[RFC PATCH v2 4/4] Bluetooth: Pause discovery and advertising during suspend

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

To prevent spurious wake ups, we disable any discovery or advertising
when we enter suspend and restore it when we exit suspend. While paused,
we disable any management requests to modify discovery or advertising.

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

Changes in v2:
* Refactored pause discovery + advertising into its own patch

 include/net/bluetooth/hci_core.h | 11 ++++++++
 net/bluetooth/hci_request.c      | 43 ++++++++++++++++++++++++++++++++
 net/bluetooth/mgmt.c             | 41 ++++++++++++++++++++++++++++++
 3 files changed, 95 insertions(+)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 49eae4a802ac..cbfaa80067d6 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -91,6 +91,12 @@ struct discovery_state {
 #define SUSPEND_NOTIFIER_TIMEOUT	msecs_to_jiffies(2000) /* 2 seconds */
 
 enum suspend_tasks {
+	SUSPEND_PAUSE_DISCOVERY,
+	SUSPEND_UNPAUSE_DISCOVERY,
+
+	SUSPEND_PAUSE_ADVERTISING,
+	SUSPEND_UNPAUSE_ADVERTISING,
+
 	SUSPEND_LE_SET_SCAN_ENABLE,
 	SUSPEND_DISCONNECTING,
 
@@ -405,6 +411,11 @@ struct hci_dev {
 
 	struct discovery_state	discovery;
 
+	int			discovery_old_state;
+	bool			discovery_paused;
+	int			advertising_old_state;
+	bool			advertising_paused;
+
 	struct notifier_block	suspend_notifier;
 	struct work_struct	suspend_prepare;
 	enum suspended_state	suspend_state_next;
diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c
index c930b9ff1cfd..487c84841351 100644
--- a/net/bluetooth/hci_request.c
+++ b/net/bluetooth/hci_request.c
@@ -1089,6 +1089,29 @@ void hci_req_prepare_suspend(struct hci_dev *hdev, enum suspended_state next)
 
 	hci_req_init(&req, hdev);
 	if (next == BT_SUSPENDED) {
+		/* Pause discovery if not already stopped */
+		old_state = hdev->discovery.state;
+		if (old_state != DISCOVERY_STOPPED) {
+			set_bit(SUSPEND_PAUSE_DISCOVERY, hdev->suspend_tasks);
+			hci_discovery_set_state(hdev, DISCOVERY_STOPPING);
+			queue_work(hdev->req_workqueue, &hdev->discov_update);
+		}
+
+		hdev->discovery_paused = true;
+		hdev->discovery_old_state = old_state;
+
+		/* Stop advertising */
+		old_state = hci_dev_test_flag(hdev, HCI_ADVERTISING);
+		if (old_state) {
+			set_bit(SUSPEND_PAUSE_ADVERTISING, hdev->suspend_tasks);
+			cancel_delayed_work(&hdev->discov_off);
+			queue_delayed_work(hdev->req_workqueue,
+					   &hdev->discov_off, 0);
+		}
+
+		hdev->advertising_paused = true;
+		hdev->advertising_old_state = old_state;
+
 		/* Enable event filter for existing devices */
 		hci_req_set_event_filter(&req);
 
@@ -1120,6 +1143,26 @@ void hci_req_prepare_suspend(struct hci_dev *hdev, enum suspended_state next)
 		/* Reset passive/background scanning to normal */
 		hci_req_enable_le_suspend_scan(&req, 0);
 
+		/* Unpause advertising */
+		hdev->advertising_paused = false;
+		if (hdev->advertising_old_state) {
+			set_bit(SUSPEND_UNPAUSE_ADVERTISING,
+				hdev->suspend_tasks);
+			hci_dev_set_flag(hdev, HCI_ADVERTISING);
+			queue_work(hdev->req_workqueue,
+				   &hdev->discoverable_update);
+			hdev->advertising_old_state = 0;
+		}
+
+		/* Unpause discovery */
+		hdev->discovery_paused = false;
+		if (hdev->discovery_old_state != DISCOVERY_STOPPED &&
+		    hdev->discovery_old_state != DISCOVERY_STOPPING) {
+			set_bit(SUSPEND_UNPAUSE_DISCOVERY, hdev->suspend_tasks);
+			hci_discovery_set_state(hdev, DISCOVERY_STARTING);
+			queue_work(hdev->req_workqueue, &hdev->discov_update);
+		}
+
 		hci_req_run(&req, le_suspend_req_complete);
 	}
 
diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 269ce70e501c..b3bd7a5ae718 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -1383,6 +1383,12 @@ static int set_discoverable(struct sock *sk, struct hci_dev *hdev, void *data,
 		goto failed;
 	}
 
