thread.c: fix deadlock

* thread.c (ruby_kill): get rid of deadlock on signal 0.
  [ruby-dev:47182] [Bug #8137]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39862 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 15 insertions, 3 deletions

diff --git a/ChangeLog b/ChangeLog
index ed55b8fde8..02c2a69969 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Mar 21 23:17:08 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* thread.c (ruby_kill): get rid of deadlock on signal 0.
+	  [ruby-dev:47182] [Bug #8137]
+
 Thu Mar 21 23:14:15 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* include/ruby/ruby.h (RB_UNUSED_VAR): move code from
diff --git a/test/ruby/test_signal.rb b/test/ruby/test_signal.rb
index c7cce9a9d7..fa385c0312 100644
--- a/test/ruby/test_signal.rb
+++ b/test/ruby/test_signal.rb
@@ -283,7 +283,13 @@ EOS
     # This ugly workaround was introduced to don't break
     # compatibility against silly example codes.
     assert_raise(SignalException) {
-      Process.kill('HUP',Process.pid)
+      Process.kill('HUP', Process.pid)
+    }
+    bug8137 = '[ruby-dev:47182] [Bug #8137]'
+    assert_nothing_raised(bug8137) {
+      Timeout.timeout(1) {
+        Process.kill(0, Process.pid)
+      }
     }
   end
 end
diff --git a/thread.c b/thread.c
index dce0ca800f..e9fe8a7ddf 100644
--- a/thread.c
+++ b/thread.c
@@ -5214,14 +5214,15 @@ ruby_kill(rb_pid_t pid, int sig)
      * When target pid is self, many caller assume signal will be
      * delivered immediately and synchronously.
      */
-    if ((th == vm->main_thread) && (pid == getpid())) {
+    if ((sig != 0) && (th == vm->main_thread) && (pid == getpid())) {
 	GVL_UNLOCK_BEGIN();
 	native_mutex_lock(&th->interrupt_lock);
 	err = kill(pid, sig);
 	native_cond_wait(&th->interrupt_cond, &th->interrupt_lock);
 	native_mutex_unlock(&th->interrupt_lock);
 	GVL_UNLOCK_END();
-    } else {
+    }
+    else {
 	err = kill(pid, sig);
     }
     if (err < 0)