normal	2018-03-06 07:58:13 +0900 (Tue, 06 Mar 2018)

  New Revision: 62668

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=62668

  Log:
    thread.c: reset waitq of keeping mutexes in child
    
    We must not maintain references to threads in the parent process
    in any mutexes held by the child process.
    
    * thread_sync.c (rb_mutex_cleanup_keeping_mutexes): new function
    * thread.c (rb_thread_atfork): cleanup keeping mutexes
      [ruby-core:85940] [Bug #14578]
    
    Fixes: r58604 (commit 3586c9e0876e784767a1c1adba9ebc2499fa0ec2)
           ("reduce rb_mutex_t size from 160 to 80 bytes on 64-bit")

  Modified files:
    trunk/test/ruby/test_thread.rb
    trunk/thread.c
    trunk/thread_sync.c
Index: test/ruby/test_thread.rb
===================================================================
--- test/ruby/test_thread.rb	(revision 62667)
+++ test/ruby/test_thread.rb	(revision 62668)
@@ -1205,6 +1205,17 @@ q.pop https://github.com/ruby/ruby/blob/trunk/test/ruby/test_thread.rb#L1205
     assert_predicate(status, :success?, bug9751)
   end if Process.respond_to?(:fork)
 
+  def test_fork_while_locked
+    m = Mutex.new
+    thrs = []
+    3.times do |i|
+      thrs << Thread.new { m.synchronize { Process.waitpid2(fork{})[1] } }
+    end
+    thrs.each do |t|
+      assert_predicate t.value, :success?, '[ruby-core:85940] [Bug #14578]'
+    end
+  end if Process.respond_to?(:fork)
+
   def test_subclass_no_initialize
     t = Module.new do
       break eval("class C\u{30b9 30ec 30c3 30c9} < Thread; self; end")
Index: thread.c
===================================================================
--- thread.c	(revision 62667)
+++ thread.c	(revision 62668)
@@ -4236,6 +4236,7 @@ rb_thread_atfork(void) https://github.com/ruby/ruby/blob/trunk/thread.c#L4236
     rb_thread_t *th = GET_THREAD();
     rb_thread_atfork_internal(th, terminate_atfork_i);
     th->join_list = NULL;
+    rb_mutex_cleanup_keeping_mutexes(th);
 
     /* We don't want reproduce CVE-2003-0900. */
     rb_reset_random_seed();
Index: thread_sync.c
===================================================================
--- thread_sync.c	(revision 62667)
+++ thread_sync.c	(revision 62668)
@@ -415,6 +415,20 @@ rb_mutex_abandon_all(rb_mutex_t *mutexes https://github.com/ruby/ruby/blob/trunk/thread_sync.c#L415
 	list_head_init(&mutex->waitq);
     }
 }
+
+/*
+ * All other threads are dead in the a new child process, so waitqs
+ * contain references to dead threads which we need to clean up
+ */
+static void
+rb_mutex_cleanup_keeping_mutexes(const rb_thread_t *current_thread)
+{
+    rb_mutex_t *mutex = current_thread->keeping_mutexes;
+    while (mutex) {
+        list_head_init(&mutex->waitq);
+        mutex = mutex->next_mutex;
+    }
+}
 #endif
 
 static VALUE

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