[PATCH v2 2/2] Bluetooth: hci_sync: Fix attempting to suspend with unfiltered passive scan

[Luiz Augusto von Dentz <luiz.dentz@xxxxxxxxx>]

From: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>

When suspending the passive scanning _must_ have its filter_policy set
to 0x01 to use the accept list otherwise _any_ advertise report would
end up waking up the system.

In order to fix the filter_policy the code now checks for
hdev->suspended && HCI_CONN_FLAG_REMOTE_WAKEUP
first, since the MGMT_OP_SET_DEVICE_FLAGS will reject any attempt to
set HCI_CONN_FLAG_REMOTE_WAKEUP when it cannot be programmed in the
acceptlist, so it can return success causing the proper filter_policy
to be used.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=215768
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
---
 net/bluetooth/hci_sync.c | 58 +++++++++++++++++++++++++++++-----------
 1 file changed, 43 insertions(+), 15 deletions(-)

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 7bdfdc6a91f5..0fa013816a9b 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -1664,20 +1664,19 @@ static int hci_le_add_accept_list_sync(struct hci_dev *hdev,
 	struct hci_cp_le_add_to_accept_list cp;
 	int err;
 
+	/* During suspend, only wakeable devices can be in acceptlist */
+	if (hdev->suspended &&
+	    !test_bit(HCI_CONN_FLAG_REMOTE_WAKEUP, params->flags))
+		return 0;
+
 	/* Select filter policy to accept all advertising */
 	if (*num_entries >= hdev->le_accept_list_size)
 		return -ENOSPC;
 
 	/* Accept list can not be used with RPAs */
 	if (!use_ll_privacy(hdev) &&
-	    hci_find_irk_by_addr(hdev, &params->addr, params->addr_type)) {
+	    hci_find_irk_by_addr(hdev, &params->addr, params->addr_type))
 		return -EINVAL;
-	}
-
-	/* During suspend, only wakeable devices can be in acceptlist */
-	if (hdev->suspended &&
-	    !test_bit(HCI_CONN_FLAG_REMOTE_WAKEUP, params->flags))
-		return 0;
 
 	/* Attempt to program the device in the resolving list first to avoid
 	 * having to rollback in case it fails since the resolving list is
@@ -4940,10 +4939,28 @@ static int hci_update_event_filter_sync(struct hci_dev *hdev)
 	return 0;
 }
 
+/* This function disables scan (BR and LE) and mark it as paused */
+static int hci_pause_scan_sync(struct hci_dev *hdev)
+{
+	if (hdev->scanning_paused)
+		return 0;
+
+	/* Disable page scan if enabled */
+	if (test_bit(HCI_PSCAN, &hdev->flags))
+		hci_write_scan_enable_sync(hdev, SCAN_DISABLED);
+
+	hci_scan_disable_sync(hdev);
+
+	hdev->scanning_paused = true;
+
+	return 0;
+}
+
 /* This function performs the HCI suspend procedures in the follow order:
  *
  * Pause discovery (active scanning/inquiry)
  * Pause Directed Advertising/Advertising
+ * Pause Scanning (passive scanning in case discovery was not active)
  * Disconnect all connections
  * Set suspend_status to BT_SUSPEND_DISCONNECT if hdev cannot wakeup
  * otherwise:
@@ -4969,15 +4986,11 @@ int hci_suspend_sync(struct hci_dev *hdev)
 	/* Pause other advertisements */
 	hci_pause_advertising_sync(hdev);
 
-	/* Disable page scan if enabled */
-	if (test_bit(HCI_PSCAN, &hdev->flags))
-		hci_write_scan_enable_sync(hdev, SCAN_DISABLED);
-
 	/* Suspend monitor filters */
 	hci_suspend_monitor_sync(hdev);
 
 	/* Prevent disconnects from causing scanning to be re-enabled */
-	hdev->scanning_paused = true;
+	hci_pause_scan_sync(hdev);
 
 	/* Soft disconnect everything (power off) */
 	err = hci_disconnect_all_sync(hdev, HCI_ERROR_REMOTE_POWER_OFF);
@@ -5048,6 +5061,22 @@ static void hci_resume_monitor_sync(struct hci_dev *hdev)
 	}
 }
 
+/* This function resume scan and reset paused flag */
+static int hci_resume_scan_sync(struct hci_dev *hdev)
+{
+	if (!hdev->scanning_paused)
+		return 0;
+
+	hci_update_scan_sync(hdev);
+
+	/* Reset passive scanning to normal */
+	hci_update_passive_scan_sync(hdev);
+
+	hdev->scanning_paused = false;
+
+	return 0;
+}
+
 /* This function performs the HCI suspend procedures in the follow order:
  *
  * Restore event mask
@@ -5070,10 +5099,9 @@ int hci_resume_sync(struct hci_dev *hdev)
 
 	/* Clear any event filters and restore scan state */
 	hci_clear_event_filter_sync(hdev);
-	hci_update_scan_sync(hdev);
 
-	/* Reset passive scanning to normal */
-	hci_update_passive_scan_sync(hdev);
+	/* Resume scanning */
+	hci_resume_scan_sync(hdev);
 
 	/* Resume monitor filters */
 	hci_resume_monitor_sync(hdev);
-- 
2.35.1