From ec826b3f93b9660825bb229251bfa28c27beea15 Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Tue, 6 Mar 2018 05:15:57 +0000
Subject: thread.c: deadlock in backtrace

* thread.c (unblock_function_set): check interrupts just once
  during raising exceptions, as they are deferred since r16651.
  [ruby-core:85939] [Bug #14577]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62673 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 test/ruby/test_exception.rb | 22 ++++++++++++++++++++++
 thread.c                    |  2 +-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/test/ruby/test_exception.rb b/test/ruby/test_exception.rb
index 08e581d4f4..bb70bf508f 100644
--- a/test/ruby/test_exception.rb
+++ b/test/ruby/test_exception.rb
@@ -1200,6 +1200,28 @@ $stderr = $stdout; raise "\x82\xa0"') do |outs, errs, status|
     end;
   end
 
+  def test_blocking_backtrace
+    assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
+    begin;
+      class Bug < RuntimeError
+        def backtrace
+          IO.readlines(IO::NULL)
+        end
+      end
+      bug = Bug.new '[ruby-core:85939] [Bug #14577]'
+      n = 10000
+      i = 0
+      n.times do
+        begin
+          raise bug
+        rescue Bug
+          i += 1
+        end
+      end
+      assert_equal(n, i)
+    end;
+  end
+
   def test_wrong_backtrace
     assert_separately([], "#{<<-"begin;"}\n#{<<-"end;"}")
     begin;
diff --git a/thread.c b/thread.c
index 2c06127292..ea0f526d2e 100644
--- a/thread.c
+++ b/thread.c
@@ -428,7 +428,7 @@ unblock_function_set(rb_thread_t *th, rb_unblock_function_t *func, void *arg, in
 	}
 
         rb_native_mutex_lock(&th->interrupt_lock);
-    } while (RUBY_VM_INTERRUPTED_ANY(th->ec) &&
+    } while (!th->ec->raised_flag && RUBY_VM_INTERRUPTED_ANY(th->ec) &&
              (rb_native_mutex_unlock(&th->interrupt_lock), TRUE));
 
     VM_ASSERT(th->unblock.func == NULL);
-- 
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