+	if (hdev->advertising_paused) {
+		err = mgmt_cmd_status(sk, hdev->id, MGMT_OP_SET_DISCOVERABLE,
+				      MGMT_STATUS_BUSY);
+		goto failed;
+	}
+
 	if (!hdev_is_powered(hdev)) {
 		bool changed = false;
 
@@ -3866,6 +3872,13 @@ void mgmt_start_discovery_complete(struct hci_dev *hdev, u8 status)
 	}
 
 	hci_dev_unlock(hdev);
+
+	/* Handle suspend notifier */
+	if (test_and_clear_bit(SUSPEND_UNPAUSE_DISCOVERY,
+			       hdev->suspend_tasks)) {
+		BT_DBG("Unpaused discovery");
+		wake_up(&hdev->suspend_wait_q);
+	}
 }
 
 static bool discovery_type_is_valid(struct hci_dev *hdev, uint8_t type,
@@ -3927,6 +3940,13 @@ static int start_discovery_internal(struct sock *sk, struct hci_dev *hdev,
 		goto failed;
 	}
 
+	/* Can't start discovery when it is paused */
+	if (hdev->discovery_paused) {
+		err = mgmt_cmd_complete(sk, hdev->id, op, MGMT_STATUS_BUSY,
+					&cp->type, sizeof(cp->type));
+		goto failed;
+	}
+
 	/* Clear the discovery filter first to free any previously
 	 * allocated memory for the UUID list.
 	 */
@@ -4094,6 +4114,12 @@ void mgmt_stop_discovery_complete(struct hci_dev *hdev, u8 status)
 	}
 
 	hci_dev_unlock(hdev);
+
+	/* Handle suspend notifier */
+	if (test_and_clear_bit(SUSPEND_PAUSE_DISCOVERY, hdev->suspend_tasks)) {
+		BT_DBG("Paused discovery");
+		wake_up(&hdev->suspend_wait_q);
+	}
 }
 
 static int stop_discovery(struct sock *sk, struct hci_dev *hdev, void *data,
@@ -4325,6 +4351,17 @@ static void set_advertising_complete(struct hci_dev *hdev, u8 status,
 	if (match.sk)
 		sock_put(match.sk);
 
+	/* Handle suspend notifier */
+	if (test_and_clear_bit(SUSPEND_PAUSE_ADVERTISING,
+			       hdev->suspend_tasks)) {
+		BT_DBG("Paused advertising");
+		wake_up(&hdev->suspend_wait_q);
+	} else if (test_and_clear_bit(SUSPEND_UNPAUSE_ADVERTISING,
+				      hdev->suspend_tasks)) {
+		BT_DBG("Unpaused advertising");
+		wake_up(&hdev->suspend_wait_q);
+	}
+
 	/* If "Set Advertising" was just disabled and instance advertising was
 	 * set up earlier, then re-enable multi-instance advertising.
 	 */
@@ -4376,6 +4413,10 @@ static int set_advertising(struct sock *sk, struct hci_dev *hdev, void *data,
 		return mgmt_cmd_status(sk, hdev->id, MGMT_OP_SET_ADVERTISING,
 				       MGMT_STATUS_INVALID_PARAMS);
 
+	if (hdev->advertising_paused)
+		return mgmt_cmd_status(sk, hdev->id, MGMT_OP_SET_ADVERTISING,
+				       MGMT_STATUS_BUSY);
+
 	hci_dev_lock(hdev);
 
 	val = !!cp->val;
-- 
2.25.0.341.g760bfbb309-goog