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")

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62668 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 1 insertions, 0 deletions

diff --git a/thread.c b/thread.c
index 27f5e5dabf..2c06127292 100644
--- a/thread.c
+++ b/thread.c
@@ -4236,6 +4236,7 @@ rb_thread_atfork(void)
     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();