I was recently browsing the kernel code in attempts to understand some of the weird kernel errors I see in dmesg on one of my machines. I was a bit surprised to see an interesting syntax I have never seen before. In the following code: 1 2 3 4 5 6 7 8 9 10 11 12 13 static int ucsi_run_command(struct ucsi *ucsi, u64 command, u32 *cci, void *data, size_t size, bool conn_ack) { .