Re: [RFC PATCH v2 3/4] Bluetooth: Update filters/whitelists for suspend

[Abhishek Pandit-Subedi <abhishekpandit@chromium.org>]

Hi Marcel,

On Wed, Jan 29, 2020 at 12:40 AM Marcel Holtmann <marcel@holtmann.org> wrote:
>
> Hi Abhishek,
>
> > When suspending, update the event filter for BR/EDR devices and the
> > whitelist for LE devices. BR/EDR devices are added to the event filter
> > and will auto-connect if found during suspend. For LE, we update the
> > filter to remove everything that is not wakeable during suspend.
> > Finally, we disconnect all connected devices and wait for that to
> > complete before returning in the suspend notifier.
> >
> > An example suspend flow with 1 BR/EDR HID device, 1 BR/EDR audio device,
> > 1 LE HID device, 1 LE non-HID (where HIDs are wakeable):
> >
> > PM_PREPARE_SUSPEND:
> >  - Set event filter for BR/EDR HID device
> >  - Clear anything from LE whitelist that is not wakeable
> >  - Add (if not there) the LE HID device
> >  - Disconnect all devices
>
> is this really the right order? Why not disconnect all devices first. We are suspending after all, so lets disconnect first and then create the appropriate accept filters.
>
> I have the feeling it would also make the overall logic a lot simpler since it fits more into the current model that is used internally for a lot of decision points (especially with LE).
>
> > PM_POST_SUSPEND:
> >  - Clear event filter
> >  - Restore LE whitelist (deleting anything not in le_pend_conn or
> >    le_pend_report and then adding from those lists)
> >
> > Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> > ---
> >
> > Changes in v2:
> > * Refactored filters and whitelist settings to its own patch
> > * Refactored update_white_list to have clearer edge cases
> > * Add connected devices to whitelist (previously missing corner case)
> >
> > include/net/bluetooth/hci.h      |  17 +-
> > include/net/bluetooth/hci_core.h |   5 +
> > net/bluetooth/hci_event.c        |  28 ++-
> > net/bluetooth/hci_request.c      | 308 +++++++++++++++++++++++++------
> > net/bluetooth/mgmt.c             |   8 +
> > 5 files changed, 298 insertions(+), 68 deletions(-)
> >
> > diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
> > index 6293bdd7d862..720d8e633f7e 100644
> > --- a/include/net/bluetooth/hci.h
> > +++ b/include/net/bluetooth/hci.h
> > @@ -932,10 +932,14 @@ struct hci_cp_sniff_subrate {
> > #define HCI_OP_RESET                  0x0c03
> >
> > #define HCI_OP_SET_EVENT_FLT          0x0c05
> > -struct hci_cp_set_event_flt {
> > -     __u8     flt_type;
> > -     __u8     cond_type;
> > -     __u8     condition[0];
> > +#define HCI_SET_EVENT_FLT_SIZE               9
> > +struct hci_cp_set_event_filter {
> > +     __u8            flt_type;
> > +     __u8            cond_type;
> > +     struct {
> > +             bdaddr_t bdaddr;
> > +             __u8 auto_accept;
> > +     } __packed      addr_conn_flt;
> > } __packed;
> >
> > /* Filter types */
> > @@ -949,8 +953,9 @@ struct hci_cp_set_event_flt {
> > #define HCI_CONN_SETUP_ALLOW_BDADDR   0x02
> >
> > /* CONN_SETUP Conditions */
> > -#define HCI_CONN_SETUP_AUTO_OFF      0x01
> > -#define HCI_CONN_SETUP_AUTO_ON       0x02
> > +#define HCI_CONN_SETUP_AUTO_OFF              0x01
> > +#define HCI_CONN_SETUP_AUTO_ON               0x02
> > +#define HCI_CONN_SETUP_AUTO_ON_WITH_RS       0x03
> >
> > #define HCI_OP_READ_STORED_LINK_KEY   0x0c0d
> > struct hci_cp_read_stored_link_key {
> > diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> > index 74d703e46fb4..49eae4a802ac 100644
> > --- a/include/net/bluetooth/hci_core.h
> > +++ b/include/net/bluetooth/hci_core.h
> > @@ -91,6 +91,9 @@ struct discovery_state {
> > #define SUSPEND_NOTIFIER_TIMEOUT      msecs_to_jiffies(2000) /* 2 seconds */
> >
> > enum suspend_tasks {
> > +     SUSPEND_LE_SET_SCAN_ENABLE,
> > +     SUSPEND_DISCONNECTING,
> > +
> >       SUSPEND_PREPARE_NOTIFIER,
> >       __SUSPEND_NUM_TASKS
