r0 = socket$inet6_tcp(0xa, 0x1, 0x0)
ioctl$sock_inet6_SIOCDELRT(r0, 0x890c, &(0x7f0000000080)={@private0, @mcast1, @ipv4={'\x00', '\xff\xff', @dev}, 0x0, 0xd1, 0x0, 0x0, 0x0, 0x81080100})