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SubjectRe: [PATCH v4 1/4] Bluetooth: Interleave with allowlist scan
Hi Howard,

On Sun, Sep 20, 2020 at 9:23 PM Howard Chung <howardchung@google.com> wrote:
>
> This patch implements the interleaving between allowlist scan and
> no-filter scan. It'll be used to save power when at least one monitor is
> registered and at least one pending connection or one device to be
> scanned for.
>
> The durations of the allowlist scan and the no-filter scan are
> controlled by MGMT command: Set Default System Configuration. The
> default values are set randomly for now.
>
> Signed-off-by: Howard Chung <howardchung@google.com>
> Reviewed-by: Alain Michaud <alainm@chromium.org>
> Reviewed-by: Manish Mandlik <mmandlik@chromium.org>
> ---
>
> Changes in v4:
> - Rebase to bluetooth-next/master (previous 2 patches are applied)
> - Fix over 80 chars limit in mgmt_config.c
> - Set EnableAdvMonInterleaveScan default to Disable
>
> Changes in v3:
> - Remove 'Bluez' prefix
>
> Changes in v2:
> - remove 'case 0x001c' in mgmt_config.c
>
> include/net/bluetooth/hci_core.h | 10 +++
> net/bluetooth/hci_core.c | 4 +
> net/bluetooth/hci_request.c | 137 +++++++++++++++++++++++++++++--
> net/bluetooth/mgmt_config.c | 10 +++
> 4 files changed, 153 insertions(+), 8 deletions(-)
>
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> index 9873e1c8cd163..179350f869fdb 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -361,6 +361,8 @@ struct hci_dev {
> __u8 ssp_debug_mode;
> __u8 hw_error_code;
> __u32 clock;
> + __u16 advmon_allowlist_duration;
> + __u16 advmon_no_filter_duration;
>
> __u16 devid_source;
> __u16 devid_vendor;
> @@ -542,6 +544,14 @@ struct hci_dev {
> struct delayed_work rpa_expired;
> bdaddr_t rpa;
>
> + enum {
> + ADV_MONITOR_SCAN_NONE,
> + ADV_MONITOR_SCAN_NO_FILTER,
> + ADV_MONITOR_SCAN_ALLOWLIST
> + } adv_monitor_scan_state;
> +
> + struct delayed_work interleave_adv_monitor_scan;
> +
> #if IS_ENABLED(CONFIG_BT_LEDS)
> struct led_trigger *power_led;
> #endif
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index f30a1f5950e15..6c8850149265a 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -3592,6 +3592,10 @@ struct hci_dev *hci_alloc_dev(void)
> hdev->cur_adv_instance = 0x00;
> hdev->adv_instance_timeout = 0;
>
> + /* The default values will be chosen in the future */
> + hdev->advmon_allowlist_duration = 300;
> + hdev->advmon_no_filter_duration = 500;
> +
> hdev->sniff_max_interval = 800;
> hdev->sniff_min_interval = 80;
>
> diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c
> index d2b06f5c93804..89443b48d90ce 100644
> --- a/net/bluetooth/hci_request.c
> +++ b/net/bluetooth/hci_request.c
> @@ -378,6 +378,57 @@ void __hci_req_write_fast_connectable(struct hci_request *req, bool enable)
> hci_req_add(req, HCI_OP_WRITE_PAGE_SCAN_TYPE, 1, &type);
> }
>
> +static void start_interleave_scan(struct hci_dev *hdev)
> +{
> + hdev->adv_monitor_scan_state = ADV_MONITOR_SCAN_NO_FILTER;
> + queue_delayed_work(hdev->req_workqueue,
> + &hdev->interleave_adv_monitor_scan, 0);
> +}
> +
> +static bool is_interleave_scanning(struct hci_dev *hdev)
> +{
> + return hdev->adv_monitor_scan_state != ADV_MONITOR_SCAN_NONE;
> +}
> +
> +static void cancel_interleave_scan(struct hci_dev *hdev)
> +{
> + bt_dev_dbg(hdev, "%s cancelling interleave scan", hdev->name);
> +
> + cancel_delayed_work_sync(&hdev->interleave_adv_monitor_scan);
> +
> + hdev->adv_monitor_scan_state = ADV_MONITOR_SCAN_NONE;
> +}
> +
> +/* Return true if interleave_scan is running after exiting this function,
> + * otherwise, return false
> + */
> +static bool update_adv_monitor_scan_state(struct hci_dev *hdev)
> +{
> + if (!hci_is_adv_monitoring(hdev) ||
> + (list_empty(&hdev->pend_le_conns) &&
> + list_empty(&hdev->pend_le_reports))) {
> + if (is_interleave_scanning(hdev)) {
> + /* If the interleave condition no longer holds, cancel
> + * the existed interleave scan.
> + */
> + cancel_interleave_scan(hdev);
> + }
> + return false;
> + }
> +
> + if (!is_interleave_scanning(hdev)) {
> + /* If there is at least one ADV monitors and one pending LE
> + * connection or one device to be scanned for, we should
> + * alternate between allowlist scan and one without any filters
> + * to save power.
> + */
> + start_interleave_scan(hdev);
> + bt_dev_dbg(hdev, "%s starting interleave scan", hdev->name);
> + }
> +
> + return true;
> +}
> +
> /* This function controls the background scanning based on hdev->pend_le_conns
> * list. If there are pending LE connection we start the background scanning,
> * otherwise we stop it.
> @@ -449,9 +500,11 @@ static void __hci_update_background_scan(struct hci_request *req)
> if (hci_dev_test_flag(hdev, HCI_LE_SCAN))
> hci_req_add_le_scan_disable(req, false);
>
> - hci_req_add_le_passive_scan(req);
> -
> - BT_DBG("%s starting background scanning", hdev->name);
> + if (!update_adv_monitor_scan_state(hdev)) {
> + hci_req_add_le_passive_scan(req);
> + bt_dev_dbg(hdev, "%s starting background scanning",
> + hdev->name);
> + }

