fix deadlock on `Thread#join`

because of 9720f5ac894566ade2aabcf9adea0a3235de1353

http://rubyci.s3.amazonaws.com/solaris11-sunc/ruby-master/log/20230403T130011Z.fail.html.gz

```
  1) Failure:
TestThread#test_signal_at_join [/export/home/chkbuild/chkbuild-sunc/tmp/build/20230403T130011Z/ruby/test/ruby/test_thread.rb:1488]:
Exception raised:
<#<fatal:"No live threads left. Deadlock?\n1 threads, 1 sleeps current:0x00891288 main thread:0x00891288\n* #<Thread:0xfef89a18 sleep_forever>\n   rb_thread_t:0x00891288 native:0x00000001 int:0\n   \n">>
Backtrace:
  -:30:in `join'
  -:30:in `block (3 levels) in <main>'
  -:21:in `times'
  -:21:in `block (2 levels) in <main>'.
```

The mechanism:

* Main thread (M) calls `Thread#join`
* M: calls `sleep_forever()`
* M: set `th->status = THREAD_STOPPED_FOREVER`
* M: do `checkints`
* M: handle a trap handler with `th->status = THREAD_RUNNABLE`
* M: thread switch at the end of the trap handler
* Another thread (T) will process `Thread#kill` by M.
* T: `rb_threadptr_join_list_wakeup()` at the end of T tris to wakeup M,
     but M's state is runnable because M is handling trap handler and
     just ignore the waking up and terminate T$a
* T: switch to M.
* M: after the trap handler, reset `th->status = THREAD_STOPPED_FOREVER`
     and check deadlock -> Deadlock because only M is living.

To avoid such situation, add new sleep flags `SLEEP_ALLOW_SPURIOUS`
and `SLEEP_NO_CHECKINTS` to skip any check ints.

BTW this is instentional to leave second `vm_check_ints_blocking()`
without checking `SLEEP_NO_CHECKINTS` because `SLEEP_ALLOW_SPURIOUS`
should be specified with `SLEEP_NO_CHECKINTS` and skipping this
checkints can skip any interrupts.

0 files changed, 0 insertions, 0 deletions