> > };
> > @@ -406,6 +409,8 @@ struct hci_dev {
> >       struct work_struct      suspend_prepare;
> >       enum suspended_state    suspend_state_next;
> >       enum suspended_state    suspend_state;
> > +     int                     disconnect_counter;
> > +     bool                    freeze_filters;
> >
> >       wait_queue_head_t       suspend_wait_q;
> >       DECLARE_BITMAP(suspend_tasks, __SUSPEND_NUM_TASKS);
> > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> > index 6ddc4a74a5e4..76d25b3f4c73 100644
> > --- a/net/bluetooth/hci_event.c
> > +++ b/net/bluetooth/hci_event.c
> > @@ -2474,6 +2474,7 @@ static void hci_inquiry_result_evt(struct hci_dev *hdev, struct sk_buff *skb)
> > static void hci_conn_complete_evt(struct hci_dev *hdev, struct sk_buff *skb)
> > {
> >       struct hci_ev_conn_complete *ev = (void *) skb->data;
> > +     struct inquiry_entry *ie;
> >       struct hci_conn *conn;
> >
> >       BT_DBG("%s", hdev->name);
> > @@ -2482,14 +2483,29 @@ static void hci_conn_complete_evt(struct hci_dev *hdev, struct sk_buff *skb)
> >
> >       conn = hci_conn_hash_lookup_ba(hdev, ev->link_type, &ev->bdaddr);
> >       if (!conn) {
> > -             if (ev->link_type != SCO_LINK)
> > -                     goto unlock;
> > +             /* Connection may not exist if auto-connected. Check the inquiry
> > +              * cache to see if we've already discovered this bdaddr before.
> > +              * Create a new connection if it was previously discovered.
> > +              */
> > +             ie = hci_inquiry_cache_lookup(hdev, &ev->bdaddr);
> > +             if (ie) {
> > +                     conn = hci_conn_add(hdev, ev->link_type, &ev->bdaddr,
> > +                                         HCI_ROLE_SLAVE);
> > +                     if (!conn) {
> > +                             bt_dev_err(hdev, "no memory for new conn");
> > +                             goto unlock;
> > +                     }
> > +             } else {
> > +                     if (ev->link_type != SCO_LINK)
> > +                             goto unlock;
>
> We are not going to get SCO_LINK auto-connected and thus we should really have it done just for ACL links. I don’t have good proposal to structure this handling at the moment, but we need to clean this up a bit.

Ack, will look deeper into this.

>
> > -             conn = hci_conn_hash_lookup_ba(hdev, ESCO_LINK, &ev->bdaddr);
> > -             if (!conn)
> > -                     goto unlock;
> > +                     conn = hci_conn_hash_lookup_ba(hdev, ESCO_LINK,
> > +                                                    &ev->bdaddr);
> > +                     if (!conn)
> > +                             goto unlock;
> >
> > -             conn->type = SCO_LINK;
> > +                     conn->type = SCO_LINK;
> > +             }
> >       }
> >
> >       if (!ev->status) {
> > diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c
> > index 08908469c043..c930b9ff1cfd 100644
> > --- a/net/bluetooth/hci_request.c
> > +++ b/net/bluetooth/hci_request.c
> > @@ -34,6 +34,12 @@
> > #define HCI_REQ_PEND    1
> > #define HCI_REQ_CANCELED  2
> >
> > +#define LE_SCAN_FLAG_SUSPEND 0x1
> > +#define LE_SCAN_FLAG_ALLOW_RPA       0x2
> > +
> > +#define LE_SUSPEND_SCAN_WINDOW               0x0012
> > +#define LE_SUSPEND_SCAN_INTERVAL     0x0060
> > +
> > void hci_req_init(struct hci_request *req, struct hci_dev *hdev)
> > {
> >       skb_queue_head_init(&req->cmd_q);
> > @@ -654,6 +660,12 @@ void hci_req_add_le_scan_disable(struct hci_request *req)
> > {
> >       struct hci_dev *hdev = req->hdev;
> >
> > +     /* Early exit if we've frozen filters for suspend*/
>
> Please fix the coding style for comments. Extra space required between suspend and */
>
> I also have the feeling that we should split BR/EDR from LE support. I think we can merge the BR/EDR support quicker since it is a lot simpler. Especially when it stands on its own.

