BPF_SOCK_OPS_RWND_INIT
rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL);
case BPF_SOCK_OPS_RWND_INIT:
case BPF_SOCK_OPS_RWND_INIT:
if (op == BPF_SOCK_OPS_RWND_INIT &&
(1 << BPF_SOCK_OPS_RWND_INIT) |
case BPF_SOCK_OPS_RWND_INIT: