x/net/ipv6: TestPacketConnReadWriteMulticast{UDP,ICMP} failing with "i/o timeout" on OpenBSD 6.8 and 7.0

[bcmills]

TestPacketConnReadWriteMulticastUDP is failing fairly consistently on the openbsd-arm-jsing builders. It should either be fixed or skipped.

--- FAIL: TestPacketConnReadWriteMulticastUDP (0.21s)
    multicast_test.go:114: read udp [::]:6423: raw-read udp6 [::]:6423: i/o timeout
FAIL
FAIL	golang.org/x/net/ipv6	0.294s

Note that this failure mode is different from the one on Darwin (#37319) and the one previously reported for OpenBSD (#33843).

2020-10-16T16:51:38-7b1cca2/openbsd-arm-jsing
2020-10-16T16:51:38-7b1cca2/openbsd-arm64-jsing
2020-10-10T22:47:23-4f7140c/openbsd-arm-jsing
2020-10-09T03:24:41-dbdefad/openbsd-arm-jsing
2020-10-08T22:28:04-59f7323/openbsd-arm-jsing
2020-10-06T15:34:59-a7d1128/openbsd-arm-jsing
2020-10-02T20:24:02-0a1ea39/openbsd-arm-jsing
2020-09-30T14:50:03-4acb6c0/openbsd-arm-jsing
2020-09-27T03:25:02-5d4f700/openbsd-arm-jsing
2020-09-25T08:00:53-05aa5d4/openbsd-arm-jsing
2020-09-23T18:22:12-328152d/openbsd-arm-jsing
2020-09-04T19:48:48-62affa3/openbsd-arm-jsing
2020-08-22T12:43:28-c890458/openbsd-arm-jsing
2020-08-13T13:45:08-3edf25e/openbsd-arm-jsing
2020-07-07T03:43:11-ab34263/openbsd-arm-jsing
2020-06-25T00:16:55-4c52546/openbsd-arm-jsing
2020-06-02T11:40:24-627f964/openbsd-arm-jsing
2020-05-28T22:51:25-3c3fba1/openbsd-arm-jsing
2020-05-20T18:23:14-0ba52f6/openbsd-arm-jsing

CC @4a6f656c @golang/osp-team

[tklauser]

This test consistently fails on the openbsd-arm64-jsing and the 386/amd64 builders running OpenBSD 6.8 as well:

openbsd-arm64-jsing: https://build.golang.org/log/be54c3c8bfe2313b55b63b76bc5af92d6c39a524
openbsd-386-68: https://build.golang.org/log/eea81ada598c39d224d3a9a40b4739bbbe739b09
openbsd-amd64-68: https://build.golang.org/log/9039640721536372ca5170299ee6e923aa3775dd

The test also failed on https://golang.org/cl/274772 on the openbsd-mips64-jsing builder.

It doesn't seem to fail on builder running OpenBSD 6.2 or 6.4.

[dmitshur]

It doesn't seem to fail on builder running OpenBSD 6.2 or 6.4.

It'd be helpful to find out if the test runs or gets skipped on OpenBSD 6.4. (It's possible it's passing in 6.4 because IPv6 isn't supported there and it gets skipped.)

[bcmills]

Marking as release-blocker via #11811, especially since this doesn't seem builder- or arch-specific.

But note that OpenBSD is not a first-class port, so it may be viable to unblock the release by skipping the test on the affected builders — especially given that this appears to be either a regression in the kernel or an incompatible ABI change.

[gopherbot]

Change https://golang.org/cl/279512 mentions this issue: dashboard: promote OpenBSD 6.8 builders to be default

[gopherbot]

Change https://golang.org/cl/280052 mentions this issue: ipv6: skip known-failing tests on OpenBSD 6.8 builders