r0 = socket$inet6_udp(0xa, 0x2, 0x0)
setsockopt$inet6_group_source_req(r0, 0x29, 0x30, &(0x7f00000000c0)={0x0, {{0xa, 0x0, 0x0, @mcast1}}, {{0xa, 0x0, 0x0, @initdev={0xfe, 0x88, '\x00', 0x0, 0x0}}}}, 0x108)