[v6,1/2] bluetooth: Handle MSFT Monitor Device Event

Whenever the controller starts/stops monitoring a bt device, it sends
MSFT Monitor Device event. Add handler to read this vendor event.

Test performed:
- Verified by logs that the MSFT Monitor Device event is received from
  the controller whenever it starts/stops monitoring a device.

Signed-off-by: Manish Mandlik <mmandlik@google.com>
Reviewed-by: Miao-chen Chou <mcchou@google.com>
---
Hello Bt-Maintainers,

As mentioned in the bluez patch series [1], we need to capture the 'MSFT
Monitor Device' event from the controller and pass on the necessary
information to the bluetoothd.

This is required to further optimize the power consumption by avoiding
handling of RSSI thresholds and timeouts in the user space and let the
controller do the RSSI tracking.

This patch series adds support to read the MSFT vendor event
HCI_VS_MSFT_LE_Monitor_Device_Event and introduces new MGMT events
MGMT_EV_ADV_MONITOR_DEVICE_FOUND and MGMT_EV_ADV_MONITOR_DEVICE_LOST to
indicate that the controller has started/stopped tracking a particular
device.

Please let me know what you think about this or if you have any further
questions.

[1] https://patchwork.kernel.org/project/bluetooth/list/?series=583423

Thanks,
Manish.

Changes in v6:
- Fix compiler warning bt_dev_err() missing argument.

Changes in v5:
- Split v4 into two patches.
- Buffer controller Device Found event and maintain the device tracking
  state in the kernel.

Changes in v4:
- Add Advertisement Monitor Device Found event and update addr type.

Changes in v3:
- Discard changes to the Device Found event and notify bluetoothd only
  when the controller stops monitoring the device via new Device Lost
  event.

Changes in v2:
- Instead of creating a new 'Device Tracking' event, add a flag 'Device
  Tracked' in the existing 'Device Found' event and add a new 'Device
  Lost' event to indicate that the controller has stopped tracking that
  device.

 include/net/bluetooth/hci_core.h |  11 +++
 net/bluetooth/hci_core.c         |   1 +
 net/bluetooth/msft.c             | 127 ++++++++++++++++++++++++++++++-
 3 files changed, 138 insertions(+), 1 deletion(-)

