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@chromium.org>
Signed-off-by: Sonny Sasaka <sonnysasaka@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
c06632a4ec