What does it mean to "cancel" a command in the linux kernel and how can one do so?

### Context I bought a CM749 UGREEN Bluetooth 5.4 USB adapter for my Nixos machine. It is recognized by lsusb as ID 33fa:0010 USB2.0-BT, but is not detected by KDE/Plasma's bluetooth daemon. I dug deeper and found an Ubuntu bug report with the exact same problem and diagnosis as me. As of today, the last post links to an AskUbuntu post with a vexingly vague answer: > I patch my kernel source to cancel command hci_read_local_ext_features in the hci_init2[] and hci_init3[] in file hci_sync.c. It worked. So, I downloaded and unpacked the 6.15.7 kernel source from cdn.kernel.org , opened the corresponding file in Keta... and was lost like a lamb. Question: What does it mean to "cancel" a command in the linux kernel and how can one do so? Please, do tell me if my question is too vague or whether more information should be provided.