Ack. I kept them merged because I didn't want to change the request
completion function but I can separate them.

>
> > +     if (hdev->freeze_filters) {
> > +             BT_DBG("Filters are frozen for suspend");
> > +             return;
> > +     }
> > +
> >       if (use_ext_scan(hdev)) {
> >               struct hci_cp_le_set_ext_scan_enable cp;
> >
> > @@ -670,23 +682,67 @@ void hci_req_add_le_scan_disable(struct hci_request *req)
> >       }
> > }
> >
> > -static void add_to_white_list(struct hci_request *req,
> > -                           struct hci_conn_params *params)
> > +static void del_from_white_list(struct hci_request *req, bdaddr_t *bdaddr,
> > +                             u8 bdaddr_type)
> > +{
> > +     struct hci_cp_le_del_from_white_list cp;
> > +
> > +     cp.bdaddr_type = bdaddr_type;
> > +     bacpy(&cp.bdaddr, bdaddr);
> > +
> > +     BT_DBG("Remove %pMR (0x%x) from whitelist", &cp.bdaddr, cp.bdaddr_type);
> > +     hci_req_add(req, HCI_OP_LE_DEL_FROM_WHITE_LIST, sizeof(cp), &cp);
> > +}
> > +
> > +/* Adds connection to white list if needed. On error, returns -1 */
> > +static int add_to_white_list(struct hci_request *req,
> > +                          struct hci_conn_params *params, u8 *num_entries,
> > +                          u8 flags)
> > {
> >       struct hci_cp_le_add_to_white_list cp;
> > +     struct hci_dev *hdev = req->hdev;
> > +     bool allow_rpa = !!(flags & LE_SCAN_FLAG_ALLOW_RPA);
> > +     bool suspend = !!(flags & LE_SCAN_FLAG_SUSPEND);
> >
> > +     /* Already in white list */
> > +     if (hci_bdaddr_list_lookup(&hdev->le_white_list, &params->addr,
> > +                                params->addr_type))
> > +             return 0;
> > +
> > +     /* Select filter policy to accept all advertising */
> > +     if (*num_entries >= hdev->le_white_list_size)
> > +             return -1;
> > +
> > +     /* White list can not be used with RPAs */
> > +     if (!allow_rpa &&
> > +         hci_find_irk_by_addr(hdev, &params->addr, params->addr_type)) {
> > +             return -1;
> > +     }
> > +
> > +     /* During suspend, only wakeable devices can be in whitelist */
> > +     if (suspend && !hci_bdaddr_list_lookup(&hdev->wakeable, &params->addr,
> > +                                            params->addr_type))
> > +             return 0;
> > +
> > +     *num_entries += 1;
> >       cp.bdaddr_type = params->addr_type;
> >       bacpy(&cp.bdaddr, &params->addr);
> >
> > +     BT_DBG("Add %pMR (0x%x) to whitelist", &cp.bdaddr, cp.bdaddr_type);
> >       hci_req_add(req, HCI_OP_LE_ADD_TO_WHITE_LIST, sizeof(cp), &cp);
> > +
> > +     return 0;
> > }
> >
> > -static u8 update_white_list(struct hci_request *req)
> > +static u8 update_white_list(struct hci_request *req, u8 flags)
> > {
> >       struct hci_dev *hdev = req->hdev;
> >       struct hci_conn_params *params;
> >       struct bdaddr_list *b;
> > -     uint8_t white_list_entries = 0;
> > +     u8 white_list_entries = 0;
> > +     bool allow_rpa = !!(flags & LE_SCAN_FLAG_ALLOW_RPA);
> > +     bool suspend = !!(flags & LE_SCAN_FLAG_SUSPEND);
> > +     bool wakeable, pend_conn, pend_report;
> >
> >       /* Go through the current white list programmed into the
> >        * controller one by one and check if that address is still
> > @@ -695,26 +751,42 @@ static u8 update_white_list(struct hci_request *req)
> >        * command to remove it from the controller.
