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

1 files changed, 3 insertions, 2 deletions

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)