Call write barriers for stack-modified fibers; fix #3699

mrbgems/mruby-fiber/src/fiber.c

@@ -171,6 +171,16 @@ fiber_check_cfunc(mrb_state *mrb, struct mrb_context *c)
  }
}

static void
fiber_switch_context(mrb_state *mrb, struct mrb_context *c)
{
  if (mrb->c->fib) {
    mrb_write_barrier(mrb, (struct RBasic*)mrb->c->fib);
  }
  c->status = MRB_FIBER_RUNNING;
  mrb->c = c;
}

static mrb_value
fiber_switch(mrb_state *mrb, mrb_value self, mrb_int len, const mrb_value *a, mrb_bool resume, mrb_bool vmexec)
{
@@ -207,9 +217,7 @@ fiber_switch(mrb_state *mrb, mrb_value self, mrb_int len, const mrb_value *a, mr
  else {
    value = fiber_result(mrb, a, len);
  }
  mrb_write_barrier(mrb, (struct RBasic*)c->fib);
  c->status = MRB_FIBER_RUNNING;
  mrb->c = c;
  fiber_switch_context(mrb, c);

  if (vmexec) {
    c->vmexec = TRUE;
@@ -308,10 +316,8 @@ fiber_transfer(mrb_state *mrb, mrb_value self)

  if (c == mrb->root_c) {
    mrb->c->status = MRB_FIBER_TRANSFERRED;
    mrb->c = c;
    c->status = MRB_FIBER_RUNNING;
    fiber_switch_context(mrb, c);
    MARK_CONTEXT_MODIFY(c);
    mrb_write_barrier(mrb, (struct RBasic*)c->fib);
    return fiber_result(mrb, a, len);
  }

@@ -336,13 +342,12 @@ mrb_fiber_yield(mrb_state *mrb, mrb_int len, const mrb_value *a)
  fiber_check_cfunc(mrb, c);
  c->prev->status = MRB_FIBER_RUNNING;
  c->status = MRB_FIBER_SUSPENDED;
  mrb->c = c->prev;
  fiber_switch_context(mrb, c->prev);
  c->prev = NULL;
  if (c->vmexec) {
    c->vmexec = FALSE;
    mrb->c->ci->acc = CI_ACC_RESUMED;
  }
  mrb_write_barrier(mrb, (struct RBasic*)c->fib);
  MARK_CONTEXT_MODIFY(mrb->c);
  return fiber_result(mrb, a, len);
}

src/vm.c

@@ -867,7 +867,12 @@ mrb_vm_run(mrb_state *mrb, struct RProc *proc, mrb_value self, unsigned int stac
  if (c->ci - c->cibase > cioff) {
    c->ci = c->cibase + cioff;
  }
  mrb->c = c;
  if (mrb->c != c) {
    if (mrb->c->fib) {
      mrb_write_barrier(mrb, (struct RBasic*)mrb->c->fib);
    }
    mrb->c = c;
  }
  return result;
}

@@ -1819,6 +1824,9 @@ mrb_vm_exec(mrb_state *mrb, struct RProc *proc, mrb_code *pc)
              else {
                struct mrb_context *c = mrb->c;

                if (c->fib) {
                  mrb_write_barrier(mrb, (struct RBasic*)c->fib);
                }
                mrb->c = c->prev;
                c->prev = NULL;
                goto L_RAISE;