Hi Manish,

> This patch introduces two new MGMT events for notifying the bluetoothd
> whenever the controller starts/stops monitoring a device.
> 
> Test performed:
> - Verified by logs that the MSFT Monitor Device is received from the
>  controller and the bluetoothd is notified whenever the controller
>  starts/stops monitoring a device.
> 
> Signed-off-by: Manish Mandlik <mmandlik@google.com>
> Reviewed-by: Miao-chen Chou <mcchou@google.com>
> 
> ---
> 
> Changes in v6:
> - Fix compiler warning for mgmt_adv_monitor_device_found().
> 
> Changes in v5:
> - New patch in the series. Split previous patch into two.
> - Update the Device Found logic to send existing Device Found event or
>  Adv Monitor Device Found event depending on the active scanning state.
> 
> include/net/bluetooth/hci_core.h |   3 +
> include/net/bluetooth/mgmt.h     |  16 +++++
> net/bluetooth/mgmt.c             | 100 ++++++++++++++++++++++++++++++-
> net/bluetooth/msft.c             |  15 ++++-
> 4 files changed, 132 insertions(+), 2 deletions(-)
> 
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> index 6734b394c6e7..2aabd6f62f51 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -598,6 +598,7 @@ struct hci_dev {
> 	struct delayed_work	interleave_scan;
> 
> 	struct list_head	monitored_devices;
> +	bool			advmon_pend_notify;
> 
> #if IS_ENABLED(CONFIG_BT_LEDS)
> 	struct led_trigger	*power_led;
> @@ -1844,6 +1845,8 @@ void mgmt_adv_monitor_removed(struct hci_dev *hdev, u16 handle);
> int mgmt_phy_configuration_changed(struct hci_dev *hdev, struct sock *skip);
> int mgmt_add_adv_patterns_monitor_complete(struct hci_dev *hdev, u8 status);
> int mgmt_remove_adv_monitor_complete(struct hci_dev *hdev, u8 status);
> +void mgmt_adv_monitor_device_lost(struct hci_dev *hdev, u16 handle,
> +				  bdaddr_t *bdaddr, u8 addr_type);
> 
> u8 hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
> 		      u16 to_multiplier);
> diff --git a/include/net/bluetooth/mgmt.h b/include/net/bluetooth/mgmt.h
> index 23a0524061b7..4b85f93b8a77 100644
> --- a/include/net/bluetooth/mgmt.h
> +++ b/include/net/bluetooth/mgmt.h
> @@ -1103,3 +1103,19 @@ struct mgmt_ev_controller_resume {
> #define MGMT_WAKE_REASON_NON_BT_WAKE		0x0
> #define MGMT_WAKE_REASON_UNEXPECTED		0x1
> #define MGMT_WAKE_REASON_REMOTE_WAKE		0x2
> +
> +#define MGMT_EV_ADV_MONITOR_DEVICE_FOUND	0x002f
> +struct mgmt_ev_adv_monitor_device_found {
> +	__le16 monitor_handle;
> +	struct mgmt_addr_info addr;
> +	__s8   rssi;
> +	__le32 flags;
> +	__le16 eir_len;
> +	__u8   eir[0];
> +} __packed;
> +
> +#define MGMT_EV_ADV_MONITOR_DEVICE_LOST		0x0030
> +struct mgmt_ev_adv_monitor_device_lost {
> +	__le16 monitor_handle;
> +	struct mgmt_addr_info addr;
> +} __packed;
> diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
> index f8f74d344297..01f74e4feb97 100644
> --- a/net/bluetooth/mgmt.c
> +++ b/net/bluetooth/mgmt.c
> @@ -174,6 +174,8 @@ static const u16 mgmt_events[] = {
> 	MGMT_EV_ADV_MONITOR_REMOVED,
> 	MGMT_EV_CONTROLLER_SUSPEND,
> 	MGMT_EV_CONTROLLER_RESUME,
> +	MGMT_EV_ADV_MONITOR_DEVICE_FOUND,
> +	MGMT_EV_ADV_MONITOR_DEVICE_LOST,
> };
> 
> static const u16 mgmt_untrusted_commands[] = {
> @@ -9524,6 +9526,78 @@ static bool is_filter_match(struct hci_dev *hdev, s8 rssi, u8 *eir,
> 	return true;
> }
> 
> +void mgmt_adv_monitor_device_lost(struct hci_dev *hdev, u16 handle,
> +				  bdaddr_t *bdaddr, u8 addr_type)
> +{
> +	struct mgmt_ev_adv_monitor_device_lost ev;
> +
> +	ev.monitor_handle = cpu_to_le16(handle);
> +	bacpy(&ev.addr.bdaddr, bdaddr);
> +	ev.addr.type = addr_type;
> +
> +	mgmt_event(MGMT_EV_ADV_MONITOR_DEVICE_LOST, hdev, &ev, sizeof(ev),
