mjit_worker.c: avoid GC when modifying ISeq

This is hoped to fix the SEGV:
https://app.wercker.com/ruby/ruby/runs/mjit-test1/5bf392cf183106002856c1f0?step=5bf3bddc87436a0006292535

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65883 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 4 insertions, 0 deletions

diff --git a/mjit_worker.c b/mjit_worker.c
index d85afb5ebe..b23d18d6bb 100644
--- a/mjit_worker.c
+++ b/mjit_worker.c
@@ -1217,6 +1217,10 @@ mjit_worker(void)
             func = convert_unit_to_func(unit, job.cc_entries, job.is_entries);
 
             CRITICAL_SECTION_START(3, "in jit func replace");
+            while (in_gc) { /* Make sure we're not GC-ing when touching ISeq */
+                verbose(3, "Waiting wakeup from GC");
+                rb_native_cond_wait(&mjit_gc_wakeup, &mjit_engine_mutex);
+            }
             if (unit->iseq) { /* Check whether GCed or not */
                 /* Usage of jit_code might be not in a critical section.  */
                 MJIT_ATOMIC_SET(unit->iseq->body->jit_func, func);