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Subject[RFC PATCH v6 3/5] Bluetooth: Handle LE devices during suspend
Date
To handle LE devices, we must first disable passive scanning and
disconnect all connected devices. Once that is complete, we update the
whitelist and re-enable scanning

Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
---

Changes in v6: None
Changes in v5:
* Add wakeable to hci_conn_params and change BT_DBG to bt_dev_dbg

Changes in v4: None
Changes in v3:
* Split LE changes into its own commit

Changes in v2: None

include/net/bluetooth/hci_core.h | 1 +
net/bluetooth/hci_request.c | 166 +++++++++++++++++++++----------
2 files changed, 113 insertions(+), 54 deletions(-)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 1a4d732bdce6..2d58485d0335 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -607,6 +607,7 @@ struct hci_conn_params {

struct hci_conn *conn;
bool explicit_connect;
+ bool wakeable;
};

extern struct list_head hci_dev_list;
diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c
index 051e1b16c988..11624645cfcf 100644
--- a/net/bluetooth/hci_request.c
+++ b/net/bluetooth/hci_request.c
@@ -34,6 +34,9 @@
#define HCI_REQ_PEND 1
#define HCI_REQ_CANCELED 2

+#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 +657,11 @@ void hci_req_add_le_scan_disable(struct hci_request *req)
{
struct hci_dev *hdev = req->hdev;

+ if (hdev->scanning_paused) {
+ bt_dev_dbg(hdev, "Scanning is paused for suspend");
+ return;
+ }
+
if (use_ext_scan(hdev)) {
struct hci_cp_le_set_ext_scan_enable cp;

@@ -670,15 +678,55 @@ 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_dev_dbg(req->hdev, "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,
+ bool allow_rpa)
{
struct hci_cp_le_add_to_white_list cp;
+ struct hci_dev *hdev = req->hdev;
+
+ /* 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 (hdev->suspended && !params->wakeable)
+ return 0;
+
+ *num_entries += 1;
cp.bdaddr_type = params->addr_type;
bacpy(&cp.bdaddr, &params->addr);

+ bt_dev_dbg(hdev, "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)
@@ -686,7 +734,14 @@ static u8 update_white_list(struct hci_request *req)
struct hci_dev *hdev = req->hdev;
struct hci_conn_params *params;
struct bdaddr_list *b;
- uint8_t white_list_entries = 0;
+ u8 num_entries = 0;
+ bool pend_conn, pend_report;
+ /* 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.
+ */
+ bool allow_rpa = hdev->suspended;

/* Go through the current white list programmed into the
* controller one by one and check if that address is still
@@ -695,29 +750,28 @@ 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.
+ 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);
+
+ /* If the device is not likely to connect or report,
+ * remove it from the whitelist.
*/
- 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);
+ 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 */
+ /* White list can not be used with RPAs */
+ if (!allow_rpa &&
+ hci_find_irk_by_addr(hdev, &b->bdaddr, b->bdaddr_type)) {
return 0x00;
}

- white_list_entries++;
+ num_entries++;
}

/* Since all no longer valid white list entries have been
@@ -731,47 +785,17 @@ 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, &num_entries, allow_rpa))
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, &num_entries, allow_rpa))
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);
}

/* Select filter policy to use white list */
@@ -866,6 +890,12 @@ void hci_req_add_le_passive_scan(struct hci_request *req)
struct hci_dev *hdev = req->hdev;
u8 own_addr_type;
u8 filter_policy;
+ u8 window, interval;
+
+ if (hdev->scanning_paused) {
+ bt_dev_dbg(hdev, "Scanning is paused for suspend");
+ return;
+ }

/* Set require_privacy to false since no SCAN_REQ are send
* during passive scanning. Not using an non-resolvable address
@@ -896,8 +926,17 @@ 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 (hdev->suspended) {
+ window = LE_SUSPEND_SCAN_WINDOW;
+ interval = LE_SUSPEND_SCAN_INTERVAL;
+ } else {
+ window = hdev->le_scan_window;
+ interval = hdev->le_scan_interval;
+ }
+
+ bt_dev_dbg(hdev, "LE passive scan with whitelist = %d", filter_policy);
+ hci_req_start_scan(req, LE_SCAN_PASSIVE, interval, window,
+ own_addr_type, filter_policy);
}

static u8 get_adv_instance_scan_rsp_len(struct hci_dev *hdev, u8 instance)
@@ -957,6 +996,18 @@ static void hci_req_set_event_filter(struct hci_request *req)
hci_req_add(req, HCI_OP_WRITE_SCAN_ENABLE, 1, &scan);
}

+static void hci_req_config_le_suspend_scan(struct hci_request *req)
+{
+ /* 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);
+
+ /* Block suspend notifier on response */
+ set_bit(SUSPEND_SCAN_ENABLE, req->hdev->suspend_tasks);
+}
+
static void suspend_req_complete(struct hci_dev *hdev, u8 status, u16 opcode)
{
bt_dev_dbg(hdev, "Request complete opcode=0x%x, status=0x%x", opcode,
@@ -991,6 +1042,9 @@ void hci_req_prepare_suspend(struct hci_dev *hdev, enum suspended_state next)
page_scan = SCAN_DISABLED;
hci_req_add(&req, HCI_OP_WRITE_SCAN_ENABLE, 1, &page_scan);

+ /* Disable LE passive scan */
+ hci_req_add_le_scan_disable(&req);
+
/* Mark task needing completion */
set_bit(SUSPEND_SCAN_DISABLE, hdev->suspend_tasks);

@@ -1018,6 +1072,8 @@ void hci_req_prepare_suspend(struct hci_dev *hdev, enum suspended_state next)
hdev->scanning_paused = false;
/* Enable event filter for paired devices */
hci_req_set_event_filter(&req);
+ /* Enable passive scan at lower duty cycle */
+ hci_req_config_le_suspend_scan(&req);
/* Pause scan changes again. */
hdev->scanning_paused = true;
hci_req_run(&req, suspend_req_complete);
@@ -1026,6 +1082,8 @@ void hci_req_prepare_suspend(struct hci_dev *hdev, enum suspended_state next)
hdev->scanning_paused = false;

hci_req_clear_event_filter(&req);
+ /* Reset passive/background scanning to normal */
+ hci_req_config_le_suspend_scan(&req);
hci_req_run(&req, suspend_req_complete);
}

--
2.25.1.481.gfbce0eb801-goog
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