Not cancelling it has caused a bug where passive background scanning is
disabled out of the blue, preventing BLE keyboards/mice to reconnect.
Here is how it happens:
After hci_req_stop_discovery, there is still le_scan_restart_work
scheduled. Invocation of le_scan_restart_work causes a harmful
le_scan_disable_work to be scheduled. This le_scan_disable_work will
eventually disable passive scanning when the timer fires.
Sample btmon trace:
< HCI Command: LE Set Scan Parameters (0x08|0x000b) plen 7
Type: Passive (0x00)
Interval: 367.500 msec (0x024c)
Window: 37.500 msec (0x003c)
Own address type: Public (0x00)
Filter policy: Accept all advertisement (0x00)
> HCI Event: Command Complete (0x0e) plen 4
LE Set Scan Parameters (0x08|0x000b) ncmd 1
Status: Success (0x00)
< HCI Command: LE Set Scan Enable (0x08|0x000c) plen 2
Scanning: Enabled (0x01)
Filter duplicates: Disabled (0x00)
> HCI Event: Command Complete (0x0e) plen 4
LE Set Scan Enable (0x08|0x000c) ncmd 2
Status: Success (0x00)
...
< HCI Command: LE Set Scan Enable (0x08|0x000c) plen 2
Scanning: Disabled (0x00)
Filter duplicates: Disabled (0x00)
> HCI Event: Command Complete (0x0e) plen 4
LE Set Scan Enable (0x08|0x000c) ncmd 2
Status: Success (0x00)
// Background scanning is not working here onwards.
Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@xxxxxxxxxxxx>
Signed-off-by: Sonny Sasaka <sonnysasaka@xxxxxxxxxxxx>
---
net/bluetooth/hci_request.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c
index d7639c4b63104..c64b4a06de708 100644
--- a/net/bluetooth/hci_request.c
+++ b/net/bluetooth/hci_request.c
@@ -2710,6 +2710,7 @@ bool hci_req_stop_discovery(struct hci_request *req)
if (hci_dev_test_flag(hdev, HCI_LE_SCAN)) {
cancel_delayed_work(&hdev->le_scan_disable);
+ cancel_delayed_work(&hdev->le_scan_restart);
hci_req_add_le_scan_disable(req);
}
--
2.29.2
