mjit_worker.c: promote mjit_copy_job from function

-local variable to global variable.

Consider this case:
1. MJIT worker: dequeue ISeq (stop_worker_p was still FALSE)
2. Ruby thread: call Kernel#exec, which calls mjit_finish(FALSE),
                sets `stop_worker_p = TRUE`, and fires RUBY_VM_CHECK_INTS() once
3. MJIT worker: register copy job, but found stop_worker_p is TRUE.
                set `worker_stopped = TRUE` and the thread stops.
4. Function-local job variable expires by the thread stop (this is eliminated by this commit)
5. Ruby thread: find `worker_stopped` becamse TRUE, start Kernel#exec.
                Kernel#exec fails but exception is rescued.
6. Ruby thread: call RUBY_VM_CHECK_INTS. copy job is dispatched but job variable
                is already expired.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66035 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 6 insertions, 6 deletions

diff --git a/mjit.c b/mjit.c
index cb84d3cd32..46223af492 100644
--- a/mjit.c
+++ b/mjit.c
@@ -24,17 +24,17 @@
 static void
 mjit_copy_job_handler(void *data)
 {
-    struct mjit_copy_job *job = data;
+    mjit_copy_job_t *job = data;
     const struct rb_iseq_constant_body *body;
-    if (stop_worker_p) {
-        /* `copy_cache_from_main_thread()` stops to wait for this job. Then job data which is
-           allocated by `alloca()` could be expired and we might not be able to access that.
-           Also this should be checked before CRITICAL_SECTION_START to ensure that mutex is alive. */
+    if (stop_worker_p) { /* check if mutex is still alive, before calling CRITICAL_SECTION_START. */
         return;
     }
 
     CRITICAL_SECTION_START(3, "in mjit_copy_job_handler");
-    /* Make sure that this job is never executed while job is being modified or ISeq is GC-ed */
+    /* Make sure that this job is never executed when:
+       1. job is being modified
+       2. alloca memory inside job is expired
+       3. ISeq is GC-ed */
     if (job->finish_p || job->unit->iseq == NULL) {
         CRITICAL_SECTION_FINISH(3, "in mjit_copy_job_handler");
         return;