> >        */
> >       list_for_each_entry(b, &hdev->le_white_list, list) {
> > -             /* If the device is neither in pend_le_conns nor
> > -              * pend_le_reports then remove it from the whitelist.
> > +             wakeable = !!hci_bdaddr_list_lookup(&hdev->wakeable, &b->bdaddr,
> > +                                                 b->bdaddr_type);
> > +             pend_conn = hci_pend_le_action_lookup(&hdev->pend_le_conns,
> > +                                                   &b->bdaddr,
> > +                                                   b->bdaddr_type);
> > +             pend_report = hci_pend_le_action_lookup(&hdev->pend_le_reports,
> > +                                                     &b->bdaddr,
> > +                                                     b->bdaddr_type);
> > +
> > +             /* During suspend, we remove all non-wakeable devices
> > +              * and leave all others alone. Connected devices will be
> > +              * disconnected during suspend but may not be in the pending
> > +              * list yet.
> >                */
> > -             if (!hci_pend_le_action_lookup(&hdev->pend_le_conns,
> > -                                            &b->bdaddr, b->bdaddr_type) &&
> > -                 !hci_pend_le_action_lookup(&hdev->pend_le_reports,
> > -                                            &b->bdaddr, b->bdaddr_type)) {
> > -                     struct hci_cp_le_del_from_white_list cp;
> > -
> > -                     cp.bdaddr_type = b->bdaddr_type;
> > -                     bacpy(&cp.bdaddr, &b->bdaddr);
> > -
> > -                     hci_req_add(req, HCI_OP_LE_DEL_FROM_WHITE_LIST,
> > -                                 sizeof(cp), &cp);
> > -                     continue;
> > -             }
> > +             if (suspend) {
> > +                     if (!wakeable) {
> > +                             del_from_white_list(req, &b->bdaddr,
> > +                                                 b->bdaddr_type);
> > +                             continue;
> > +                     }
> > +             } else {
> > +                     /* If the device is not likely to connect or report,
> > +                      * remove it from the whitelist.
> > +                      */
> > +                     if (!pend_conn && !pend_report) {
> > +                             del_from_white_list(req, &b->bdaddr,
> > +                                                 b->bdaddr_type);
> > +                             continue;
> > +                     }
> >
> > -             if (hci_find_irk_by_addr(hdev, &b->bdaddr, b->bdaddr_type)) {
> >                       /* White list can not be used with RPAs */
> > -                     return 0x00;
> > +                     if (!allow_rpa &&
> > +                         hci_find_irk_by_addr(hdev, &b->bdaddr,
> > +                                              b->bdaddr_type)) {
> > +                             return 0x00;
> > +                     }
> >               }
> >
> >               white_list_entries++;
> > @@ -731,47 +803,30 @@ static u8 update_white_list(struct hci_request *req)
> >        * white list.
> >        */
> >       list_for_each_entry(params, &hdev->pend_le_conns, action) {
> > -             if (hci_bdaddr_list_lookup(&hdev->le_white_list,
> > -                                        &params->addr, params->addr_type))
> > -                     continue;
> > -
> > -             if (white_list_entries >= hdev->le_white_list_size) {
> > -                     /* Select filter policy to accept all advertising */
> > +             if (add_to_white_list(req, params, &white_list_entries, flags))
> >                       return 0x00;
> > -             }
> > -
> > -             if (hci_find_irk_by_addr(hdev, &params->addr,
> > -                                      params->addr_type)) {
> > -                     /* White list can not be used with RPAs */
> > -                     return 0x00;
> > -             }
> > -
> > -             white_list_entries++;
> > -             add_to_white_list(req, params);
> >       }
> >
> >       /* After adding all new pending connections, walk through
> >        * the list of pending reports and also add these to the
> > -      * white list if there is still space.
> > +      * white list if there is still space. Abort if space runs out.
