r0 = socket$inet6_udp(0xa, 0x2, 0x0)
setsockopt$inet6_group_source_req(r0, 0x29, 0x2c, &(0x7f0000000180)={0x0, {{0xa, 0x0, 0x0, @empty}}, {{0xa, 0x0, 0x0, @mcast2}}}, 0x108)