We should probably try to follow the same names as used for
background_scan here, e.g. name it __hci_update_interleaved_scan, also
perhaps that should fallback to hci_req_add_le_passive_scan on its
own.

> }
> }
>
> @@ -844,12 +897,17 @@ static u8 update_white_list(struct hci_request *req)
> return 0x00;
> }
>
> - /* Once the controller offloading of advertisement monitor is in place,
> - * the if condition should include the support of MSFT extension
> - * support. If suspend is ongoing, whitelist should be the default to
> - * prevent waking by random advertisements.
> + /* Use the allowlist unless the following conditions are all true:
> + * - We are not currently suspending
> + * - There are 1 or more ADV monitors registered
> + * - Interleaved scanning is not currently using the allowlist
> + *
> + * Once the controller offloading of advertisement monitor is in place,
> + * the above condition should include the support of MSFT extension
> + * support.
> */
> - if (!idr_is_empty(&hdev->adv_monitors_idr) && !hdev->suspended)
> + if (!idr_is_empty(&hdev->adv_monitors_idr) && !hdev->suspended &&
> + hdev->adv_monitor_scan_state != ADV_MONITOR_SCAN_ALLOWLIST)
> return 0x00;
>
> /* Select filter policy to use white list */
> @@ -1002,6 +1060,7 @@ void hci_req_add_le_passive_scan(struct hci_request *req)
> &own_addr_type))
> return;
>
> + bt_dev_dbg(hdev, "interleave state %d", hdev->adv_monitor_scan_state);

Is this really needed here, I though hci_req_add_le_passive_scan would
only be used if interleaved scanning was not used.

> /* Adding or removing entries from the white list must
> * happen before enabling scanning. The controller does
> * not allow white list modification while scanning.
> @@ -1871,6 +1930,64 @@ static void adv_timeout_expire(struct work_struct *work)
> hci_dev_unlock(hdev);
> }
>
> +static int add_le_interleave_adv_monitor_scan(struct hci_request *req,
> + unsigned long opt)

Rename to hci_req_add_le_interleaved_scan

> +{
> + struct hci_dev *hdev = req->hdev;
> + int ret = 0;
> +
> + hci_dev_lock(hdev);
> +
> + if (hci_dev_test_flag(hdev, HCI_LE_SCAN))
> + hci_req_add_le_scan_disable(req, false);
> + hci_req_add_le_passive_scan(req);
> +
> + switch (hdev->adv_monitor_scan_state) {
> + case ADV_MONITOR_SCAN_ALLOWLIST:
> + bt_dev_dbg(hdev, "next state: allowlist");
> + hdev->adv_monitor_scan_state = ADV_MONITOR_SCAN_NO_FILTER;
> + break;
> + case ADV_MONITOR_SCAN_NO_FILTER:
> + bt_dev_dbg(hdev, "next state: no filter");
> + hdev->adv_monitor_scan_state = ADV_MONITOR_SCAN_ALLOWLIST;
> + break;
> + case ADV_MONITOR_SCAN_NONE:
> + default:
> + BT_ERR("unexpected error");
> + ret = -1;
> + }
> +
> + hci_dev_unlock(hdev);
> +
> + return ret;
> +}
> +
> +static void interleave_adv_monitor_scan_work(struct work_struct *work)