> >        */
> >       list_for_each_entry(params, &hdev->pend_le_reports, action) {
> > -             if (hci_bdaddr_list_lookup(&hdev->le_white_list,
> > -                                        &params->addr, params->addr_type))
> > -                     continue;
> > -
> > -             if (white_list_entries >= hdev->le_white_list_size) {
> > -                     /* Select filter policy to accept all advertising */
> > +             if (add_to_white_list(req, params, &white_list_entries, flags))
> >                       return 0x00;
> > -             }
> > +     }
> >
> > -             if (hci_find_irk_by_addr(hdev, &params->addr,
> > -                                      params->addr_type)) {
> > -                     /* White list can not be used with RPAs */
> > -                     return 0x00;
> > +     /* Currently connected devices will be missing from the white list and
> > +      * we need to insert them into the whitelist if they are wakeable. We
> > +      * can't insert later because we will have already returned from the
> > +      * suspend notifier and would cause a spurious wakeup.
> > +      */
> > +     if (suspend) {
> > +             list_for_each_entry(params, &hdev->le_conn_params, list) {
> > +                     if (add_to_white_list(req, params, &white_list_entries,
> > +                                           flags))
> > +                             return 0x00;
> >               }
> > -
> > -             white_list_entries++;
> > -             add_to_white_list(req, params);
> >       }
>
> This goes to my point above. If we just disconnect everything, then the white list programming should be easily. Everything that is pending and have been elected for wakeup + incoming connection will be added. And then we are done. I don’t think much has to change except one extra check if wakeup is allowed or not.
>
> >
> >       /* Select filter policy to use white list */
> > @@ -861,11 +916,26 @@ static void hci_req_start_scan(struct hci_request *req, u8 type, u16 interval,
> >       }
> > }
> >
> > -void hci_req_add_le_passive_scan(struct hci_request *req)
> > +void __hci_req_add_le_passive_scan(struct hci_request *req, u8 flags)
> > {
> >       struct hci_dev *hdev = req->hdev;
> >       u8 own_addr_type;
> >       u8 filter_policy;
> > +     u8 window, interval;
> > +
> > +     /* We allow whitelisting even with RPAs in suspend. In the worst case,
> > +      * we won't be able to wake from devices that use the privacy1.2
> > +      * features. Additionally, once we support privacy1.2 and IRK
> > +      * offloading, we can update this to also check for those conditions.
> > +      */
> > +     if (flags & LE_SCAN_FLAG_SUSPEND)
> > +             flags |= LE_SCAN_FLAG_ALLOW_RPA;
> > +
> > +     /* Early exit if we've frozen filters for suspend */
> > +     if (hdev->freeze_filters) {
> > +             BT_DBG("Filters are frozen for suspend");
> > +             return;
> > +     }
> >
> >       /* Set require_privacy to false since no SCAN_REQ are send
> >        * during passive scanning. Not using an non-resolvable address
> > @@ -881,7 +951,8 @@ void hci_req_add_le_passive_scan(struct hci_request *req)
> >        * happen before enabling scanning. The controller does
> >        * not allow white list modification while scanning.
> >        */
> > -     filter_policy = update_white_list(req);
> > +     BT_DBG("Updating white list with flags = %d", flags);
> > +     filter_policy = update_white_list(req, flags);
> >
> >       /* When the controller is using random resolvable addresses and
> >        * with that having LE privacy enabled, then controllers with
> > @@ -896,8 +967,22 @@ void hci_req_add_le_passive_scan(struct hci_request *req)
> >           (hdev->le_features[0] & HCI_LE_EXT_SCAN_POLICY))
> >               filter_policy |= 0x02;
> >
> > -     hci_req_start_scan(req, LE_SCAN_PASSIVE, hdev->le_scan_interval,
> > -                        hdev->le_scan_window, own_addr_type, filter_policy);
> > +     if (flags & LE_SCAN_FLAG_SUSPEND) {
> > +             window = LE_SUSPEND_SCAN_WINDOW;
> > +             interval = LE_SUSPEND_SCAN_INTERVAL;
>
> I think we just want this done via some hdev->suspended variable or similar.

In support of setting a separate flag, it is easier to grep for when a
specific flag is being used and passed to a function than it is to
check when a variable is being set in a global context variable.

