k0kubun	2018-11-18 22:32:49 +0900 (Sun, 18 Nov 2018)

  New Revision: 65790

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=65790

  Log:
    mjit.c: fix deadlock introduced by r65785
    
    in mjit_pause() fired by before_fork_ruby(). When calling
    RUBY_VM_CHECK_INTS() in mjit_pause()'s loop, other threads may call
    start_worker() which sets `stop_worker_p = FALSE` and it could wait for
    MJIT worker stop forever even while `stop_worker_p` is FALSE.
    
    http://ci.rvm.jp/results/trunk-mjit@silicon-docker/1466333
    https://gist.github.com/ko1/a57ef1a03e1c7cfd22f1495e0864b63d
    
    http://ci.rvm.jp/results/trunk-mjit-wait@silicon-docker/1466335
    https://gist.github.com/ko1/96e867e36e6b75559b3d926f8c0bdaeb
    
    https://app.wercker.com/ruby/ruby/runs/mjit-test1/5bf1221c183106002855989c?step=5bf1225987436a0006192c31

  Modified files:
    trunk/mjit.c
Index: mjit.c
===================================================================
--- mjit.c	(revision 65789)
+++ mjit.c	(revision 65790)
@@ -681,10 +681,10 @@ stop_worker(void) https://github.com/ruby/ruby/blob/trunk/mjit.c#L681
 {
     rb_execution_context_t *ec = GET_EC();
 
-    stop_worker_p = TRUE;
     while (!worker_stopped) {
         verbose(3, "Sending cancel signal to worker");
         CRITICAL_SECTION_START(3, "in stop_worker");
+        stop_worker_p = TRUE; /* Setting this inside loop because RUBY_VM_CHECK_INTS may make this FALSE. */
         rb_native_cond_broadcast(&mjit_worker_wakeup);
         CRITICAL_SECTION_FINISH(3, "in stop_worker");
         RUBY_VM_CHECK_INTS(ec);

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