r0 = socket$inet6_tcp(0xa, 0x1, 0x0)
setsockopt$inet6_tcp_TCP_FASTOPEN_KEY(r0, 0x6, 0x21, &(0x7f0000000040)="000000000000f5ffffffffffffff00", 0x20)
getsockopt$inet6_tcp_buf(r0, 0x6, 0x21, 0x0, &(0x7f0000000440))