %u, %u",
+			    &ev->bdaddr, ev->monitor_handle, ev->monitor_state);
+		return;
+	}
+
+report_state:
 	switch (ev->addr_type) {
 	case ADDR_LE_DEV_PUBLIC:
 		addr_type = BDADDR_LE_PUBLIC;
@@ -681,12 +1055,18 @@ static void msft_monitor_device_evt(struct hci_dev *hdev, struct sk_buff *skb)
 		return;
 	}
 
-	if (ev->monitor_state)
-		msft_device_found(hdev, &ev->bdaddr, addr_type,
-				  handle_data->mgmt_handle);
-	else
-		msft_device_lost(hdev, &ev->bdaddr, addr_type,
-				 handle_data->mgmt_handle);
+	if (ev->monitor_state) {
+		msft_device_found(hdev, &ev->bdaddr, addr_type, mgmt_handle);
+	} else {
+		if (address_filter && address_filter->state == AF_STATE_ADDED) {
+			address_filter->state = AF_STATE_REMOVING;
+			hci_cmd_sync_queue(hdev,
+					   msft_cancel_address_filter_sync,
+					   address_filter,
+					   NULL);
+		}
+		msft_device_lost(hdev, &ev->bdaddr, addr_type, mgmt_handle);
+	}
 }
 
 void msft_vendor_evt(struct hci_dev *hdev, void *data, struct sk_buff *skb)
@@ -724,7 +1104,9 @@ void msft_vendor_evt(struct hci_dev *hdev, void *data, struct sk_buff *skb)
 
 	switch (*evt) {
 	case MSFT_EV_LE_MONITOR_DEVICE:
+		mutex_lock(&msft->filter_lock);
 		msft_monitor_device_evt(hdev, skb);
+		mutex_unlock(&msft->filter_lock);
 		break;
 
 	default: