merge revision(s) 58587,58588: [Backport #13526]

	variable.c: cleanup waitq upon thread death

	* variable.c (autoload_reset): use idempotent list_del_init
	  (autoload_sleep): moved code from rb_autoload_load
	  (autoload_sleep_done): cleanup for use with rb_ensure
	  (rb_autoload_load): ensure list delete happens in case the
	  thread dies during sleep
	* test/ruby/bug-13526.rb: new script for separate execution
	* test/ruby/test_autoload.rb (test_bug_13526): new test
	  [ruby-core:81016] [Bug #13526]
	* properties.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@59219 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

5 files changed, 73 insertions, 9 deletions

diff --git a/ChangeLog b/ChangeLog
index 35207e138c..b78aedff8b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,18 @@
+Fri Jun 30 19:50:25 2017  Eric Wong  <e@80x24.org>
+
+	* variable.c (autoload_reset): use idempotent list_del_init
+
+	* variable.c (autoload_sleep): moved code from rb_autoload_load
+
+	* variable.c (autoload_sleep_done): cleanup for use with rb_ensure
+
+	* variable.c (rb_autoload_load): ensure list delete happens in case the
+	  thread dies during sleep
+
+	* test/ruby/bug-13526.rb: new script for separate execution
+
+	* test/ruby/test_autoload.rb (test_bug_13526): new test [Bug #13526]
+
 Fri Jun 30 19:46:46 2017  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* sprintf.c (rb_str_format): while "% 2f" and "% 4f" result in " Inf"
diff --git a/test/ruby/bug-13526.rb b/test/ruby/bug-13526.rb
new file mode 100644
index 0000000000..f42e1913ce
--- /dev/null
+++ b/test/ruby/bug-13526.rb
@@ -0,0 +1,20 @@
+# From https://bugs.ruby-lang.org/issues/13526#note-1
+
+sleep if $load
+$load = true
+
+n = 10
+threads = Array.new(n) do
+  Thread.new do
+    begin
+      autoload :Foo, "#{File.dirname($0)}/#{$0}"
+      Thread.pass
+      Foo
+    ensure
+      Thread.pass
+    end
+  end
+end
+
+Thread.pass while threads.all?(&:stop?)
+100.times { Thread.pass }
diff --git a/test/ruby/test_autoload.rb b/test/ruby/test_autoload.rb
index b793fd2a7f..aabcb4a400 100644
--- a/test/ruby/test_autoload.rb
+++ b/test/ruby/test_autoload.rb
@@ -235,6 +235,11 @@ p Foo::Bar
     end
   end
 
+  def test_bug_13526
+    script = File.join(__dir__, 'bug-13526.rb')
+    assert_ruby_status([script], '', '[ruby-core:81016] [Bug #13526]')
+  end
+
   def add_autoload(path)
     (@autoload_paths ||= []) << path
     ::Object.class_eval {autoload(:AutoloadTest, path)}
diff --git a/variable.c b/variable.c
index 2b8ee6672b..738494110c 100644
--- a/variable.c
+++ b/variable.c
@@ -2127,7 +2127,7 @@ autoload_reset(VALUE arg)
 	    VALUE th = cur->thread;
 
 	    cur->thread = Qfalse;
-	    list_del(&cur->waitq.node);
+	    list_del_init(&cur->waitq.node); /* idempotent */
 
 	    /*
 	     * cur is stored on the stack of cur->waiting_th,
@@ -2140,6 +2140,34 @@ autoload_reset(VALUE arg)
     return 0;			/* ignored */
 }
 
+static VALUE
+autoload_sleep(VALUE arg)
+{
+    struct autoload_state *state = (struct autoload_state *)arg;
+
+    /*
+     * autoload_reset in other thread will resume us and remove us
+     * from the waitq list
+     */
+    do {
+	rb_thread_sleep_deadly();
+    } while (state->thread != Qfalse);
+
+    return Qfalse;
+}
+
+static VALUE
+autoload_sleep_done(VALUE arg)
+{
+    struct autoload_state *state = (struct autoload_state *)arg;
+
+    if (state->thread != Qfalse && rb_thread_to_be_killed(state->thread)) {
+	list_del_init(&state->waitq.node); /* idempotent */
+    }
+
+    return Qfalse;
+}
+
 VALUE
 rb_autoload_load(VALUE mod, ID id)
 {
@@ -2177,13 +2205,9 @@ rb_autoload_load(VALUE mod, ID id)
     }
     else {
 	list_add_tail(&ele->state->waitq.head, &state.waitq.node);
-	/*
-	 * autoload_reset in other thread will resume us and remove us
-	 * from the waitq list
-	 */
-	do {
-	    rb_thread_sleep_deadly();
-	} while (state.thread != Qfalse);
+
+	rb_ensure(autoload_sleep, (VALUE)&state,
+		autoload_sleep_done, (VALUE)&state);
     }
 
     /* autoload_data_i can be deleted by another thread while require */
diff --git a/version.h b/version.h
index 26b180e91c..d3738f20ed 100644
--- a/version.h
+++ b/version.h
@@ -1,6 +1,6 @@
 #define RUBY_VERSION "2.3.5"
 #define RUBY_RELEASE_DATE "2017-06-30"
-#define RUBY_PATCHLEVEL 315
+#define RUBY_PATCHLEVEL 316
 
 #define RUBY_RELEASE_YEAR 2017
 #define RUBY_RELEASE_MONTH 6