>
> > +     } else {
> > +             window = hdev->le_scan_window;
> > +             interval = hdev->le_scan_interval;
> > +     }
> > +
> > +     BT_DBG("LE passive scan with whitelist = %d", filter_policy);
> > +     hci_req_start_scan(req, LE_SCAN_PASSIVE, interval, window,
> > +                        own_addr_type, filter_policy);
> > +}
> > +
> > +void hci_req_add_le_passive_scan(struct hci_request *req)
> > +{
> > +     __hci_req_add_le_passive_scan(req, 0);
> > }
> >
> > static u8 get_adv_instance_scan_rsp_len(struct hci_dev *hdev, u8 instance)
> > @@ -918,6 +1003,76 @@ static u8 get_adv_instance_scan_rsp_len(struct hci_dev *hdev, u8 instance)
> >       return adv_instance->scan_rsp_len;
> > }
> >
> > +static void hci_req_clear_event_filter(struct hci_request *req)
> > +{
> > +     struct hci_cp_set_event_filter f;
> > +
> > +     memset(&f, 0, sizeof(f));
> > +     f.flt_type = HCI_FLT_CLEAR_ALL;
> > +     hci_req_add(req, HCI_OP_SET_EVENT_FLT, 1, &f);
> > +
> > +     /* Update page scan state (since we may have modified it when setting
> > +      * the event filter).
> > +      */
> > +     __hci_req_update_scan(req);
> > +}
> > +
> > +static void hci_req_set_event_filter(struct hci_request *req)
> > +{
> > +     struct bdaddr_list *b;
> > +     struct hci_cp_set_event_filter f;
> > +     struct hci_dev *hdev = req->hdev;
> > +     int filters_updated = 0;
> > +     u8 scan;
> > +
> > +     /* Always clear event filter when starting */
> > +     hci_req_clear_event_filter(req);
> > +
> > +     list_for_each_entry(b, &hdev->wakeable, list) {
> > +             if (b->bdaddr_type != BDADDR_BREDR)
> > +                     continue;
> > +
> > +             memset(&f, 0, sizeof(f));
> > +             bacpy(&f.addr_conn_flt.bdaddr, &b->bdaddr);
> > +             f.flt_type = HCI_FLT_CONN_SETUP;
> > +             f.cond_type = HCI_CONN_SETUP_ALLOW_BDADDR;
> > +             f.addr_conn_flt.auto_accept = HCI_CONN_SETUP_AUTO_ON;
> > +
> > +             BT_DBG("Adding event filters for %pMR", &b->bdaddr);
> > +             hci_req_add(req, HCI_OP_SET_EVENT_FLT, sizeof(f), &f);
> > +
> > +             filters_updated++;
> > +     }
>
> If we would use the wakeable list just for BR/EDR then the filters_updated++ would become redundant and we could just check if the list is empty.
>
> > +
> > +     scan = filters_updated ? SCAN_PAGE : SCAN_DISABLED;
> > +     hci_req_add(req, HCI_OP_WRITE_SCAN_ENABLE, 1, &scan);
> > +}
> > +
> > +static void hci_req_enable_le_suspend_scan(struct hci_request *req,
> > +                                        u8 flags)
> > +{
> > +     /* Can't change params without disabling first */
> > +     hci_req_add_le_scan_disable(req);
> > +
> > +     /* Configure params and enable scanning */
> > +     __hci_req_add_le_passive_scan(req, flags);
> > +
> > +     /* Block suspend notifier on response */
> > +     set_bit(SUSPEND_LE_SET_SCAN_ENABLE, req->hdev->suspend_tasks);
> > +}
> > +
> > +static void le_suspend_req_complete(struct hci_dev *hdev, u8 status, u16 opcode)
> > +{
> > +     BT_DBG("Request complete opcode=0x%x, status=0x%x", opcode, status);
> > +
> > +     /* Expecting LE Set scan to return */
> > +     if (opcode == HCI_OP_LE_SET_SCAN_ENABLE &&
> > +         test_and_clear_bit(SUSPEND_LE_SET_SCAN_ENABLE,
> > +                            hdev->suspend_tasks)) {
> > +             wake_up(&hdev->suspend_wait_q);
> > +     }
> > +}
> > +
> > /* Call with hci_dev_lock */
> > void hci_req_prepare_suspend(struct hci_dev *hdev, enum suspended_state next)
> > {
> > @@ -932,6 +1087,44 @@ void hci_req_prepare_suspend(struct hci_dev *hdev, enum suspended_state next)
> >
> >       hdev->suspend_state = next;
> >
> > +     hci_req_init(&req, hdev);
> > +     if (next == BT_SUSPENDED) {
> > +             /* Enable event filter for existing devices */