Rename to interleave_scan_work

> +{
> + struct hci_dev *hdev = container_of(work, struct hci_dev,
> + interleave_adv_monitor_scan.work);
> + u8 status;
> + unsigned long timeout;
> +
> + if (hdev->adv_monitor_scan_state == ADV_MONITOR_SCAN_ALLOWLIST) {
> + timeout = msecs_to_jiffies(hdev->advmon_allowlist_duration);
> + } else if (hdev->adv_monitor_scan_state == ADV_MONITOR_SCAN_NO_FILTER) {
> + timeout = msecs_to_jiffies(hdev->advmon_no_filter_duration);
> + } else {
> + bt_dev_err(hdev, "unexpected error");
> + return;
> + }
> +
> + hci_req_sync(hdev, add_le_interleave_adv_monitor_scan, 0,
> + HCI_CMD_TIMEOUT, &status);
> +
> + /* Don't continue interleaving if it was canceled */
> + if (is_interleave_scanning(hdev)) {
> + queue_delayed_work(hdev->req_workqueue,
> + &hdev->interleave_adv_monitor_scan, timeout);
> + }
> +}
> +
> int hci_get_random_address(struct hci_dev *hdev, bool require_privacy,
> bool use_rpa, struct adv_info *adv_instance,
> u8 *own_addr_type, bdaddr_t *rand_addr)
> @@ -3292,6 +3409,8 @@ void hci_request_setup(struct hci_dev *hdev)
> INIT_DELAYED_WORK(&hdev->le_scan_disable, le_scan_disable_work);
> INIT_DELAYED_WORK(&hdev->le_scan_restart, le_scan_restart_work);
> INIT_DELAYED_WORK(&hdev->adv_instance_expire, adv_timeout_expire);
> + INIT_DELAYED_WORK(&hdev->interleave_adv_monitor_scan,
> + interleave_adv_monitor_scan_work);

We can probably remove adv_monitor term on functions/variables and
just use interleave_scan.

> }
>
> void hci_request_cancel_all(struct hci_dev *hdev)
> @@ -3311,4 +3430,6 @@ void hci_request_cancel_all(struct hci_dev *hdev)
> cancel_delayed_work_sync(&hdev->adv_instance_expire);
> hdev->adv_instance_timeout = 0;
> }
> +
> + cancel_interleave_scan(hdev);
> }
> diff --git a/net/bluetooth/mgmt_config.c b/net/bluetooth/mgmt_config.c
> index b30b571f8caf8..2d3ad288c78ac 100644
> --- a/net/bluetooth/mgmt_config.c
> +++ b/net/bluetooth/mgmt_config.c
> @@ -67,6 +67,8 @@ int read_def_system_config(struct sock *sk, struct hci_dev *hdev, void *data,
> HDEV_PARAM_U16(0x001a, le_supv_timeout),
> HDEV_PARAM_U16_JIFFIES_TO_MSECS(0x001b,
> def_le_autoconnect_timeout),
> + HDEV_PARAM_U16(0x001d, advmon_allowlist_duration),
> + HDEV_PARAM_U16(0x001e, advmon_no_filter_duration),
> };
> struct mgmt_rp_read_def_system_config *rp = (void *)params;
>
> @@ -138,6 +140,8 @@ int set_def_system_config(struct sock *sk, struct hci_dev *hdev, void *data,
> case 0x0019:
> case 0x001a:
> case 0x001b:
> + case 0x001d:
> + case 0x001e:
> if (len != sizeof(u16)) {
> bt_dev_warn(hdev, "invalid length %d, exp %zu for type %d",
> len, sizeof(u16), type);
> @@ -251,6 +255,12 @@ int set_def_system_config(struct sock *sk, struct hci_dev *hdev, void *data,
> hdev->def_le_autoconnect_timeout =
> msecs_to_jiffies(TLV_GET_LE16(buffer));
> break;
> + case 0x0001d:
> + hdev->advmon_allowlist_duration = TLV_GET_LE16(buffer);
> + break;
> + case 0x0001e:
> + hdev->advmon_no_filter_duration = TLV_GET_LE16(buffer);
> + break;
> default:
> bt_dev_warn(hdev, "unsupported parameter %u", type);
> break;
> --
> 2.28.0.681.g6f77f65b4e-goog
>


--
Luiz Augusto von Dentz

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