> +		   NULL);
> +}
> +
> +static void mgmt_adv_monitor_device_found(struct hci_dev *hdev,
> +					  struct mgmt_ev_device_found *ev,
> +					  size_t ev_size, bool discovering)
> +{
> +	char buf[518];
> +	struct mgmt_ev_adv_monitor_device_found *advmon_ev = (void *)buf;
> +	size_t advmon_ev_size;
> +	struct monitored_device *dev, *tmp;
> +	bool matched = false;
> +	bool notified = false;
> +
> +	/* Make sure that the buffer is big enough */
> +	advmon_ev_size = ev_size + (sizeof(*advmon_ev) - sizeof(*ev));
> +	if (advmon_ev_size > sizeof(buf))
> +		return;
> +
> +	/* ADV_MONITOR_DEVICE_FOUND is similar to DEVICE_FOUND event except
> +	 * that it also has 'monitor_handle'. Make a copy of DEVICE_FOUND and
> +	 * store monitor_handle of the matched monitor.
> +	 */
> +	memcpy(&advmon_ev->addr, ev, ev_size);
> +
> +	hdev->advmon_pend_notify = false;
> +
> +	list_for_each_entry_safe(dev, tmp, &hdev->monitored_devices, list) {
> +		if (!bacmp(&dev->bdaddr, &advmon_ev->addr.bdaddr)) {
> +			matched = true;
> +
> +			if (!dev->notified) {
> +				advmon_ev->monitor_handle =
> +						cpu_to_le16(dev->handle);
> +
> +				mgmt_event(MGMT_EV_ADV_MONITOR_DEVICE_FOUND,
> +					   hdev, advmon_ev, advmon_ev_size,
> +					   NULL);
> +
> +				notified = true;
> +				dev->notified = true;
> +			}
> +		}
> +
> +		if (!dev->notified)
> +			hdev->advmon_pend_notify = true;
> +	}
> +
> +	if (!discovering &&
> +	    ((matched && !notified) || !msft_monitor_supported(hdev))) {
> +		/* Handle 0 indicates that we are not active scanning and this
> +		 * is a subsequent advertisement report for an already matched
> +		 * Advertisement Monitor or the controller offloading support
> +		 * is not available.
> +		 */
> +		advmon_ev->monitor_handle = 0;
> +
> +		mgmt_event(MGMT_EV_ADV_MONITOR_DEVICE_FOUND, hdev, advmon_ev,
> +			   advmon_ev_size, NULL);
> +	}
> +}
> +
> void mgmt_device_found(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
> 		       u8 addr_type, u8 *dev_class, s8 rssi, u32 flags,
> 		       u8 *eir, u16 eir_len, u8 *scan_rsp, u8 scan_rsp_len)
> @@ -9606,7 +9680,31 @@ void mgmt_device_found(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
> 	ev->eir_len = cpu_to_le16(eir_len + scan_rsp_len);
> 	ev_size = sizeof(*ev) + eir_len + scan_rsp_len;
> 
> -	mgmt_event(MGMT_EV_DEVICE_FOUND, hdev, ev, ev_size, NULL);
> +	/* We have received the Advertisement Report because:
> +	 * 1. the kernel has initiated active discovery
> +	 * 2. if not, we have pend_le_reports > 0 in which case we are doing
> +	 *    passive scanning
> +	 * 3. if none of the above is true, we have one or more active
> +	 *    Advertisement Monitor
> +	 *
> +	 * For case 1 and 2, report all advertisements via MGMT_EV_DEVICE_FOUND
> +	 * and report ONLY one advertisement per device for the matched Monitor
> +	 * via MGMT_EV_ADV_MONITOR_DEVICE_FOUND event.
> +	 *
> +	 * For case 3, since we are not active scanning and all advertisements
> +	 * received are due to a matched Advertisement Monitor, report all
> +	 * advertisements ONLY via MGMT_EV_ADV_MONITOR_DEVICE_FOUND event.
> +	 */
> +
> +	if (hci_discovery_active(hdev) ||
> +	    (link_type == LE_LINK && !list_empty(&hdev->pend_le_reports))) {
> +		mgmt_event(MGMT_EV_DEVICE_FOUND, hdev, ev, ev_size, NULL);
> +
> +		if (hdev->advmon_pend_notify)
> +			mgmt_adv_monitor_device_found(hdev, ev, ev_size, true);
> +	} else {
> +		mgmt_adv_monitor_device_found(hdev, ev, ev_size, false);
> +	}
> }

so you are breaking the stack-frame-size now. You might need to re-design the general device found event handling to fit into a 1k stack frame size.

Regards

Marcel