> > +             hci_req_set_event_filter(&req);
> > +
> > +             /* Enable passive scan at lower duty cycle */
> > +             hci_req_enable_le_suspend_scan(&req, LE_SCAN_FLAG_SUSPEND);
> > +
> > +             hdev->freeze_filters = true;
> > +
> > +             /* Run commands before disconnecting */
> > +             hci_req_run(&req, le_suspend_req_complete);
> > +
> > +             hdev->disconnect_counter = 0;
> > +             /* Soft disconnect everything (power off)*/
> > +             list_for_each_entry(conn, &hdev->conn_hash.list, list) {
> > +                     hci_disconnect(conn, HCI_ERROR_REMOTE_POWER_OFF);
> > +                     hdev->disconnect_counter++;
> > +             }
> > +
> > +             if (hdev->disconnect_counter > 0) {
> > +                     BT_DBG("Had %d disconnects. Will wait on them",
> > +                            hdev->disconnect_counter);
> > +                     set_bit(SUSPEND_DISCONNECTING, hdev->suspend_tasks);
> > +             }
> > +     } else {
> > +             hdev->freeze_filters = false;
> > +
> > +             hci_req_clear_event_filter(&req);
> > +
> > +             /* Reset passive/background scanning to normal */
> > +             hci_req_enable_le_suspend_scan(&req, 0);
> > +
> > +             hci_req_run(&req, le_suspend_req_complete);
> > +     }
> > +
> > +     hdev->suspend_state = next;
> > +
> > done:
> >       clear_bit(SUSPEND_PREPARE_NOTIFIER, hdev->suspend_tasks);
> >       wake_up(&hdev->suspend_wait_q);
> > @@ -2034,6 +2227,9 @@ void __hci_req_update_scan(struct hci_request *req)
> >       if (mgmt_powering_down(hdev))
> >               return;
> >
> > +     if (hdev->freeze_filters)
> > +             return;
> > +
> >       if (hci_dev_test_flag(hdev, HCI_CONNECTABLE) ||
> >           disconnected_whitelist_entries(hdev))
> >               scan = SCAN_PAGE;
> > diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
> > index 58468dfa112f..269ce70e501c 100644
> > --- a/net/bluetooth/mgmt.c
> > +++ b/net/bluetooth/mgmt.c
> > @@ -7451,6 +7451,14 @@ void mgmt_device_disconnected(struct hci_dev *hdev, bdaddr_t *bdaddr,
> >
> >       mgmt_event(MGMT_EV_DEVICE_DISCONNECTED, hdev, &ev, sizeof(ev), sk);
> >
> > +     if (hdev->disconnect_counter > 0) {
> > +             hdev->disconnect_counter--;
> > +             if (hdev->disconnect_counter <= 0) {
> > +                     clear_bit(SUSPEND_DISCONNECTING, hdev->suspend_tasks);
> > +                     wake_up(&hdev->suspend_wait_q);
> > +             }
> > +     }
> > +
>
> I think this disconnect_counter is a bit racy. I would rather check that our connection hash is empty.
>
> In addition, I have the feeling we better disable LE scanning BR/EDR page scan first. So that we clearly do not have any artifacts of accidental incoming connections.
>
> The first step when going to suspend should clean the house
>
>         1) Set a flag that all BR/EDR and LE connection attempts are rejected
>         2) Disable BR/EDR page scan
>         3) Disable LE advertising
>         2) Disable LE scanning / BR/EDR inquiry
>         4) Disconnect all
>
> Now we have a clean house and we now prepare for wakeup triggers
>
>         1) Clear flag and allow incoming connection
>         2) Set BR/EDR event filter and enable page scan if needed
>         3) Set LE whitelist and enable scanning if needed
>
> When we wake up, then we also just need to reset the filters
>
>         1) Clear BR/EDR event filter and enable page scan if needed
>         2) Update LE white and enable scanning if needed
>         3) Restore LE scanning / BR/EDR inquiry
>

I think this is reasonable so I will try to implement it. Might take
me a couple of days (traveling out of country) so expect the next
patch series early next week.

> Regards
>
> Marcel
>

Cheers
Abhishek