RB_VM_LOCK_ENTER_NO_BARRIER

Write barrier requires VM lock because it accesses VM global bitmap
but RB_VM_LOCK_ENTER() can invoke GC because another ractor can wait
to invoke GC and RB_VM_LOCK_ENTER() is barrier point. This means that
before protecting by a write barrier, GC can invoke.
To prevent such situation, RB_VM_LOCK_ENTER_NO_BARRIER() is introduced.
This lock primitive does not become GC barrier points.

1 files changed, 4 insertions, 4 deletions

diff --git a/gc.c b/gc.c
index 219c54882e..77229768bf 100644
--- a/gc.c
+++ b/gc.c
@@ -7740,7 +7740,7 @@ rb_gc_writebarrier(VALUE a, VALUE b)
             // do nothing
         }
         else {
-            RB_VM_LOCK_ENTER(); // can change GC state
+            RB_VM_LOCK_ENTER_NO_BARRIER(); // can change GC state
             {
                 if (!is_incremental_marking(objspace)) {
                     if (!RVALUE_OLD_P(a) || RVALUE_OLD_P(b)) {
@@ -7754,11 +7754,11 @@ rb_gc_writebarrier(VALUE a, VALUE b)
                     retry = true;
                 }
             }
-            RB_VM_LOCK_LEAVE();
+            RB_VM_LOCK_LEAVE_NO_BARRIER();
         }
     }
     else { /* slow path */
-        RB_VM_LOCK_ENTER(); // can change GC state
+        RB_VM_LOCK_ENTER_NO_BARRIER(); // can change GC state
         {
             if (is_incremental_marking(objspace)) {
                 gc_writebarrier_incremental(a, b, objspace);
@@ -7767,7 +7767,7 @@ rb_gc_writebarrier(VALUE a, VALUE b)
                 retry = true;
             }
         }
-        RB_VM_LOCK_LEAVE();
+        RB_VM_LOCK_LEAVE_NO_BARRIER();
     }
     if (retry) goto retry_;