tcp_connect test failed on FreeBSD on Cirrus CI

[taiki-e]

https://cirrus-ci.com/task/5088564308869120

---- tcp_connect stdout ----
thread 'tcp_connect' panicked at 'assertion failed: `(left == right)`
  left: `TimedOut`,
 right: `ConnectionRefused`', tests/async.rs:57:9
stack backtrace:
   0: rust_begin_unwind
             at /rustc/90743e7298aca107ddaa0c202a4d3604e29bfeb6/library/std/src/panicking.rs:575:5
   1: core::panicking::panic_fmt
             at /rustc/90743e7298aca107ddaa0c202a4d3604e29bfeb6/library/core/src/panicking.rs:65:14
   2: core::panicking::assert_failed_inner
   3: core::panicking::assert_failed
             at /rustc/90743e7298aca107ddaa0c202a4d3604e29bfeb6/library/core/src/panicking.rs:203:5
   4: async::tcp_connect::{{closure}}
             at ./tests/async.rs:57:9
   5: <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll
             at /rustc/90743e7298aca107ddaa0c202a4d3604e29bfeb6/library/core/src/future/mod.rs:91:19
   6: futures_lite::future::block_on::{{closure}}
             at /.cargo/registry/src/github.com-1ecc6299db9ec823/futures-lite-1.12.0/src/future.rs:89:27
   7: std::thread::local::LocalKey<T>::try_with
             at /rustc/90743e7298aca107ddaa0c202a4d3604e29bfeb6/library/std/src/thread/local.rs:446:16
   8: std::thread::local::LocalKey<T>::with
             at /rustc/90743e7298aca107ddaa0c202a4d3604e29bfeb6/library/std/src/thread/local.rs:422:9
   9: futures_lite::future::block_on
             at /.cargo/registry/src/github.com-1ecc6299db9ec823/futures-lite-1.12.0/src/future.rs:79:5
  10: async::tcp_connect
             at ./tests/async.rs:38:5
  11: async::tcp_connect::{{closure}}
             at ./tests/async.rs:37:1
  12: core::ops::function::FnOnce::call_once
             at /rustc/90743e7298aca107ddaa0c202a4d3604e29bfeb6/library/core/src/ops/function.rs:251:5
  13: core::ops::function::FnOnce::call_once
             at /rustc/90743e7298aca107ddaa0c202a4d3604e29bfeb6/library/core/src/ops/function.rs:251:5

note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
failures:
    tcp_connect

test result: FAILED. 12 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in 75.10s

error: test failed, to rerun pass `--test async`

[notgull]

I ran the async-io test suite on a FreeBSD 13 VM, and I can't replicate this issue. Maybe it's a Cirrus issue?

[notgull]

Maybe related: cirruslabs/cirrus-ci-docs#483

[taiki-e]

Thanks for the info. I confirmed sudo sysctl net.inet.tcp.blackhole=0 fixed the problem.